[Blazin72]

Ok, this seems a bit odd to me but one of you might have had this problem. Whenever I drive my truck at night my battery is not charging like it does during the day. I know the first thing you're probably thinking is that it must be my head lights. Heres the interesting part, I can turn everything on (headlights, heater, amp, fuel pump, fans, etc...) during the day and it will not have a problem, the alternator will keep a constant charge of about 14.8v but when it's dark and all non-essential electrical items will be turned off and I get something around 11-11.5v. Ive had problems in the past but they were because I didnt have a powerful enough alternator, I upgraded to a 100 amp alternator and solved the problems and I have not added any electrical components since. Any ideas?

[Spank]

check wiring for broken or cracked insulation or a loose connection allowing moisture to get to the wires breaking down the circuit

[Blazin72]

The wires are fine, I installed a new wiring harness about two years ago. When I upgraded the alternator the existing wire from the alternator couldnt handle the current so I replaced it with another 10 ga wire as well as a 6 ga battery cable from the alternator directly to the battery.

[KULTULZ]

Is this a single-wire ALT?

[Blazin72]

Originally Posted by KULTULZ

Is this a single-wire ALT?

Yes, it's a one wire

[KULTULZ]

-ONE-WIRE COMPARED TO THREE-WIRE ALTERNATORS-

-REMOTE VOLTAGE-SENSING -

[docvette]

Doc here

Go get a new Alternator..

The Diode pack, regulator/or wave shaper rectifier, has broken down on one or more diodes (of 3 or 6) .. and is not charging under load..(reverse bias)

You Can either get a new one , about 30 bucks or a diode kit (about 15 bucks) and rebuild it yourself..

The Voltage at the battery should NEVER be below 13.75 while running AT any speed below 300 RPM..and never more than 16 at any speed..

Doc

[Blazin72]

Originally Posted by docvette

not charging under load..

But it does charge under load, for some reason only during the day. I can have every electrical component on the truck running and it will be fine (around 14.5v). I have no clue why but at night everything except the fuel pump and ignition can be turned off and voltage is under 12v, I can turn everything on and it's still under 12. I first noticed is about a month ago when I was leaving a friends. The next day I drove it and everything was fine, it's been doing that ever since. It just seems really strange.

[docvette]

Doc here,

Again...The regulator is on it's way out..

Have it tested, It 's usually free at the mega auto parts store..BUT remember that won't (usually ) Show AC in the presents of DC..so it may say 14.4 volts but only 11 or so of it will be DC ... the rest useless AC..To check that you need a good oscilloscope.

Doc

[Blazin72]

Hmmm...that would be a shame considering it's only a couple years old and it wasnt cheap.

[pimpin72]

It sounds like docvette has the right advice for you blazin! You have a couple of options though. You can stop spending so much time over at your friends house at night, or you can fix the alternator. Call your local alternator/starter repair shop. They are usually very knowledgeable and they won't charge you near as much as a new one. I have never had bad luck with one of my starters or alternators after they were rebuilt. Good Luck!

Scott
PS - just kidding about the friend

[docvette]

Originally Posted by docvette

Doc here

You Can either get a new one , about 30 bucks or a diode kit (about 15 bucks) and rebuild it yourself..

Doc

Doc here,

The Diode pack is simple and cheap to replace..If the Alternator actually cost you that much, then you may want to rebuild it yourself..



Standard GM Kit..

If you get the kit, you can replace the rectifier pack, the regulator, install new bearing (s) , Bush (s), New brush holders/Brushes, Burnish the stator pickups..seals,

and when you go to install the new bearings , get a small sharp punch and dimple the endbell races 1/3 of the way around..

It makes it harder to reassemble the endbells, but the bearings will NEVER spin in the races..

Also, if you look at the rear endbell, about where the brushes sit..you'll see two holes .. insert a paper clip in each to hold the brushes off the stator during reassembly..Don't forget to remove them!

Total Cost: $15.00 thereabouts plus your time..and you may want to gunk it down real good and pressure wash it, after you pull it so it's good and clean and ready for rebuild

Doc