So I have an old electric bike sitting around, no battery. Replacement 24V 10Ah batteries are $200+. However, I have/can get 10Ah power banks (to charge phones) for under $10. They all have standard 5V 2A outputs. Same brand and model. Bike is an ancient Ezip eco ride; 250W motor.
Can I wire 5 power packs in series to get a ~24-25V output? I can't do it via the USB ports, because I can't pass voltage back through the USB port – it overloads and shuts down.
I'm afraid of opening the power packs and wiring the batteries directly, because the PCBs are still connected and might get damaged.
Assume I disconnect the PCBs from the batteries before wiring them in series. Also assume I time the battery usage so they don't over-discharge. What's the chance this will go up in flames, Note 7 style?
If you're gonna call me an idiot for even suggesting this, please do so kindly. Thanks! ^_^
Best Answer
Your power banks provide 5V 2A output or 10W, and cost about $10. To power a 250W motor, you'll need 25 power banks which will cost you $250. Why not just buy a $200 battery then?
Also, think how bulky those 25 power banks will be on your bike, and what a pain they will be to charge.
Hopefully these simple arguments are enough to persuade you, before I'll have to explain all the balancing issues you'll face once you connect Li-ion cells in series, or consider custom charging circuits you'll need to design if you remove the original PCBs.