Dual Batteries on a BBSHD

[Shawn Graham]

I have a BBSHD on a full suspension mountain bike with a 52v 14ah high power and long range GA Shark Battery mounted to the frame. When I'm going for a long ride I'd like to have more battery life so I want to purchase another battery to hook in parallel. I have a Topeak rear bag and rack. I know the voltage has to be the same but does the amp hours have to be? I was thinking of going with the 52v PF 11ah performance pack or the 52v GA 10ah high power and long range pack. My second question is Can you charge these two batteries in parallel or would I need to charge them one at a time?

[Sebz]

Hi

Simple answer: they have to be identical in voltage, capacity and cycle life and also if possible chemistry,

They cannot be charged together.

The voltage on the smaller one will go down faster than the big one so the bigger one will try to charge the smaller one.

Also good thing to know, when you parallel them make sure they are at the same voltage...a lot of amps can flow from one pack to the other if they are a couple volts off!

[spinningmagnets]

I highly recommend that you only plug in one battery at a time. Then, switch batteries when the first is low. There are many issues when paralleling two batteries, and I just want to save you a lot of headaches.

Swapping out two batteries is bulletproof.

[jakethe5nake]

Agreed. I thought I could make a 96v lithium battery by connecting 2x 48v 20ah in series (from diff. sources) with seperate BMS etc. Lucky I didn't I heard it might have cause some kind of explosion

[tomjasz]

Mount both and add a on off on switch. Simply flip the switch between packs.

[Shawn Graham]

Thanks a lot for all of your replies you have help me tremendously. I'm leaning towards the on off switch. I think it would make things more simple if I ever loan the bike to my wife or son.