Voltage

scruffboy · 01-31-2006, 12:32 PM

This may seem like a dumb question, but I have no electrical capabilities. How can I tell if my battery is being charged by my alternator? I had an old battery and it recently died. I noticed that the voltometer would usually read over 12 and fluctuate as I accelerated and decelerated. Then last week the rear wiper motor stopped working. Then I noticed it was taking longer for the windows to go up and down. Then the other day the battery just quit. Very slight turnover than nothing. I jumpstarted it, but noticed when I was idling all the dash warning lights were on. I put in a new battery, and VAROOM, she starts right up. Now the needle is at 12 and pretty much stays there. All the electrical motors run in good condition. I checked my belts and they are all tight. Did I just have an old battery (it came with the car when I bought it), or could there be something else going on. (I guess I'll know in a couple of weeks anyway, but I'd rather not get suprised).

Thanks,

James in NJ

Fuel · 01-31-2006, 04:32 PM

One way to tell if your alternator is working proprerly is to take off the positive battery while the car is running.If the car dies then this means that the alternator is bad.

scruffboy · 01-31-2006, 07:40 PM

Okay, I heard that this was the old school way of doing it. But is it safe? Just remove the pos wire "while its running"? I won't go into cardiac arrest will I.

Thanks,

James

Fuel · 02-01-2006, 12:50 AM

I did it to my car and I'm still alive and kick'n.Also nothing bad happened to my car.

mrnickleye · 02-01-2006, 01:26 AM

I would not do the above mentioned 'test' of the alternator. These cars, and most on the road nowadays, have computers. The computers run on 5 volts. A voltage 'spike' can occur if you remove the battery cable while the engine is running. This can 'fry' a circuit in the computer, or weaken it, which may give out while driving. Then you'll have another problem to fix, and it won't be cheap.

Get a volt meter, from radio shack or similar store. You can use it to test the battery voltage, and many other wiring and circuits. It will be a valuable tool to have around. I have 2.

lethalwithasupra · 02-01-2006, 08:39 AM

... oldskool generators don't fuck the external regulator when you d/connect the battery, but all those heavy relays and springs are a bastard to work with. that'll also mess with the regulator in your altenator. the alt puts out about 25 amps and you take the battery out, there's nothing to soak that amperage up so it finds its own path to ground through the regulator ... if your alt isn't working then you might get away with it.

annyways ... mrnickleye speaks righteously ( tho the supra computers are pretty tough ... don't ask ). voltmeter should show between 13.5 and 14.5 volts for a charging alt. if it reads 12.5 or less, it isn't charging.

do the lights stay on with this new battery ? check how tight the belts are, if the lights only come on at idle. and keep an eye on things cos if it's the alt you might find the new battery running flat as you use the car.

scruffboy · 02-01-2006, 01:44 PM

Yeah, I read my Haynes manual (wish I had a Chilton's) and it said for cars with transistorized ingitions, do not remove the wires while car is running. Anyway, since I put in the new battery, everything seems A-OK. The Voltometer reads about 12 or slightly above. Everything electrical works. I'll keep my fingers crossed and see how it turns out.

Thanks for the info,

James in NJ

01-31-2006, 12:32 PM	#1
scruffboy walbro fp Join Date: Sep 2005 Location: Kearny, New Jersey, USA Posts: 427	Voltage This may seem like a dumb question, but I have no electrical capabilities. How can I tell if my battery is being charged by my alternator? I had an old battery and it recently died. I noticed that the voltometer would usually read over 12 and fluctuate as I accelerated and decelerated. Then last week the rear wiper motor stopped working. Then I noticed it was taking longer for the windows to go up and down. Then the other day the battery just quit. Very slight turnover than nothing. I jumpstarted it, but noticed when I was idling all the dash warning lights were on. I put in a new battery, and VAROOM, she starts right up. Now the needle is at 12 and pretty much stays there. All the electrical motors run in good condition. I checked my belts and they are all tight. Did I just have an old battery (it came with the car when I bought it), or could there be something else going on. (I guess I'll know in a couple of weeks anyway, but I'd rather not get suprised). Thanks, James in NJ

01-31-2006, 07:40 PM	#3
scruffboy walbro fp Join Date: Sep 2005 Location: Kearny, New Jersey, USA Posts: 427	Re: Alternator Okay, I heard that this was the old school way of doing it. But is it safe? Just remove the pos wire "while its running"? I won't go into cardiac arrest will I. Thanks, James

02-01-2006, 01:26 AM	#5
mrnickleye 1000whp postwhore Join Date: Jun 2005 Location: Mojave Desert, Calif. Posts: 1,705	I would not do the above mentioned 'test' of the alternator. These cars, and most on the road nowadays, have computers. The computers run on 5 volts. A voltage 'spike' can occur if you remove the battery cable while the engine is running. This can 'fry' a circuit in the computer, or weaken it, which may give out while driving. Then you'll have another problem to fix, and it won't be cheap. Get a volt meter, from radio shack or similar store. You can use it to test the battery voltage, and many other wiring and circuits. It will be a valuable tool to have around. I have 2. __________________ Had a Red 1989 N/A. Automatic. Sports Pkg. w/wing. TEMS, and some nice MODS. Sold to a friend 10/08/08.

02-01-2006, 08:39 AM	#6
lethalwithasupra 3" Exhaust Join Date: Sep 2005 Location: south cantebury Posts: 112	... oldskool generators don't fuck the external regulator when you d/connect the battery, but all those heavy relays and springs are a bastard to work with. that'll also mess with the regulator in your altenator. the alt puts out about 25 amps and you take the battery out, there's nothing to soak that amperage up so it finds its own path to ground through the regulator ... if your alt isn't working then you might get away with it. annyways ... mrnickleye speaks righteously ( tho the supra computers are pretty tough ... don't ask ). voltmeter should show between 13.5 and 14.5 volts for a charging alt. if it reads 12.5 or less, it isn't charging. do the lights stay on with this new battery ? check how tight the belts are, if the lights only come on at idle. and keep an eye on things cos if it's the alt you might find the new battery running flat as you use the car. __________________ So I bought this old Honda bike, an NSR250. Bit of a street racer, I guess. I'm told they're fast. Delivering it home with a friend driving the Supra for the first time. I drop gears and make a scream from the twin pipes flowing down this pony's flanks and it takes off like it's tail's on fire. I look back when the Honda gets to its tap-out and the Supra's only two lengths behind. No one I've let ride my bike has told me its slow, they've all loved the thing. That car is a good thing indeed.

02-01-2006, 01:44 PM	#7
scruffboy walbro fp Join Date: Sep 2005 Location: Kearny, New Jersey, USA Posts: 427	RE: Charging Yeah, I read my Haynes manual (wish I had a Chilton's) and it said for cars with transistorized ingitions, do not remove the wires while car is running. Anyway, since I put in the new battery, everything seems A-OK. The Voltometer reads about 12 or slightly above. Everything electrical works. I'll keep my fingers crossed and see how it turns out. Thanks for the info, James in NJ

01-31-2006, 04:32 PM	#2
Fuel Stock Join Date: Jan 2006 Location: Gresham,Oregon Posts: 22	One way to tell if your alternator is working proprerly is to take off the positive battery while the car is running.If the car dies then this means that the alternator is bad.

02-01-2006, 12:50 AM	#4
Fuel Stock Join Date: Jan 2006 Location: Gresham,Oregon Posts: 22	I did it to my car and I'm still alive and kick'n.Also nothing bad happened to my car.

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