Battery Voltage Issue

[JonCheun]

I have a 68 C10 with a 1-wire configuration.
A few weeks ago I was driving to work and noticed my lights were dim and the voltage gauge read 11 Volts.
I first think the battery so instead of testing it, I just went ahead and replaced it with a new one.
Still the voltage was dropping. So I replaced the 1-wire 160 Amp Alternator with a new one from motor city reman.
I still had the receipt and it's 9 years old, I thought that was good so I bought a new one.

My issue is the volt gauge still reads 11 Volts when I am at a complete stop. I know the alternator is good b/c when I hit the throttle it goes to 13-14 volts but when I slow down and come to a stop it drops to 11 volts.

Tomorrow (Friday) I am going to go take back the battery and get another one b/c I don't think it is holding the charge.

I got the battery from Pep Boys so ProStart brand b/c it died in a parking lot and there was a pep boys in the lot.

It's a marine/rv battery.

[Shyguy]

If Pep Boys is like other auto parts stores they will want to charge and test your battery to make sure it is bad.

It depends on what marine/rv battery you have, if it is of the deep cyle type and not the starting type it will not hold up as well.

[cdowns]

i would start by disconnectin wires and cleanin thenm and where they mount to nice shiny metal// especially gronding points so the electric flow

[JonCheun]

I went to pep boys and decided to change the pro start battery to the optima battery.
I use a marine deep cycle battery (blue top) optima b/c i use the extra terminals for the 1-wire alternator, stereo, and extra stuff.
Does it matter if I use a Blue top in a truck?
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[BMERDOC]

What is your idle speed? Like cdowns said clean the connections. Not just the battery terminals but the other ends too, especially the ground at the block. If everything else is known good a low voltage at idle is usually from corrosion at connections or an excessively low idle speed.

[VetteVet]

Your idea of using a marine deep cycle battery is just as wrong as using a one-wire alternator for the loads you have in mind for your truck.
Get an optima red top and if you must have a one wire, then wire the output wire to a point that is a common junction for most of the loads in your truck.

The problem you are having is that you are reading the voltage drops on your wiring down stream from the battery, and the alternator is just charging the battery, (which is not designed to be used for repeated starts in short intervals like an automobile needs), and not compensating for these voltage drops by increasing it's output like a three wire alternator would.

If you are reading less than 12.3 volts on your battery with the engine idling, then the battery is not fully charged or it's bad. When the alternator drops to 11 volts the fields need more current to generate more output. A three wire alternator does this but the one-wire has to spin faster.

Cleaning all the connections is a good idea but I don't think it will make a difference. It might make the lights brighter but it won't help the alternator output.

[aussiec20]

i had similar problem and it turned out to be pulley size was to big and didn't charge on idle, so i put in a smaller diameter pulley and fixed the problem.

[68gmsee]

As mentioned above check wiring and grounding points first. That's the easiest thing to do. Check and/or add ground strap from back of engine to cab, install addtional ground straps to any component that is isolated by bolts or rubber mounts like the cab or bed to the frame and even the radiator support. Bolts rust and reduce path to battery ground.

Also as mentioned above, get rid of the one wire and spend the effort to go with the proper alternator. They're cheaper and not that difficult to convert. One wire are easy to install but not the best for trucks or cars used in everyday driving situations. I have one on my farm tractor but it operates at high rpms almost all the time.

[BMERDOC]

VetteVet has this stuff down pat. My experience is with stock style charging systems. After reading his post I decided to look up the cons of a one wire set up seeing as I have no experience with them.

http://www.madelectrical.com/electri...hreewire.shtml

[JonCheun]

Okay I got rid of the marine battery and did some rewiring so now I use the yellow top optima battery.

I will look into converting away from the 1 wire.

I bought this pick up a year ago and just been keeping it up and running so I just have been replacing parts with what was existing. Now that I have the time and some money. I will start to redo this truck the right way.

Thank You everyone for your help and for your help in the future. I have lots of little projects so let it begin.

[68gmsee]

Originally Posted by JonCheun

...I bought this pick up a year ago and just been keeping it up and running so I just have been replacing parts with what was existing. Now that I have the time and some money. I will start to redo this truck the right way.

Thank You everyone for your help and for your help in the future. I have lots of little projects so let it begin.

That's the way most of us have been doing our trucks -save some money and fix them up as we go. Also don't forget to let us know what the fix was. This will help others.

[Andy4639]

Originally Posted by VetteVet

Your idea of using a marine deep cycle battery is just as wrong as using a one-wire alternator for the loads you have in mind for your truck.
Get an optima red top and if you must have a one wire, then wire the output wire to a point that is a common junction for most of the loads in your truck.

The problem you are having is that you are reading the voltage drops on your wiring down stream from the battery, and the alternator is just charging the battery, (which is not designed to be used for repeated starts in short intervals like an automobile needs), and not compensating for these voltage drops by increasing it's output like a three wire alternator would.

If you are reading less than 12.3 volts on your battery with the engine idling, then the battery is not fully charged or it's bad. When the alternator drops to 11 volts the fields need more current to generate more output. A three wire alternator does this but the one-wire has to spin faster.

Cleaning all the connections is a good idea but I don't think it will make a difference. It might make the lights brighter but it won't help the alternator output.

U can clean all u want, but if the system is only putting out 11 volts then your going to kill that new battery. The system is 12 volts min. and if your not seeing it then it's not going to help cleaning anything. Vett knows his stuff he has helped me more than once.

[PanelDeland]

Alt should put out 14 volts or so.If the battery is below 12 and charged it's gonna be toast soon.If the alt isn't putting 14 into the batt something else is wrong.

[VetteVet]

If you take your 160 amp alternator to any reputable shop they can change the voltage regulator to a three wire type and save you some $$$$$.Be sure to ask them if you have the SI style alternator or the CS style.Being a 160 amp I'd say it is the CS style.

In any case when your are ready to wire it in, come back and post in the electrical section and we'll get you fixed up. VV