Running batteries in parallel?

[Totality]

I have some 2200mah 3S 25C batteries from the heli days. Was thinking about ordering higher capacity ones then thought why not just attach them in parallel for in theory 4400mah using what I have.

Is this too simple to be true?! Would save some cash when I wanted to do longer flights being able to simply recycle packs I have in parallel. What are the downsides to this?

 

[Mr.Biker]

I'm doing the same, I haven't had any problems doing that.
For my setup I'm using 2 x 2200 mAh, 2 x 3300 mAh, etc.
Of course I first checked if using them parallel is allowed without setting your multicopter on fire. And it is.

However, there are some rules you have to follow:
- only use the same brand and same type of lipo (e.g. never connect a 2200mAh with a 2000mAh lipo)
- they have to have the same age and cycles (I always keep them paired)
- only connect them when they are complete charged and perfectly balanced

If you pay attention to the above, you won't have any problems!

 

[Totality]

Thanks. Good to know. I just feel having lots of 2200mah batteries will serve me better as you can use them individually or tied up for longer flights. Plus if one fails you can just use 2200mah single battery whilst waiting for replacements. Worth a shot anyway!