Split Charge relay - advice

I am no car electrician but would have thought:

1) there is no need for two fuses, after all when the relay closes live from car battery and live to aux. battery is one circuit. Size of fuse would depend on the rating of the relay.

2) Don't quite get this. What negative feed from the relay? The only "negative" would be the earth in the actuation part (if that is the right word in English, sorry am Dutch) of relay (i.e. small current from the alternator terminal that also controls the charge light of your dash), the current that closes the relay to join positive terminals of battery together. The aux battery obviously would need a good earth to charge.

Pieter

I'm using this as a guide:

plus the printed instructions with the fancy relay I've bought - both suggest a fuse to both positive terminals. The relay is rated at 25 Amps so I'll use that size fuse.

The relay needs to be earthed to the chassis - I was just wondering if it would be beneficial to run it back to the battery -ve terminal rathe rthan faff around with yet another chassis earthing point.

Graeme

There's no point putting two fuses in, and I'd use a 12v MCB instead personally. The fuses are in the same piece of wire, when the switch is closed, and they aren't connected anywhere when the switch ISN'T closed, so why two fuses ?

Also, don't use a 1N4001 across the relay - use at least a 1N4007, and again, there isn't a right lot of point, its a nice touch, but the starter motor will put out rather more inductive kickback than a poxy bloody relay.

No problem, if its easier to put it back to the battery, do it.

Hi Steve

Thanks for that - I'll bung one fuse in for the time being and get a MCB next time I get anything from Maplins or RS.

I was not going to be doing the diode bit as the beast is only going to be powering a couple of internal LCD spotlights and a ciggy lighter fitting to run laptop/shaver/whatever.

Trouble is it's too dang cold out there to do any meaningful work - oh for a garage/big shed/101 with a cabin heater

:-))

Now I w>

Maplin ? Bwahhahahhaahh.

RS will have something though. Or Vehicle Wiring Products.

Vital. And if she's like Lizzy, hide the keys.

Steve

On Tue, 28 Feb 2006 16:58:34 -0000, "Graeme" scribbled the following nonsense:

mine took about 1 second to convince, in the end, it was more her than me that wanted an ambi, cos she got fed up with the tent, and now lloks forward to a life of luxury camping!

Funnily enough - when we first met she (somehow) ended up using my Range Rover as her daily vehicle and I got relegated to the 88" - spooky things these femaliens

GT

Graeme,

Having given it some more thought I can see (some) sense in two fuses, in the unlikely case that there would be a short in the relay (i.e. from either of the battery lives to earth) it could still draw current from the non-fused battery, if you only put a fuse in one side. Unlikely, if you ask me, but if you want to be fool proof two fuses would be better.

Pieter