Hi @ac9144,

Welcome to the Dyson Community, and thanks for letting us know about this. It does sound very unusual!

Just to check, did you order an identical replacement cleaner head to the one you had originally? There may be some similar Dyson motorised cleaner head variants which fit your machine, but are slightly different in specification. If the brush bar motor wattage is higher than your original cleaner head, this could result in a shorter runtime. 

It’s also worth double-checking which power mode you’re using your Dyson V11 vacuum on, as this can make a significant difference to the available runtime. We would normally recommend using your machine in Auto mode, as the best way of balancing available battery charge with the amount of power needed for the cleaning task.

Thanks for your reply. I bought the only brush bar listed on the Dyson website for my cleaner, I didn’t realise there could be alternatives. It looks exactly the same as the old one and fitted the motorhead so I think it’s the correct replacement. I mostly use the auto setting and, when fully charged it indicates around 45 minutes. Since I’ve changed the brush it’s only showing a max of 21 minutes. Very annoying as I love the cleaner.