99 Suburban Charging problem????

[ohio45344]

I have a 1999 Suburban 4X4 that the dash gauge for the charging system show half way between the 9 and the 14. I checked the voltage at the battery with the car running and it said 14.1 volts DC. If I turn on all the accessories the needle shows in the red and I get a chek gauges light on the dash. I then checked the battery voltage and got a 14.0. Could there be something wrong with the alternator is could this be a gauge problem? I have replace both of my batteries (it does have dual batteries)

[buckshooter1]

It sounds like the guage might be the problem if you have 14 volts at the battery with the engine running and everything turned on your alt. is working. you could have a short somewhere in the system?

[jdmccright]

The gauge readings don't look to be abnormal...should be ~12 volts w/ key on and 14.0-14.5 volts with engine running. Remember that the engine at idle isn't turning fast enough for the alternator to pump out full amperage. So, everything turned on at idle will be a higher burden on the charging system. Also, the battery voltage should be checked with the NEG cable disconnected to prevent any bias from "always on" circuits.

DMMs (digital multi-meters) are great for hunting down rogue power robbers. Connect one in series between the removed negative cable end and the NEG battery post with the engine off and key off to see how much amperage your accessories are drawing. Then check it with key on. DON'T start the truck! The alternator output will blow your DMM. Most of your draw will be the fuel pump as it builds pressure, then stops.

Got alot of aftermarket equipment? Is there any one particular accessory that you can see causes the drawdown? Try turning them on one at a time while measuring the battery voltage versus the gauge (battery connected).

Could be as simple as needing a heavy-duty alternator...write back with any more clues.