how does the 12 volt system work?

[stevecritchlow]

I have a 2005 tourer with both mains 240v and 12 volt systems via a Sargant electrics mCB and fuse baord unit. All the lights run off the 12 volt as does the water system.

I want to try and understand the 12 volt system as I have had a few small problems with it.

Obviously, when no mains is present, the 12 volt is supplied by the battery, but when mains is present does the 12 volt still come from the battery (which is then topped up by the charger)or is it supplied via a transformer? If the latter is the case, is the presence of a lesiure battery unneccasary when I'm on a mains site? When mains is supplied should I constantly have the battery on charge, or should I turn the charger off when the battery shows full?

Any experience on this would be appreciated

thanks

Steve C

 

[George_374396015]

all other considerations aside, your 12v supply is limited by the capacity of the charger, about 8 amps or say 100 watt. If you are using less than 100 watt then you could get away with no battery, but the moment you exceed 100 watt the voltage will drop and things go wrong electrically or electronically. Similarly if you turn off a load the voltage will rise momentarily, with similar detrimental results. The presence of a battery smooths out all these odd events and gives a much more reliable and stable 12v. Yes you can run on the 12 supply side of your charger BUT DO NOT if you want reliable and durable electrics. geo

 

[rayc]

my last two caravans have the following functions:

Battery supply to the 12v systems when not on EHU.

Battery supply backed up by the on board charger when on EHU and charger switched on.

With no battery fitted, on EHU and the Charger switched on the charger can supply up to 16Amps to the 12v equipment [with the dc control panel switch in the mid position].

 

[stevecritchlow]

thanks guys, very informative. So, if i have mains the best thing is to set the switch to mid position, but leave the battery in place? in this situation the 12v would be coming direct from the transformer? If I switch the toggle to van position the 12v would be coming from the battery with the EHU charging the battery?

steve

 

[rayc]

If you are on EHU the best thing is to put the switch in van position and run the equipment off the battery and switch the charger on as and when you wish to top the battery up, or leave it on all the time if you wish as it will not overcharge the battery.