XC90 battery issue

[Quacker]

Wait a few days or a week or two and it will again be flat. Once a battery goes absolutely flat it will never hold charge properly again.

[Boatie]

Originally Posted by Fursty Ferret

Just to add to what Quacker said, if you get the car started you'll need several hours of driving at motorway speeds to recharge the battery, and two or three times that to refill it to the extent that start-stop works reliably again.

I've accidentally discharged a battery to the point where it wouldn't turn the engine (left a door ajar for a week) but it went with a jump start and is still going strong.

AGM batteries are actually pretty tolerant to deep discharge. I now keep a lithium ion battery pack in the car which has enough juice for one good start attempt.

To take a flooded cell or car type AGM battery from flat to fully charged (if it isn't *na**ered ) takes at least 10 hours. A popular misconception is that a high amperage charging source is faster than a lower one. Battery charging is a complex issue 'controlled' by the battery and charge [B]voltage[B]. It may be charged to 80% in 3-4 hours but the remaining 20% (to actual capacity not what it says on the label) will take perhaps an other 6 hours. It's all to do with voltage and tail current.

[Clan]

Originally Posted by Boatie

To take a flooded cell or car type AGM battery from flat to fully charged (if it isn't *na**ered ) takes at least 10 hours. A popular misconception is that a high amperage charging source is faster than a lower one. Battery charging is a complex issue 'controlled' by the battery and charge [B]voltage[B]. It may be charged to 80% in 3-4 hours but the remaining 20% (to actual capacity not what it says on the label) will take perhaps an other 6 hours. It's all to do with voltage and tail current.

Very true , i would advise at least 24 hours on a 20A charger preferable more if you have the time . the last 20% takes twice as long as the first 80% ...

[docjd]

Same problem-due to take car for its scheduled service-car completely dead-volvo assistance came unlocked using metal key and started with jumper pack volvo main dealer confirmed new battery required fitted £220 after discount.

At least mine was a few yrs old.

[CocoPops]

So turns out it wasn't battery related.

But one of the Modules had a brain fart, massive list of fault codes.
Software reflashed and all is well again...