This is an intermittant problem that only happens when driving with the
headlights on -- but does happen every time. Any ideas how to
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
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?
On Saturday, May 21, 2016 at 8:20:56 AM UTC-4, dpb wrote:
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.
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"
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.
On Saturday, May 21, 2016 at 5:21:34 PM UTC-4, Snuffy "Hub Cap" McKinney wr
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?
On Saturday, May 21, 2016 at 8:20:56 AM UTC-4, dpb wrote:
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
On 5/21/2016 2:17 AM, Snuffy "Hub Cap" McKinney wrote:
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. .
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...
On Saturday, May 28, 2016 at 11:25:53 PM UTC-4, Snuffy "Hub Cap" McKinney w
n. Then I cleaned all the connections in the starting systems from batter
y terminal to hot connections and grounds, and the problem stopped.
re. Then when I started, the battery needle start oscillating from 50% to
100% regularly, and the battery warning light started blinking off and on.
/2 mile the oscillating and flashing stopped.
r, and not the actual reading.
e battery terminal.... Turn signals seems to cause the cycling tonight, alt
hough I have seen it cycling with just the lights on.
You sure your meter isn't busted? Fully charged battery is just 12.7V
Those look like they are about 1V high too. I suspect your meter
is off. You could try a fresh 9V battery to check, that should be around 9
Assuming the meter is off, I don't see anything unusual in your
readings. It's not dropping anywhere that would indicate a
charging problem that would put the dash light on. Exactly what
puts the light on varies from car to car. Some use the old method,
where it's essentially a light bulb tied to 12V on one end, the
other goes to the alternator. If the voltage there drops low,
the bulb lights up. Others now have the computer monitoring the
voltage at the alternator and it decides when to turn the light on.
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