Vectrix VX-1 Battery swap

I recently acquired a Vectrix VX-1. It had its original 125v 3.7kwh NiMH Battery pack. It did actually function, but had an approximate range of around 20 miles. Not suprising condisering its “new range” was 50 odd miles.

I have removed the original NiMH batteries and have replaced them with left over GEN1 Nissan leaf modules from my fazer 600 + another 6 modules.

This gives a total of 19 modules, or 38 effective cells in series, or a theoretically fully charged pack voltage of 159.6V. We will only be charging these cells up to 4.15V and down to 3.1V to give them the longest lifetime, so our max pack voltage should be 157.7V

The packs fit nearly perfectly in the Vectrix. The modules have 4 holes in them, and the most common way to mount them, is to run threaded rod down the packs and clamp them together with plates on either end. The cells do need to have an amount of compression on them, otherwise they will expand with heavy current draw and their capacity will be reduced. However,once installed,there is no way to get the batteries on their rods (unless you reduce the number of modules 2-3). The best way would be to build the module up and then lower it in. This requires the use of an engine crane, or 2-3 strong people and chains etc. My alternative is to use 4mm stainless steel wire, and crimp on threaded connections.:

Here is what they look like, mocked up in the vectrix:


Here are the old NiMh Cells removed. I may try and repurpose this as a solar storage or something, but I do need to test their actual capacity.


To clamp the batteries together, I made up a female 4mm crimp on ferrule > 4mm stainless steel wire to 8mm threaded crimp on ferrule:



This allowed me to mount all the batteries in the battery tray, then thread the link through all the batteries one by one, with the end plates in place, you can spin the nut on the end and tension the packs up. This only allows you run the wire through the top two holes, so it is a compromise, but it does allow you implent some type of clamping force onto the packs. I then placed rubber blocks on the back and front to prevent the whole pack moving forward or back under braking etc.

Now we must ensure the pack is balanced before we connect each module in series with the next. I am top balancing this pack by charging each cell pair to 4.1V. My experience is that the modules will stay balanced by themselves, but we will include a balancing lead to all cells so that we can monitor this externally. There will be no active BMS on this cells, by keeping the max cell voltage to 4.15 and min to 3.1, they are less likely to go out of balance. If they do, a full pack charge is unlikely to get cells past 4.2v, but we will need to balance them every 5-600 miles, using an external balancer.

This is a bit of a slow process, but is necesary:



The bike has been converted for 6 months now,m and has done roughly 500 miles trouble free. I am hoping to get some more time to ride it, although not in the current lockdown 🙁

I have now developed an integrated BMS system and offer a full conversion service through my garage. Visit for more information.

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