Driving with alternator wire disconnected


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Old 11-27-08, 11:52 AM
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Driving with alternator wire disconnected

Will there be any negative results in disconnecting the output of the alternator to the battery and starting the vehicle and driving it?
Other than the obvious fact that I wont be charging the battery.

I was thinking (Thats usually the first step of creating one of my problems) that I could test my battery reserve capacity in a real world environment and find out exactly how long I have until I go down to 10.5 volts and how the car will act at that voltage.
I would have my voltmeter sitting by me as I drive via long wires.
 
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Old 11-27-08, 12:40 PM
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how long will depend on which accessories you are running. it will not hurt the alternator. or the engine, low voltage is not good for electronics and it is bad for lead acid batteries to discharge them and recharge them. keeping lead acid batteries fully charged is one of the keys to longevity

life begins when the kids leave home and the dog dies
 
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Old 11-27-08, 12:51 PM
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Thanks
I would take my spare battery and install it if the car died. I forgot to mention that.
I wish to "load test" them.
So a RC (reserve capacity) of my battery which I use now is 90 minutes
So at a 25 amp draw at 80 degrees F I should be able to go 90 minutes until I hit 10.5 volts.
BUT
For once in my life I want to test my car FOR REAL. That is with present temps here in ONT Canada in the winter and I want to have my lights on and the windshield wipers going and the rear defogger and the heater fan cranked to high as if I were in a real snow storm trying to get home or to the nearest town.
I think that would be the only true test to know how many miles I could go before the car quit and left me beside a snowbank it white out conditions.
The difference would be knowing when to pull over to someones lane-way to avoid stalling on the snow covered highway and causing and accident.

I'm guessing that 10.5 volts is the magic number for the coil to be close to the end of service.
So I would go by that benchmark also.

I wonder if it would be better to pull the field wire or the output wire???? Or none????

I dont care about the battery but I dont want to damage the electronics even though it is an old car.

I would go with the 10.5 volt bench mark.
 
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Old 11-27-08, 01:32 PM
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field wire. 10.5 volts would be a good spot to stop at, any lower and you risk ruinning the battery.

are you going to cowboy up or just lay there and bleed?
 
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Old 11-27-08, 02:19 PM
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Understand I should pull the field wire.
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Purpose of the excercise is to load test the battery
 
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Old 12-01-08, 04:25 AM
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Why not find someone with a Sun VAT-40 or similar equipment, these have a variable carbon pile resistor, so you can set the load to 25 amps and put a watch on the battery while in your driveway. You could put an amp meter on the car(clamp on type) turn on all the things you mentioned and take a reading, this would give you a real world reading of the current draw.
 
 

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