Elec./Charging issues

[jnsane84]

I've got a 71 C-10 with 350 thats has elec. probs since I picked it up. The quik and dirty......I got 20+ ohms of resistance at the positive lead on the battery. It's killed at least 2 Alt.'s and Reg.'s. I dont wanna replace either until I solve this issue. Anybody had this prob and got any ideas.....I know this is vague but I'll add more later........The previous owner did a lot of riggin and useless crap.

[sneakysnake]

With the truck running, what is the voltage at the battery?should be between 13-14 volts.
Test for a drain, turn every thing off. unhook the positive cable and place a 12v bulb in series. If the bulb lights then you have a drain that is zapping Your battery over night.

[jnsane84]

The alt. and reg. are dead as of now but when they were still active it charged as high as 16 volts at one point. I've disconnected the positive lead from the battery and checked it to ground and got as much as 26 ohms. I've also left it all hooked up and placed my meter on the positive to ground and watched the voltage slowly drain. Currently I've got the Beverly Hillbilly method goin on....I unhook it everytime I park....havent taken the time to hook up a kill switch. The guy I got the truck from was having the same problem and replaced the alt. and reg. twice. I think theres been some hack wiring and someone has managed to ground something that shouldnt be. I just wanted to check and see if anyone else has had a similar problem with this gen of truck. I currently throw a charger on it every night.


-edited for grammar

[lowriden58]

to me it sounds like a bad ground somewhere. like if the regulator isnt grounded properly the alt will overcharge the battery, just my thoughts

[jnsane84]

I think that was part of the original issue. They had some really bad connections and seriously undersized wiring. I've changed out all of the stuff I was able to locate that was questionable but I've been too cautious to go out and buy a new setup and take the chance of burning it out too. I went into the trouble shooting process on this expecting to find some hugely obvious issue and it hasnt been the case so it has me thinking that I've missed the issue al together.

[Andy4639]

CAN YOU GET SOME PICTURES OF THE WIRING? THAT WILL HELP. WHAT KIND OF VOLTAGE REGULATOR ARE WE TALKING ABOUT...EXTERNAL OR ONE OF THE INTERNAL ONES?

Hook the batery + cable up as mentioned and see if you can pull the fuses and tell where it's at.

[BigDaddyDave]

My 71 C10 had the same problem as yours. I replaced 3 starters,3 batteries,and 2 alts before finding a bad ground in the front harness.Every time i would change a part,the truck would crank great for a day or two,then out of nowhere i was stranded again. The funny part is depending on the store and their help,some times the part checked good and other times bad. One bad ground can cause a lot of head scratching!

[Senator350]

just as a precaution... ground the HECK out of it! especially block to frame and cab to frame. rough up some metal, throw some 4 gauge copper in there (i use zero gauge)..

it'll cost you a couple dollars, but it'll work forever.. check the easy stuff first, right?

report back

[ChevLoRay]

I'm having a little misunderstanding in comprehending your statement as to your problem.

Are you sure that OHMS is the correct word? Ohms is a unit of resistance. If you are measuring resistance, your circuit would have to include something like a resistor, which limits the current through a specific part of that circuit. Amperage, on the other hand, is current flowing through the circuit. The voltage is merely a potential. I don't think OHMS is the right unit of measure.

If you are using a multimeter, and have it set to resistance (ohms), you are using the wrong setting. To measure voltage, you will have to be sure it is measuring AC or DC (you want DC) and you will have to observe the correct polarities (positive to positive/negative to negative). In this case, a "hot" terminal to ground will yield a measurement of the voltage. To measure the current flow, the meter will have to be in the circuit, so the current flow to be measured will be going through the meter. Resistance is measured with the power flow interrupted, i.e., no voltage flowing through the circuit and (therefore) no current either.

If you have CURRENT FLOW from the positive terminal on the battery (with the cable disconnected from the battery) when you touch the test leads to the battery and the cable, then you should be measuring amperage. If you meant that you have 20+ amps of current flow, you have a serious drain on your battery and something is seriously shorted and/or drawing current when it should be off.

You could start by pulling all of your fuses and then reinstall them one at a time until you find the device that is drawing down your battery. At that point, you'll know where to start looking to find out why it is drawing so much current.

[Andy4639]

ChevLoRay,

Yea...what he said!!!!

[jnsane84]

No I'm using my meter correctly. I'm a journeyman electrician and millwright just so noone thinks that i'm runnin round aimlessly with my meter. LOL Anyway I checked Ohms to see how much resistance I actually had in the system going back to the positive lead since I had such a quick drain.

[ChevLoRay]

Okay, you know your stuff. I just never thought about checking the resistance/conductivity like you did. I got to thinking about there being some resistance between the post of the battery and the cable clamp, which should be a dead short. I guess that 20 ohms isn't much resistance if that is where it would be done....which would tell me that the post or the cable clamp isn't clean.

But that wouldn't have anything to do with the drain on the battery. I'd still go back and pull all the fuses like I said before. I wouldn't know how else to find it. But, when you do it's gonna hit you like a ton of bricks.

[sneakysnake]

You cant use ohms to check the alt. the diodes will let the test current pass through.Best method to test is jerk it off and run to parts store.If you were over charging then you have a regulator related issue, either in the part,connections or grounding.