Different size batteries in parallel

[LouEyez]

Hi everyone,
as the title says, is it possible to put different size batteries in parallel?
I have 2 14650 and 2 14500 that I would like to put in parallel, along with a charging board (dna20 charger)
Is that something i can do? If no, please tell me why...

Thanks,

Lou

 

[cskent]

It is possible to do so, but it isn't recommended. The different sizes typically have different mah ratings, this means that the smaller one will drop in voltage quicker than the larger one. You want the two cells to stay at the same voltage so there isn't current drain from the higher voltage cell to the lower voltage cell. It would also be possible for the lower voltage cell to drain below the safe level which could damage it or make it impossible to recharge.

 

[LouEyez]

That's pretty much what I figured...thanks for the info

L

 

[darkzero]

Different size batteries will have different internal resistance. Don't do it, very bad things will happen with lithiums. Even with alkalines it's not recommended. If you have ever read the instructions for any consumer product that uses multiple batteries it will state to always use new batteries when replacing. Usually over cautious to protect the manufacturer from litigation if something were to happen but it can happen if the conditions are right.