Hi All

I’ve committed a deadly sin and let a 70Ah AGM battery completely discharge for a few weeks.  I know this is the worst thing a battery of this type can be subjected to, but I’ve given it a 24 hour charge, rested it (let surface voltage subside) and it’s given me a reading of 12.8V. It looks like it’s about £150 worth of battery and it was brand new last year (car has stood mainly unused).

I’ve not load tested it yet, but here’s the question.  Does anyone know the best place to get this battery properly tested?  I considered Halfords or the like but probably not best place for a test that’s conclusive.  It would be good to have someone honest with some good testing kit to test it for me.

Cheers

1 hour ago, Marineboy said:

but I’ve given it a 24 hour charge, rested it (let surface voltage subside) and it’s given me a reading of 12.8V.

If the battery is not connected to the vehicle and the voltage measured at the terminals 24 hours after it was taken off charge is 12.60V or better then it is safe to assume the battery has recovered.

Halfords do have a simple to use Yuasa battery tester in most stores. They will test your battery for free but to get an accurate result it needs to be disconnected fro the vehicle and rested for at least an hour.

Unofix, thanks mate.  Yes, took it out of the car to charge it.  My take-away from your comment that their Yuasa is “simple to use” and that even one of the Halfords YTS scheme kids would be able to test it for me and tell me something worth knowing 😉.   This would be a good thing!  I guess sometimes it really is about the kit rather than the tester.  I’ll do that.

As an aside, from what I’ve read, an ABS battery is at 100% charge at 12.89V rather than 12.64V for the old flooded variety (brands might differ a bit) otherwise I’d be chuffed and the reading I got.  My other thought is that if I got a half-decent Smart ABS charger, it might be capable of charging up to what's "expected" using it's wizzy "inteligence" - who knows...

The other aspect of this is that it’s not my car (sadly a Stop/Start model) but it’s been in my care, and if the battery’s stuffed, the decent thing to do would be to buy him another one 😱.

1 hour ago, Marineboy said:

their Yuasa is “simple to use” and that even one of the Halfords YTS scheme kids would be able to test it for me and tell me something worth knowing 

Yes even the tea boy/girl/person 😉 can use it. Just clip it on, tell it the battery capacity and in about 60 seconds it will tell you the condition.

The peak charge level is 12.8?V for a AGM battery but don't confuse that with it's standing voltage once the charge has been removed. I'd be willing to bet your pension that the battery is fine 🤣

Cheers for the confirmation re the Yuasa/teaboy and glad to see you're optomistic about it's heath, pension - Ha ha... Maybe I'll put it back in the car and see how it goes.  Also taken onboard what you said about voltages, thanks a lot for that.