DC voltage drop.

As a ‘resting voltage’ 12.5v is at the low end of OK - about 80% charged. If that’s a charging voltage your battery may well be getting tired. 

That's voltage when on hookup, I've not yet checked what it is with the EHU disconnected. I will check it in the morning, and also the fuse to the charging unit, which down not seem to be as warm as it should be. The battery is not that old and has regularly been charged, as we are away every month throughout the year.

If that is the voltage when on EHU, i would check your battery charger first, it sounds more like its not charging the battery. Even with a duff battery I would expect to see more than 12.5v. Has a fuse blown?

peedee

Morning

I'll agree with peedee NTH, it's not charging. If you have a multimeter, plug in into the EHU and check your lead is live. I say that as we get a lot of members asking for help with no power which has been a loose wire in the hook up lead.

If you're not home for a bit, disconnect your van charger and get a cheap battery charger to tide you over, always handy when you get home as well

JK

As well as the possibility that there is a disconnection, the voltage of the mains supply may be lower on your current site - either temporarily or always.

Thanks for the replies.

We are on EHU on site, and have been all trip, and all the 240v appliances are a working fine....TV, Alde Heating, and mains sockets in the van. When I got up this morning the meter was reading 13.5v or there abouts, but when I run the water pump it drops to a little over 12v, similarly when I switch on the internal lights. I did change the 20 amp fuse for the battery charger but without any change. I am using a brand new EHU lead, and have been since we set off. At the moment, with the heating running, and a couple of ipads on charge it is showing over 13.5v. 

Nellie. I'm not an expert but with 13.5 showing when on EHU it does look s though the charger is ok but with a light drain on the battery dropping it to 12v it looks as though the battery may be on its last legs.  Maybe the cold temperatures are having an effect? I had a similar symptoms a few months ago; on EHU 13.5 but as soon as I disconnected EHU and used mover battery flat!! Cost me a new battery but ok now.

I think you can be fairly confident that your battery isn’t fully charging. Any charging voltage in excess of the resting voltage will charge the battery, but it needs to deliver something like 13.8 to 14.5v to fully charge the battery (12.8v resting voltage). So, 2 options….your charger maybe faulty or battery not maintaining its charge - process of elimination would be my next step.

I know this is a daft question but how do I disconnect the battery charger. As you can see eletrickery is not my strong point. I do have a charger with me, so once I disconnect the van's charger can I run my charger from my 240v socket? Our van is a 2010 model Bailey Unicorn Madrid if that helps, and the battery was new in Sept 2019.

It would easiest to pull the fuse or trip the breaker for the charger at the fuse box.