I wouldn’t be hasty by jumping towards a faulty battery. There are scenarios that could stop capacity reaching maximum. 

For example, is it plugged directly into a mains outlet, not in an extension cable? It should be charging directly from a mains supply. Have you tried another outlet?

When charging, it isn’t either too hot or too cold? This can change the charge time/storage of the battery cells. 

Is the battery a genuine. It isn’t an after market purchase? Non genuine parts aren’t recommended and could have unwitting side effects. 

If it’s meeting these conditions and is a genuine battery, I’d be tempted to contact Dyson. They offer a two year warranty from new. 

David. 

This original battery, the original charging unit plugged directly into a house 120V outlet.  I have two Dyson units both new (less than 5 months) and both display the same symptom.  Both were fine the day after I purchased and allowed 24 hours to charge.  I have metered my house outlet and it is 123 volts AC.

Our model (V10) displays three lights on the battery. Once they’re all lit, it’s fully charged.

The first or third light, depending how you look at it, takes around 5-10 minutes of constant low suction use for it to go out. Less than 5 minutes when in boast. Completely different when in comparison.

As you’re still under warranty, I’d be inclined to contact CS. They should send you replacements batteries.

Hi @Stepper,

All Dyson cordless vacuums have a charger, which converts the voltage into a very low level which cells could accept. So it would be not something to do with the house voltage.

It rather seems that your battery pack is faulty, and I would recommend to get it replaced if it is within the warranty.

Even though the machine’s warranty has expired, the battery’s warranty would be valid for 1 year if you’ve purchased directly from Dyson. It would cover the part itself, and something resulted from a defect of the part. 

If it is genuine, I would highly suggest you to  contact Dyson.

Hope this helps.

Jay