Battery charger extension leads


16 May 2001
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Having come to 2 dead batteries at the weekend (my fault!) I want to make it easier to leave one or the other battery on charge when I leave the boat.
One is in the engine compartment and one in the outside locker. I want to set up permanent leads so that I can set up the charger from inside the main cabin.
I have an Accumate charger & 2 Optima batteries

I need to have longer leads but would rather make some up - as the Accumate extensions aren't quite long enough (and not so cheap)

Any ideas what wires I should get to make the leads up (I was just looking in Halfords today, and speaker wires look like they'd fit the bill, but is there any reason why not ?)

25 Feb 2010
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You didn't say what current is churned out by your charger but, so long as the wire can carry that current, then almost any type of wire will be OK.
Don't forget fuses (sorry; granny, eggs, sucking comes to mind)


Well-known member
13 Jul 2002
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The leads must obviously be heavy enough to take the maximum output from the charger safely. Therefore need to know the exact model or the current output. ( although the size of domestic flex used for that current would be appropriate as a minimum ).

BUT in order to avoid excessive voltage drop the length of the cable run should also be taken into account. This will probably mean heavier cable than the above would suggest.
Need therefore to know the lengths of these cables in order to determine a size which will not result in excessive volts drop.

The basic Accumate has an output of only 1.2 amps.
0.5mm² cable ( 3amp) would in theory be heavy enough up to 15ft and 0.75mm² ( 6amp ) cable up to 20 ft. In practice you would probably want to use heavy cable than either of these for robustness.

If you have the Accumate Pro with a 7 amp output then much heavier cable will be required. 5mm² for a 20ft run!
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