Noob dual battery setup

[bluesoleli]

Hi Everyone,

I recently received my Progear electric bike this week. The battery on board (silverfish type) is completely dead as it was left in storage for too long and the BMS cannot function. I am in the process of buying a new battery later this week. However, I do have a spare 36V flat pack rack type battery in good condition which I'd like to use along with the onboard battery to increase range.

I don't know much about Li-Ion technology in regards to linking batteries, but I was planning to hook the two batteries up in parallel (not series obviously to retain 36V). Will this be okay? Or will I have to manufacture a switch device to manually switch battery 1 and battery 2? (Found a schematic for that on here).

Thanks.

 

[mlt34]

You'll need to wire a diode in to keep one battery from charging the other battery if there is ever an imbalance of charge (a likely occurrence if you have time to charge one but not the other, etc).

A better solution would be to just have a single connector that plugs into one pack or the other. That way when you ride one pack dead, you pull the connector out and stick it in the second battery.

I know the silverfish batteries are generally less good for this since the connector is sort of built into the bike down there, but you can always rig a new connector, or just put an inline switch to open the circuit to the silverfish battery when you want to plug in the second flat pack battery.