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Generally given a battery chemistry and manufacturing technology, the charge rates and discharge rates are given in units of "C" which means it allows 1A charge

by fryguy 15y ago

Generally given a battery chemistry and manufacturing technology, the charge rates and discharge rates are given in units of "C" which means it allows 1A charge/discharge per Ah capacity of the battery. For instance, the lipoly batteries I got for my combat robot last year were 20C discharge, and 1C charge, and had a capacity of 1800mAh. This means I can discharge at 36A, charge at 1.8A. While true, the charge rate doesn't scale with discharge rates directly, for a given chemistry, it does.

grannyg00se 15y ago
I wouldn't be so sure about it scaling directly even within the same chemistry. Batteries can be manufactured for different purposes. I've seen 10C, 20C and even 40C discharge rates in lithium ion polymer batteries. But the charging rate usually stays under 2C. Personally I don't really care too much about charging rates. My battery powered vehicle would be parked overnight. But I do like acceleration. And that's where discharge rates (and other problems) become an issue.
- fryguy 15y ago
  That's why I added the "...and manufacturing technology" part at the end. What I've seen is that a company will have a whole line of cells of varying capacities all at the same discharge "C" rating. To be honest, I'm too worried about discharge rates, since we use them in combat robots, which are designed to last 3 minutes (which ends up being 20C continuous discharge rate). If you consider that you want at least 2 minutes of "full throttle" power over the course of a charge of the batteries, the capacity of them must be enough that the maximum current would be 30C, otherwise the batteries would be dead from just the hot rodding. Being that you're driving more than the 2 minutes of full throttle, I'd suspect that any batteries with enough capacity for an hour drive would have enough discharge rate to support what you needed to do.

by fryguy 15y ago

grannyg00se 15y ago

I wouldn't be so sure about it scaling directly even within the same chemistry. Batteries can be manufactured for different purposes. I've seen 10C, 20C and even 40C discharge rates in lithium ion polymer batteries. But the charging rate usually stays under 2C. Personally I don't really care too much about charging rates. My battery powered vehicle would be parked overnight. But I do like acceleration. And that's where discharge rates (and other problems) become an issue.

fryguy 15y ago
That's why I added the "...and manufacturing technology" part at the end. What I've seen is that a company will have a whole line of cells of varying capacities all at the same discharge "C" rating. To be honest, I'm too worried about discharge rates, since we use them in combat robots, which are designed to last 3 minutes (which ends up being 20C continuous discharge rate). If you consider that you want at least 2 minutes of "full throttle" power over the course of a charge of the batteries, the capacity of them must be enough that the maximum current would be 30C, otherwise the batteries would be dead from just the hot rodding. Being that you're driving more than the 2 minutes of full throttle, I'd suspect that any batteries with enough capacity for an hour drive would have enough discharge rate to support what you needed to do.