# Extending Battery Cables



## BeeMike (Aug 3, 2011)

I am in the process of replacing the battery pack and other components in my Escort EV; the cables that were run from back to front for the original set-up are too short to reach where the new post connections will be. I also have to change the connectors from automotive to lug end. The original company did a good job of pulling all the cables together through 2" PVC conduit, and they are a very snug fit; I can't tell if they strapped all of the cables together or not, which makes pulling out the 2/0 cable and pulling new cables through (which would be my first choice) very difficult if not impossible. I have used heavy copper bus bars in the past on other EV's as connectors between lug ends on 2/0 cable in some places. 
Is there a better way to extend cables? I wouldn't think that a crimped butt splice connector would be anywhere near capable of safely passing full pack amperage for an EV. In low voltage (36 & 48 volt) EV's. I have just bolted the lug ends together without ever seeing problems, but it doesn't seem like it would be sufficient for this application.
What would be the best way(s) to do this?
Thanks!
Michael B


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## Woodsmith (Jun 5, 2008)

How much do you need to extend them by?

If it is only a short distance from where an original battery was to the new battery terminals then you could use it as a convenient point to add a fuse block and cut out.

Mount a board on near the cable entry and mount on it an ABS box with bolt post terminals to fit a fuse or two. The the new cables can go from the fuse to the pack.


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## BeeMike (Aug 3, 2011)

That is a great suggestion--and one that I can use. I have a monster fuse that I want to put between the positive lead and the contactor; I can put it in the back battery box and connect it that way.
Thank you!
Michael B


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## PeterH (Mar 20, 2009)

I'd like to try breathing some life back into this thread... 
This is the only thread to ask the question so rather than start a new one, let me see if anyone has a different answer to the original question.

I've just discovered that I need to extend a double-0 cable by about 3 feet so my maintenance switch can be at then end of the battery pack instead of between 2 of the 5 boxes of cells.

I don't have the room or the need to install a fuse close to where the splice should go or I'd take that great advice. So I'm back to wanting to splice the 00 cable.

Any safe suggestions?

Thanks,
Pete


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## BeeMike (Aug 3, 2011)

I started this thread, so I guess I should have posted what I did to make it work for me in installing my new LiFePo4 pack.
The Most Negative lead already had a lug connector, so I crimped another lug connector to my new piece of 2/0, brushed both lugs with electrically conductive wire glue, bolted them together, wrapped with electrical tape, then sealed it with heat shrink. I only needed to go about 20" to the Most Negative terminal, but that kept me from having to pull a new cable from front to back on the EV.(http://www.evalbum.com/4181)
I haven't seen any increase in resistance in that circuit yet.
Hope this helps!
Michael B


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## PeterH (Mar 20, 2009)

Thanks Michael. That is helpful and sounds close to an idea I had in mind. I don't have to do this immediately. A damaged BMS board has to be replaced first so while I wait, I'll test it "BMS Free" for a few days. Hoping for my VERY FIRST drive as soon as the rain lets up here in Norther Idaho. 
Pete


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## mizlplix (May 1, 2011)

In the past, I have spliced welding cables together and been OK with it.

I bared 1-1/2" of each cable, inserted the ends in a 2" piece of copper tubing, crimped them and sweated it solid, from both sides. A layer of fusion tape and it was good to go.

We used it on an air/arc cutter running 600 amps current at 75 volts without any local heating or melting. Meaning it was good enough (or as good as the rest of the cable.)

Miz


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