LIPO Packs C rating in parallel

I want to know if the overall C rating goes up if you hook up two or more batteries in parallel assuming that the batteries have the same specs or does it stay constant?

In other words, do you add the C ratings together for each cell just like you would do with current?

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LIPO Packs C rating in parallel

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lol
by: Matt

No problem,

I had actually never pondered that question before..

Didn't take that much out of me, but the flashbacks from geometry class was brutal, lol

Thanks
by: Jon

Matt,

Thank you for your speedy response. That was an amazing proof and everything makes sense now. It sounds like that took a lot out of you lol.

Let's work through it...
by: Matt

That's a good questions.

You're making my brain hurt, lol.

OK, lets assume we have one 20C 1800mah battery.

Tha maximum safe discharge rate for one cell would be:
20 x 1800mah = 36 amps

So if you have three 20C 18mah batteries in parallel you could safely discharge:
3 x 36Amps = 108 amps

The capacity of three 20C batteries in parallel would be:
3 x 1800mah= 5.4 amps

If the total capacity of the pack is 5.4 amps and the maximum safe discharge is 108 amps then the C rating for the entire pack would be:

108 amps divided by 5.4 amps = 20C

So the C rating is 20 for the entire pack.

So, to answer your questions. You do not add the C ratings together. The total C rating for batteries in parallel remains the same as each individual cell.

So what about the overall C rating when adding in series?

The capacity of three 20C 1800mah cells in series is:
1800 mah

The maximum safe discharge of the entire pack is:
20x1800mah= 36amps

The total C rating of the entire pack is:
36amps divided by 1800mah= 20C

So we just proved that you don't add the C rating when adding in series either.

This is some deep thoughts... I feel like I'm back in high school doing geometry proof's, lol.