Thread: Do I need a BCDC charger?

Originally Posted by John_D2

My bad, fuses were an assumed part of the discussion. I have 1x 80amp at the dual end of the 3b&s and another 80amp at the camper battery. I thought this would be sufficient.

Hi John and if you have run 3B&S from the cranking battery to the battery in your camper, then yes, the 80 amp fuses are fine.

Originally Posted by John_D2

Also, on the tow bar I have 1x150amp Anderson plug, plus I’ve spliced in a 50amp to sit next to it to make it more universal

The 80 amp fuses are fine with the 150 Anderson plug, but you should consider fitting a 50 am fuse between the junction and the 50 amp Anderson plug.

You will "probably" be safe with the 80 amp fuses protecting the 50 amp anderson plugs, but you are stretching the safety limits a bit.

There's nothing wrong with running 25 mm sq cable John, when you're talking reasonably high currents such as 80 amps there's no such thing as cable that's too big though I'm surprised that industry still use the obsolete and totally meaningless AWG (American Wire Gauge) and B&S (Brown & Sharpe) wire gauge descriptors when talking cable size. There's only one meaningful measurement of cable size and that's square millimeters, fancy that, a unit that actually conveys meaningful information and we went metric when ? 1974
Don't confuse this though with automotive wire gauge where they use a totally misleading cable size that includes the diameter of the cable AND insulation to define cable size so that an Automotive 4mm cable is actually only 1.8 sq mm. Talk about misleading the average punter and ripping them off when buying cable.
Considering your fuses though, what type of fuse did you use ? Normal blade fuses are way too small for this but maxi blades go up to 100 amp or so but still have quite small 'cross sectional area' contacts IMO for currents of this magnitude. HRC type fuses might be big and bulky but I'm yet to see one with burnt contacts at this current level Codan actually recommended using this type of fuse for my HF radio.

Deano

Originally Posted by DeanoH

when you're talking reasonably high currents such as 80 amps there's no such thing as cable that's too big

When are you going to get an 80A load in the trailer?

[QUOTE=Mick_Marsh;2757348]When are you going to get an 80A load in the trailer?[/Q

what about using an inverter on a microwave/coffeemaker etc

My auto electrician put 60 amp fuses and appropriate cable between my batteries, with a Traxide in the middle.
As was said, 80 amp fuses seems a fair bit higher than 50 amp Anderson plugs.

Originally Posted by drivesafe

The 80 amp fuses are fine with the 150 Anderson plug, but you should consider fitting a 50 am fuse between the junction and the 50 amp Anderson plug.

You will "probably" be safe with the 80 amp fuses protecting the 50 amp anderson plugs, but you are stretching the safety limits a bit.

Poop...I forgot that. I only left about 4 or 5” of wire between the 2. I’ll see what I can do. 50amp ok?

Originally Posted by DeanoH

There's nothing wrong with running 25 mm sq cable John, when you're talking reasonably high currents such as 80 amps there's no such thing as cable that's too big though I'm surprised that industry still use the obsolete and totally meaningless AWG (American Wire Gauge) and B&S (Brown & Sharpe) wire gauge descriptors when talking cable size. There's only one meaningful measurement of cable size and that's square millimeters, fancy that, a unit that actually conveys meaningful information and we went metric when ? 1974
Don't confuse this though with automotive wire gauge where they use a totally misleading cable size that includes the diameter of the cable AND insulation to define cable size so that an Automotive 4mm cable is actually only 1.8 sq mm. Talk about misleading the average punter and ripping them off when buying cable.
Considering your fuses though, what type of fuse did you use ? Normal blade fuses are way too small for this but maxi blades go up to 100 amp or so but still have quite small 'cross sectional area' contacts IMO for currents of this magnitude. HRC type fuses might be big and bulky but I'm yet to see one with burnt contacts at this current level Codan actually recommended using this type of fuse for my HF radio.

Deano

True. A house sparky friend was advising me on wire size for the 2 x 130w/7.5 amp solar panels and was telling me to use 6mm wire. Meaning 6mm2 or 4mm wire. I was confused thinking he meant 6b&s. I couldn’t work out why he wanted 2 runs of 6b&s for 15amp if load!