Excellent info there again, Sim

I have about 20m of 135mm (or there abouts) cable I scored from the last shutdown I did (ratted it from the scrap bin). Should do the trick, huh? Looks like I'll have to get busy before the alum radiator goes in (still off being modified so it will actually fit - but that's another long story)

So in short, run the earth wire from battery along the length of the car, and where it bolts to the chassis, attach the other earth strap (which goes to the engine block), so that the chassis is clamped between the 2 cable lugs - yes?

Also, mine is a rally car that will see lots of dirt and water, (possibly even on the inside). I would imagine I'm better off trying to get the connection as high as possible to keep it dry.

The +ve cable is housed inside heater hose along the main length of the car for additional insulation. I imagine cable tying the earth cable to the +ve wouldn't cause problems? Save trying to route the cable somewhere else.

135mm. is that regular cable or multi core cable??

So in short, run the earth wire from battery along the length of the car, and where it bolts to the chassis, attach the other earth strap (which goes to the engine block), so that the chassis is clamped between the 2 cable lugs - yes? yes

if ya positive is inside a heater hose then cable tying the earth to it should be ok.

with a rally car have the bolt point in the fire wall up the wall rather than in the floor pan.
you can get contact grease to stop the point from rusting as well under the lugs.

id also recomend using one of those circuit breakers on the previous page. especially in a rally car

a decent side impact from a tree can strip cable etc if it comes in far enough and split metal with enough damage to the shell.

better to be safe and have something that will trip, rather than being stuck in a burning car

Sim - you have PM

Sim any advice on the diagram a page back ? how does the gauges look etc etc.

sorry dude only just saw it.

ill print it off and have a look. (one thing ive picked up, need dual 8 gauge wire for alternator B+)

Thanks Sim really appreciate it. Ive really hit a bit of a blank for help on it.

From what Ive also found out, lots of guys in the US are running 150 amp circuit breakers and thats ok for the starter motor (personally still want a 200 amp one)

Sim if you want the file in .dwg I can email it to ya I work in CAD as well.

bought some 2 gauge wire from jaycar, forgot how much the stuff was $14/m..

-Anth

E-MAIL AWAY DUDE

that way i can put comments on it for ya..

sim_rx3@hotmail.com

You might also want to consider how hot the battery is going to get when you park it in the sun... keeping the box (usually black) out of the direct sun will extend the life of the battery.

My battery is already in the boot and was mounted prior to me purchasing my car.

I need to have a good look at what is going on with mine though. I had the alternator rebuilt a year and a half ago and i am pretty sure everything was ok prior but i am not 100% certain.

Basically i am getting a high voltage drop from the alt to the battery. On idle at the alternator i am getting around 13.8v but at the battery it is only reading 13.4 volts give or take.

This during the day as opposed to night when i have to use lights then it drops even more. Idle will be about 13.4volts and at the battery about 13volts. So this has got me concerned now.

I've been under my car many times and i am quite certain i have decent gauge wire running from front to rear, but i will have to have a proper check now.

I am not sure if i should take the alternator back to the auto elec and ask him to check it out, i just have a gut feeling after the reco it hasn't been the same.

I feel like those are still pretty good readings, specially for a remote battery set-up.
I'd only start to worry if the volts approached/dropped-below 12v at the battery end.
To simplify, the battery is 12v so anything over that should mean it's still charging to some degree, even though it's up and down a little due to other loads.

um no there not.

a perfect sytem should be around 13.8 to 14.2 at the battery. which is how any system should run all the time.
13.8 to 14.2 is the industry standard of what is acceptable anything outside that range is not acceptable.

its done this way for very good reasons.

1. battery life. it doesnt get the guts sucked out of it everytime the car is started cause its already at low volts if the system isnt charging correctly. especially when there are parasidic loads like clocks etc that feed while the car sits.

2. by having less volts to charge the battery therefore leaving it lower on the voltage scale, this also puts alot more stress on the starter motor as well. burning contacts in solenoids etc also the drain then also takes more power away from ecu's etc and so takes longer to start the car which intern puts more stress on the starter and solenoid. its a compounding effect.

3. if your not getting proper volts at the battery then you loose efficiency in the rest of the electrical system. notice when an alt is maxed or is struggling from age, how lights dim as the load increases. that also effects everything else in the electrical system. which is why ya engine starts to run shit etc etc as there is less power to go around.

a properly setup battery in the boot install shouldnt have ANY voltage drop at all. to have voltage drop means the system is inadequate.


plus in Ol-Skool case it is being maxed. give it less than 6 months and the reg will shit itself.

cause when a system is dropping volts under full load it does max out the reg and overwork them and they will shit themselves as do all FC....which has given them the apparent "shit alternator" tag. when they arent.
its just them working outside there design requirements takes them out.

hi man,

do you have a second hand alt or one you can grab from a mate to try??

see if its running fine on another alt to rule yours out being the problem first.

also to be loosing volts from alt to battery means either

1. the cable isnt the correct size
2. a connection has "gone hot" (high resistance connection, you will see melting of cable at lugs for this) or has loose connection.

I don't know why I even bother sometimes.

well telling someone there system is ok when it clearly isnt doesnt help..


but atleast people (and yaself) will read this now and get a better understanding of the charge system and how its suppost to work.

so its not all in vein!!

thanks for the advice guys... Maybe one day ill just come around to yours sim and throw you under the car for a beer of course.. warm and half drunk .. mmm

sounds like a plan

Which yellow top optima battery would better ? There are a few models on their website How are the diagrams coming along ? lol... cause i am the sorta guy that learn by practise or by pictures

hi mate,

any rated over 550 amps

diagrams are almost done. ive just got to proof read to make sure i havent missed anything.

Sim,
look forward to seeing those diagrams. They will be a real help.
Cheers

After you have done everything and are about to drill holes and bolt your new battery box up

Does it matter with weight distribution where you position the battery? in the dead centre, off to the side? closer to the petrol tank? Just put it out of the way to maximise uneeded boot space?
Would it make any noticable difference?

What do you guys think?