Charging problems

dragstang88 said:

Ok, now i put in a 3g alternator a while ago, using 4 gauge from the post to the positive battery, unmodified d-plug, and a female spade on the white/black wire from the square plug. ok, now the problem. Every once in a while, the amp light will light up and the volt meter will show just at the top of the red. According to a dvom, its only reading 10.98 volts at the battery post and at the post on back of the alternator. Now its doing this perminantly and i can't figure it out. i double check/cleaned all connections, but still the same thing. The only thing i did recently was routed the parking lights/foglight through a relay to stop melting switches. i don't know if thats related or not, but.... Anyway, after i did that it was fine for a few days, now this problem. Any ideas will be greatly appriciated because i have to drive 300 miles sunday.

Added info: battery is 1 year old, never had a problem with it, 3g is 6 months old, and got the alt checked at advance and it checked out good.

thanks

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If the alt is only putting out 10. something volts than the alt is no good, there is no out put. The 10.98 volts is whats left in the battery. That will drop as well when you use the rest of it's reserve. Do you have a warrenty?

have you read the volts at the alternator? was it bench tested or dynamically tested?

something worth checking is the battery. if you have a dead cell, you can put all the juice in it you want, but it will read low (if a cell is actually dead, you would lose 2.1 volts. i.e., instead of 12.6 at rest, you would have 10.5). this will appear if the alt reads that it is putting out decent voltage (measured at the alt), and the the battery shows lower voltage at the battery terminals. either has to be voltage drop in the wire (not likely if you have done the wiring upgrade). that leaves battery.

an easy was to test battery is at the parts store or with a specific gravity tester (about a buck at wally world). check each cell.

we are assuming that you have proper ground too, not only at the battery, but engine to chassis grounds. when i do the upgrade, i will run a ground cable from the alt to frame (overkill), and also another from motor to chassis. juice flows from neg to pos. if ground is insufficient, doesnt matter if you have a 15 G alt (J/K), it will be in vain (to an extent).

thats what comes to mind. good luck.

dragstang88 said:

ok, just got the battery load tested and it checks out perfect...i picked up a 4 gauge cable that i'm gonna run from the alt to the frame....would from the top mounting bolt work, or will i have to go to one of the housing bolts?

thanks

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Is it a sealed battery or can you axcess the cells. A battery can load test good but still have a dead cell.