Thread: Charging Deep Cycle in my camper

When we put in split charge systems we use 35mm^2 between batteries.

The bigger the cable, the less resistance you have = better. Add into the scenario voltage drop - you will have several metres of cable between your battery box and trailer battery so you need to consider voltage drop.

I would expect to see 35mm^2 cable running back to the anderson plug at the rear of the vehicle and onwards to the trailer as a minimum, maybe even 50mm^2.

As for Anderson plugs, there are different sizes over here, a small one, a 175A and a 375A one. These are continuous power ratings and the 175A one would be more than enough for you.

The way I see it here, the main culprit is your 3 way fridge, these genrally draw around 15amps on 12 volts, so no matter (to a point) what cable you use your camper battery is at a huge disadvantage as this load will always pull the voltage down a bit. Have you thought about something like an "Arrid" charger unit to put in the camper for it's battery? These actually can take a voltage as low as 8 volts (I think) and step it up to provide up to 25amps to charge the battery. The other (and cheaper) option would be to run 2 more cables all the way from your dual battery controller to your camper battery so the voltage drop caused by your fridge is only affecting the fridge voltage.
Or you could run the fridge on gas all the time.

Fraser

Originally Posted by fraser130

The way I see it here, the main culprit is your 3 way fridge, these genrally draw around 15amps on 12 volts, so no matter (to a point) what cable you use your camper battery is at a huge disadvantage as this load will always pull the voltage down a bit. Have you thought about something like an "Arrid" charger unit to put in the camper for it's battery? These actually can take a voltage as low as 8 volts (I think) and step it up to provide up to 25amps to charge the battery. The other (and cheaper) option would be to run 2 more cables all the way from your dual battery controller to your camper battery so the voltage drop caused by your fridge is only affecting the fridge voltage.
Or you could run the fridge on gas all the time.

Fraser

15 AMPS!!! WOW.

A 40l engel uses 2.5 peak and that has proven enough to keep a family of 4 fed for at least 2 weeks. I think people get a bit carried away with refrigeration.

Originally Posted by VentureOverland

As for Anderson plugs, there are different sizes over here, a small one, a 175A and a 375A one. These are continuous power ratings and the 175A one would be more than enough for you.

Hi VentureOverland, why on earth would you want to use anything bigger than 50 amp Anderson plugs.

As far as cable goes, bigger is better but as posted, the advantages of thicker cable starts to be undermined by cost and handling size for what is usually only a minimal reduction in voltage drop and then only in cases of where the auxiliary battery is very low but the use of large size Anderson plugs is just a waste of money.

The bigger cable size will still not allow anywhere near 175amps to be carried because you would need to have an alternator of at least 200 amps capacity to provide anywhere near that sort of current.

Furthermore, even with a low auxiliary battery and the fridge running, it is highly unlikely that the set up could pull much over 50 amps at any time and as 50 amp Anderson plugs can take short bursts of up 180 amps, why go to bigger plugs.

Last but not least, I don’t know what the RV industries choice is in Britain but here, Grey 50 amp Anderson plugs are now pretty well the RV industry's standard for connecting battery cables between the tow vehicle and a caravan, camper trailer or float.

So using 50 amp Anderson plugs will not only meet wardy1’s needs but will keep his set up standard.

Cheers.

Yes I know Captain!
3 way fridges are REALLY heavy on the current as they use a heating element in place of the gas flame when running on electricity. They are very inefficient on 12v, but are great on Gas (if it's not too hot) I don't think they even have a thermostat wired in to the 12v circuit. Really only to be used while the car is running.

Fraser

Thanks guys. Captain Rightfoot, I run 2 fridges, one is a Waeco 50 ltr and then the 3 way in the camper. I find this provides a level of flexibilty in that the 3 way will provide 'cooling' while I can set the Waeco to freeze when required.
It is impossible to run any fridge on gas all the time as the flame will not remain lit when you are on the move, there would be a significant fire risk involved here also as the flame vents through a small flue which could in turn, turn the camper into a mobile bonfire!
I'll be upgrading the cable etc some time very soon.

I think we may have an inter-continental clash in descriptions here...

Of course a fridge and a few bits and bobs wont pull more than 50A. We rate the plugs at there max peak loading and not constant load rating (gray = 175A)... I therefore suspect that we are talking about the same plug!

Overland, I think we must be talking about two different types of plugs.

Anderson 50 amp plugs are rated at 50 amps continuos load with a surge load of up to 230 amps for around 1 second.

The colour actually has nothing to do with the current carrying capacity of any of their load ranges.

The colour is used to distinguish between different voltages and a plug of one colour is keyed so that it can not be connected to a plug of another colour ( voltage ).

Yellow = 12v

Orange = 18v

Red = 24v

Grey = 36v

Blue = 48

Green = 72v

For some unknown reason, here in Australia, we have adopted Grey as the RV industry’s standard for 12v use, while Red is commonly used for 24v.