Defective battery charger?

You need to measure the voltage across the battery terminals with a volt meter when the charger is working, it should read 14 to 14.6 volts.

Depending on where the battery and charger is in its charging cycle I would expect to see about 13.8v if it is at float charge or 14.4v - 14.7v if in absorption mode.  I would disconnect the battery and leave it for 24-48 hours then check the voltage which should then be 12.6v to 12.8v or more.  If your charger is achieving those sort of figures there is little wrong with either the battery of charger. 

on my caravan's last service I was told that the fridge wasn't working on 12 volts. I questioned it as there was nothing on the fridge to indicate this. I plugged in my car and showed him .... it turned out there was a fault on his power supply unit. 

my point being ... it could be the fault of the spark or his test gear.

But .... Your battery might have read 14.2V when you got home as a result of your towcar charging the battery on the journey home. 🤷‍♂️

A good point in your last para ED .

Thanks, pretty much what I thought.

Car did of course charge battery on the 4.5 hour drive home on the 16th, but battery then powered the mover for about 10 minutes to move van off road through 90degrees and up our 10% slope driveway, with several back and forth shuffles, which takes a bit out of the battery.

It was then on EHU till we took it for service on the 21st, only a 45 minute trip.  Plus of course 45 minutes home again followed by the mover being used again.  I measured right after the van was plugged in again.

While on EHU, panel above door shows 14.4v, at battery terminals my meter shows 14.2v.

When charger is off, above the door reads 13.2v and at battery terminals 13,5v.

It sounds fine to me.   I have had a couple of problems with their electrician over the years, assuming it is still the same fellow.  He did not like that I had interrupted the mains cable to fit the Alde load monitor and install a device to monitor power use so we know what we use on metered sites  (common in Germany).    He removed the devices,  and refused to sign the service record or inspect the van again until that was sorted to his satisfaction.     And  our battery to battery charger has him totally stumped!

@KjellNN He removed the devices,  and refused to sign the service record or inspect the van again until that was sorted to his satisfaction.

I'd have had words with him!!!!! .... who is he to remove things from your 'van? I would have found somewhere else to take my caravan for service. The cheeky barsteward!!!!

All the voltages you've quoted sound spot on to me.

He sounds pretty much incompetent.  I hope you refused to pay for a job not done and interference with your property.

He did not take the devices out of the van,  just removed them from the installation and reconnected the cable to his satisfaction.

I had words with his boss and we came to an understanding!

I put in an additional RCD.........he agreed not to interfere with things again.

Not had any problems since then, but of course it may not be the same fellow now.

Dealership is good, so we are still with them.

Our Alde current load monitor is a circular coil which fits around the incoming mains feed, without interrupting it, although the feed had to be temporarily disconnected to thread it through the coil. As such it can be considered as a passive device and not interfering with the van’s fitted equipment. Clamp ammeters work in the same way.

We too have suffered from workshop mechanic’s I’ll considered interference. In our case, the Alko  breakaway cable hung down far enough to rub on the road when attached to the tow bar’s fixed attachment hole. So the surplus was carefully taped in a U underneath the A frame. It was done in such a way as to prevent catching, with light tape to ensure that it could pull straight if the van became detached. The interfering mechanic removed the tape so that once again it rubbed on the road surface.

We’ve had long threads here on the Alko clips, around the tow ball attachment, legal notices placed at police checkpoints, and I’ve personally had some correspondence with Alko regarding cable length. All to no avail. The plain truth is that on some tow bars, Alko cables may rub on the road if the cable fixed point is used with the correct Alko cable/ clip. And the police interpret looping around the tow all as illegal when there’s a fixed point available. Alko don’t recognise the problem. The mechanic ignored the worn through red plastic covering of the cable, and we don’t want to tangle with a policeman’s interpretation.

The simple solution would be for Alko to manufacture a shorter cable as an alternative. But they won’t.