battery cable getting hot?
08-18-2012, 10:54 PM
#1
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battery cable getting hot?
85.5 944
The negative side of the battery cable gets hot to the touch when the lights are on and car running. the lights shine fine and bright. also the voltage on the car maybe a bit on the low side. with a voltmeter, i get 13.6v with car running, no acc running. with lights on it gets 13.2 and with lights, a/c, rear defog and radio on it goes to 12.9v running. the volt gauge on the dash shows a bit lower than what the voltmeter shows. the car runs fine btw....no issues there
we replaced the battery with a new one, the old one wasnt holding a charge any longer. we swapped the alternator with another known good one, we also cleaned battery posts, engine ground, chassis ground next to battery. we also removed the starter and cleaned the contacts on it.
we inspected as much of the wiring as we could. all the engine wiring looks good. we removed the fuse block, wiring looks good and unmolested. same with the wiring under the passenger dash. the car is all original. no mods at all. it even has the factory radio.
with engine running...we also removed fuses while checking voltage. depending on the fuse..it may go up .1 or .2v
the other thing we did was remove an old codealarm keypad alarm that wasnt working. when we removed the alarm we reconnected all wires that were spliced
now....this might be a culprit.
1) the door switch light. it will dim the light to about half when the door is closed..driver or passenger. we removed the door switches and they both look good. we removed the light switches between the visor and the rear hatch and the wiring looks good. also does the rear hatch have a door switch? we couldnt find one anywhere in the rear.
what else can i check? what did i overlook?
BTW...is it normal for the fan blower to be on low with the a/c switch and fan speed off?
The negative side of the battery cable gets hot to the touch when the lights are on and car running. the lights shine fine and bright. also the voltage on the car maybe a bit on the low side. with a voltmeter, i get 13.6v with car running, no acc running. with lights on it gets 13.2 and with lights, a/c, rear defog and radio on it goes to 12.9v running. the volt gauge on the dash shows a bit lower than what the voltmeter shows. the car runs fine btw....no issues there
we replaced the battery with a new one, the old one wasnt holding a charge any longer. we swapped the alternator with another known good one, we also cleaned battery posts, engine ground, chassis ground next to battery. we also removed the starter and cleaned the contacts on it.
we inspected as much of the wiring as we could. all the engine wiring looks good. we removed the fuse block, wiring looks good and unmolested. same with the wiring under the passenger dash. the car is all original. no mods at all. it even has the factory radio.
with engine running...we also removed fuses while checking voltage. depending on the fuse..it may go up .1 or .2v
the other thing we did was remove an old codealarm keypad alarm that wasnt working. when we removed the alarm we reconnected all wires that were spliced
now....this might be a culprit.
1) the door switch light. it will dim the light to about half when the door is closed..driver or passenger. we removed the door switches and they both look good. we removed the light switches between the visor and the rear hatch and the wiring looks good. also does the rear hatch have a door switch? we couldnt find one anywhere in the rear.
what else can i check? what did i overlook?
BTW...is it normal for the fan blower to be on low with the a/c switch and fan speed off?
08-18-2012, 11:27 PM
#2
It sounds like you have a high Resistance negative battery cable, that should be replaced.
Alarm disable: http://www.clarks-garage.com/pdf-manual/elect-23.pdf
There is a small HVAC fan used by the HVAC controller for cabin temperature ( not the blower fan),
this small fan should only run with the ignition in the on position.
Alarm disable: http://www.clarks-garage.com/pdf-manual/elect-23.pdf
There is a small HVAC fan used by the HVAC controller for cabin temperature ( not the blower fan),
this small fan should only run with the ignition in the on position.
08-19-2012, 02:11 PM
#3
Three Wheelin'
I would second that. If the cable is heating, it's resisting. Is yours the bare-metal braided sucker? You might think about replacing it with new, insulated copper after cleaning the ground points. I've read some guys use 0/1 welding cable as it is cheaper and more flexible. You might even be able to search this forum for IceShark and get some excellent discussion about the electrical system of these cars. He was the man who knew.
When I drove my 944 through the Winter my starter posts would get corroded to the point where I couldn't start the car until I cleaned them off. This happened every few weeks until I coated the posts in Liquid Electrical Tape. Never happened again. Now I coat all infrequently-touched electrical connections with the stuff. I put dialectric grease on the battery posts for good measure.
It's not Porsche-specific, but a lot of guys do the "big 3" upgrade of replacing the ground strap, battery positive, and starter cable to get better performance out of lights, stereos, etc.
When I drove my 944 through the Winter my starter posts would get corroded to the point where I couldn't start the car until I cleaned them off. This happened every few weeks until I coated the posts in Liquid Electrical Tape. Never happened again. Now I coat all infrequently-touched electrical connections with the stuff. I put dialectric grease on the battery posts for good measure.
It's not Porsche-specific, but a lot of guys do the "big 3" upgrade of replacing the ground strap, battery positive, and starter cable to get better performance out of lights, stereos, etc.
08-19-2012, 11:58 PM
#5
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thanks for the suggestions guys...i will look into replacing the battery cable. also i didnt see the ground strap. i remember when i had my 84 944 it had a braided ground strap. in my 85.5 i dont see it. the battery negative cable goes straight to the engine and from the battery negative...it connects to the chassis next to the battery. it looks factory
