Battery Indicator Oscillating

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 car. Then when I started, the battery needle start oscillating from 50% to 100% regularly, and the warning light started blinking.
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?
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On Fri, 20 May 2016 14:06:36 -0700, "Snuffy \"Hub Cap\" McKinney"

You probably already did this: have battery checked
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On Sat, 21 May 2016 07:39:00 -0700, "Snuffy \"Hub Cap\" McKinney"

Or the brushes are worn out.
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On Sat, 21 May 2016 07:39:00 -0700, "Snuffy \"Hub Cap\" McKinney"

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"
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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.
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On Sat, 21 May 2016 14:20:33 -0700, "Snuffy \"Hub Cap\" McKinney"

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.
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troubleshoot it?

headlights on. Then I cleaned all the connections in the starting systems from battery terminal to hot connections and grounds, and the problem stopped.

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.

about 1/2 mile the oscillating and flashing stopped.

attention-getter, and not the actual reading.

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Thanks for all the help. Still trying to find the time to spend TS...

Last night I was able to catch it cycling just now. No time to check at
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in message

troubleshoot it?

headlights on. Then I cleaned all the connections in the starting systems from battery terminal to hot connections and grounds, and the problem stopped.

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.

about 1/2 mile the oscillating and flashing stopped.

attention-getter, and not the actual reading.

--

Thanks for all the help. Still trying to find the time to spend TS...

Last night I was able to catch it cycling just now. No time to check at
  Click to see the full signature.
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battery was pretty new.......

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.
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