auxillary battery cable charge question

[camper]

I have been reading through topics about split charging a second battery and a suitable relay ie intelligent or alternator controlled.But seeking advice as to a suitable 12 + feed cable to the auxillary battery.The vehicle is a diesel and the starting battery is in the engine compartment i will be installing the second battery behind the passenger seat .The 12 volt + supply needs to be enough to overcome losses in aprox 3 /4 metres of length .I have seen 240 volt mains supply cable for welding equipment on ebay and would consider this.Example http://cgi.ebay.co.uk/Welding-Cable-180 ... 2552f96dd1" onclick="window.open(this.href);return false; Advice apprecciated.

[Red Westie]

I had a quick look at an Auto Electrical Supplies and they quote 25mm/2 as being capable of 170amps which is more than enough infact well over rated (80amp cable would be enough) but heavier is never a bad thing. The terminals are always going to be the weak point in a high load carrying circuit like this, so be sure they are either professionally crimped or soldered, infact, getting terminals that fit between a large core wire and the relay can sometimes be a problem.
http://www.autoelectricsupplies.co.uk/product/752" onclick="window.open(this.href);return false;

Martin

[camper]

Thanks Martin your reply&advice is appreciated.

[ghost123uk]

And may I add the obvious = make sure any place the cable might chafe against metal it is protected.
You don't want a heavy cables insulation wearing through sometime in the future and shorting to earth =

[CovKid]

Amen to that. Rubber grommits used in electrical backboxes are good protection. I keep a stock in my toolbox and they frequent'y get used for this sort of thing. Cheap for what they are too.

[Willoughby]

And may I add the obvious = make sure any place the cable might chafe against metal it is protected.
You don't want a heavy cables insulation wearing through sometime in the future and shorting to earth =

Gives a new meaning to welding cable

Kev