Voltometer Reading

scruffboy · 02-09-2006, 01:06 PM

I put a new battery in my car after the old one apparently died (it was a Sunday and I had my son for the weekend and just bought a new battery to get him to his mother before she threw a fit). I would have liked to have had the old battery checked but couldn't. Anyway, since putting in the new battery, the voltometer usually reads between 12 and 14 (I think the top number is 18). It also moves up when I rev the engine. Is this a good sign that my alternator is working? I don't want to do that old school test of removing the pos wire as my manual says not to and you guys told me I could fry some computer components. So, does it sound like my alternator is working and my battery really just crapped out on me?

Thanks

Scruffboy

joel w · 02-09-2006, 09:01 PM

if it moves when you rev this sounds like its working to me if it stays above 12 and below 14+.. Do not do the "pull the battery terminal off test" i agree this is a bad idea... i dont have a voltage gauge, but i can hear the alt. load up and slow the rpm's a little when i turn on the headlights or the heater on... and it frees up when i turn back them off..

scruffboy · 02-10-2006, 12:02 PM

How would you use a voltage reader to check the altenator. It seems it would be easy to use to test the battery, but that would not tell me if my alternator is working, as I'm sure a new battery is going to hold its charge for a little while. Where would you place the terminals and what other things would you need to do to check the alt. I may be able to borrow one.

Thanks

joel w · 02-10-2006, 05:14 PM

most volt meters have a red and a black lead, red goes to positive on the battery and black goes to negitive side of the battery..

lethalwithasupra · 02-13-2006, 09:49 AM

they try to keep the voltage steady at 13 - 14.5 V all through the rev range. your altenator is stuffed, or the belt is very loose. but i'd get it fixed by a pro, there's nothing in there you can fix yourself without buying enough tools to pay for the pro's time anyway. doesn't sound like brushes, prolly diodes or regulator.

here's another test ;
lights on, engine off -> lights on, engine on. and are the lights any brighter now ?

02-09-2006, 01:06 PM	#1
scruffboy walbro fp Join Date: Sep 2005 Location: Kearny, New Jersey, USA Posts: 427	Voltometer Reading I put a new battery in my car after the old one apparently died (it was a Sunday and I had my son for the weekend and just bought a new battery to get him to his mother before she threw a fit). I would have liked to have had the old battery checked but couldn't. Anyway, since putting in the new battery, the voltometer usually reads between 12 and 14 (I think the top number is 18). It also moves up when I rev the engine. Is this a good sign that my alternator is working? I don't want to do that old school test of removing the pos wire as my manual says not to and you guys told me I could fry some computer components. So, does it sound like my alternator is working and my battery really just crapped out on me? Thanks Scruffboy

02-10-2006, 12:02 PM	#3
scruffboy walbro fp Join Date: Sep 2005 Location: Kearny, New Jersey, USA Posts: 427	Voltage Reader question How would you use a voltage reader to check the altenator. It seems it would be easy to use to test the battery, but that would not tell me if my alternator is working, as I'm sure a new battery is going to hold its charge for a little while. Where would you place the terminals and what other things would you need to do to check the alt. I may be able to borrow one. Thanks

02-13-2006, 09:49 AM	#5
lethalwithasupra 3" Exhaust Join Date: Sep 2005 Location: south cantebury Posts: 112	they try to keep the voltage steady at 13 - 14.5 V all through the rev range. your altenator is stuffed, or the belt is very loose. but i'd get it fixed by a pro, there's nothing in there you can fix yourself without buying enough tools to pay for the pro's time anyway. doesn't sound like brushes, prolly diodes or regulator. here's another test ; lights on, engine off -> lights on, engine on. and are the lights any brighter now ? __________________ 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.

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02-09-2006, 09:01 PM	#2
joel w Lexus & 550's Join Date: Aug 2005 Location: In the shadows Posts: 506	if it moves when you rev this sounds like its working to me if it stays above 12 and below 14+.. Do not do the "pull the battery terminal off test" i agree this is a bad idea... i dont have a voltage gauge, but i can hear the alt. load up and slow the rpm's a little when i turn on the headlights or the heater on... and it frees up when i turn back them off..

02-10-2006, 05:14 PM	#4
joel w Lexus & 550's Join Date: Aug 2005 Location: In the shadows Posts: 506	most volt meters have a red and a black lead, red goes to positive on the battery and black goes to negitive side of the battery..