Spooks are back !!
Fleet Owner
Joined: Aug 2010
Posts: 21,255
Likes: 1,657
From: Reynoldsburg, Ohio
FWIW the alternator diodes can not be checked if it is still electrically connected to the vehicle. It can be left installed but all wiring needs to be removed at the alternator itself.
Lead Driver
Joined: Mar 2006
Posts: 6,264
Likes: 438
From: IL
To check if you have a bad diode while the Alternator is still hooked up, take your DVM, put it to the lowest AC setting, take your probes red to positive black to negative on your battery posts......if you get ANY voltage reading at all, you have a bad Diode, and just an FYI, a bad diode can drain your battery anywhere from just a few minutes to 4 or 5 days. So as the rest of the guys have been saying , there is a very good probability it's your alternator gone bad.
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Cross-Country
Joined: Sep 2010
Posts: 50
Likes: 0
To check if you have a bad diode while the Alternator is still hooked up, take your DVM, put it to the lowest AC setting, take your probes red to positive black to negative on your battery posts......if you get ANY voltage reading at all, you have a bad Diode, and just an FYI, a bad diode can drain your battery anywhere from just a few minutes to 4 or 5 days. So as the rest of the guys have been saying , there is a very good probability it's your alternator gone bad.
Lead Driver
Joined: Mar 2006
Posts: 6,264
Likes: 438
From: IL
My question to you is are you charging the battery when it dies or are you jumping it?
if you're charging it then yes it could take a week to drain and die, if you're just jumping it then it would die even quicker.
if you're charging it then yes it could take a week to drain and die, if you're just jumping it then it would die even quicker.
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Cross-Country
Joined: Sep 2010
Posts: 50
Likes: 0
Pulled fuses and diodes and found nothing......did nothing w/ alternator.....started and ran it for 2 weeks now and all ok except I don' trust it...also found out the alternator was replaced in 2017 ,about 20,000 miles ago by my garage($450) ...I had no recollection of this (old age).....also the battery (w/ multitester) shows 12.3v each morning ..when iI start it my aftermarket ,cigarette litter volt meter shows a charging rate of 14.7v ...this slowly goes (15 min.) down to 13.7-8) ...is this too high of a charging rate ????
More Turbo
Joined: Aug 2017
Posts: 516
Likes: 72
From: Tucson
Pulled fuses and diodes and found nothing......did nothing w/ alternator.....also the battery (w/ multitester) shows 12.3v each morning ..when iI start it my aftermarket ,cigarette litter volt meter shows a charging rate of 14.7v ...this slowly goes (15 min.) down to 13.7-8) ...is this too high of a charging rate ????
If the battery is getting fully charged one day but in the morning it only reads 12.3 volts, then that's low. A drain could cause that but also a weak battery.
Here's info on charging volts. The voltage will go down as the battery is charged up:
https://www.google.com/search?client...arging+voltage
Lead Driver
Joined: Mar 2006
Posts: 6,264
Likes: 438
From: IL
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Cross-Country
Joined: Sep 2010
Posts: 50
Likes: 0
the problem, with finding the cause was that it repaired itself after the system automatically shut down when the voltage went below about 9v.....before 3 days ago everything worked fine for 3 weeks and then the battery was dead once again in the AM......but this time the fault STAYED faulty and a drain on the battery showed on a meter....pulled the plug on the alternator and the drain halted...right now a new alternator is being installed ,so we will see....thanks to all !
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Cross-Country
Joined: Sep 2010
Posts: 50
Likes: 0
new alternator seem to have fixed the problem of a dead battery,,,,,,been used for 2 weeks , however after a ride and the engine shut off for 15 min. the voltage shows 12.5.....in the am the voltage shows 12.1 or even 11.9..but it never drops lower . new battery........is this normal???..
Lead Driver
Joined: Mar 2006
Posts: 6,264
Likes: 438
From: IL
3 possibilities
1 bad battery...fully charge then load test it.
2 new alternator is weak....Replace it.
3 something is not shutting down and it's draining the battery (parasitic draw).... drag out the voltage meter and start testing.
1 bad battery...fully charge then load test it.
2 new alternator is weak....Replace it.
3 something is not shutting down and it's draining the battery (parasitic draw).... drag out the voltage meter and start testing.
More Turbo
Joined: Aug 2017
Posts: 516
Likes: 72
From: Tucson
new alternator seem to have fixed the problem of a dead battery,,,,,,been used for 2 weeks , however after a ride and the engine shut off for 15 min. the voltage shows 12.5.....in the am the voltage shows 12.1 or even 11.9..but it never drops lower . new battery........is this normal???..
How long are your normal 'rides'? Are you just buzzing around town for short distances or are you getting it out for longer rides of at least 20-30 minutes? Daily? Or does it sit for several days in between?
If you're just doing infrequent, short rides then your battery isn't getting fully charged. Also, if on those short rides you have the stereo on and you have the HVAC blower (or blowers) going, then that will decrease any charging.
Are you measuring voltage right at the posts? Or are you reading it on a ciggy plug meter?
PS: Keep this new battery charged one way or another or it will quickly be ruined!
Laughing Gas
Joined: Apr 2013
Posts: 1,049
Likes: 65
I don’t know anything about your model year but… there is a small “I” terminal on my starter relay that sends power to my electric fuel pump. This I terminal is only supposed to be energized when the starter is engaged, however I had one that failed in such a way that it would stay hot every once in a while and drain the battery. It was a real puzzler.
maybe you have something similar going on. Like a bad relay that sticks on every so often. .02c.
maybe you have something similar going on. Like a bad relay that sticks on every so often. .02c.
Tuned
Joined: Jul 2019
Posts: 382
Likes: 79
Originally Posted by JWA;[url=tel:20580580
20580580]Still sounds suspiciously like failed alternator diodes---those need to be check by someone who knows how to do this properly. This video may be helpful if this becomes a DIY project: Alt Diode Test
Good luck!
Good luck!