Electrical

Battery Cable Upgrade

Kevin wrote:
> I noted with some interest the battery cable upgrade Sterling did on
> www.928SG.com. I am wondering if the 1/0 wire that I can get from Home Depot is
> going to be as good as the 1/0 wire you can get at a high end audio store.
> We all read about oxygen free monster cable and all that. But, in a car
> application does it make a difference. I'm on the fence.
>
> Do any of the EE folks have an opinion?



Hi Kevin and all,

While I'm not (and never will be) an EE, I have done this "battery cable upgrade" several times on assorted vehicles over the years. I really doubt that there is any *real* benefit to using oxygen-free
copper in this application - you are trying to send the maximum possible current through the cable, not audio spectrum frequencies.

I have always gone to a welding supplies wholesaler to obtain the
cable. Welding cable is specifically built for very high current
flow and a harsh service environment. Irrelevent of where you source
your cable, here are a few hints:

- when you buy your cable, ask them to cut you an additional piece about 2 or 3 inches long. Strip about 3/4" of the insulation off of one end.

- take this short piece with you when you go shopping for your terminal ends (much more convenient than dragging 15' (and 30+ lbs) of cable into your auto parts store!).

- #1 AWG (and you can actually get #0 AWG, even larger) cable is BIG. You may have a hard time finding terminal ends with large enough holes in the end to insert the big cable. Buy the terminal ends with the closest available bore size and be prepared to drill these larger to accept the cable. Avoid the temptation to use the battery terminal ends that use a "clamp" and bolts to affix the cable to the end piece. This is an inferior connection with reduced conductivity.

- a hand-held propane torch will be the weapon of choice to perform your soldering.
- as in any electrical or electronic application, NEVER use acid-core solder or the acid flux in a tin. Use rosin-core solder!

- you will find it easier to get a good solder joint if you heat and apply solder to the end of your stripped cable prior to inserting the cable into the terminal end. If you get a lump or two when you do this, it is very easy to take a hand file and remove the lumps (solder is an alloy of tin and zinc, and is very soft) to return the cable to "round".

- insert the "pre-tinned" (common soldering expression) cable end into the terminal end and apply heat with the propane torch. When the solder on the cable end begins to liquify, take additional solder and "flow" it into the joint. Make sure you have the pieces hot enough that the solder has a shiny appearance - otherwise you will have what is referred to as a "cold solder joint", which reduces electrical conductivity.

- the cable end/terminal is going to retain heat for quite a while so be careful before you grab it with your hand!!!

- as Sterling did, use heat-shrink tubing to cover your joint. Gives the entire end a much more professional appearance, reduces the chances of inadvertent electrical shorting, and keeps the dreaded "green stuff"
from growing!

- at the starter end, I always use some braided heat-resistant sleeve material (looks similar to asbestos, but isn't) to cover the last 8" or so of the cable. This reduces the effect that the proximity of the cable to the exhaust manifold/header/pipe has, which due to the heat in the area will cause the cable rubber insulation to become dry and brittle over time. Short lengths of heat-shrink tubing at each end of this "sleeve" will hold it in place. Obviously, make sure you have slid all of these pieces onto the cable BEFORE you solder the starter terminal "eye" onto the cable....

Hope this helps someone out there contemplating this upgrade.

Brad Orr
'78 euro 5 speed
OBC
928-OC