12 V battery choice

[Fredxx]

a 1m cable from battery to winch. So if we limit cable Vdrop to 5% or 0.6v...

My calculation assumed 50 Amps, which I felt is not an unreasonable starting point for a winch.

Secondly your calculation is per metre. So a 5 metre cable, ie there and back would be a total cable length of 10m with a 5% drop would require a cross-sectional area of 18mm^2. Just a total cable length of

1.0m isn't going to get you very far.

higher current draw, 2 pieces of 2.5mm^2, each with conductors parallelled would do that. That would be my preference.

Only on a very good day without any frictional losses.

[Bill Wright]

I'm not advocating getting a battery three times too big (as you imply). I'm advocating getting one that can handle the job with a bit in reserve. Less chance of a failure, with all the attendant inconvenience. Better to have a battery that isn't completely flattened each time it's used, then it won't need replacing every verse end. Hence my suggestion makes economic sense. Incidentally, why pay £125 for an 85Ah battery when you could have three

30Ah ones in parallel giving 90Ah at a cost of £102? (based on your figures).

Bill

[meow2222]

use a 1m cable from battery to winch. So if we limit cable Vdrop to 5% or 0.6v...

Its a 2 tonne winch rated to take about 83A at max load, pulling a 2 tonne weight up a shallow slope. So 50A is unrealistic. Idle current plus around

1/10th of 83A is nearer the mark, 25A is being generous.

No, its for a total cable length of 1m

I'm not seeing a problem with a winch staying in one place pulling the load home.

higher current draw, 2 pieces of 2.5mm^2, each with conductors parallelled would do that. That would be my preference.

Perhaps you misread. Those unlikely conditions would shift 20 tons, in real life it would only shift most of 20 tons due to friction, exactly as said.

NT