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HOW TO: Build or shorten a battery cable

John E Davies

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You can buy custom length cables of any type and size, and they are quite affordable, but this really limits how well they will fit and also you have to wait for them to be made and shipped. I don't believe they will install anything but straight ends, but you can order one unfinished, with one raw end for you to complete.


They also sell high quality battery cable by the foot, they have all sizes. The prices are a little lower than most other suppliers.


A good crimper is essential, a crude "beat on it with a hammer" one will be acceptable if you can access the parts away from the trailer. If they are in a tight location, or to make perfect crimps, you need a good hydraulic tool:


TEMCo Hydraulic Lug Crimper Tool TH1818 DIELESS Indent 10AWG to 400MCM

And some heavy self adhesive heat shrink tubing to cover and reinforce the connection:


For cutting, a big cold chisel and that great big hammer will work, with the cable laid onto a piece of steel plate or a bench vice. This is way more elegant, it gives precise even cuts, it won't slip and smash your hand, and you won't say any bad words:



That particular tool will fit over the big 4/0 welding cable that Oliver uses (with inverter) but only if it is slid down the length of it from one end. If you need to chop a long 4/0 or larger cable in situ, you will need a big size cutter. I had no troubles using this medium sized one on all the Ollie cables.

TEMCo TH0001 4/0 (0000 Gauge) Wire and Cable Cutter – with 12 in. Handles



Sometimes an angled end terminal fitting will be useful, to allow the cable to lie in a more natural position. These are very hard to find locally, and it is not recommended that you bend a straight one, it can cause cracks and eventual failure. Choose a terminal end with the exact hole size you need, or one smaller (you can drill it larger). For any cable carrying high current, do not install oversized ends on a smaller post, it limits the contact area and could possibly cause issues like overheating or loosening.







I hope this is useful. Measure three times, cut once!

John Davies

Spokane WA



Edited by John E Davies
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I bought one of these many years ago when I was installing an inverter and updating the Outlaw Oliver to 4/0 battery cables. It will make a hexagon shaped crimp that really looks good. Out of curiosity, I once cut thru a connector and examined the crosscut strands inside under high magnification. Each strand had been compressed into a hexagon shape and fused together.

Here is a really good video showing exactly how it should be done although he calls it a "flaring" tool!

Edited by ScubaRx

Steve, Tali and our dog Rocky plus our beloved Storm, Maggie, Lucy and Reacher (all waiting at the Rainbow Bridge)

2008 Legacy Elite I - Outlaw Oliver, Hull #026 | 2014 Legacy Elite II - Outlaw Oliver, Hull #050 | 2022 Silverado High Country 3500HD SRW Diesel 4x4 





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Good video - the hex crimpers are definitely worth it, even for a small project.  I also tried to take a lug off and you're correct, the only way it's coming off is to cut it.  If done correctly, everything will be fused together - like putting pennies on a train track.  

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Another vote for a hydraulic hex crimper.  I have used both stab and hex crimpers extensively in boat building and am convinced the results from a hex crimper are by far superior.  Coupled with a good adhesive / heat shrink tubing will give you a really fine cable.   I do not remember the brand I purchased but it was under $100.

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