Battery wont charge.

[BML]

Camper wouldn't start a few days ago after the freeze so I put charger on it and it showed 12.1 after six hours it still only showed 12.1 and eventually I slave started it with our car. Does the performance of the charger show the battery is stuffed?

[spirou]

What battery, what charger? If the charger supplies only a small current to a large empty battery it isn't too surprising that you didn't see a significant increase.

[Stuwsmith]

Yes. At least in my experience if a charger struggles to raise the battery volts to that which the charger is designed to reach usually around 14.4 volts before it drops the voltage back to 13.6 ish then the battery is past its sell by date. Increased internal resistance of the battery from sulphation I would imagine.

[Derek Uzzell]

A couple of earlier threads (September and June 2020) relating to charging Brian’s motorhome’s batteries.

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Keeping-both-Motorhome-batteries-charged-/56380/

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Two-battery-Motorhome-Setting-it-up-/55404/#M651757

 

As spirou says, with no details of the starter-battery (particularly its age) or the charger being used (my CTEK charger provides an indication when a battery won’t accept a charge) it’s hard to diagnose where the problem lies.

 

As a rule of thumb, when the attempt was made to start the motorhome, if there had been no sign of life in the battery and the battery itself is getting on in years, replacing the battery would probably be wise.

 

Now that the vehicle has been junp-started (and presumably been driven far enough for its alternator to put a chunk of charge into the starter-battery) it might be worth connecting up the battery-charger again to see if it puts out more than 12.1V.