Might be a random question, but does the smart charger (permanently plumbed in to the camper via a mains hookup) need to be wired directly to the leisure battery. Or can it be to wired say to the power coming in to the auxiliary fuse box? (Just trying time reduce running around of of wires). Does the -ve need to be physically attached to the leisure battery -ve pole, or can this just we well earthed? Cheers
This depends on whether the wiring is low enough resistance that there is essentially no voltage drop along it between where you connect the charger and the battery, that depends on the wire thickness and length and the charger current. Its best to keep the low voltage side shorter , putting the charger near the battery is better than having long wire runs, its better to have one thick wire to the common point though than having a two separate bits of thin wire one for charge and one for discharge .. Using the chassis for negative may be lower resistance than using a wire but in the case of the battery charger it needs to "see" the voltage on the battery without other effects down to current flowing. Best off is battery charger near battery with its own short wires, and run a mains lead to it as that doesnt bring up voltage drop issues.
Assuming you have used heavy enough cable to the fuse box and the leisure battery is earthed to the bodywork then no problem connecting to the fusebox and earth to the body, best to run it through one of the fuses in the fusebox.
Thank you both, thought that might be the case. What ampage cable would be heavy enough do you think if I ran a dedicated cable from the LB to the ancillary fusebox? The cable length between the charger (located next to the fusebox) and LB would be 3-4 foot. Nothing fancy will be running from the leisure battery via the ancillary fusebox. Water pump, couple of LED light strips, couple of USB ports and a fridge every now and then. Thanks!
I usually use 6mm2 to the ancillary fuse box which is around 50A with a 40 or 50A maxi or midi fuse next to the battery, gives you the option of being able to add things at a later date.
I think mine is 6.0mm2 and the charger/inverter is about 2 feet from the battery, it charges at 10 amps and discharges at up to 60 amps if the inverter is running flat out. There is a 100Amp resettable circuit breaker on the wire at the battery end. Also good for isolating the batteries when working on the bus.. solar cell isolator switch off, leisure battery breaker open, undo wing nut on starter battery.. . Earths are all joined to chassis but all on a common stud. Negative lead on leisure battery is 10mm2 or so, so a single jump lead from positive to positive lets me jump start the starter battery if I need to, without having to worry about the current going down the leisure battery negative cable.
I'm trying to finish off the interior and electrics etc, I have a question, why have a 100Amp circuit breaker protecting a 50 Amp cable? (6mm) is it just used as an isolator? I'm just trying to get it right without buying thing twice
You don't, you use a max 50A fuse for the cable protection. Short lengths of cable you can increase the capacity, you then need to work it out from the ohms per mtr.
