If I was to have one of those 20 amp power socket put in the boot would it need a new larger cable run from the battery and what sort of money would it cost to get fitted. Cheers thanks.

To get a 20 Amp supply to the rear would cost a fair bit, as there's a lot of car to strip out to run the cable. You could probably tap it off the rear fuse box, but it would depend on when you're needing the power.
What do you want to power that needs 20 Amps? You also couldn't power it for long on the vehicle battery, so the engine would need to be running. Hyundai Ioniq 5 Ultimate. The family car.
2009 Rimini Red SE TD4. Gone.
2006 Tonga Green i6 HSE. Gone.
Audi A5 convertible, my daily driver.
1972 Hillman Avenger GT, the project.

It’s for a fridge or and charging a battery while driving around while the caravan is parked up. As the time would not be long I thought a big socket would charge it quickly and not wreck the normal electric stuff, like melting wires or other horror stuff.

For 20 amps run a seperate cable & make sure it is heavy enough gauge. Wire resistance is the total length of both + & - also put in a DC-DC charger next to the battery in the caravan. Procrastination, mankind's greatest labour saving device!

Acoustic insulation ARB TPMS 3xARB air compressors After cooler Air tank On-board OCD pressure air/water cleaning Additional 50L fuel Carpet in doors ABE 2x1kg Waeco 28L modified fridge Battery 4x26ah Solar 120w Victron MPPT 100/20 DC-DC 18amps 175amp jumper plug Awning 6x255/60R18

Morning, I have seen the Australian trucks with b2b and Anderson connection I was not thinking that much. I am no mechanic so would be paying to have it done and it is an 09 motor so not something to spend a fortune on. It was when we had another car the plug at the front said 120 max on it and my son plugged his computer stuff in while I was driving and it was to much for the plug. That’s why I was thinking big plug and cable, but if it’s going to run into hundreds I will have to think of something different. Thanks for replying.

You say '120 max', what is it, 12v, 240v, amps or watts? Procrastination, mankind's greatest labour saving device!

Acoustic insulation ARB TPMS 3xARB air compressors After cooler Air tank On-board OCD pressure air/water cleaning Additional 50L fuel Carpet in doors ABE 2x1kg Waeco 28L modified fridge Battery 4x26ah Solar 120w Victron MPPT 100/20 DC-DC 18amps 175amp jumper plug Awning 6x255/60R18

If you want to power a fridge, most of those are well under 20Amp, normally less than 10Amps.
Charging a battery isn't so easy, as you'd need to use a split charge relay. This prevents current from the battery you're trying to charge from flowing the wrong way when cranking the engine, and also prevents the vehicle battery from feeding energy to the battery in the back when the engine isn't running.

I'd install solar on the van, then the van battery will be charged for the most part. Hyundai Ioniq 5 Ultimate. The family car.
2009 Rimini Red SE TD4. Gone.
2006 Tonga Green i6 HSE. Gone.
Audi A5 convertible, my daily driver.
1972 Hillman Avenger GT, the project.

You can always rip it out of the car. If wire is a bit short for next car, add a bit, or add a metre & coil it up in current car.

2 DC-DC chargers at bottom of photo, MPPT just above.

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Nodge68 wrote:

If you want to power a fridge, most of those are well under 20Amp, normally less than 10Amps.
Charging a battery isn't so easy, as you'd need to use a split charge relay. This prevents current from the battery you're trying to charge from flowing the wrong way when cranking the engine, and also prevents the vehicle battery from feeding energy to the battery in the back when the engine isn't running.

I'd install solar on the van, then the van battery will be charged for the most part.

Hi, that’s an impressive set up. I wasn’t going to go that mad plus cost. It was really for the dull days in early or late in the year as we do have solar but sometimes it’s not putting out as much as we hope for. The 120 was12 v in the dash, I only said 20 amp as that was the size that seems to be for sale. I did nothing want to pay for a cigarette lighter thing in the boot only to find it was too small. As I said if it’s a lot of money I would re think. I would not want to spend to much on an old motor as if stolen or written off I would never get my money back, another reason I don’t put top range tyres on it . They would be half the value of the motor, plus paying for them.

There seems to be 2 different issues.

1. You want to charge the caravan battery when driving.

2. You want to power a computer in the car when driving.

You can do both on different circuits.

Doesn't the towing electrical plug have an auxiliary power circuit. I think it is fused at 20 amps. So you could say 10 amps continuous feed. If so, use that, but shove a small DC-DC charger next to the caravan battery.


I hope you are not using a 12 to 240v inverter to power the computer when driving. Even if it is a little inverter, just don't use it. If you were in an accident you could have live 240v. Even for a second it is lethal.

Putting the 240v issue to the side. Isn't 10amps on a 12v circuit enough to run a laptop computer. Procrastination, mankind's greatest labour saving device!

Acoustic insulation ARB TPMS 3xARB air compressors After cooler Air tank On-board OCD pressure air/water cleaning Additional 50L fuel Carpet in doors ABE 2x1kg Waeco 28L modified fridge Battery 4x26ah Solar 120w Victron MPPT 100/20 DC-DC 18amps 175amp jumper plug Awning 6x255/60R18

Hi no idea what he was doing with his laptop, that’s way above me. Are 10 amp plugs just the same as 20 with different numbers on them. I think I will have to ask an auto electrician, I just didn’t want to waste their time if it was going to be very expensive and of the limit. Nothing is simple, haha. Cheers, thanks.

Just make sure he is not using 240v. Inverters are not called death boxes for no reason.


As far as the 12v sockets in the car. I have a MY13 & it has 3 sockets each with a 20 amp fuse, but one of them is a high temperature socket for cigarette lighter, but it is still fused at 20 amps.

Even though they have 20 amp fuses the continuous safe working load is about 10 amps. I have cooked a circuit in the fuse box & I wasn't really overdoing the load. It is mostly printed circuit inside the fuse box so one needs to be careful. Or like me you will have to wire around the problem.


Sounds like you need to find out the loads your son is trying to run. Quite frankly 10 amps should be enough to power toys in the car.


There is a photo down this thread of what the back of a 12v socket looks like.
https://www.freel2.com/forum/topic33954.html

Apart from the circuit being fused at 20 amps. These sockets are pressed metal & have poor electrical contact.


But it does come back to what are you trying to run. Once that is established, then an appropriate socket & fuse can be installed. Procrastination, mankind's greatest labour saving device!

Acoustic insulation ARB TPMS 3xARB air compressors After cooler Air tank On-board OCD pressure air/water cleaning Additional 50L fuel Carpet in doors ABE 2x1kg Waeco 28L modified fridge Battery 4x26ah Solar 120w Victron MPPT 100/20 DC-DC 18amps 175amp jumper plug Awning 6x255/60R18

Laptops normally only run at 19volts or so anyway so you don’t really need to be able to plug in the laptops mains adapter, rather find something that will ramp 12v up to 19v!

The 12v ignition switched and the constant power circuits in the tow bar electrics are both 15A. For charging the battery a voltage sensitive relay ('split charge' relay is a misnomer - it doesn’t split the charge) switches the auxiliary battery into the charging circuit once the voltage has risen enough to show that the engine is running, and switches it out again when the voltage drops because the engine has been switched off. While this will boost the charge in the battery, it won’t do a great job of fully charging it. For that you really need a DC to DC or battery to battery charger. However, it’s not easy to find one that won’t fry your electrics as most of them draw 20A or more. I couldn’t find one at reasonable cost that didn’t draw too much current and I ended up getting an Optimate one, but it maxs out at 2A. Fine for my small winch battery but not much good for a caravan leisure battery.