2 lipos in series vs parrallel....whats the c rating?

[kfxguy]

I haven't seen this question or any info on this so I thought I'd ask. Say I have two 6s packs with a 35c rating and I run them in parrallel, is my c rating increased to 70c or is it the same? Conventional wisdom tells me the amperage is increased.....?

[SloHD]

C rating stays the same both ways. Parellel is better on the batterys, and electronics.

[kfxguy]

C rating stays the same both ways. Parellel is better on the batterys, and electronics.

Not trying to discount what you say but think about a diesel....has two batteries for more cranking amps in parrallel

[Rocstar]

That's not how it works. If you have a 35c 2500mah lipo, that's 87 amps max. Now two 35c 2500mah in parallel is 175 amps (on paper anyways). Yes you increase your capacity but the discharge rate is the same.

[kfxguy]

How can you increase amp-hours without increasing amps?

[Rocstar]

You're not "increasing amps", batteries don't supply amps. Amps is a measurement of electrical current. The C rating is the maximum safe continuous discharge rate of the pack and is limited by the packs physical characteristics. To understand the battery's maximum current draw, convert mah to amps and multiply by the C rating. Only the capacity of the pack is doubled when in parallel, so you are still increasing the maximum current draw. The C rating is the multiplier and does not change.

[Fluid]

Safe discharge rate is calculated by multiplying the "C" rating by the total amp-hour capacity.

40C x 5000 mAh = 200 amps

Parallel the packs and

40C x 10,000 mAh = 400 amps

The "C" rating does not change, but you can safely draw twice the amperage from the 2P pack. The "C" rating is something which the consumer cannot measure, so some (many?) battery suppliers inflate these values to sell more packs. Example, a club member had raced a 10S cat with old 25C ThunderPower packs and was able to run for two minutes easily. He wanted fresh packs so he bought new Turnigy Nano-tech cells with a 25C rating. On 10S2P these should have been good for a safe 250 continuous amps, but after less than a minute this happened.

Jim's Nano Fire 3.jpg

The same thing happened to another club member using the same 25C packs in his 10S mono. And 10S is easier on packs than most smaller voltage systems....

DSC00028.jpg