voltage meter issue!!???

[jay]

hi, i have a 2002 ws6 t/a with about 33,000 miles on it and my alternator recently went out. i changed the alternator and have now had an issue with the voltage meter going nuts. it actually will some times go low enough to trip the check gauges light off then go back to normal. i have tried putting numerous alternators in thinking that possibly the voltage regulator was bad on the alternator (autozone pieces), but same problem. i checked the connection to the voltage regulator on the alternator and is fine. i was told to look into replacing the positive battery cables for possibly having a bad connection, did it and same problem. the problem occurs more so when it is hot out side. i can even be cruzing on the highway where the alternator is clearly being spun fast enough to charge properly and it will happen. the gauge will read fine then drop suddenly, go back to normal and fluctuate back and forth. i dont think that the gauge is bad. because when the meter drops the lights will actually dim also. i actually had a buddy hook a scan tool while car was running and problem occurring and was told that for some reason the car would read voltage and then not read it and so on.

any ideas will be greatly appreciated!!!

[Jeff_in_Atl]

This may sound crazy but I would crank the car, disconnect the battery and drive it and see if it does it again. I had a similar problem one time and it turned out to be an intermittent short in the battery.

[RangerBob]

A battery may stop functioning very suddenly if an internal short circuit is caused. Such a short circuit may be the result of the sediment in the sediment chamber coming into contact with both positive and negative plates. Otherwise it may be that the plates have come into contact with each other as a result of buckling of the plates or "treeing" between the plates.

Treeing" is the result of a very slow recharge rate (500 hours or more) when the spongy lead deposits on the negative plates in a "tree" like formation. This may eventually bridge the gap between the positive and negative plates. Another possible cause of failure of a lead-acid battery is when the contacts between plates, straps, terminals and/or intercell connectors are broken.

Car batteries

[jay]

thanks...I'll have to try checking the battery out. I hope that's all it is, that would be a simple fix!!!

[JeffM]

Another vote for the battery - mine did the same thing..

Sometimes the radio would just shut off, and the volts would drop, then shoot back up. Other times every gauge would max out, all dummy lights would light, then everything would go off again, then come back on like normal.

Thought it was the alt - but the battery tested out bad. Replaced it 5 months ago and it's never happened again.

[jay]

If the battery is the culprit, would it affect the cranking (slow crank) when starting up? Because the car starts fine.

[Joe 1320]

It may start fine, but vibration could be causing an intermittant short. See if you can swap batteries with another known good battery and see if the problem persists.

[jay]

Sorry has been a while... i was going to get a new battery and i briefly explained to the sales person at a local radio shop the issue that i was having and he agreed and has heard of that problem occurring with normal batteries, but not with an optima yellow top battery (which is what i have) because they are jell filled. I therefore didn't purchase another one, because he thinks there may be another issue. My only question i guess to you guys from here, if anyone knows, is can this occur with the optima battery??? or is there anything else obvious that could be contributing to my situation. thanks!!!