Rear 12v Power options

Hi Boss, your 20 amp switches will be more than adequate for what you are intending.

As to to spikes and surges, this is a real con job in an automotive situations.

Every vehicle get spikes all the time your motor is running and you never hear of anyone’s ECU/computers being destroyed.

A lot of salesmen try to make out that you need spike and surge protection as means of making their products sound like they are something special or that the salesman knows something about and area they quiet obviously know absolutely nothing about.

Every single electronic device in your vehicle is manufactured with built-in spike protection already so don’t concern yourself about something that is no more than a sales gimmick.

As to surge protection, if you were talking about 240 VAC applications then yes you need surge protection but again in automotive DC applications, the only time you could have a surge problem is if your alternator started turning out 18 or 20 volts instead of 12v or a battery charger connected to your battery did the same, and in either case, your can’t protect against such surges, so again, don’t worry about it, it’s just a sales gimmick.

Your proposal sounds good. Just a couple of comments -

Most importantly, the wire from the front to the back should be good solid copper, better still, run two wires with one of them dedicated to the fridge. (Voltage losses in the cable are unavoidable but should be minimised for the sake of the fridge. By giving it a dedicated cable, other loads won't interfere with it.) Also to avoid loss of voltage, ensure you have a good earth connection to the vehicle at the back.

There should be a fuse or circuit breaker (don't need both) close to the battery to feed the cable/s running to the back. I wouldn't be too fussed about individual fuses for the back outlets - it's a minor convenience not to have everything close down if there is a disaster on one outlet, but in my opinion the extra complexity isn't justified. KISS - keep it simple. The more bits there are to shake apart on corrugations the less reliable is your system.

20A toggle switches sound good, though again, do you really need them? I wouldn't switch the fridge line. In our rig I've used cigarette lighter outlets for all lighting and general use - pull the plug out a few millimetres and it's switched off, push it in and it's on. For any fixed lights I'd use switches, otherwise less things to go wrong if you avoid them.

You might get some ideas from our blog Electricity for Camping.

Surge protection - surges shouldn't be a concern. kiss!!

In-line discharge protection - This amounts to switching everything (including the fridge) off unless the engine is running. Essential if you are running a second battery, but do you want the fridge turned off? I'd suggest that a second battery might be pretty high on the priority list, but until then simply be mindful of the fact that you are using your starting battery and won't travel far if you use too much!!

HTH


John

Hi TB

Spike protection is used where there are large collapsing magnetic fields like water pumps, large solenoids and most DC motors. It is best to read our newsletter on this to understand it better. Spike-Protection

If your installation is going to be exposed to the weather I would recommend using a component box and sockets with caps / covers.

I don't like switches exposed to UV as they don't last long and will fail. If possible fit switches to your lights rather.

Cable should be at least 6mm2 for what you need but if possible go up one size to 8 B&S or 10mm2.

You will need to fuse each socket at its rated load.



Regards

Derek from ABR

I wont add to all the other posts as they all make sense.....one thing I would draw your attention to is the amount of current that Low Voltage Battery protectors / cut outs can draw

These can vary from anywhere between 0.13a/h up to double that...depending upon their design...as some have the relay built in and others have an output to a seperate relay...some can be put in sleep mode and some cant.

Be aware of this as even the lowest draw (such as relay) of say 0.13 ah is equal to 22 ah over a week of stand by if the vehicle is not in use.........a lot of battery reserve sucked out and wasted...........by the second week you could have a battery below the recomended SOD

if the vehicle / battery is not in regular use / or charge i would fit a LVC device that had the ability to go to "sleep mode" and one that had the outlet to power an external relay and fit an isolation switch between it and the external relay that actualy allowed the power through to the accessories to be cut off when not in use.........at least this way the actual LVC that is only monitoring voltage is drawing negiligible power when not needed...(such as parked up for a week etc)...and the relay drawing nothing

You will definitely *NEED* an in-line battery discharge protector, because as you say, you "don't have a dual battery system"

Run the fridge on an independent wiring system.

Maîneÿ . . .