e-Bike battery

I’m far from being an expert on e-bikes and their power units but I’ve done a bit of reading and have some knowledge of lithium ion batteries as a result of all the fiddling around that I’ve done making up power units for my sport video cams and other devices (smart phone, pad etc). So I’ve been thinking about what would be involved in re-celling the duff battery that came with the e-bike that I’ve just bought.

As I had nothing better to do today (we’ve still got freezing fog outside) I thought that I’d start my investigations by taking it apart and having done so, I’ve become quite encouraged by what I’ve found.

The unit’s innards comprise ten large Li-ion batteries in two banks of five connected together with a control board on each bank, which are then wired to the bottom connector that attaches to the bike and the key operated switch on top. I’ve searched to find a source of the existing large Li-ion cells but with no luck, but that doesn’t mean that I can’t go ahead with re-celling the unit in a different way.

If you search for similar e-bike packs you find that some are powered by 40 type 18650 Li-ion batteries connected in 10 banks of 4 and some higher quality, higher capacity packs by 50 x 18650 batteries in 10 banks of 5. After assessing the construction of my duff battery pack and musing over the geometry of connecting up banks of 18650 batteries to replace the existing cells, I came up with a potential arrangement for 50 that will easily fit into the existing outer shell and should, in theory, perform better than the original power unit.

And better still, if it works, it will only cost around 65€, compared to around 165€ for a replacement new Chinese battery pack and 300€ for one sourced in France. I’m going to have to wait until the battery pack that I’ve already ordered arrives so I know that its charger will fit the duff pack and if so, I’ll then go ahead and order the 18650 cells that I’ll require. It should be an interesting little project, so watch this space!

To finish off, here are a couple of shots of the innards of the duff battery pack.