- Thread starter nickk
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brightspark
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use the chart as above and measure the csa of your existing cable 
thanks,i found that yesterday,but the question is which amp figure do i use 770 or 110?use the chart as above and measure the csa of your existing cable
AndyStobbs
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Figures on the chart appear to be how much current you expect your cable to carry - rather than battery capacity/performance.
eg. The 25mm cable will carry 170A before you being to run up against voltage drop - which is your enemy. How big is your forklift engine? Is it diesel or gas?
eg. The 25mm cable will carry 170A before you being to run up against voltage drop - which is your enemy. How big is your forklift engine? Is it diesel or gas?
madkayaker
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I use 50mm for main battery cables then as grot gets into cables and increases resistance it still starts
Lawnmowerboy
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Where's me post gone?
normspanners
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Youve cut it off with ya mower!!!
its a 3cyl perkins diesel,as in mf tractors,prob'about 35-40bhp.MK's idea of reserve capacity seems wise.
madkayaker
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It's also partly due to the fact that I have access to lots of 50mm welding cable
good reason!
AndyStobbs
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50mm will be fine, with capacity in reserve.
So will the cable be carrying 770 or 110?
its unclear.
madkayaker
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Upto 770A that's the cranking capacity of the battery. As its short time though the cables won't heat up that much
so do i assume cable size is calibrated @110a?
madkayaker
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No 110 amp hours is a measure of how long the battery can provide 1 amp (or number of amps) I've never really tried to work out starter cable sizes I've just used as big as possible. My tractor has a almost same size battery and that's got 25mm cables and start fine. However due to change lugs on battery so will use 50mm for new ones for the reasons I've stated.
AndyStobbs
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Very rough estimate off the top of my head would be 150- 200amp starter motor draw. Will depend on condition of your engine and other factors what the actual current is.
Your battery can supply a theoretical absolute maximum current of 770A, this is derived from battery construction etc.
However it will supply (claimed) 110A for one hour. Or 1A for 110hours, or any figure inbetween,
say you asked it to supply its max of 770A,
it could supply 770A for 0.14 hours - approx 4 mins, before it was so flat the voltage would have dropped enough to not be useful.
Your battery can supply a theoretical absolute maximum current of 770A, this is derived from battery construction etc.
However it will supply (claimed) 110A for one hour. Or 1A for 110hours, or any figure inbetween,
say you asked it to supply its max of 770A,
it could supply 770A for 0.14 hours - approx 4 mins, before it was so flat the voltage would have dropped enough to not be useful.
madkayaker
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I put a ammeter on tractor starter as was having a few issues it was pulling 260 amps if that helps
brightspark
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a 25mm cable will pi.,,.,.s the starting on a 3 cylinder perkie no bother it isnt constant current rating 
well thats sorted then -i've used 35mm w.cable,although the strands are much lighter,hope it can suffice.a 25mm cable will pi.,,.,.s the starting on a 3 cylinder perkie no bother it isnt constant current rating
