NIMH or Li-Po Battery for My RC Car

Many new RC car beginners get confused about what kind of batteries they should choose for their RC car NIMH or Ni-Po battery? What are the differences between them? As you may hear some questions like “ What kind of RC car batteries should I buy? “ “Can I use LIPO battery for my RC car?”“What are the differences between 6s 7.2v NIMH battery and 2s 7.4v Lipo battery?” So let’s take these batteries as an example and make a comparison between them in several ways.


NIMH, Nickel Metal Hydride, serves as a replacement for NiCd as it has only mild toxic metals and provides higher specific energy.

LIPO, lithium polymer battery, is a rechargeable battery of lithium-ion technology in a pouch format.

Let’s compare these batteries in the following aspects:

Price:

NiMH:It is cheaper than the Lipo battery. You may find the price of an 7.4V Lipo battery could afford two 7.2V NiMH batteries for your rc car.

Lipo: It is more expensive, but as the production scale of Lipo battery gets bigger, the production cost will get lower and lower and so as the price.

Voltage

NiMH: It’s nominal voltage is 1.2v per cell. As we can see from the picture, the common voltages for NiMH battery are 6v, 7.2v, 12v, 14.4v.
Lipo: It’s nominal voltage is 3.7v per cell. So we usually find Lipo batteries in 7.4V, 11.1V, 14.8V, 18.5V, 22.2V.

Weight/size

NiMH: 7.2v NiMH batteries are heavier than 7.4V Lipo batteries for the same capacity. And it’s bigger than the Lipo one.
Lipo: Lighter and smaller than the NiMH one, this makes a great difference for rc cars . That’s why Lipo batteries are getting more and more popular in the RC cars.

Memory effect

NIMH: It has the memory effect. It is commonly believed that when rechargeable batteries are not fully discharged between charge cycles that they remember the shortened cycle and are thus reduced in capacity. Which is also called “voltage depression”.

Lipo: Do not have the memory effect. So the full capacity of the Lipo will always larger than the NIMH one after being used for weeks.

Charge and discharge:

NIMH: It is not that dangerous if it is over discharged or over charged. But over charging or over-discharging will shorten the life span of the NiMH batteries.

Lipo: Can never be over discharged or over charged. Or it will damage the battery, explode, or even get your rc car on fire.

Battery charger

NIMH&Lipo: You have to choose the correct battery chargers for them or use charger that can both charge NiMH and Lipo batteries.

Power&Capacity

NIMH:A nimh battery has a consistently less power as you run it down.

Lipo: Lipo batteries will provide longer and quality run time for its larger capacity and C rates.
To make a conclusion, lipo batteries are better choice for RC cars.

What are the precautions for li-po battery?

According to the electrolyte materials that are used in Lithium Ion Batteries,Lithium Ion batteries are divided into Liquified lithium-Ion battery (abbreviation:LIB) and Polymer Lithium-Ion Batter (abbreviation:PLB) ,It used in the PLB cathode materials and LIB is the same, the anode materials are divided into cobalt acid lithium, manganese acid lithium, ternary material and lithium iron phosphate material, negative extremely graphite, working principle of the battery is almost the same.Their main difference is that the different electrolytes, LIB using liquid electrolyte, PLB with solid polymer electrolyte as a substitute for, at present most of the polymer gel electrolyte.

1.classification

solid

Solid polymer electrolyte of lithium ion battery electrolyte for the polymer with a mixture of salt, the battery the ionic conductivity at room temperature is low, can be used at room temperature.

gel

Gel polymer electrolyte for lithium ion batteries is in solid polymer electrolyte adding plasticizer and other additives, thus improve the ionic conductivity, the battery can be used at room temperature.

polymer

Polymer lithium ion battery having a thin shape, and of any area of any shape, etc., so you can use plastic composite film manufacturing the battery case, which can improve the ratio of the entire battery capacity; polymer lithium ion battery can also be high molecule as cathode material, its quality will be improved by more than 20 percent more energy than the current liquid 2200mah lipo battery.

2.Do not charge overcharge

Polymer lithium-ion battery, if the charging time is too long, will increase the possibility of expansion.

3. Advantages and disadvantages Advantage

A. single battery voltage up to 3.6v ~ 3.8v 1.2V voltage is much higher than the nickel-metal hydride and nickel cadmium batteries.

B. capacity density, and its capacity is 1.5 to 2.5 times the density of nickel-metal hydride batteries or nickel-cadmium batteries, or higher.

C. Self-discharge, place a long time after the loss of its capacity is small.

D. Long life, the normal use of the cycle life can reach more than 500 times.

E. no memory effect, before charging is not necessary to vent the remaining capacity, easy to use.

F. Good safety performance

Polymer lithium aluminum flexible packaging structure adopted in the event of safety problems occur, polymer batteries will not explode, it will only drums.

4. small thickness, can do thinner

Slim, the battery can be assembled into the credit card. Ordinary liquid lithium using the first custom shell, after the Cypriot village of positive and negative material method, the thickness of 3.6mm or less technical bottlenecks do exist, and the thickness of the polymer batteries can be done 1mm or less.

5. Light weight

Using a polymer electrolyte battery without metal shell as protection packaging.5000mah lipo 2s battery weight compared with the same capacities of steel lithium, 40% lighter, 20% lighter than aluminum battery.

6. The internal resistance

Polymer batteries internal resistance than ordinary liquid small core, the current domestic polymer batteries internal resistance of 35mΩ can do even less, greatly reducing the battery from the power to extend the standby time, can be achieved with the international level. This support large discharge current lithium polymer is ideal for remote control model as the most promising alternative to nickel-hydrogen battery products.

7. The shape can be customized

Manufacturers need not be limited to standard form, it can be economically made of appropriate size. Polymer battery can be added according to customer demand or reduce the thickness of the batteries, the development of new models of batteries, cheap, mold cycle is short, and some can even be tailored according to the shape of a mobile phone to take advantage of the battery housing space, improve battery capacity.

8. Excellent discharge characteristics

Polymer battery with gel electrolyte, compared to liquid electrolyte, gel electrolyte having a stable discharge characteristics and higher discharge platform.

9. Plate Design Simple

As a result of polymer materials, batteries no fire, no explosion, batteries itself has adequate security, thus protecting the circuit design polymer battery can be considered omitted PTC and fuse, thereby saving the cost of the FPV battery.

RC lipo battery above discharge and also the good utilization of motive

Some rookies feel that lithium batteries brand improved,ever the greater the price,it is actually improved to work with the longer. But normally not the situation, even the best lithium batteries,over-discharge phenomenon will appear.

How to use the suitable of lithium battery?

Regardless of whether lipo battery 3.7v or 1.2v NiMH,won't suggest voltage once the battery is thoroughly charged.For 2200mah lipo battery, the common after total voltage reaches four.2v,I feel plenty of people have the mobile phone batteries universal charge,it output voltage is generally indicated above four.2v.NiMH full charge can attain 1.5v. Moreover to voltage,and after that there is certainly capability and discharge price.the capacity of your battery in mah,the discharge charge is an unit with C. In brief,1C for distinct capacity battery just isn't exactly the same. 1C discharge signifies that batteries can final for one hour. Illustration: 1500mah capacity battery lasted 1 hour of operate, the typical current is 1500ma, namely one.5A,one.5A and that that is if the battery 1C above the nominal greatest 10C the battery discharge latest is 15A... That is definitely under the battery 15A is harmless to use. Once more 1000mah capacity inside the 1C is 1000ma, namely 1A. When the over nominal 15C. Then the utmost discharge current is 1A * 15 = 15A, the utmost discharge recent of the battery is 15A. Having said that, the above get the job done the batteries 15A, 10C discharge is, in theory, the maximum recent operate employing 60/10 = six minutes . And 1000mah get the job done to 15A, 15C is discharged for the recent theory may be used to get the job done 60/15 = 4 minutes. So rather speaking, 1500mah, 10C battery to become used for a extended time factors. So invest in the battery by looking at the quantity of C just isn't acceptable. C compact variety of discharged battery may discharge a big quantity greater than C. Related with this particular capacity.

Remote manage model aircraft lithium battery termed the lithium polymer battery, typically referred to as lithium or lithium batteries. I've to 11.1V lithium battery remote manage model aircraft as an example to illustrate tips on how to correctly use lithium battery. Generally, 11.1V lithium battery of remote control model aircraft by 3 lithium batteries in series (3S1P), per piece batteries voltage is three.7V. The lithium model, cell phones, cameras, and so on. The nominal voltage is named marking voltage is obtained from your typical working voltage. The actual voltage monolithic lithium batteries is 2.75~4.2V, lithium within the topic of electrical power capacity of 4.2V to 2.75V discharge obtained. Remote handle model aircraft lithium batteries need to be made use of inside the voltage selection of two.75~4.2V. The remote management model aircraft lithium battery voltage is lower than 2.75V belongs excessive discharge, lithium expands, chemical liquids within crystallize, these crystals may pierce the internal framework with the layer caused by a short circuit, make the lithium voltage turns into zero. Remote control model aircraft lithium battery voltage is over 4.2V belong overcharging, inner chemical reactions also intense, lithium will blow expansion, if it continues to swell charge combustion. Whether or not it really is above discharge or overcharge can have remote manage model aircraft lithium batteries produce lots of injury.

1.the charge

1-1 Charging recent: the charging existing should not exceed the specs book stipulated highest charging recent (below usual circumstances is 0.five ~ 1.0C or much less), the use of larger than encouraged charging existing may well lead to the battery charge and discharge performance, mechanical effectiveness and protection performance difficulties and may bring about heat or leakage. At the moment marketed 5C model aircraft battery charging current, charging is just not advisable regular use 5C, so as to not affect battery lifestyle.


1-2 charging voltage: the charging voltage shall not exceed the restrict voltage (gens ace 2s lipo / single cell), four.25V charge voltage of every part of the highest limit. (Non-straight to enrich my understanding, this could result in overcharging the batteries, users use the battery because of an error produced by the consequences).


1-3 Charging temperature: The battery needs to be charged inside of product or service specs prescribed ambient temperature variety, otherwise the battery vulnerable to injury. Once they locate the battery surface temperature anomaly time (refer to your battery surface temperature exceeds 50°C), must straight away stop charging.


1-4 reverse charging: Connect the battery constructive and unfavorable, non-reverse charging. In case the constructive and unfavorable reversed, we'll not have the ability to charge the battery. Reverse charging the battery are going to be destroyed, and even cause fever, leak, fire.

2.discharge

2-1 Discharge current: discharge present may not exceed specifications specified greatest discharge latest, high-current discharge capability will cause the sharp decline inside the battery to overheat and cause swelling.

2-2 Discharge temperature: The battery has to be discharged inside of specs specified working temperature assortment. Once the battery surface temperature exceeds 70??C, to suspend use until finally the battery is cooled to room temperature thus far.

2-3 over-discharge: over-discharge can harm the battery cannot be so single battery discharge voltage is reduced than 3.6V.

3. Storage

The battery should be positioned in awesome storage environment, long-term storage battery (a lot more than 3 months), it is actually advisable at a temperature of 10-25°C and a minimal temperature non-corrosive fuel environments. In the long-term storage battery each 3 months to sustain the battery charge and discharge activity and make sure that every cell voltage 2s lipo battery 5000mah inside the range of 3.7~3.9V.

Ways to eradicate the battery memory impact

What's the battery memory result?

If the battery is nickel cadmium battery, long-term will not be complete charge and discharge,it easy to leave a mark within the battery, the battery capability, this phenomenon is called battery memory effect.That mean, it appears that battery memory consumer daily charge and discharge charge as well as mode, time is tough to modify this kind of mode, can no longer do significantly charging or discharging.Lithium-ion batteries, no such result.

The reason behind the battery memory result

Resulting from adverse really sintering form in the traditional system, cadmium coarser grains, if nickel cadmium battery recharge in advance of they may be totally discharge, cadmium grain effortlessly gathered into pieces and produce a 2s 7.4v lipo battery discharge kind secondary discharge platform.

Battery will retailer the discharge platform and it since the finish from the discharge within the subsequent cycle, despite the fact that the capability of the battery itself could be make the battery discharge to your decrease platform.During the procedure of following the discharge of battery will only do not forget that lower capability.Exactly the same in each use, any incomplete discharge will deepen this effect, make the capability with the battery is reduced.

The best way to do away with the battery memory result?

To remove the effect, there are two techniques, 1 will be to use tiny latest depth of discharge (including with 0.one C to 0 v) 1 is to use big latest charge and discharge (e.g., one C) several times.

In practice, the method of elimination of memory results have strict specs and an operating method. Improper operation will be counterproductive.

For nickel cadmium battery, the upkeep of usual is deep discharge on the standard basis: the common use to get a month (or thirty instances circulation) on the deep discharge (discharge to 1.0 V/each section, named the work out), popular use is usually to use photovoltaic cells or make use of the signifies which include shutdown can lower the formation of the memory effect, but this is not training, since the instrument (including cell phone) is not employed 1.0 V/only to flip it off everyday, has to be special gear or line to finish the do the job, but luckily a lot of nickel cadmium battery charger with this particular perform.

For no nickel cadmium 7.4v lipo battery to training for any extended time, as the cumulative memory impact, cannot reply in training capacity, you then will ought to deeper discharge (termed a recondition), this is often an incredibly small present to get a long time for every area to 0.4 V battery discharge of the procedure, want specialist equipment.

For nickel metal hydride batteries, exercise within the frequency of about as soon as each three months can properly alleviate the memory result. Since the cycle daily life of nimh battery is lower than that of nickel cadmium battery, with little recondition this strategy.

Suggestion one: each and every time there is no really need to charge the 14.8v lipo battery just before discharge, and it really is hazardous, for the reason that useless shorten the lifestyle with the battery.

Suggestion two: use a resistor connect would be the cathode with the battery discharge is just not desirable, cannot management recent, easy to 0 v, even result in series of battery cell polarity reversal

How to charge of NiMH rechargeable batteries right

With the rapid development of digital industry,NiMH batteries with the advantage of its benefits,environmental protection is more and more get the favor player and bulk purchases.use also from traditional small household appliances product: lamps,clocks,electric toothbrushes,etc and other widely used to our new products,such as digital camera,electric toys,RC and others.

As people is constantly increasing,the number of NiMH batteries using and maintenance of science is gradually taken seriously by people,As we all know,the brand the service life of NiMH batteries according to the official claimed that can charge up to 1000 times,actually this is an ideal value,often less than this life. But as long as reasonable use charger,more in-depth understanding of NiMH batteries,we will still be able to let her prolong life. Tattu(lipo battery 5000mah) warm prompt the following tips:

Under normal circumstances,the new NiMH batteries contain only a small amount of electricity,when you buy to recharged and then use.But if the battery factory relatively time is shorter,power is adequate,recommended use before recharging.

1.A new NiMH battery generally after 3-4 times of charging and use,in order to play to the best performance.

2.This is very important:although NiMH batteries memory effect is small,still recommend recharging after each use as far possible,and with a full-time,not a charge in a while and then filling in a minute. 

3.When the battery is charging, the charge should pay attention to the heat around the charge,Don’t put to much stuff around,keep the battery clean.This is to avoid the problem such as power loss,keep the contact point at the ends of the battery and battery cover interior clean. 

4.Long time no use it ,remember to remove the batteries from the battery compartment ,put in dry environment recommended in the card battery box,to avoid short circuit. 

5.The NiMH batteries not use in long time can deposit in a few months later, nature into a state of ”dormancy”?batteries,the battery life is reduced greatly. If the NiMH batteries(3s 2200mah lipo) have been placed for a long time ,it is recommended to use the slow charge for charging. 

Protect the environment starts from recycling batteries

Batteries has been deep into every corner of our lives,for usage of the battery has been growing,mobile phone battery,car battery,FPV battery and the other electric toy is inseparable from it.

1.why to recycle used battery?

1st:Used batteries are of great harm to our living environment.

Scientific research shows that section 1 battery-14.8v lipo battery rot in the field,can lost 1 square meters of soil permanent utilization value;A grain of button batteries can make 600 tons of water has been polluted,the equivalent of one people’s life’s water consumption.

2nd:Used battery is potential threat to human health.

In the biggest threat to the natural environment,several substance in the battery contains a variety of materials such as mercury,lead,cadmium etc.,if will live with rubbish landfill waste battery,or discarded,will permeate the soil,pollution of groundwater,and in turn destroy the human survival environment,indirect threat to human heath.

2.how to recycle used battery?

We should pay more attention to about the danger of waste battery,for how to reduce the harm,people carry out a lot of good ways,for example,in setting the battery garbage classification and recycling bins in our lives,for some battery production units and market to reward people for recycling batteries 7.4v lipo battery,etc.Waste battery recycling is an integrated process, it produces pollution nots allow to ignore, from recycling to deal with interlocking, supplement each other.Want to improve the quality of waste battery recycling, we must pay special attention to each link, forming a virtuous cycle, proper set of battery recycling on the regular way.
The government should also attach great importance to, recycling and disposal of waste batteries will issue really on the agenda, the perfect legal laws and regulations, and establishing social recycling service system, promote the formation of the recovery and recycling of waste battery industrialization, achieve reduction and recycling of waste batteries and harmless, it may cause harm to the environment to a minimum.

3.conclusion

Everyone needs to help protect the environment,and each of us should actively cooperate with,don’t throw waste batteries.

Battery-The modern life necessity

An electric?battery?is an energy conversion and storage devices?that convert stored chemical energy into electrical energy.?

With the fast developed science and technology, improvement of human living standards, more and more variety of new features, high-tech electronic products are widely used to humans.Correspondingly,it will promote the arising of all kinds of different appearance and performance batteries.

The big brand such as Nanfu battery,GP battery,Panasonic and so on are known by people.Another 2 big brands have attracted worldwide attention with their excellent quality,innovative style and performance-Grepow and ATL.

Shenzhen Grepow Battery Co.,Ltd is a professional R&D,design,manufacture and selling company.From the establishing year 1998,Grepow has changed greatly in its development.
Grepow manufactured and supplied Ni-Mh battery from 1998 in a large quantity with its stable quality,reasonable price and perfect service.It is a kind of no-pollution,no cadmium new green energy battery widely used in areas like civil life,cars,toys, telecommunication and so on. We recommend NiMH for applications where a device has already been designed to use AA type batteries.

This batteries,?however,?have a short?lifespan,heavy,low discharge rate,and low voltage characteristics,so Grepow update to manufacture 2200ml Li-po battery from about 2009.

With a professional R&D team,and extensive experience in manufacturing battery, excellent technical documentation and advanced processing management system,Grepow’s 2 big brand Li-po battery-Gens Ace and Tattu are greatly known and used in RC ans UAV.which ensures battery’s consistency and stability in mass production.

Gens Ace batteries are very useful for embedded electronics. They offer the highest density readily available on the market. Because cell phones predominantly use this battery type, they are easy to find for reasonable prices. They?do?require special charging, so be sure to use the right charger for the job.

Gens Ace LiPo batteries cell has a?nominal voltage of 3.7V. When fully charged you will see nearly 4.2V on the cell but it will quickly drop to 3.7V under normal use. When depleted, the cell will be around 3V. This means your project will need to handle various voltages if you are running directly from a cell. If you need 5V you will need to combine two LiPos in series to create a 7.4V pack（2s 7.4v lipo battery） and regulate down to 5V.

We recommend Gens Ace LiPo for nearly every portable application like helicopter,RC,jump starter and so on.They are fairly robust and when used safely provide a great power source.
DJI-the world market leader in easy-to-fly drones and aerial photography systems,adopts Grepow’s Tattu battery to control its famous UAV.With the advantage of professional R&D, humanized?service,mass production capacity,amzing explosive power,Tattu is widely used by other big brand GoPro,Panasonic,LG and so on.

In the future,Grepow’s Tattu will be used in more fields and Grepow will pay attention and be allergic to more potential development trend and supply better bettery or other amzing products to the world.

Electricity and Battery Basics

What is a battery?

A  battery is simply a‘chemical machine’designed to store electrical energy. The term battery is generally taken to mean two or more individual electric cells. There are two basic types of cell; primary and secondary. Primary cells, such as ordinary ‘dry’ cells, are not rechargeable and must be discarded when exhausted. Secondary cells, such as the Lithium-Polymer type are rechargeable.

Voltage (Unit of measurement: Volts; V)
Voltage is equivalent to ‘electrical pressure’.

Current (Unit of measurement: Amps; A)

Electric  current  is  measured  in  Amperes,  abbreviated  to  Amps  or  even  just  A  for  short. Values of currents smaller than 1 Amp are usually referred to in terms of milliamps (mA). One milliamp is 1/1,000 Amp, so 500 mA is 500/1000 of an Amp, or ½ Amp.

Electrical resistance (Unit of measurement: Ohm; Ω) All  electrically conductive materials have some electrical resistance. This includes the materials from which batteries, motors and speed controllers (ESCs) are made.

Internal resistance

The electrical resistance of a battery has a special name – the resistance of the battery is termed its internal resistance. The internal resistance of a battery is a major influence in determining how suitable a battery is for high currents.

Cell capacity (Ah)

Suppose we have a one gallon water tank. This would be able to provide a flow of one gallon per hour for exactly one hour before it was empty. We could say the capacity of the tank was 1 gallon-hour. Similarly, a battery that could provide a current of 1 Amp for 1 hour is said to have a capacity of one Amp-hour, also written ‘1Ah’ or 1,000mAh.

‘C’ Rate

This is a term much used when referring to lipo batteries for use in RC models. The term indicates the amount of current provided by a battery in relation to its capacity, or C. For example, the 1C current for a Gens ace 3S lipo 1,200mAh cell is 1,200mA or 1.2 Amps. The table below illustrates this concept:

From the table, we can see that 1,200mA is the 1C current for a 1,200mAh battery. Notice that 1,200mA is also the 2C current for the smaller 600mAh battery. To recap, when using the idea of C ratings, we are specifying a current in relation to the capacity of the battery in question, rather than mentioning a specific current. 

The C rate is therefore a useful indication of how hard a battery is working. For example, a fully charged battery pack would become discharged in about one hour at 1C, or only half this time, 30 minutes if the pack was made to work twice as hard with a discharge rate of 2C.

Note that C rates apply to both charge and discharge currents. It follows therefore that C rates are also a convenient way to describe the‘speed’  at which a battery is charged. For example, an empty battery charged at a constant 1C would theoretically be charged in an hour. (In practice, the charge current will need to be varied when charging lipo batteries, as we shall see later on.)

Some Questions about Lipo Battery

LiPo or Lithium Polymer batteries are batteries that are designed to be light and more efficient than other batteries by eliminating the outside “shell” you find on many other batteries. While this makes them great for a lot of applications, especially RC Aircraft, but they can be dangerous if treated carelessly.

What does the C rating mean on Lipo batteries, example: (10C, 20C, 35C ect.)

“C” rating is the allowable amp draw of the battery. It relates to discharge limits of the Lipo battery. The higher “C” number means that the battery is capable of taking a higher discharge load without causing damage to the battery. There is no real industry standard on testing for the “C” rating and each manufacture test determines what the “C” rating will be for their batteries based on their findings. It is possible to buy two Gens ace 3s lipo by two different manufactures with the same “C” rating the batteries will have completely different performances. I see 180mah, 2000mah, 3600mah, ect. What does “mah” stand for? MAH is the (Milli Amp Hours); this is the capacity or run time of the battery. The higher the milli amp capacity 2000, 3600 and so on equates to how much run time the battery will have. Be sure that you check the motors temperature during the first run for proper gearing. Incorrect gearing will over heat the motor and could cause irreversible damage.

What is the difference between a one, two or three cells lipo battery?

The primary difference is voltage! A single cell or (1S) Lipo is 3.7 volts, 2-cell or (2S) Lipo is 7.4 volts; 3-cell or (3S) is 11.1 volts. I am sure you have figured out, each cell is 3.7 volts and depending on how many cells you have in series you can multiply those numbers by 3.7 and that will give you the packs voltage. (Example 3 x 3.7 = 11.1) Running a 3-cell 2200mah lipo will give you the relative equivalent voltage if you were to run 9 to 10 NiMh or NiCad type cells that are 1.2 volts per cell. Electric motors are capable of running different amounts of voltage.However, it is important that you pay attention to gearing; incorrect gearing with prolong runs from high capacity batteries can results in excessive heat to the motor and the battery. If you are not careful, it is possible the battery could overheat which will cause it to swell and possibly catch on fire or explode be sure to check for proper gearing no matter what motor you run, brushed or brushless.

I see batteries on the market and some say TX or RX even though they may have the same specifications:

TX = (Transmitter) and RX= (Receiver) each uses different voltage batteries. Typically, an RX 2-cell is no more than (7.4 volts) and TX is (11.1 volts）plugging in a11.1-volt battery into your RX could cause a catastrophic failure unless you have a voltage limiter also connected. Depending on the specifications of your receiver, you may need to run a voltage limiter with your RX when using higher voltage battery, a typical RX runs up to 6.0 volt, but that does not mean you cannot use higher voltage batteries, just be sure to check with the manufacture on the receiver’s capabilities.

C Ratings and IR Lithium Battery Packs

I understand the  "C" rating on LiPo battery packs (e.g.  15C, 20C, 25C, etc.) refers  to the "discharge  current". How does that translate into differences in performance? For instance if I have 2 different packs for the similar plane, both 11.1v & 1800mAh, but one is rated 15C and one is 25C, what's going to be the noticeable difference in performance?

You are right, "C" rating refers to how much the battery can discharge and how many amps you can pull from it. The amps you can pull from a battery are directly proportional to the capacity of the pack. So for instance, you've two packs, both are lipo 5000mah 7.4 v, but one  is 25C and the other 15C. The 25C lipo pack should be able to deliver about 45amps where the 15C will only give you around 27amps.

So if you have a plane that is drawing around 27amps and use the 15C Gens ace 3s lipo pack you may find your performance down a bit because you are working the battery at its limits of what it can deliver. Any extra load and the battery may actually cut out on you. If you use the 20C pack, it still has amperage in reserve (for lack of a better term) and isn't operating  at its upper most limits. It will be able to more easily dump its current, and will be unlikely to heat up as badly as the 15C pack.

If you are using these batteries in a vehicle that doesn't draw much current you may still see a difference in performance even though you  are not pushing the batteries to their limits. The standard of the battery pack cell and its internal resistance play a huge roll in how easily the  battery will dump its voltage and model helicopters are the most demanding application of all.

In theory, any battery will provide all of its rated capacity in one hour when discharged at 1C. Its voltage during this one hour 1C discharge, will drop from the peak 'open circuit'voltage when freshly charged down to the minimum allowable voltage per cell of that particular battery's composition. The nominal voltage of a cell is typically the average of the peak, charged open circuit voltage and the minimum allowable or minimum useful voltage.

In the case of LiPo's the nominal voltage quoted is 3.7V per cell, which is the average of the 4.2V peak charged voltage and 3.2V, which we take to be the min working voltage.

So a 1000mAh LIPO battery could theoretically deliver 1 amp current at 1C for 1 hour while maintaining an average of 3.7V.

For all practical purposes, and for 8 to 10 minute flight times, leaving enough extra capacity for a go around landing and taxi back, we should really only be drawing an average of around 5C out of any given pack in any given flight or drive. So what good are 20C or 30C packs then?

The C rating is also a good indicator of low internal resistance. The higher the C rating, the lower the internal resistance (IR). Low IR tells us that voltage will remain high during the discharge in comparison to high IR cells and that low IR cells will run cooler, since the higher resistance the cells convert more energy to heat, this is why the better cells have closely matched IR¡¯s. We want the lowest IR cells we can afford.

One Battery vs Two batteries that Equal The Same Mah

Electric car battery packs are made this way with many sub units collected in a array of series and parallel packs to reach both current and voltage desired. I have a battery system for my solar array.  Here  I use batteries sets in parallel to be able to meet the current requirements. 

Take the DJI (sorry) Phantom 2 pack.  It is a Gens ace 3s lipo 5200mah; Internally it has 6 cells 3 series  sets of 2 cells in parallel.  Each cell is 2600mah giving a total capacity of 5200mah. It makes no difference whether this is done by wiring the sets internally or externally as separate batteries. 

While I agree that manufacturers blow up their claims and this can lead to sets not meeting specifications this does not change the basic rules that apply.

I also agree that more connections wire etc increases chances of failure but in the case of one or two batteries I think the chances are extremely low compared to other failure modes. I have never had a battery failure in the air but have had many other failure mode cause a ground intersect.Personally I am not arguing 1 versus 2. I see this as primarily a packaging issue space size COG etc.

My setup

11.1v 2200mah lipo, new and from the same manufacturer (not mismatched) AUW with batteries and camera is 2748 grams and she hovers at about 35-40% throttle (a little over powered I know and should probably be closer to 45-50%)

I get about 13-14 minutes of lazy to medium flying until I it 13.7 volts and bring her in. (it's a stable hexa camera rig, not set up for speed)

One should use batteries that are matched and in good shape. Same chemistry and discharge curves. In this case issue with unequal loading are relatively insignificant. If batteries of different type are used Martin note and not producing a pure additive current capacity would be true. But not with same chemistry / construction. The variation between cells is very low in good batteries.  Mixing a old used battery and new one can cause problems as well. Whether using a single battery with cells in series or batteries in parallel monitoring each battery cell and total pack health is a good idea to prevent in air failure. I do pack charge discharge curve on new packs looking at overall capacity and cell matching.  I do this periodically  ensuring the life of the battery to help ensure I do not have in use failure.  Typically with lipos I see single cell failures which is bad however wired up.

3S or 4S Battery Question

The KV rating indicates an unloaded ( no prop) RPM that the motor will spin at. The actual RPM you get will depend on the prop you use. The ESC will work with a 4S battery, but for any given set up ( load and throttle setting) the 4s will result in a higher average current delivery than the 3S.

The 11.1 v assumption you are making on the the 3S battery is the low end of the charge/ discharge voltage curve, I would use a fully charged battery voltage to think about current draw. If the top end the motor will deal with is 660 watts, at 12.5 v that will be a current draw of 52 to 53 amps, which exceeds the capacity of your ESC ( 45 amp continuous, 50 burst). The ESC seems to be the limiting factor in your power system, so to use the Gens ace 4s battery you may need to consider reducing your prop size and or pitch to maintain the same overall current draw on the system.

Because the ESC deliver current in a time gated fashion ( full current on then off with the interval determined by your thottle setting) you cannot depend on the just assuming you can fly at less than full throttle to keep your current delivery in a safe range for your ESC.

There is the benefit of getting more watts out of your setup. The Afro 20A slim ESC (2S-4S) and 18AWG wire are rated for 20A. Amps is what melts your wires and ESCs. Watts is what makes your motors powerful generally speaking.

For each motor:
A 3S setup will have a theoretical watt limit of 12v x 20A = 240 watts
A 4S setup will have a theoretical watt limit of 15v x 20A = 300 watts

Also the LiPos “contain” more watts per mAh in a 4S lipo vs a 3S lipo:

Lets compare 2200mAh 40C lipos

2200mAh 3S 40C lipo: 2200mAh x 12v = 264 watts – continuous draw: 88A
2200mAh 4S 40C lipo: 2200mAh x 15v = 330 watts – continuous draw: 88A

4S tends to be a bit heavier than Gens ace 3s lipo with the same mAh and C rating though. What makes most sense is to compare the watt to weight ratio.

Another vital factor to be aware of with the Silver series ESC is that they use a % of initial voltage to determine the LVC, as opposed to the fixed voltage that most other manufactures use. As stated in their instructions, never use a partially discharged battery on thier ESC as it may set the LVC at a point that will result in battery damage if flown to the LVC.

The motor will WANT to increase speed by 1000 rpm (per volt), but will lose some to heat and what have you. I wouldn't get too bogged down on that part right now.

Watts = volts X amps

A higher VOLTAGE setup is often used to REDUCE the AMPS required. If you look at the formula above, if you increase the voltage, you reduce the amps.

The esc amp rating has NOTHING to do with the amount of power your setup will draw. It is a MAXIMUM rating for the esc. Think of an electrical fuse. You can flow anything from zero up to the fuse limit with no problems. Exceed the maximum rating and bad things happen. Smaller esc's are usually used to save weight, room, and money.Similar with the C rating of the battery pack. C rating x the battery capacity (in amp hours) = the number of amps the battery CAN provide at its maximum level. You can certainly use a higher C rating battery, but not a LOWER C rating.

Going from 3S to 4S Lipo Battery

4S lipos use 4 cells in serial and therefore reach a nominal voltage of 14.8V. If you increase the battery voltage by 33% (3S to 4S) then you are effectively increasing the motor speed by 33%. To keep all things equal you need to decrease the prop size to match this increased motor speed and prevent the motors from heating up. Once at the same wattage (roughly the same speed and thrust in flight) you would draw 33% less current, and therefore  get about 33% longer flying time. The reasoning behind that is: Watts = Volts x Amps. Thus increase volts by 33%, then drop amps x 33% for same watts.

If you don’t decrease the prop size, the faster spinning prop will generate a lot more speed and a lot more current, increasing the watts very significantly. The resulting effect will be a higher powered (lower hover throttle) quad, with a higher current draw (resulting in shorter flight times). You may also run the risk of overheating your motors or drawing more current than the ESC can handle. This is obviously not desired. Although we do want to increase the power slightly vs. the 3S config.

Also keep in mind that not all equipment can handle the higher voltage of Gens ace 4s. The Tarot Gimbal cannot handle this voltage and therefore needs a voltage regulator. If you are using additional FPV equipment, you also need to check if they can handle the maximum 16.8V that 4S brings.

Material for testing
For testing IRIS with 4S batteries, we need a 4S Lipo, but also smaller propellers. Here is what I’m using for the tests:

1. 7.4v 5000mah lipo battery from Genstattu. This battery is very cheap and delivers roughly as much wattage as a 3S-4000mAh battery. It fits the IRIS battery bay perfectly and already comes with an XT-60 plug. I already own a IMAX B6-AC Charger/Discharger, which is capable of charging these batteries without any issues.
2. APC SlowFly 9×4.7 Pusher and Puller propellers. They are basically the same propeller as the stock propellers that come with IRIS, except that they are 9″ in outer diameter instead of 10″. As they use the same spacer rings for the propeller shaft, you can even leave your current ones on IRIS.
3. Voltage regulator from 4S (16.8V) to 12V. The Tarot Brushless Gimbal is recommended to be operated with 12V and cannot handle voltages higher than 14.8V. We therefore need to place a voltage regular between the 4S battery and the Gimbal. This will reduce the voltage from up to 16.8V on the lipo side to 12V for the Gimbal. As the Gimbal only draws a maximum of 500 mA, the linked voltage regular is a perfect choice. Also the regulator already comes with the right plugs, is very small and lightweight.

How to Calculate Lipo Battery Max Amps

A LiPo battery consists of multipe cells. These cells deliver approx. 3.7 Volts. A 4S LiPo would therefore supply 14.8V.The battery's capacity is defined in mAh. mAh means milli-Ampere per hour. 

A battery pack with a 1000mAh capacity can deliver 1 Ampere (1000mA/1000) for 1 hour. Or 1mA for 1000 hours. The battery capacity, together with the LiPo battery's discharge rate will define its maximum current output (Ampère, A). This fact is very important to bear in mind, when selecting a LiPo battery. The combination of capacity and discharge rate is what you will need. It's important to know that the battery cells don't count up for maximum current draw. The quantity of cells only determine the voltage (V) of your LiPo, when needed for your equipment. 

A battery such as the 4000mAh 20C Gens ace 4s or the other 4400mAh 15C will suffice you. For an average quad, say weighing around 1.5kg, you will draw around 250watts of power on average, say 350watts at peaks. This means about 25-35 amps max. Divide that by the 4 motors and you get about 9 amps per motor at the max. Both of those batteries are capable of delivering that and so you are OK.

And let me also add that the discharge rate is either given in C's (capacities) or in amps. When given a C rating, simply multiply that by the rated capacity (mAh or Ah) to get the maximum rated discharge rate of the battery in mAmps or Amps. Thus, the 5000mah lipo battery 20C battery is suppose to supply a maximum of 80amps and the 4400mAh 15C one 66amps.

Formula: (C-Rating) X  (AH) = Maximum Constant Amp Draw

Now to use this formula you first need to transform your battery size from the common MilliAmpHours to AmpHours.  A MilliAmp is One-Thousandth of an Amp.  So here are some Examples of converting MilliAmpHours to AmpHours:

800mAH = .800AH

1350mAH = 1.350AH

2200mAH = 2.200AH

The converted number will be the “(AH)” in the formula. Now that you've your “(AH)” number, hook it up to the formula with the “C” rating number of your Battery and Calculate.

For example:

(800mAH 10C Lipo Battery):   .800AH  X  10C = 8Amps Max Constant

(800mAH 20C Lipo Battery):   .800AH  X  20C = 16Amps Max Constant

(1350mAH 15C Lipo Battery):  1.350AH  X  15C = 20.25Amps Max Constant

(1350mAH 30C Lipo Battery):   1.350AH  X  30C = 40.50Amps Max Constant

(2200mAH 20C Lipo Battery):   2.200AH  X  20C = 44.00Amps Max Constant

(2200mAH 30C Lipo Battery):   2.200AH  X  30C = 66.00Amps Max Constant

Example calculation of discharge rate:

A 3S 2200mAh 40C LiPo pack can get you this: 2200mAh x 40C = 88.000 mAh discharge rate 88.000 mAh / 1000 = 88 Ampere constant discharge rate.

So, a 2200mAh / 40C LiPo can only handle an Ampère draw of 88A at max. So that's why the combination capacity/discharge rate is of such importance for selecting the right LiPo for you project.

Can I use a 2s lipo instead of 7.2v Nicd

Lipo has some advantages more than a 6 cell NiCad or NiMh, no doubt. You could draw far more current from the pack when it holds a larger voltage, so acceleration and top speed are enhanced. Lipos are about 40% lighter for the same capacity, so you'll be able to drive longer. And you may charge a few of these quite quick, up to 5C, so that signifies your pack will probably be full in about 10 to 15 minutes.

The quantity next to the" C" , discovered within the description of lipos , will be the discharge price. The C number multiplied by the capacity in amps. so a lipo of gens ace 4s 2000mah is 4S(four cells I don't know why they use S but meh...) 20X2000mah =40A max discharge but an 11.1V 3S10C 1000mah will have a discharge price of only 10 amps . If your motor wants 14 amps(random number) you will really get a slower rof using the 11.1V than the 7.4v. So retain in mind the numbers when purchasing lipos.

But, you can find also drawbacks that has some sticking to NiMh for now. Some prefer to preserve an older car fully "vintage" so all gear used to be in the era the car or truck is from. Lipo batteries also are a greater fire hazard than NiMh or NiCad, each while driving and when stored. You'll need unique warning program to prevent discharging them also low, whilst on NiMh you can simply notice the pack is starting to dump, and stop just before troubles arise.

7.4 V is definitely the typical two cell lipo. Every single cell includes a range involving 4.two per cell (so eight.4 completely charged) and three.2v per cell (or six.4v completely discharged.) Massive point here is, lipos are certainly not like nihms, or nicads. You cannot and Have to NOT discharge them under three.2V per cell. For those who do, they swell, and come to be unusable. Looking to recharge an unusable pack may well result within a quite huge fire. Which brings me to the crux of the dilemma. A 7.4v 5000mah lipo battery would probably be fine in your auto, you'd get much better speed and great run instances, On the other hand your esc (electronic speed handle) is not going to tell you when you'r finding close to empty on the battery. Most brushless escs (brushless becoming a distinct kind of electric, google it) may have a 'low voltage reduce off' (google that also). Generally the esc keeps track of the packs voltage, and when it gets to 3.4V per cell, cuts the motor. YOUR esc Is not going to do that, and it's as a result inadvisable to use lipo's within your auto. As in, do not. Visit a nearby hobbyshop and geta greater answer than this, LiPo's could be dangerous, you truly want to do your homework just before you start off using them. 

Besides, not absolutely everyone is prepared to invest revenue into a lipo compatible charger, or requirements the added speed and energy of lipos.

I for example do use lipos on some cars, but I also have a car with brushless system that already screams on NiMh, getting top speeds of over 70 km/h. It's already a handful to drive this way. Imagine putting in a lipo, and getting a 10% or more performance boost in top speed, and even faster acceleration. So I keep using the 2 NiMh packs that came with the car when I bought it second hand, and when these die, perhaps I will get a lipo instead.

Coming back to your auto, I feel a lipo would do well, it would boost acceleration and major speed, and runtimes. And also you currently have the charger, so it is not a huge investment to begin driving with lipos.

How to Increase Quadcopter Flight Time

There is a good chance that there are more efficient batteries available now than the ones you got delivered with your quadcopter. The manufactures are continually improving the batteries. You will need to look for the same type of battery that you got with your drone, but with higher mAh will make the battery run longer.

Batteries that get much more than just warm (105F or so) are being permanently damaged. Unrecoverable damage starts at 115F or so and the higher it goes the more damage there is. Too hot to hold onto is about 130F for most people.

And you are putting the pack at risk of puffing, rupturing, and even bursting into flame. If they are puffed now, you need to be very careful when charging them to make sure they don't over heat. A healthy battery taken down to 80% of it capacity will usually take a little more than 80% on recharge. As a battery ages the recharged capacity will get smaller and smaller and the battery will drop to the 3.7-3.8V under load more quickly. A develops all the aging and used up symptoms more quickly.

If your Gens ace 4s 2200 mAH battery will give you 80% of usable capacity you can use 1760 mAH out of the 2200 that is supposedly there. So your available capacity would be:

1760 mAH = 1.76A
1.76A x 60 = 105.6 Amp/Minutes

At a 32A discharge rage your flight duration would be:

105.6 / 32 = 3.3 minutes (3 min 18 seconds)

So guess what? You've been beating that battery up pretty hard if you flying it for 5 minutes..

Two batteries in parallel will give you the capacity of both batteries and they will both share the load so the C rate would drop in half from the above if it was the same batteries. It would be best if the batteries were the same capacity and even better if they were same brand and bought at the same time.

If you keep an eye on the pack temperatures and amount of capacity that is put back when you recharge it will do a lot for battery life. Keep the recharges down around 80% or so. And checking the pack voltage immediately on landing will tell you a lot. If you land and find the cells at 3.8-3.9V 10-15 seconds later, you were most likely down to 3.7 or less under load.

A battery taken down to 3.7V while under load is 80% discharged and that should be the end of it's day. And it should not be more than warm then either. If you land with a battery at 3.7-3.8V and shut down it will start recovering immediately and may be back up to 3.9V or 4.0V within minutes. But it is still depleted. If you run the motors up the voltage will drop immediately.

Everyone needs a watt meter so see load on their battery and how the battery is doing as far as dealing with the load. If you really want to know what is going on a data logger like the eLogger can be flown to see what is going on. The image is the eLogger data from a flight, the red line is the battery and you can see how the voltage falls as the flight proceeded.

The flight was a stable hover, then three full throttle punch outs, then a few circuits of fast forward flight, then a brief hover and landing. The red line is the pack voltage. The 3S lipo battery 5000mah pack was down to 11.15V at the lowest point and that is your 3.7V quitting time. The voltage recovered a little as he back off on the throttle, hovered, and landed.