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Hot wiring after jump start
Posted: Tue Feb 28, 2006 4:46 pm
by grazza
Noticed something not so nice after jump starting my Patrol.
Left the lights on the other night and flat battery in the morning. Jump started the car and the alternator-to-battery wire started to burn its insulation. Charged the battery up overnight from 240V and the wiring is not longer hot.
I am guessing that the alternator was pumping heaps of amps down the wire since the battery was dead and "sucking" a lot more than usual.
Do you think I have a serious problem or is this common for dead batteries?
Posted: Tue Feb 28, 2006 5:03 pm
by chimpboy
It does sound like the battery was drawing more current than the wiring was designed for. Easy fix - upgrade the cable. I would be surprised if it's anything else. Is the alternator a standard one or an upgrade?
Jason
Posted: Tue Feb 28, 2006 7:46 pm
by grazza
I guess I am asking for problems - its a 1uz-fe motor with (I think) 90A alternator but its probably the standard wire, which looks like 50A.
I have booked it into see the auto lekky since I have some other strange problems like - cannot stop the car (ignition) without pulling on the handbrake!
The thing is, its hard to find an auto electrician who really makes an effort on custom jobs.
thanks Jason.
Posted: Tue Feb 28, 2006 9:44 pm
by 84ZOOKSTA
That short bit of wire is designed to burn out, thats if it is the same as a 75 series, or maybe that wire is just way undersized.
a 6mm cable is good for about 32amps
a 10mm cable is good for about 50amps
a 16mm cable is good for about 80amps
a 25mm cable is good for about 100amps.
these figures are round figures and certain cables do vary and also depends on the cable length ie.voltage drop.
I installed a winch in a mates 75 series and it has a 120amp alternator. under normal condition the max current drain with every thing on and charging the batery was only around 45amps so that small bit of cable had no problem at all, But try winching with a winch that draws 300amp+ i put the Clamp meter/tong tester(Clip on amp meter) on the alternator and it was working overtime. the fix was to remove that fuse all together and have never had that problem since.
Cheers
Simon...