Dyson V6 battery repair

Recently our Dyson V6 started to shutoff after running for about 20 seconds. It would just sit there with the blue battery light on and not restart.

Looking around on the internet some people suggested that the vacuum might be clogged, but even after thorough cleaning all the way down to disassembling cyclone chambers, the fault still remained.

Given there was nothing to lose, I decided to crack open the battery to look further.

In theory the battery should come apart with six or so plastic tabs, but I ended up brute forcing it apart and cracking all the tabs open.

Once apart I decided to measure the cell voltages.

Although there was some variance they weren't massively unbalanced,

The Dyson battery management system has a connector to each cell so it can obviously monitor voltage of each individual cell, but it seems like they do not balance them.

So the next step was to manually balance the cells. Although I could have charged each cell using a battery charger, I have read that Dyson is very conservative about cell voltages, so I figured it would be safer to discharge down to the lowest cell voltage.

I used an old electric screwdriver motor than happened to be 3.8v rated, and connected it up to each cell for a while to bring the voltage down to 4.088 for each cell. This took probably 15 minutes all up.

Once done I put some duct tape to stick the battery back together and retried the vacuum - it ran for about 15 minutes!

Given this reasonably easy fix I have ordered a ZB2L3 discharger with automatic cutoff for a few bucks on Aliexpress - it will hopefully arrive before the next time I need to balance the battery in a years time - that way it can be left to do its thing on each cell rather than manually attaching a load and measuring intermittently with a volt meter.