# Outdoors > Outdoor Transport >  Split Charge system : How big a fuse do I need?

## norsk

I am in the process of installing some LED lights and a Diesel heater in my Camper,so I thought it was a good time to install a split charge system.

My question is:How big a fuse do I need between the first battery and the Voltage Sensitve Relay? The one I am installing is rated for 125 Amps,should a 100 Amp fuse do the job?

I will install a couple of USB ports and probably LED flood lighting around the outside of the box too,not that its really go alot to do with that circuit.

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## 2post

The fuse is there to stop the wire burning if a short circuit occurs but you can add up the load and make the fuse slightly higher that the total. Do you have the data on the heater and the LEDs? As long as the cable is big enough and the fuse rated lower than the cable you should be ok.

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## XR500

I suppose your house battery/ies are a decent size. Those diesel heaters are neat, but if you have it running all night will use up a bit of juice. 10-11 amps on start up, settling back to 1-1.5 amps when running steady state.

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## norsk

> I suppose your house battery/ies are a decent size. Those diesel heaters are neat, but if you have it running all night will use up a bit of juice. 10-11 amps on start up, settling back to 1-1.5 amps when running steady state.


Yes thats exactly what I found out from the internet too.

The LED's in total draw 0.75 Watt

Adding a USD Charger for Drone/Phone etc won't up the draw too much?The Calbe is going to have to be around 5 meters long,will that have anything to say?

Its a truck battery I am installing so I could use it to star the truck if I needed to.

I see what you mean about the heater drinking a bit of Diesel,I was thinking about plumbing it into the tank on the mog.It came with a 10L tank but I think just plumbing it straight into the truck tank plus carying a spare jerry can is a better idea.

The heater is just to keep the inside warm while I am away during the day,I might install the wood stove I had in the other one to keep things cozy at night.

I will sort out the wiring on the LED's today and hopefully get the heater installed.

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## norsk

I have a quite a bit of battery cable.The likes of which you would run to the starter on a truck.I will use that.

I like the idea of a fusable link but I will hook everything up and see if there are any points the cable could rub through.I don't want an untidy mess but the house battery and truck battery are on opposite sides.

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## XR500

Re your cabin diesel heater, they are a brilliant invention, esp with the ability to program when you want it to start up. There's a dude on YT by the name of David McLuckie who's done about every conceivable test you can think of on those heaters. If you have any issues with it check out his channel.

Mogs are great machines to get about the bush in. Go anywhere. Do anything.

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