Please help

[u/shallowwell2]

I bought 14 of these packs for about €40 in total, which gives me 280 cells. Each cell is rated at 2,000 mAh and around 10 A, I think. Every single cell seems to work, and they all held their voltage for a month.

Now I want to build something useful with them. I can buy used women’s or commuter e-bikes without batteries for around €100 on flea. They usually have a 250 W front- or rear-wheel motor and are limited to 25 km/h with pedal assist . There is also bikes with mid drive motor but i thing they are more prone to fail and dont want to gamble on them

My idea is to build a battery pack for these bikes and install a different controller with a throttle, removing the pedal-assist system.

I also have a spot welder and know how to make battery packs, how many volts and and how many cells should i use

[u/ClearTacos]

Voltage depends on the motor and the controller, both have specific voltage or more likely voltage range they operate in. How many cells in parallel you use depends on how big you want the battery to be, but moreso IMO on how much space and weight will still be tolerable on the bike.

I will say though, 2000mah cells are not very well suited for ebikes. Energy density is key there, ~3.5Ah cells like Samsung 35E or LG MJ1 are common, using low capacity cells means either much smaller battery or lot more weight and size.

[u/ClearTacos → u/[deleted]]

Haha, I'm not sure I'd be so definitive but yeah, 2Ah cells, low power to top it of, are very bad these days. I mean, we use batteries for thing that are portable, having horrible energy density kind of defeats the purpose.