I have what I'm pretty sure is a dodgy battery on my van, it will charge but doesn't last for long.
However I had the van plugged into 240v domestic mains today with battery connected as well but noticed that when the rocker switch was moved to van it kept trying to switch to the almost dead battery rather than 240v mains.
Is there some logic which says that when connected to mains the van will default to mains rather than using the battery or do I need to physically disconnect the battery each time I put it on mains?
When on EHU, the mains equipment will run on EHU (eg fridge, water heater etc) and the 12v equipment will run off the battery (eg water pump, most of the lights, though you may have some mains powered lights too)
If the battery is showing almost dead with EHU connected, it sounds as if the charger is faulty. (Though it could be the battery too)
Check all the fuses in case there is a fuse blown on the charging system.
Thats what I thought, however I didn't have any lights on at the time, just the water pump - the meter dropped a little when I switched on the tap then dropped to nothing a few seconds later - all with the EHU attached to domestic mains. Everything was fine as soon as battery was disconnected.
If you set the rocker switch in the middle position it will be on the transformer if on hookup so will bypass the battery. Sounds like the batteries duff tho
Ok all good advise above - still no clearer in my mind though...
I DO have the domestic mains EHU plugged in, with the battery not connected all runs fine on 240v. But when both mains and battery are connected the voltage drops to low to nothing (though not always) and appears to be running off battery instead of defaulting to mains when connected.
I think what might be happening is that the battery charger is sensing that the battery is connected and sends charge to that . When you disconnect the battery it then changes the battery charger into a transformer .
So if on EHU should I always ensure the battery is disconnected - seems like a bit of a parlava..
I can see how what i posted can be miss-read , so i'll try again . I'm guessing that when the charger/transformer senses a battery is connected, it sends it some charge as well as supplying the caravan with DC voltage , so when you aren't connected to mains the battery is charged . If your battery has failed the caravan will still try to charge it , but if the battery has a shorted or dead cell you may find the 12 volt system doesn't work too well .
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Topic: Battery switching
