caravan battery problem

Hi, I have had all of that checked by an Auto elect he said everything was fine?????

Hi Rod

I'm not sure what the voltage is when plugged in but I had the plugs checked buy an auto elect the other day he said there was 14.5v at the car end and van end of the anderson plug and the battery was also showing 14.5v
I have checked the terminals they seem fine, the only thing that was running at the time was the fridge, could the inverter have anything to do with it as it is connected at all time?

Hi
I would suggest you get the auto lecy to check for voltage drop due to undersized cables under full load.
If he does not under stand that get one who does.
This test must be done with fridge running hooked up to tug &
engine running.
You WILL get a differrant reading,lower @ the van battery & the fridge terminals than @ the car battery.
It is the size of the differrance that is critical. I will take a guess & say you will probaly find your voltage under load @ the fridge is around 11v .noooo good. THe fridge will be loading the undersized cables to such an extent that the battery is not getting any charge & the fridge will be drawing part of its power from the van battery
The van battery could also be no good, capacity wise, battery can still charge to 14+ v & have very little capacity
If it is a flooded wet cell check it with a hydometer.
If the cables including the ones in the car are seriously undersized even a Ranox may not solve your problem.
Also do not rely on frame return for neg line , should have full sized cable back to car battery

Hi Ray, Yes the inverter is connected at all time, do you think that could be the problem? if so when should I be useing the inverter?

Hi Tim

The battery was fully charged when we left, I had the battery and connections checked by an auto elect he said everything was fine, there was about 14.5 volts at the battery and also the anderson plug at the car and van. I did have the parking lights on while driving and the only thing running in the van is the 3 way fridge switched over to 12v. I do have an inverter connected at all time could that have anything to do with the problem? if so when should the inverter be used??? By the way the car is a Ford falcon.

Cheers
Roy

Hi Roy,

Parking lights won't make much difference (both to power usage and to your visibility on the road!)

3-way fridges do use quite a bit of power on 12v so it will use up your caravan battery quite quickly if it's not getting a decent top-up from the car.

It seems to me that the fridge is using more power from the caravan battery than the alternator is putting back in. Yes, you said the connections were all checked by auto-elec and were fine - did he check for the rating/size of the wires etc. as well? It is possible to have a good connection but have wires that are too small. If the wires are too small, you will still get some charge to the battery but not enough to keep up with the power used by the fridge. The issue is more critical having such a long run of wire (ie. from the alternator at the front of the car all the way back to the battery in the caravan). When the Anderson plug was connected, were new wires (ie. thick cored with lots of copper) run all the way driectly from the car battery?

Do you know what the car alternator is rated at? It may only be sufficient for the car in standard form - ie. Ford possibly didn't design it to run a fridge as well as all the standard equipment in the car so it's possible you might need to upgrade the alternator - yes, more $$$!

Your auto-electrician should be able to test the alternator and see if it's keeping up, check the health of your batteries (car and caravan), assess the power required to run your fridge etc. and check the wires etc. are adequately sized for the job, etc.

Finally, if nothing was plugged into the invertor, switch it off or disconnect it. They usually do use a little bit of power even if nothing is plugged into them (eg. to run a cooling fan, etc.). It's not usually much, but it is unnecessary if you're not using it at the time.

Hope this helps - let us all know how you get on.

Cheers,
Tim.

Hi Roy,
I'm with Tim on this.

I'd put money on the wiring being way too small for the job at hand.

It'll all look fine with the engine running, caravan hooked up and everything in the caravan turned off.

As soon as you spark up the fridge on 12 volt I guarantee the voltage at the caravan battery will begin to fall. It'll continue to fall until the battery is dead flat regardless of whether the engine is running and the alternator is outputting power.

How thick exactly is the wiring between the alternator and the caravan battery and how long is it exactly?

Geoff