To charge or Discharge...that is the #@!^%$#*^&% questio

Veriwide · Post by **Veriwide** » Sat May 21, 2005 3:59 pm

My truck likes draining its battery. When ever I touch any thing electrical, such as turning on the lights, turn signsls, emergency flashers, or step on the brakes, the ammeter drops to the "D" side. Some items cause a larger movement than others. I have never seen it go to the "C" side.

The local concensus was the alternator, which I replaced today. No change in my problem. Any help?

Patrick

Jeffc · Post by **Jeffc** » Sat May 21, 2005 5:40 pm

Really you need to test to see that the alt is putting out at least 13v or more (should be around 14v to be heathy), any less will not charge the battery....
If it is in fact putting out the voltage and you still
are getting discharging then you have a grounded short in the system somewere.....

Part 2
If the alt is not putting out the voltage then you have a problem with the voltage regulator or the wire from the voltage regulator to alt (field wire), this assumes that the replacement alt it a good one.

It is not uncommon at low rpm for there to be some discharge as most alts do not produce a full 12+volts
at less than 600 engine rpms, how far it discharges will depend on the load placed on the system and what is drawn from the battery; the voltage regulator controls how much is drawn from the battery vs alt output..

Website · Post by **wideblock** » Sat May 21, 2005 7:34 pm

sounds like the regulator might have crapped out. test the alt to insure its putting out good voltage, then hook it up to the truck and see if you get above 13v at the battery. if not, id replace the regulator and go from there.

WD · Post by WD » Sat May 21, 2005 9:55 pm

Huh, mine is the opposite, I show charge, anywhere from a needle thickness to 1/2 way up the scale. Even with NONE OF the accessory circuits drawing current and high engine speed. Everything works fine for now, so I decided the gauge is wonky. I'll fix it when it stops raining (predicted to be sometime in 2008 according to the latest forecast)...
-WD

Veriwide · Post by **Veriwide** » Sun May 22, 2005 9:17 am

Let me back up a little. What should I be seeing at the ammeter at normal opperation? All I have seen is discharge.

I have replaced the alternator and the voltage regulator because the battery continues to drain. I still need to cut open the engine wiring harnesses to run down wires, but I need to know where I am going. What should I be seeing at the ammeter at normal opperation?

Patrick

Jeffc · Post by **Jeffc** » Sun May 22, 2005 11:25 am

Normal would be just to the charge side without anything but the engine on, turn on more> like lights or heater,ect will move it to a discharge a little till engine rpm is up.
This will 'very' with how much the battery is drained
after starting and needs charging, may spike to the C
side till battery is fully charged (how far it goes
to the C side will depend on engine rpm and how drained the battery is).

Website · Post by **wideblock** » Sun May 22, 2005 11:28 am

on mine, when you first fire it up, it goes to about 6 amps on the charge side, then settles out at a hair over 0. at idle, with lights on, it shows a mild drain, but the second the rpm comes up, it goes to the charge side and settles back to 0 after it has made up for the drain. you will see it rise a few amps and settle back down here and there as the regulator kicks in and out depending on load. i installed a volt gauge as well, just cause i thought at one time my amp gauge was flakey. they instal reall easy, i just picked an ignition hot, run to the + side of the gauge and grounded the other side to the fire wall. its reads a steady 14 volts, except at start up i occaisionally see it get to around 15-16 then settle back down at 14. it will drop to 12 at idle if i got the bright lights on.

SnowCatSkinner · Post by **SnowCatSkinner** » Sun May 22, 2005 5:48 pm

If your regulator's good, are you sure it's getting power?

I don't know what year your truck is, but my '67 shop manual shows a 6 amp fuse that powers the regulator in the top left cavity of the fuse block. It gets juice from the "accessory" terminal of the key switch. That terminal also powers your turn signals, horn and windshield wipers. If these work, then your key switch is probably good.

In '68 they made a change and powered the regulator off the key switch's "ignition-1" terminal. The splice is located at the 12 volt side of the ballast resistor.

That's my best guess. The only other thing I can think of is the cab to block ground strap. The alt. is grounded to the block, but the regulator is grounded to the cab. Even if that ground strap is bad, I'd think you'd get some charging though.

Good luck!

Stinky · Post by **Stinky** » Fri Mar 10, 2006 4:12 pm

So what I'm getting from this is that if my alt is putting out, and my battery is ok, it's most likely my vr? I've got a 66 d100 with a transplanted 440, and last night while driving, my ammeter was reading 1/4 of the way into the discharge area. i tried kicking the rpm up a bit, and got no change. after a minute or so, it shot up to the charge side, then rested back just over even. It did that 2 or three more times on the way home, once while driving on the highway. Also, I'm unsure as to which vr to get. Does anyone have a parts book that can tell me what vr's would go with a late 60's 440? The guy I bought the truck from wasn't told what year/make/model the engine came from, and so he couldn't tell me exact, just that he was told it was late 60's.

Thanks,
James

Jeffc · Post by **Jeffc** » Sat Mar 11, 2006 2:36 am

Voltage reg does not have to match your engine size, all it needs to do is match your charge system; if you have a point type- strait replacent would be in order, or if you drop into my tec section you could get a later type that are listed there (blue box)......with wire upgrade
drawings if you choose to up grade to 2 wire alt and reg.....

Stinky · Post by **Stinky** » Sat Mar 11, 2006 11:00 am

Thanks Jeff. I've got the upgraded ignition, with the 2 wire system, looking at the pics in your tech section really helped. I'd go out and get to work on it, but wouldn't you know that this is the first day that we've had rain in the Valley in 142 days, so I'm stuck just thinkig about it.