Tech spec for battery cable?

[Gary Symons]

Can anyone give me a pointer as to what I need cable wise to front mount the battery.

Guess I am looking for info on cable gauge, max current etc?

Also where would the best place be to get it?

[Jiff Lemon]

I always go back to what my tutor tought us at college;

"if it'll carry more, it'll carry less"

Wire in the Uk is generally measured by the number of strands and the thickness of those strands, then how much current it'll carry. More strands means more flexible cable.
Its been well over 10 years since I packed in being a sparky, and me saying that a few metres of that roll on the left isn't going to be much use! I'll check with my mate (who's still a sparky) and see if I can get any good contacts.

[djdna2000]

Demon Tweeks do a 135A rated type, the conductor has a 20 sq mm cross-sectional area.

[JB]

I have been doing a bit of research on cables ready for putting my battery back in so here's what I've found. Sparkies please comment.
First I looked in Haynes Car Builders Manual which gives recommended wire size and currents. This took the form of lots of wire sizes and currents but to cut a long story short if you take the csa in sq mm and multiply by 7 that gives you the current rating in amps. So for example if you have 65 strands of 0.3mm dia wire, since 0.3 mm dia gives 0.0707sq mm you get 4.6 sq mm which is good for about 33A. This of course assumes continuous currents and presumably wire lengths which could run front to back of car at least.
I also looked at jump leads which I found in 5sq mm, 10sq mm and 16sq mm sizes. The 10sq mm ones were 3m long and recommended for up to 2litre engines. The 16sq mm were 3m long and for engines up to 4.5litres for a cranking current of 400A and charging current, presumably continuous, of 200A (this is about double what the csaX7A formula gives!)
Next I removed the negative earth lead from an old Camry battery connector and found it had 175 0.3mm strands:rolleyes: which gives 12.4sq mm I also noted that on the Camry the starter current does a round trip of 1.2m Now this length of this cable,copper, has a resistance of 0.0016ohm In the Mk1 the round trip will be about 3 - 4m so if you want the same resistance you probably need 36sq mm However, the cable resistance only causes about 4%of the energy loss if the starter takes 300A at 12V so an increase in resistance may not cause a massive problem.
So from all this I have come to the conclusion that 16sq mm cable would be suitable but using thicker cable would bring the resistance closer to the original. Same as Dan's 20sq mm from Demon Tweaks above#-o
I also checked out my local welding supplies chap and he sells 25, 35 and 50sqmm cable for welders and he gave me a price of ?3/metre (all the same) so that's what I plan to use.
One of my mates at work teaches electrical installation but, more importantly he used to work with a rally team. He says they never used fuses on the starter circuit but just made sure the positive lead was well secured and insulated. On their cars everything went inside the cockpit to stay away from stone damage. I think if this positive lead was to short it is likely to be when the car is mobile so a battery isolator switch and fire extinguisher should cover this possibility.:tumble:
Yeah I know --- Get a life JB:nuts:

[superchargedsam]

JB did you actually "count" 175 strands of wire ? Please tell me you didnt !

[JB]

JB did you actually "count" 175 strands of wire ? Please tell me you didnt !
I'd rather not answer that question:oops:

[superchargedsam]

JB cant imagine how else you would know so now this means you gotta get some help, perhaps we ought to look at settting up TB users anonymous for those with certain swap issues, I mean going through a swap like this could be hard for some as they come "out" and admit they want to rip out the perfectly good 4AGE in favour of tubby or V6 power, I really do sympathise with you and know what your goin through and its gotta be hard, but JB remeber your not alone there are others like you really there are ! Now doesnt that feel etter already now you have shared your problems with everyone else !

[Paul Woods]

ha ha tb users anonymous! goes something like this....

hello,my name is JB,i count strands...

hi,my name is sam,ive got a compulsive mk1 buying disorder...

hello,my name is paul,ive got no roof on my car....

heellooo,my name is adam,you can never have too many speedo drives...

hi,im alan,i have a hardwired internet connection on the toilet,unfortunately i can only access ebay.....

hello,im nik,its too hot.... :D

hi,my name is malcolm,er....i have a really cool licence plate that nobody else can get in the uk...and um...oh yes! my roof is black.

hello,my name is podge,my intercooler is too small....

etc etc etc he he! :ha:

[superchargedsam]

lol yup rekon youve hit the nail on the head there paul !

[JB]

Gee thanks fellas. I just knew you'd understand:cry:
I've tried therapy and despite claiming to be sensitive women never understand my compulsions.
If this forum didn't exist I don't know where I'd turn.
Nik I just want to thank you with all my heart[-o<

[lodgeman]

i can access other things as well!!!!!:tongue: i think?:shock:

[adamh]

heh heh.. JB.. you need to get out more , mind, i guess every strand counts ey http://www.adamhutchison.co.uk/graphics/biggrin1.jpg