Connecting two batteries to one phone through the case

Thread Starter


Joined Sep 17, 2016
My Samsung Galaxy S5 is a little old and I would really like to augment the aging battery by connecting my old battery in parallel with my even older battery. I could just buy another new battery but that will only get me a relatively small improvement and this solution uses what I have already. I think one way to do this might be to drill holes in the back for a couple of wires to connect to the terminals of the battery to the two things in the back of the phone. I don't know the identity of all those electrical contacts but I do know that the wireless charging pad connects to the lower two so maybe I can use those? I plan to glue the external battery to the back of the case. It's going to look like a piece of junk but I'm okay with that.

The main problem I foresee is that the case I'm using is the Otterbox Commuter wallet thing which has a sliding tray to store bank/ID cards and as a result I'm going to need the wires to be able to move which is eventually going to break them, I think. They're going to be quite vulnerable.

Of course I don't care that this will compromise the waterproofing and the warranty expired a long time ago. There is no acceptable solution that involves the USB port because connection to USB is already flaky as it is and I don't want to make that worse.


Joined Nov 4, 2013
It will work but given the ages of the batteries there is no guarantee that they will work perfectly in parallel for very long or if at all without causing problems with the charging process the phone uses.