top of page

Dyson Cordless Vacuum V8 V7 Double Battery Capacity and Run Time Using KOBALT 24V Max Power Tool Batteries | GREENWORKS and SNOWJOE 24V Max Batteries (21.6V Nominal)

The battery life on our Dyson V7 and Dyson V8 vacuum was decreasing to the point where boost mode did not work for more than a few seconds. Normal mode was still usable but lasted less than half the time that it did when new. I would prefer even more battery life than new, especially to be able to use turbo mode for longer periods of time, and since we always use the brush. The fluffy roller brush is used most, followed by the regular carpet brush.

Dyson sells replacement batteries which are expensive, and don't increase the run time more than what the vacuum was new.

Third-party batteries are of questionable quality and safety. Most use no name, poor quality cells. They may work well when new, but the lifespan is likely to be much shorter. Any packs that claim more than about 2500mAh (for the normal size pack, which is 6 cells) are lying. Most 18650 cells that can handle the high current draw are in the 2500 mAh or less range. There are 1850 cells that have a higher capacity, up to about 3500mAh, but they can't handle the high current draw required by the Dyson vacuum cleaner. In addition, the BMS (Battery Management System) of a 3rd party may not be of as high quality as the Dyson BMS.

So, the only way to effectively increase the run time is to use physically larger lithium cells or double the number of cells. When the cells are doubled, the batteries are placed in parallel, which has a downside that now the cells can go out of balance.

There are a pleathora of 18V (or 20V deceptively advertised Dewalt batteries) power tool battery adapters. The problem with all of those is that the Dyson is actually 21.6V nominal (24V peak charged), so the 18V power tool battery voltages quickly drop below the cutoff threshold of the Dyson V7/V8 vacuum cleaners, and the vacuum will shut off long before the battery is drained.

The only power tool batteries that will work like the original Dyson batteries are the ones advertised as 24V MAX (21.6V nominal). KOBALT's power tools are 24V MAX. There's also GREENWORKS 24V MAX and SNOW JOE 24V MAX.



The problem with using any power tool batteries and adapter for a Dyson cordless vacuum is that you can no longer use the wall mount charger. It won't even fit on the wall mount, nor will it charge.

I'm working on an add-on adapter that allows the KOBALT 24V Max battery to be charged while attached to the vacuum cleaner and acts as a wall dock. The KOBALT battery charger will be wall-mounted, and the Dyson with the Kobalt 24V battery will drop into the wall mount.

The adapter will be 3D printed. It needs female contacts, which are difficult to find in exactly the same form factor as the factory ones.

Here are some female contacts that should work:


Using an OEM battery from a reliable cordless power tool brand like KOBALT is much safer than a 3rd party Dyson battery with questionable quality control, cell quality and battery BMS circuitry. Third-party Dyson batteries have caught fire and caused fires. I trust the KOBALT 24V Max batteries much more than a third party Dyson battery.


The products shown here were purchased by me with the intent to use them. I did not receive any free items, and I am not being paid or compensated for this review. The video and description may contain affiliate links. If you click on a link, I may receive a commission. Money earned helps to support my channel and bring you more informative videos about engineering, crafting, and DIY.


Recent Posts
Search By Tags
Follow Us
  • Facebook Basic Square
  • Twitter Basic Square
  • Google+ Basic Square
bottom of page