# Will the maximum discharge current double for two parallel batteries?

Panamanian
Hello.

Say I have a high powered device that draws continuous 18A. 3.7v
And I have one 3.7v 3500mah 18650 with a maximum continuous discharge of 10A, I know the battery will overheat and will most likely get damaged or shorten its life, or even catch fire.

But If I have another battery (same model).
Now I have two 3.7v 18650 3500mah in parallel. Will the maximum continuous discharge be 20A? or same 10A?

Mentor
It is a bit tricky. If you connect them in parallel you should get 20 A, but there are some details that make it less safe than one can think.

First - it is not guaranteed each one gives exactly 10 A, as a lot depends on their internal resistance, which is never exactly the same. So, while getting 20 A you can in fact be getting 12/8 - with one batter being overloaded.

Second: they have to be connected when they are both charged to exactly the same voltage. Otherwise one will try to charge the other till their voltages are identical, and that's asking for troubles.

That being said, sometimes I fly my Sky Surfer with two 2.2 Ah batteries connected in parallel. While single one is enough in terms of the current, having 4.4 Ah gives twice the flight time.

Panamanian
Ok, thanks.

Another question, Will a wire (for example: 14 AWG) resist the same AMPs with 12v vs the same AMPs with 3.7v?

Mentor
Will a wire (for example: 14 AWG) resist the same AMPs with 12v vs the same AMPs with 3.7v?

No idea what you mean.