BMS Reset ideas- Dyson V8 Vacuum

Thread Starter


Joined Mar 10, 2018
Hello everyone,
Thank you in advance for your input...

- I discharged my Dyson Battery too low and so the BMS (I'm assuming has gone in to Low-Voltage-Cutoff Mode)
Following this, I
- Recharged the 18650 Li-ion pack manually using a DC-Power Supply.
- I have recharged to 4.10V per cell, giving a total pack voltage of 24.6V (6x 18650 in series),
- However, the BMS still refuses to allow the pack to charge or discharge via the Vacuum cleaner/adapter - It still doesn't work - red error LED blinking.

I was hoping that raising the pack voltage back above the minimum cut off would have reset the BMS, this doesn't appear to be the case.
- I have also tested the continuity of the fuses on the BMS, they haven't blown.
- I have disconnected the main +ve (top right in photo) terminal to the BMS and reconnected it.

I am wondering if there is any way to reset a BMS such as this... Would disconnecting and reconnecting ALL the of connections to the BMS make a difference?
Other info...
*Black and White wires - Charger +ve,-ve.
*Blue and Brown Wires - "ON" button on Dyson to start/run the vacuum.

Looking forward to some insight and replies... Thank you so much for your help.



Joined May 22, 2018
Hello, I was at the very same situation. Finally I was trying to "reset" controller by pulling up/down the pin-holes (bottom of your image). Bad thing, I was not using any resistor. That ended in frying the microcontroller. So do not try this, at least with +22V
Hi RickOchet44, did you have any progress with resetting the Dyson battery?
I have the exact same issue. I have dismantled the battery and manually charged the cells to 4.13v using an external balanced charger. So I am now getting ~24v for the 6 cells. Unfortunately, the official Dyson charger is still refusing to charge the cells.

I am wondering if I can replace the BMS altogether with a generic 6 cell one from eBay, but I am pretty sure that there is a handshaking going on between the battery and the vacuum that would disallow that. Plus, id have to find room somehow to add it to the battery pack. A much cleaner approach would be to reset the BMS.


Joined Mar 8, 2019

How to reset BMS from Luna Cycle dot com E-bike forum.
I have found many really informative posts about batteries and chargers on this site.

"The BMS is the protection system that keeps your battery safe (read the article on BMS)
Unfortunately sometimes an overzealous BMS can keep an otherwise good pack from working. More often than not in a failed pack it is a bad BMS.
For example many BMSs have a short circuit protection. If they detect a short they shut down the pack and the BMS can sometimes not be reset so easily.
One typical thing that can happen with a high amperage battery is plugging in the battery or even switching on the wrong kind of on/off switch can trigger a spark which the BMS reads as a short and instantly shuts down.
To avoid this use xt90s spark resistor connectors when plugging in your battery.
If your BMS has shut down the pack, the first thing is to try charging the pack. but if you are here this means it did not work and you need more extreme measures to revive it.

Sometimes to reset a BMS requires charging through the discharge wires for a few seconds to jolt the BMS back to normal mode. After charging for a few seconds from the lead wires try charging now through the normal charge wire and see if the pack charges normally.
If it charges OK, now try it on the bike and make sure it discharges OK.

NOTE: It is important that you do not use the discharge wires to charge your battery for more than a few minutes because you will have no BMS protection if you do so.
Thanks for the response brokenshade. I attempted to reset the BMS by charging the battery temperamentally through the discharge wires. Unfortunately, it did not do the trick. The Dyson BMS must be a trickier beast to reset.

I attempted to look up the spec sheet for the two ICs on the board but they look to be bespoke: I got no google hits.
Recently I DIYed it. You have to replace the faulty BMS. The battery cells are okay as long as they are over 3.0 V. Check my YouTube video (
) with some English subtitles. More details can be found at the video series from #1-#5, but no subtitles. Good luck DIYers!!


Joined May 2, 2020
Hi guys, I have a similar issue, however my BMS was working fine until I pulled off one of the cells for a complete 18650 overhaul. Once I changed the batteries the BMS still gave me the red light. It somehow disables the pack if it detects an issue with continuity, so I'm guessing... so, within this pack (btw I have a V6 Dyson cleaner) there must be a way of resetting the BMS right? Has anyone successfully figured out how this is achieved?


Joined Dec 29, 2021
Hi, any news on this? I bricked my v6 dyson bms trying to replace the cells. Charged and discharged the cells, the voltages are ok but it's blinking red.. Did you guys manage to fix it?