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
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