Caravan battery discharged by 12V fridge when travelling.

G'day champ,

What size cable do you have from your vehicle to the caravan battery?

My guess is that you are not putting enough charge into the c/van battery from the vehicle's alternator, to make up for the HEAVY draw that the 3 way fridge has on your battery.

I have an Ultimate Camper which come standard with a 3 way fridge (NB: I've ditched my 3 way fridge in favour of an Engel 80 litre upright, 2 way fridge cos the 3 way jobbies suck big time IMHO).

Anyway, the Ultimate people wire the vehicle up in such a way that the VEHICLE supplies the 12 volt power for the fridge, directly from the alternator (I think). That way, the on-board fridge is able to be charged during the day (also from the vehicle, but via a different cable). The downside is that if you pull-up somewhere for lunch or a bush walk etc, the fridge isn't getting any juice at all. The idea is that you would switch it over to gas if you were gunna be stopped for any length of time.

To me it was all too much hassle and the 12v/240v is much more practical.

You must check a number of things.

1) Have the battery load tested.
2) Check the connections (plugs, fuses, earths)
3) Test the relay or isolator for voltage drop or burnt / corroded contacts.
4) Check the alternator output.

Regards

Derek.

Hi there. Sounds familiar to me. I'd be suspicious of the 12V element in the fridge. Mine was blowing 15A fuses until I repaced the 12V element, then all was sweet.

pay you to ask on one caravan forums where they have experience with that type of problem. People there dont guess and push you up the wrong tracks.

Sounds as though your charge rate isn't upto your usage rate.

SO which method of re-charge do you use when travelling, or is it all 3?

Mengs, I understood that vans etc have 12v supply to the 3 way fridge only available when connected to the vehicle, ie the 12v for the fridge does not come from the van battery, for the very reason you are experiencing. The fridge will draw about 15 A on 12v.
What may have happened is the fridge supply was incorrectly [in my view] connected to the van battery and the battery may have handled it for a short time but after repeated heavy power drain it is now no longer capable of running the fridge and fails after a short time.
I have never seen or heard of an isolating diode in a van to separate the 12V supplies. Generally diode isolation is a recipe for undercharged batteries unless there is some means of compensating for the voltage drop across them.
Ken

If you have a deep cycle battery in the van the alternator in the car will not charge the battery to 100%, so the more you use the battery the less it will be charged. By using the 240 charger it will charge to 100%, but not on a overnite charge if the battery has run down to a very low level. You would be better running a normal heavy duty start battery which the alternator will be able to charge fully on a normal days drive. have a look at the warranty on most deep cycle batteries and they will be signifantly less than a simaler priced starter battery, because under any application a car alternator will not fully charege a deep cycle battery, only a smart 240 charger will do that. col