what size cable to use

[jamie langstone]

I want to up my battery bank with another battery but what size in mm2 or awg wire do i use. This will be for the domestic side of things not the starter battery.

 

[aquapower]

I want to up my battery bank with another battery but what size in mm2 or awg wire do i use. This will be for the domestic side of things not the starter battery.

25mm would be good as long as there's not thruster connected, will take 170a.

 

[Seastoke]

25mm would be good as long as there's not thruster connected, will take 170a.

??

 

[sarabande]

not enough info to say 25mmsq, shirley ?

Capacity of batteries
Distance between batteries
Max load out and in
Ambient temp range
Cable in conduit or air
Thickness of insulation plastic


25mm seems a bit on the skinny side.

 

[aquapower]

not enough info to say 25mmsq, shirley ?

Capacity of batteries
Distance between batteries
Max load out and in
Ambient temp range
Cable in conduit or air
Thickness of insulation plastic


25mm seems a bit on the skinny side.

How much do you want to run off domestic batts?, unless thruster is connected I'm going by the size used on most new installations.

 

[sarabande]

not unusual to run a mains inverter for hair dryer or similar heavy startup current. I've got a 450W inverter on 24v system.

How many people fuse their batteries anyway ?

 

[nigelmercier]

25mm would be good as long as there's not thruster connected, will take 170a.

The current capacity of the cable is almost totally irrelevant. FWIW, my battery cable is all 95mm²

 

[Danfarry]

70mm cable will carry 181.82A over 5 metres with a volt drop of 0.56v

 

[Sneds]

Try an ho7 rnf or a tq type ho7 bn4
85 degrees c insulation and very flexible

 

[Seastoke]

all good posts but surely cable is relavent to the fuse protecting it if you run your cable from batteries a long way to your fuse distribution panel what is protecting the cable ,we need more info

 

[jamie langstone]

all good posts but surely cable is relavent to the fuse protecting it if you run your cable from batteries a long way to your fuse distribution panel what is protecting the cable ,we need more info

All what i want to do is add another battery to gain extra time when i am using the domestic side of things before the batteries start to drain . The cable length will be 1/2 meter for each cable as the batteries will be alongside each other.

 

[rosssavage]

Still no help Jamie!! You could be drawing 1 amp or 1000 amps!!!

A starter for ten would be to use the same size as the other battery(ies) use to go out to the distribution centre.

But more info is really needed....

 

[Cruless]

what size cable is currently used between your existing batteries?
what size are your current batteries? an extra battery should be the same type and rating as the other batteries in the circuit. to avoid over and under charging issues
what rating is your charging system will it beable to able to cope with another battery without too much strain being added?
what equipment is on your vessel , bow thruster? windlass, demisters, etc

 

[Lon nan Gruagach]

In theory you would use a cable with half the capacity of the existing cable, given that half the current you already used will come from the new battery. However thats really being a bit picky. I would go with what rossavage says and use the same size. Provided your useage remains the same.

 

[GrahamHR]

The big current draw circuit is the starter, My D4 has a 70mm2 ( the US equivalent) cable for that. I rewired from one to two domestics using the same size cable, so the emergency connect from the domestics to starter is more than ample.

A hint to anyone doing battery rewiring; buy a hydraulic crimper and make your own custom length cables; cheaper and neater.

 

[Gemini]

Use the same size as the existing cables, if you isolate your battery and remove the connection on the cable lug will
be 2 numbers 70 8 this means the cable size is 70mm2 lug hole size 8mm , cable sizes are generally 70mm, 95mm or
120 mm hole sizes 6,8,10,12 etc

Electricity will take the shortest route of resistance , so keep to the same size cable .
HO7 cables are good choice as flexible.