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Charging intermittently


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fuzzy1
User

Feb 26, 2022, 6:36 PM

Post #1 of 7 (598 views)
Charging intermittently Sign In

Hello again folks, I am currently having an issue with a 2003 Oldsmobile Alero 4 cylinder. This car was given to an elderly woman at Church who desperately needed transportation. From what i was told the car had sat for a period of time before it was sold. The currently owner had it now about 3 months with no issues. now for the last 3 weeks the charging system indicator light has been coming on intermittently. I discovered the belt tensioner was frozen and allowing the belt to slip. I replaced the tensioner and belt and thought problem was fixed. That lasted a week. Light came back on intermittently and continued to drain the battery while being driven. I tested the basic charging system after fully charging the battery and found i had no power going to the battery +12 from the battery to back of alternator. I cleaned all the related terminals and had constant power. Alternator was then charging and no light. 2 days later the light started coming on again intermittently took alternator off to be tested at local parts place and it was weak. replaced with new alternator. Things were great for 7 days. Yesterday light was back on and off again, battery died, I took battery back, recharged, reinstalled, retested and all tests good. I have learned through this process that this particular vehicle had a PCM and BCM controlled alternator that controls the ground to the built in regulator of the alternator. I have not yet checked for codes but Im thinking that one or both modules are not working as they should. I cannot find a test procedure to test the PCM/BCM modules to see what is wrong. Do all have a flow chart available or and explanation how to proceed? Thanks, the Fuzzy1


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Feb 26, 2022, 7:39 PM

Post #2 of 7 (590 views)
Re: Charging intermittently Sign In





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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
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Feb 26, 2022, 9:25 PM

Post #3 of 7 (569 views)
Re: Charging intermittently Sign In

Fuzzy 1: It worked for a while to do belt and tensioner on a weak battery? I'll go by that as a clue and reason for this now.
Bet is this is a low use vehicle alternator is working hard up to too hard, gets a but hot unseen will test weak. If a rebuilt one it's mostly cleaned up not wearing all replaced namely brushes to contact shines up with heat make a poor contact.
If new could be a clone some OK some not alternators can easily be the drain.
Was just there, Harbor Freight has/had a very basic floating battery maintainer if any OK charge in a battery takes a day will charge one up to peak and stop there. Look for words like "floating" for that stuff.
Problem is they are slow leave those on a whole day. New in package right now says puts out 500 mHa? Better if watch it do that also says put out 13.2 volts some confused translated info on package I do know they work + have a pilot light.
Remove hood light or disconnect and tie wire away harmlessly.
Trouble is and you know this scene and where car is parked if this owner doesn't use this car much is up to putting this on and take it off when they use this car. That's not practical for everyone if just hooked up wrong unsafe too.
Good for you to find the belt + tensioner out of the gate I think just that fixed stressed out some other items it's a system to keep battery charged not just one test instantly.
It's tough. Cars should get some use not just sit around - check tires too if for pressure only do her a favor too and check spare nobody does is a bummer if bad luck it has 2 flats those don't hold much volume of air so are low all the time,


T



fuzzy1
User

Feb 27, 2022, 8:03 AM

Post #4 of 7 (537 views)
Re: Charging intermittently Sign In

Battery has never been in a weakened condition during any testing event nor was it weak after replacing the belt and tensioner. Battery has always been recharged and retested. My battery charger is a manual charger. Those automatic chargers you mentioned are junk and only put a surface charge on them. Problem causing weak battery is when charging indicator light comes on, at the point alternator is not charging and entire vehicle is running just on battery power only. This in turn is why battery gets weak or dies all together. Again this is an intermittent problem. The above posted flow chart should reveal the problem as soon as i gather the proper equipment. I will update when the time comes. Thanks for your input, it means a lot. BTW, vehicle is driven daily, so not a low use vehicle. There is no parasitic drain so no need to unplug lights or disconnect battery leads.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Feb 27, 2022, 8:44 AM

Post #5 of 7 (528 views)
Re: Charging intermittently Sign In

Re-name what I was talking about. Trickle charging, low and slow. That and auto shut off! When and normally battery is not fully charged, like right after you crank it CCA is what they do the rest is to cover surges alternator can't for a moment not too long.

If low alternators work hard and max out their output. That wrecks both alternators and batteries.

Intermittent charging is frequently stuck brushes if watching and catch it live tap on alternator (reverse idea of whacking a starter motor) the bushes might loosen up and make proper contact again.

It's a pest you could take those apart and fix it see what happened. It's glazed from heat and overworking - no brains it was told to.

If this goes on too much or just chance of lousy NEW parts other things get wrecked or harmed.

Fast charging is a killer so is being low for lead-acid liquid batteries are the rule not the exception.

New isn't always good - scary. It might have been dropped another killer may not show up and the thing is new.

Fuzzy - I have way too many toys of my own ALL are on trickle chargers/maintainers some of those don't work so OMG need to know that too.

It's not easy but intermittent problem frequently are any of these things that are not operating perfectly. Finding which one if only one is really hard if it will behave with proper testing.

The best deal is always going to be catching the problem when happening and just touch something watch it snap out of it is great but no surety that you'll be that lucky with intermittent stuff,

Tom



fuzzy1
User

Feb 27, 2022, 5:17 PM

Post #6 of 7 (509 views)
Re: Charging intermittently Sign In

scanned for codes today, found a P0621. Definitely a charging system code. Need to study up and see what its all about.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Feb 27, 2022, 6:05 PM

Post #7 of 7 (501 views)
Re: Charging intermittently Sign In





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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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