Yamaha XPC26 battery recell

[jhruk]

That being the case then ,how feasible is it to make bike batteries from power tool batteries. Unless I am wrong, the big advantage would be long life . Is there still acase for NiCads?

I can certainly vouch for their longevity. Only last week I dug out an old e-bike of mine from the back of my garage. It’s a Heinzmann conversion bought second hand, when it was already four years old, in 2004. The NiCad battery is the original, now nearly twelve years old, and hasn’t been touched for over a year. After a couple of conditioning cycles I tested it and found it still has well over 50% of its original capacity - good for 10-15 miles.

I wonder how many of today’s Lithium ones will still be usable in twelve years time.

 

[Pedunculate]

An update... I soldered up a new battery pack, after having a practice on some cheap Poundland zinc-carbons. It needs a really hot iron - I had a 450degC bit for my Weller TCP temp-controlled iron, and use lots of flux. I tinned up a baked bean tin by covering it all over with solder (plumbers' leaded solder is cheaper and thicker than the electrical stuff), chopped it up into strips and soldered them between the cells. The trick is to put flux on the cell, cover the end of the strip with a blob of solder, let it cool, then push the strip onto the cell using the iron... done in less than a second.

The replacement cells just about fit in the battery case, but I had to omit the shrinkwrap due to the raised bumps on the positive ends of the ends which take up a bit of extra height. I charged the battery on the standard charger by watching the power on a mains wattmeter and it was roughly right (~5 hours at 70W = 350Wh).

The battery works just fine, and is able to power the bike... but I get about the same range as the old battery (about 5-10 miles) until it complains of low battery. At this point the terminal voltage is still 25V so I suspect the on-bike battery manager is getting confused. I'm not keen on pulling my bike to bits (the circuit is probably potted in epoxy), so I'm currently looking around for a spare bike battery circuit so I can pull it apart to see what might have gone wrong...