My wife has a '95 Chevy 1500 truck. The voltmeter normality reads right at
14 on the gauge. Just the other day the gauge started to read lower, 13.5 or as low as 13; if I am reading the gauge right. My wife is concerned about this, however the truck starts and runs fine with no indication that there is not enough volts (dimming headlights, etc.). Should I change the alternator?Any thoughts?
Thanks
Check the voltage at the battery AND the alternator post with the truck running to verify ti's putting out the correct current.
Doc
"R. J. Folkman" had writtennews:rBwld.12068$ snipped-for-privacy@bignews6.bellsouth.net:
Should I change the alternator?
The alternator must be working to show 13 volts. Dirty contacts or a draw from somewhere. Perhaps an old battery. Check voltage at the battery as the previous poster suggested.
Try leaving a trickle charger on overnight. What you describe is common with an old battery that has only seen an alternator for a long time. Over time the battery will loose capacity because the alternator MUST stop charging BEFORE it charges the battery fully. If it doesn't, it has no voltage difference left to signal it to stop and the battery will boil. I know a guy who says "If I need to charge it I need a battery." He runs his battery until it lets him down and then he just buys a new one. We live in Northwestern Ontario and it dips to -10F on a mild night. Can hit as low as -40F on occasion.
-- Best Regards Gordie
Sorry Gordie, your explanation is wrong. Properly operating alternators provide a constant voltage that carries the system elec. load and charges the battery. That voltage is about 14V and provides a constant float charge to the battery. The battery will be fully re-charged if the engine runs long enough.
Batteries do NOT run down if connected to an alternator. The battery will draw current until it's terminal voltage nearly reaches the alternator output voltage. At that point the charging current is down to a few hundred milliamps. This is enough to overcome internal leakage/loses and maintains a fully charged, stable condition. If you don't believe this, simply check the specific gravity of the battery acid after a long trip and compare it with the factory specs for a full charged battery.
Randy
As you have said (same as me only different) the difference between full charge and cut off is only milliamps but it DOES exist and over time the battery runs down. An alternator is insufficient to bring the battery to FULL charge. Consider this. The alternator MUST stop charging at some point. This point is either before, right at, or after the battery is fully charged. IF after, the battery is overcharged. IF before, the battery is undercharged. If right at (highly improbable given the accuracy required to accomplish this feat) than the battery will be fully charged. Anyway, the proof is in the pudding and a simple one night experiment with a battery charger will prove whether yes or no and then one has to come up with some kind or reasonable explanation to make things make sense.
-- Best Regards Gordie
Sounds like my 1500 acted when I first noticed a problem. Remove the ground wire at the engine end and clean the cable end and the area around the stud going into the intake with a wire brush More than likely you are loosing ground and if you ignore it your honey will go out and find that it wont start and the gauges are doing strange things.
Hope this does the trick for you.
Steve
MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.