charging battery in trailer

thanks roadwarrior, good points. I suggested my setup to utilize what I have to avoid buying more hardware at the moment if possible.

Thanks for the comment, Phil. Do you mean just connecting the batteries at the back to the auxiliary battery under the hood should be okay? I was worried that power drop from long cable would mean the rear batteries would never fully charge...

good points Phil. Where is the 3rd battery situated? The main reason to put the fridge in the trailer is space consideration 2 adults and 4 kids onboard.

good points Phil. Where is the 3rd battery situated? The main reason to put the fridge in the trailer is space consideration 2 adults and 4 kids onboard.

Our 3rd battery is an AGM in the canopy.

We had 4 kids as well and used to cart them around in an 11 seater troopie 20 years ago. I know what you mean about space! We used to tow a trailer as well for the camping gear, but occasionally went without the trailer and crammed it all in - only had 1 fridge back then! For some unknown reason we now need 2 fridges for the 2 of us :-))

On the old troopie I welded up a cradle that took 2 batteries in front of the radiator (where a winch would normally go).

Thx John. Currently the fridge is in the vehicle but it's inconvenient because of space restrictions. I just bought an offroad trailer with a separate box in it set up for a couple more batteries and room to put the fridge and stove.

My place in Qld is off the grid so extra power never hurts- we currently have a simple solar setup there of 120W solar panel, regulator and 2 truck batteries which isn't quite sufficiant for our needs. I want to boost the car capacity to have more power to use both camping and when we are around the house. (I could run a lead from the inverter in the van to the house). I want to use the car alternator more effectively as it is used daily anyway . I dislike charging from the generator at home.
I run the home fridge on gas. Maybe I should run the car camping fridge on gas when we stop.

additionally I thought power through direct connection and anderson plug would supply the lions' share of the power needed and the ac trickle charger may just top it up to get the batteries full. And it'd use items which I already have.

Rainbowprof,
What sort of fridge do you have? If its a 3-way then I'd suggest everyone's comments are no longer relevant because they draw way too much power off 12V.

Rainbowprof,

New ball game! Or maybe that’s two ball games, the travelling one and the stationary one!

First – using a good connection from Troopy to trailer will provide charging, but (for reasons given in our blog) you will not get close to full charging. The little trickle charger will not be sufficient to top up and charge the batteries full either. (The solar panel might be very useful for this. Our Troopy carries one on the roof largely for this purpose.)

Quite understand your need to shift the fridge out of the vehicle. Even in a Troopy they take up a lot of space. So let’s assume that it goes to the trailer. One option is to use a 3 way fridge in the trailer, though that involves the initial cost of the fridge plus the cost of the gas installation (there may be legal requirements here too), as well as cabling and switchgear from the alternator. A 3 way fridge would run on gas while stationary, and 12V direct from the alternator when travelling. Running on 12V is very demanding (12 to 15 amps continuously) and running from batteries is not an option.

Putting the existing fridge (assuming it is a compressor type) with some batteries in the trailer seems the way to go.

At home, being off the grid, some extra storage and generating capacity sounds very desirable. The difficulty of course is that the Troopy charges when moving and the house doesn’t move! I assume that your domestic requirements are really only for lighting?

Options
It would be pretty inefficient, but you could charge batteries in the Troopy, and later transfer that charge to the house batteries using heavy cabling and a dc-dc charger. This would cost a charger ( $150-350 for 15-30 amps) plus batteries and cabling. The dc-dc charger would also help in charging the battery bank when mobile. Suggest search ebay for “dc-dc charger” – it’s a good catalogue even if you don’t buy there. Some respected ExplorOz business members do advertise there. Look for Derek, ABR, Battery Value…. for quality gear and support.

Another possibility is to carry extra batteries in the Troopy and plug the house into the Troopy battery bank as required. Perhaps one battery in the house to deal with those times that Troopy isn’t home at night, and swap to the Troopy bank (or simply plug the Troopy battery bank in parallel with the house battery) when Troopy comes home. (There will be very little battery to battery charging, and the house lighting will run mainly from the most fully charged battery/ies.) This is probably the least costly option.

Batteries – You are probably already aware - Batteries used in backup supplies for big computer systems are usually discarded long before end of life. It’s worth talking to electricians who deal with these systems. You can often pick some up at no cost when they are routinely replaced. Not all will be perfect, but at that price you can afford to be choosey.

HTH

John

Excellent, John. Sound advice.