split/realy charger

[Caveman1]

Ok i need to buy split relay charger so im thinking of going with one of the smartcoms, just want it to charge the leisure battery run my fridge,bu t im reading about people fitting 100a relays in the circuit. Is this neccasery?

[California Dreamin]

Ok i need to buy split relay charger so im thinking of going with one of the smartcoms, just want it to charge the leisure battery run my fridge,bu t im reading about people fitting 100a relays in the circuit. Is this neccasery?

It doesn't hurt...necessary, well probably not but the thinking behind it is reliability because it's heavier duty...still, I would consider a 40amp relay as being the absolute minimum but looking at something 60amp or higher.

However.....as you specifically want a switched fridge live (so the fridge only uses 12 volts with the engine) you might want to look at one of these: Durite also do a 70amp version.

http://www.autoelectricsupplies.co.uk/p ... tegory/113" onclick="window.open(this.href);return false;

Martin

[1664]

Besides the reliability of a heavier duty relay the other consideration is the leisure battery recharge current. Although the fridge takes a constant load of just under 10amps the leisure battery recharge current is dependant on how discharged it is; the more discharged, the more current it will drag from the alternator once the engine is started and the relay is energised. This load can be quite considerable, I've seen my leisure battery pull well over 50A on occassion, (plus your fridge if you use the same relay to perform both functions), all of which is flowing through the split charge relay, fuses and associated cabling.
Before I fitted a heavy duty relay I had a 20A relay fitted (with 20A fuses obviously) and sometimes the fuses would go and sometimes not. Even when not, the plastic insulation around the fuses would get hot and melt. Once that happened I had to recharge the leisure battery using jump leads from the starter battery - a risky endeavour that needs constant supervision as fuses have now been taken out of the equation.
When these vans were originally designed we didn't have the plethora of electronic devices capable of being run off a leisure battery, just a couple of lights and a black and white TV if you were really lucky. Nowadays people plug in everything except the cat.