Ok so I have this ebike I purchased a while back. I want to do some kind of upgrade to it wheather it be longer battery life. Inagrate the batteries together. Maybe even set up a switch where I can switch to my backup battery when original dies. Or if you have a better idea great. I have general knowledge with soldering and wiring the only thing is I don’t know much about batteries, controllers, bms etc. I don’t want to destroy my bike or the batteries for that matter so I’m looking for some help. Here’s the info.
Link to model of bike
Bike specs I know of
250W brushless geared hub motor with max torque of up to 38Nm
Info on Second battery I have.
36V 756Wh 21000mAh Limited Charge Current 4A Limited Charge Voltage 42V Nominal Voltage 36V- Rated Capacity, 21000mAh Minimum Capacity: 20000mAh
If I just can’t possibly do any of the things I’d even be willing to ditch the old and start using the other one I have. I’m open to whatever is clever.