Battery Indicator Oscillating

[Snuffy "Hub Cap" McKinney]

This is an intermittant problem that only happens when driving with the headlights on -- but does happen every time. Any ideas how to troubleshoot it?

For awhile the needle would oscillation between the normal 50-60% position a few degrees after driving a half hour or more with the headlights on. Then I cleaned all the connections in the starting systems from battery terminal to hot connections and grounds, and the problem stopped.

Then last week, I had driven to a store at dusk with the lights on - no problem indicated. I left the lights on for 20 minutes while in the store. Then when I started, the battery needle start oscillating from

50% to 100% regularly, and the battery warning light started blinking off and on.

Car was running fine so I turned off the headlights and just put on the parking lights so I could drive the 2 miles home. After driving about

1/2 mile the oscillating and flashing stopped.

I have tried to duplicate the problem so I could show a mechanic, but all is back to normal for now.

Without knowing anything, I would guest that the computer detected some kind of low voltage and the swinging and flashing was an attention-getter, and not the actual reading.

Any ideas how to troubleshoot this?

[dpb]

On 05/21/2016 1:17 AM, Snuffy "Hub Cap" McKinney wrote: ...

...

My money would be on the internal regulator in the alternator is acting up...

[trader_4]

That's a likely possibility. I'd start with having the battery load tested, which you can get done at most auto parts stores for free. Many will also test the charging system at the same time. If the battery is good, you're pretty much left with the alternator or a bad connections. The alternator common failures are either the VR already mentioned, or the brushes wear out. Those can usually be replaced separately but most people just swap out the alternator for a rebuilt one.

[Snuffy "Hub Cap" McKinney]

Thanks, is that something that can be checked before it acts up again?

[Ed Pawlowski]

Leaving the lights on 20 minutes would put more load on the alternator when you did start the car. The first thing that comes to mind is that for some reason the alternator is unable to work properly under high load.

The second thing that comes to mind is some serious sounding problems have simple solutions. Higher load makes the alternator work harder. It can be something as simple as a slipping belt. I'd tighten or replace it before rebuilding the alternator. Yes, I've seen it happen more than once. .

[trader_4]

headlights on -- but does happen every time. Any ideas how to troubleshoo t it?

ion a few degrees after driving a half hour or more with the headlights on. Then I cleaned all the connections in the starting systems from battery terminal to hot connections and grounds, and the problem stopped.

problem indicated. I left the lights on for 20 minutes while in the store . Then when I started, the battery needle start oscillating from 50% to 10

0% regularly, and the battery warning light started blinking off and on.

parking lights so I could drive the 2 miles home. After driving about 1/2 mile the oscillating and flashing stopped.

ll is back to normal for now.

kind of low voltage and the swinging and flashing was an attention-getter, and not the actual reading.

Good point about checking the belt.

[bob haller]

get the battery load tested, batteries can get internal intermittent shorts. had that happen once, it was terrible and couldnt be found. the battery was pretty new.......

finally decided to repplace battery, problem went totally away..

a year later a buddy cut the batter apart andfound on cells plate was bent, and must of intermittetly shorted

[Snuffy "Hub Cap" McKinney]

shorts. had that happen once, it was terrible and couldnt be found. the battery was pretty new.......

bent, and must of intermittetly shorted

Thanks BH. Will check it out. I remember that the meter started slightly cycling from time to time when the headlights were one before the battery was replaced.

[dpb]

On 05/21/2016 10:00 AM, trader_4 wrote: ...

Albeit doesn't virtually everything now use just the single multi-rib serpentine belt with the auto tensioner setup? Not to say can't eventually stretch where there's insufficient takeup and I have had the tensioners fail/hang up where not doing its job but overall not nearly the issue used to be w/ separate, manually adjusted v-belt setup.

The oscillating nature makes me wonder also about the symptom, but could alternatively (so to speak :) ) grab/slip a little I suppose...

Agree the symptom being so much more observable after the battery drain is indicative it's happening under the heavier load...

[clare]

Or the brushes are worn out.

[clare]

My 1991 Aerostar did the same. I replaced the regulator and brushes and it was good for a couple months, then started doing it again. The local wrecker had a rebuild off a wreck I was able to purchace for less than another new regulator with a 2 year replacement warranty - it lasted several years 'till I sold the truck.

[trader_4]

Agree, the belts today would typically be a lot less susceptible, particularly with automatic tensioner.

I'd say an alternator problem, most likely VR or brushes, is the most likely problem.

[clare]

Sadly, the answer is basically no. You MIGHT be able to trick it into misbehaving again by putting a carbon pile load tester on the battery to draw down the voltage with the vehicle running - but I wouldn't count on it. That's why, knowing the problem was in the alternator, and having already replaced the regulator and brushes once on mine, I simply replaced rhe alternator when it started intermittently doing it again. I couldn't be bothered digging deaper into it for the $30 cost of a used, very recently rebuilt unit from the local "used parts emporium"

[Ed Pawlowski]

What is he driving? Could be a '62 Chevy with no auto tensioner.

[clare]

I believe the OP drives a 1995-ish Aerostar, but I could be mistaken.

[Snuffy "Hub Cap" McKinney]

Thanks. $30 is a bargain. Alternators here are $150 new with lifetime warranty, $100 rebuilt w/ 1 year. If it were easier to swap out, that's what I would do. Still looking for a way to isolate to battery or alternator first. Already checked that connections are all good.

[clare]

and OEM new alternators are closer to $600.

I checked the wreckers and took the best one they had - had been installed less than 2 weeks bdfore the car was wrecked and cost the same as a 10 year old one.

[trader_4]

On Saturday, May 21, 2016 at 5:21:34 PM UTC-4, Snuffy "Hub Cap" McKinney wr ote:

[e-mail]...

arranty, $100 rebuilt w/ 1 year. If it were easier to swap out, that's wha t I would do. Still looking for a way to isolate to battery or alternator first. Already checked that connections are all good.

Driving over to one of the auto parts stores that does free battery and cha rging system tests is too hard?

[Snuffy "Hub Cap" McKinney]

the headlights on -- but does happen every time. Any ideas how to troubleshoot it?

position a few degrees after driving a half hour or more with the headlights on. Then I cleaned all the connections in the starting systems from battery terminal to hot connections and grounds, and the problem stopped.

no problem indicated. I left the lights on for 20 minutes while in the store. Then when I started, the battery needle start oscillating from

50% to 100% regularly, and the battery warning light started blinking off and on.

the parking lights so I could drive the 2 miles home. After driving about 1/2 mile the oscillating and flashing stopped.

but all is back to normal for now.

some kind of low voltage and the swinging and flashing was an attention-getter, and not the actual reading.

I'll try to take a look at this weekend post what I find out if anything. But if I find a nice BBQ on sale, all bets are off.

[Snuffy "Hub Cap" McKinney]

the headlights on -- but does happen every time. Any ideas how to troubleshoot it?

position a few degrees after driving a half hour or more with the headlights on. Then I cleaned all the connections in the starting systems from battery terminal to hot connections and grounds, and the problem stopped.

no problem indicated. I left the lights on for 20 minutes while in the store. Then when I started, the battery needle start oscillating from

50% to 100% regularly, and the battery warning light started blinking off and on.

the parking lights so I could drive the 2 miles home. After driving about 1/2 mile the oscillating and flashing stopped.

but all is back to normal for now.

some kind of low voltage and the swinging and flashing was an attention-getter, and not the actual reading.

I'll try to take a look at this weekend post what I find out if anything. But if I find a nice BBQ on sale, all bets are off.