Newbie to MH - advice please

Firstly, I can't say how your MH is wired re the charger...however, a couple of things...

the 13.7/13.8 readings were there as a result of a previous charging stint, either EHU or from the alternator when driving the van...

after a rest period, they have dropped back to their fully charged state of 12.6/12.7

you can do this test...put the van on hook up at home and with a voltmeter test the levels on the cab and leisure battery....if the charger is charging each then they should present a raised charge well above 12.7 closer to 13.8 to 14.1

Agree with BB battery voltages are entirely normal and indicate both are fully charged. You don’t say anything about the circumstances leading to the flat battery. Was this after the van hadn’t been used for an extended period and was just starter or leisure battery also involved? It’s not unknown on some vans for EHU to charge the leisure battery only. 

re the flat battery - we hadn't used the MH for 3/4 weeks although we had the mains electric connected for a period as we were testing TVs.  So I suppose it is best practice to take it for a ride every 3/4 weeks?  The leisure battery levels were normal.  I am just a bit worried that we may have somehow set to use the vehicle battery which I would never want to do.  Will check as BB has suggested. Thanks both for help

Sounds like EHU only charges your leisure battery. You might want to buy a solar panel to maintain the starter battery? You can get a small one that will sit on the top of your dashboard and connect to the starter battery with a couple of crocodile clips. If you can get the correct angle with a southerly facing aspect out of shade that will do the job. Other more elaborate (and expensive) solutions are available.

Agree with Bill....if you had the van on hook up but the cab battery went down, it isn't charging...my test above will confirm.

re solutions...we have plenty of solar but a fairly simple solution is to fit something called a Battery Master. It takes charge from a full leisure battery and trickle charges the cab battery from there...this means you can use the hookup at home (or on site) and the cab battery will receive a charge.

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Dependent on your monitoring of the batteries and if your LV is wired to charge only the leisure battery on EHU (hopefully you are able to do this easily) then personally I wouldn’t rely on a small solar panel to charge the vehicle battery especially at this time of year in the UK.  It would probably be best to take the LV for a run, maybe every couple of weeks or so dependent on your monitoring.  There was a similar discussion not too long ago on here but I can't see it just now.  Good Luck and enjoy. 

A Battery Master cost about £60 from Vanbitz or £30+ from Votronic and is easy to fit and work really well. This way, just plugging the EHU in periodically as before will then charge both batteries not just the leisure battery. A simple remedy to a common problem.

agree, taking the van for a run periodically is good for warming the oily bits through but you have to take it for a pretty long drive to put much charge in, especially as starting the van takes a good chunk from the cab battery.

“…..I wouldn’t rely on a small solar panel to charge the vehicle battery especially at this time of year in the UK…..”

Why not? UK average sunshine hours in winter is about 1.5 hours. A 10A solar panel is capable of maintaining a 100Ah battery on a trickle charge basis assuming the panel is properly located. In summer that figure increases to about 4.5 hours. Added bonus is a battery charged on that basis will likely last longer than one subject to frequent deep discharge/charging. 

Meant to say 10W solar panel

Out of preference I would fit the Battery Master, the reliablity is better. In the winter it is very hit and miss as to whether a solar panel will keep a battery fully charged. I have two solar panels, a 120w one on the motorhome and a 10w one trying to keep an electric fence battery charged. At the moment in the gloom I am lucky if I can get a 0.3A charge out of the motorhome panel and when the sun shines, it is so low in the sky, it is not much better. The 10w one is not keeping its battery charged either but that is not helped by the battery being past its use by date and not in prime condition.

A 10 w panel  can cost as much as a battery master, possibly more if you fit a regulator (recommended) to help keep the battery safe. The choice is yours.

Another plus for the battery master is if ever you decide to fit a solar panel to your motorhome both batteries can be maintained by it.

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