Lithium Polymer (Lipo) battery technology has been perhaps the best leap of technology in the RC world. The relatively high energy density and absurdly high continuous current capability has meant that quadcopters have become a viable hobby and electric RC cars can now outperform their Nitro cousins without most of the fuss. Voltage as measured in volts (v) A single lipo cells has a maximum charge voltage of 4.2v which is usually reported as 3.7v for real-world purposes. Voltage can be increased by connecting these cells in series (s for series) and is reported as 1s (1 cell in series), 2s (2 cells in series) 3s (3 cells in series and so on). Voltage is additive when cells are placed in series i.e. 1s = 3.7v, 2s = 7.4v, 3s = 11.1v and so on. Capacity as measured in milli Amp hours (mAh) Lipo cells can vary in capacity, these are measured in mah and signify the amount of 'fuel' the lipo battery can output before it is depleted. All else being equal the larger the capacity they larger the physical size and mass (weight). C - Rating Where voltage and capacity are simple physical parameters, C-rating is slightly more complex. It is closely tied to capacity and has no relationship to voltage. In short the C rating signifies the maximum continuous output that the battery can maintain. Strictly speaking the C value multiplied by the capacity is the maximum continuous current output which we measure in Amps. The best way to describe this is to give examples:
So it's interesting to see from above that increase Capacity has a similar effect to sticking with the same size and increase C-rating.
Will a battery with a larger c-rating push more amps to my ESC? This is a misunderstanding I see a lot. Batteries don't push current, current is demanded from them by the circuit in question, in our case the ESC/motor (much less so for the servo). The only way a larger C-rated battery will make your car go faster or put too much current to your ESC is if the current battery is a bottle-neck. Without measuring equipment the easiest way to see if your battery is the bottleneck is if it is warm or hot after running. As you can probably figure the battery in this case is being pushed to its limits and this is where the performance of your battery can start to diminish. If this is the case and the new larger or higher-C battery can supply more power to your motor/ESC then you should get more power and hopefully not overload the ESC (or motor). Personally I'd rather have an over specced battery and limit throttle/punch on my ESC to have more consistent control and operate within system capability.
Hopefully this helps you understand things a little better and at least gives you a good starting point. One thing to be wary of is that C-ratings can be used as a bit of a marketing tool so since the concept is a little more obtuse - I'd recommend comparing within a brand but not so much between brands. Overall RC cars are not as demanding on lipo batteries as quadcopters so you can see there is more wiggle room. If you must have the best batteries Gaoneng (GNB) batteries are probably the best commonly available ones from the demanding quadcopter world with CNHL in second. If you found this helpful also check out my article on upgrading your charger for RC car batteries Thanks for reading, if you found this article useful please feel free to like or share, the facebook links below directly link/like this article. Links are affiliated and help me buy the bits I need to produce this type of content. If you are looking for RC cars, quads or parts check out my coupons and discounts page which I keep updated with only the RC cars, parts and quads I like at a proper discount
13 Comments
Dave
15/10/2020 06:32:39 am
Hello hows it going what would be the burst rate on a continuous 35c 2200mAh 2s battery cheers
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QuadifyRC
15/10/2020 09:07:30 am
Hey Dave, It's going great! Burst rate = 35c x 2200mah = 77000mah = 77A. That is plenty for most setups. FYI it's 855W which is just over 1 horsepower at full noise
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Daniel
16/2/2021 11:08:24 pm
855 Watt @ 3S 😉
QuadifyRC
16/2/2021 11:21:44 pm
🤦♂️ Daniel is correct on the wattage below, I'm too used to seeing 2200mah batteries in 3s
Neil
17/2/2021 10:33:17 am
Excellent right up, most of what you have written I had a basic understanding of after much research myself, but this explains it so well, however just one question, you mention you'd Personally rather have an over specced battery (which I understand) and limit throttle/punch on my ESC to have more consistent control and operate within system capability. Could you elaborate a little on what you mean by "limit throttle/punch on Esc?
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QuadifyRC
1/3/2021 09:23:09 am
Sorry for the late response, I'm having notification issues. This should explain: https://www.quadifyrc.com/rccarreviews/better-brushless-esc-control-budget-program-card-for-racerstar-surpass-goolrc
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Paul Van den bogaard
1/3/2021 07:48:56 am
Im running on stock motor with a stock 2200mah batt. If im gonna buy a lager batt with a higher c rating. What mah/c-rating should i get to run without problems? For example a 4000mah 50c?
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QuadifyRC
1/3/2021 09:26:43 am
Hi Paul
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Samuel Scholey
23/11/2021 09:44:48 am
Hello, I have just ordered the parts for your cheap 144001 brushless upgrade.
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QuadifyRC
10/12/2021 12:48:11 pm
Awesome! To be honest your stock battery will do just fine here as this brushless motor is way more efficient. You will have a lot of fun with this setup. If you really want you can go to the 124019 2200mah battery for a bit more runtime but I have a car setup like this one you have here and it is brilliant with the stock batt.
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Iain Langley
18/2/2022 09:21:55 pm
Hi,
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the article was very helpful on understanding more about the c rating. I myself have a bug's 3 quadcopter and it uses a 2s 25c 1800 milliamp battery. usually close to 15 minutes of run time. less than 10 when I am wide open on the controller. so I've noticed that after a hard full wide open run the motors the ECU and speed controllers & batt. are usually not even warm. this leads me to believe that a bigger battery and c rating should give it some more punch. ALOT MORE...
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Peter
30/4/2023 08:18:51 pm
I've seen a comment stating that a higher C rating from a given capacity will give a longer quadcopter flight time. But surely the flight time is wholly dependent on the mAh capacity? It's my understanding from what you say in the article that the C rating simply means the battery can deliver a higher current if required without being damaged.
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