Thread: 12V power in the rear boot.

If you install drawers, consider getting a short drawer, leaving space hidden behind for a second battery.

Originally Posted by Bohica

The fridge draws 0.7 to 1.0 Ah
USB's are 2.0 A each, led lights? not sure
maybe 8 Amps all up. 10A fuse then.
25mm square cable. good for more than 15 amps over 2m

As for "Oh, and you have a D2 with a rear boot? " I do not understand. Do they not all have a rear boot?

I’d be running a 15a fuse in the feed. Minimum.

On my D2 feed it’s a 50a circuit breaker

The circuit breaker or fuse is to protect the cable,nothing else.

A 10 amp fuse on a circuit drawing 8 amps is a bit lite on.

Definitely don't want to under specify it and risk that nasty burning smell.
If its anything like our old Engel it could draw over 4 amps at times.
2x USBs could equal 4 amps with phones, but tablets can draw more.
You could hit 10 amps at times.
If the cable is 15+ then I'd suggest a 15 amp fuse.
Is that the cable size recommended by the manufacturer of the plugs?
Don't under-estimate the fridge's maximum power demand.
When we bought our current camper trailer the Primus fridge-freezer kept throwing error messages on the standard power feed. We had to get an auto electrician in, who said the standard cable was far too light, and put in a whole new heavier wiring system. No problems since.

I also fitted extra rear power sockets but got live wire from bay and protected it with a fuse at the bay (you always fuse as close to the battery as possible). I am protecting the battery by connecting the power sockets through a relay which is activated by the factory power socket line, so the sockets are only powered with the ignition.

An important note about fuses is that you should fuse according to what the wire and the power socket (which ever is the least) are rated to. Basically you check the cable thickness and length and calculate the maximum current capacity, and that is what the fuse should be. You do not fuse according to what you are going to plug in. Of course, if you had done your homework, you would have passed the correct wire thickness .

Originally Posted by DiscoMick

Definitely don't want to under specify it and risk that nasty burning smell.
If its anything like our old Engel it could draw over 4 amps at times.
2x USBs could equal 4 amps with phones, but tablets can draw more.
You could hit 10 amps at times.
If the cable is 15+ then I'd suggest a 15 amp fuse.
Is that the cable size recommended by the manufacturer of the plugs?
Don't under-estimate the fridge's maximum power demand.
When we bought our current camper trailer the Primus fridge-freezer kept throwing error messages on the standard power feed. We had to get an auto electrician in, who said the standard cable was far too light, and put in a whole new heavier wiring system. No problems since.

USB and current require a bit more thinking

A USB port is nominally 5v @ 2a, that’s 0.84a at 12v (assuming no losses so let’s say 1a)

Originally Posted by DiscoMick

Don't under-estimate the fridge's maximum power demand.

Different ambient temperatures can make a huge difference to the current a fridge will draw.

The aux battery is on the air compressor shelf, no sls.
A USB port is nominally 5v @ 2a, that’s 0.84a at 12v, yes, a good estimate is 1 amp. Do the ipads pull more? an iPad charger runs at 10V 2 amps. The unit has 4.2 amps @ 5V is that each or combined? I wonder.
The cable is 2.5mm square good for more than 15 amps for a 3m length. Mine is less than 3 meters., 2.3m from memory.
A good idea to change the fuse to 15A. I checked the fridge and it has a 15A fuse.
Thanks for the advice. It all helps.

Julian