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dual charging setup question


ozzmonaut

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17 minutes ago, Sam Buchanan said:

 

Seek out your local farm supply store that sells batteries for tractors (Tractor Supply in my neck of the woods), they will have 6v wet-cell batteries. You should get several years out of one if you use an alternator that keeps it charged all the time. The old-school batteries worked pretty well when our cars were youths....and they still do (with proper cables).   :)

 

I agree with Sam. I had a Group 2 6 volt lead-acid battery from Farm & Fleet in my truck for 8 or 9 years before it finally died. And it may have lasted longer if I hadn't ignored my battery maintenance and kept the water level up. I replaced it with another F&F battery that is going on 5 years now. I keep a battery charger/maintainer on it when not in use and it has plenty of juice to start the truck, even in colder weather and when it's been sitting a while (which requires extended cranking).

 

Higher amp rated Optima's seem appealing, but they're not worth the added expense in my opinion. They do have their place, but their benefits don't outweigh the cost in this application.

 

Something seems very odd in your system though. There is no logical reason that a pair of 6v Optima batteries would discharge quickly while running, whereas your old battery works fine. Are you sure you had them connected correctly? A positive ground charging system pumping into batterys connected with negative ground may account for this rapid discharge.

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2 hours ago, DonaldSmith said:

I vaguely remember something about one-wire alternators discharging Optima batteries.   Was it James Douglas who wrote about it?

It's not that they discharge Optimas, it's more like the Chebby one wires are not optimized for charging AGM (Absorbed Glass Mat) batteries. A true charging setup for an AGM has a multi-stage charging process with the final stage being a slow charge to a higher voltage than a conventional lead-acid battery.  That said, I drove my 47 for years with a one-wire charging my 6V Optima with no problems.

Later when I converted to 12V I still used a one-wire with a different brand AGM.  The interesting part is that I used a battery tender product with a 3 stage charge for AGM's.  Any time I started the car it would run for about 10 minutes with no charge showing until the AGM voltage got down to the "normal" level for a lead-acid battery, then it would start charging.

 

Marty

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There is a chance that one of the optima's was bad, ie., internal short, because you had them in parallel, this would have caused the other to go flat as well even when the alternator was trying to charge them.

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I think one went bad and ruined the other. They were definitely hooked up correctly. Positives tied to each other, negatives to each other, both with heavy gauge battery cable. The positives went to the chassis. I did like how easily they started the car. The problem existed before I put the alternator in. I noticed while running that the battery voltage never got above 5.85. The voltage regulator was allowing the generator to charge the battery, but I believe the batteries were losing voltage constantly. I put the alternator on, but waited til the next day to hook up the wiring. I found that the batteries were fully discharged, 0 volts flat. I placed them on the charger. They got to 4.8V then the trouble light on the charger came on. At this point the charger stopped and battery voltage began quickly dropping, even while off the charger. I pulled the batteries and placed them each on separate chargers. Same thing happened to both. 

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So I removed the optima batteries, put my old battery back in, which was working before. Cranked the car up, checked voltage, etc. The next day the battery was dead.  Tried charging it. It is ruined just like the optima batteries now. The single wire from the alternator runs to the battery prong of the VR. Correct? My suspicion is that the seller I got the alternator from lied about it being positive ground. Is there an easy way to test without running the vehicle?

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New alternator may have a defective regulator in it which does not shut off and drains battery totally flat overnight which is extremely hard on used batteries.  Does also shorten the life span on the optimas also, but I have had my antique Optima battery so low 3-4 times where the radio would not work.     OR- - And?

 

Optima batteries when discharged to far will not often recharge without another battery with a higher voltage connected in line. This is caused by the fail/safe mechanism in the charger itself to prevent attempts to recharge shorted out batteries being recharged and explosion is possible. Hooking up the 2nd. battery fools the charger to start up charge. After some time the second battery can be removed from the circuit and charger will now continue with the recharge>\

 

Some thoughts to check?

 

DJ

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1 hour ago, ozzmonaut said:

So I removed the optima batteries, put my old battery back in, which was working before. Cranked the car up, checked voltage, etc. The next day the battery was dead.  Tried charging it. It is ruined just like the optima batteries now. The single wire from the alternator runs to the battery prong of the VR. Correct? My suspicion is that the seller I got the alternator from lied about it being positive ground. Is there an easy way to test without running the vehicle?

 

You do have the A and F leads disconnected from the voltage regulator and the old harness lead is still connected to the bat terminal....right?

 

What voltage are you seeing at the regulator battery terminal with the car running? If it is ~7.5vdc then you have a good alternator. If it is ~6.0 vdc than the alternator isn't charging. You can disconnect the battery overnight to see if there is a drain in the car's electrics that is discharging the battery. This isn't rocket science......just systematically eliminate possibilities.   :)

 

Draining a battery usually won't kill it, I suspect you have issues with your charger as mentioned previously. If you have access to a "dumb" charger, put it on the battery for a couple of hours. Some of the modern, smart chargers won't start the charge cycle if they don't see a certain threshold voltage on the battery. An idiot ? left the master switch in my plane on for ten days one time and the Odyssey PC680 battery (same AGM tech as the Optimas) was so flat it wouldn't budge a voltmeter or take a charge from the Battery Tender smart charger. I put it on a dumb wall-wart charger for a few hours then back on the Battery Tender. It took a full charge and I flew it for a few more years. Batteries are hard to kill dead.

 

 

Edited by Sam Buchanan
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I had 7.5V from the alt. I got the optimas to charge with an old charger. Unfortunately, once disconnected from the charger, the voltage began to drop quickly. It was at 2V in a couple of minutes. Being as nothing in the cars electronics was draining the battery before, I tend to think that is not the case. The old battery will charge to 6.3V on a charger, but once I try to start the car it barely turns the starter and immediately drops to about 5.3V. However, if the alternator is a negative ground, I fear it may be sending power to the negative side, and grounding through the chassis. If this occurs, it seems the battery could discharge due to this. The gen and F leads are disconnected and all is taped up. 

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Looks like you do have three bad batteries.

 

Not sure what happens if you connect neg ground alt to positive ground system........I suspect it would blow up the alternator regulator.....or something.....

 

If you are getting 7.5 at the battery’s negative terminal I think you have a good positive ground alternator. Find a known good battery and give it a go......you’re gonna have to buy a new battery if you want to drive your car.  ?

Edited by Sam Buchanan
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  • 2 weeks later...

So I got another new battery, just a basic battery. Hooked it up. Cranks fine and all, but after turning off the car, I didn't drive it for a few days and drained the battery. I charged it up, cranked the car, etc. Alternator is still pushing out 7.5V or so. After turning the car off, the voltage on the battery is 6.46, but starts to drop quickly, gets to 6.27 and then drops slower. I have disconnected any electrical, lights, gauges, ignition. Just wanted to see if it still drops. It does. Is it possible that the one-wire alternator, being self-exciting, it pulling voltage while the car is off? It is run to the regulator, so it should not be able to draw with the key off. But just in case...   Thanks

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1 hour ago, kencombs said:

Did you get a wiring diagram, wiring pieces, plugs  or any other components other than the alternator with the purchase?  What is the alternator model and make?

 

Was the seller an established vendor? I purchased my 6v alternator from Quality Power and have been pleased with the performance and support:

 

https://www.qualitypowerauto.com/category_2/Special-Applications--6-Volt-8-Volt-and-12-Volt-Positive-Ground.htm

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6 hours ago, ozzmonaut said:

I may just have to get one from quality power to eliminate the possibility. Another option may be to place a relay between the alternator and external VR, and wire the relay to close when the key is on. 

 

The relay is just a bandaid to fix a problem that shouldn't exist.

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7 hours ago, ozzmonaut said:

I may just have to get one from quality power to eliminate the possibility. Another option may be to place a relay between the alternator and external VR, and wire the relay to close when the key is on. 

Can you clarify the wiring you have installed?  I seem to be missing something in the design.  What type of alternator and external VR do you have?  Do you have an ammeter or indicator light?  Blocking diode? 

 

I agree with Sam, a relay isn't needed except to cover up some other issue.  Fix the root cause, don't complicate the installation would be my advice.

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1 hour ago, kencombs said:

Can you clarify the wiring you have installed?  I seem to be missing something in the design.  What type of alternator and external VR do you have?  Do you have an ammeter or indicator light?  Blocking diode? 

 

I agree with Sam, a relay isn't needed except to cover up some other issue.  Fix the root cause, don't complicate the installation would be my advice.

 

Yes, let's revisit the alternator hook up, I thought we went through this earlier but now I'm wondering about it. The old, external regulator, if still in place, should ONLY be used as a terminal block to connect the wire from the alternator to the car's wire that goes to the ammeter. Disconnect everything from the A and F terminals on the regulator.

 

Tell you what I would do (and did on my car)......remove the old regulator and toss in on the work bench (or trash). Then use a high-quality butt splice to connect the alternator lead and ammeter wire (the one that was connected to the BAT terminal of the old regulator). There MIGHT be a faulty internal drain to ground in the old regulator, removing it eliminates that possibility.

 

One more test. With the ammeter lead disconnected from the alternator and the ignition switch off, check to see if there is any continuity between the ammeter wire and chassis ground. This will explore the possibility of a ground drain occurring in the harness or ignition switch (or headlight switch?).

 

If your car passes that test and the alternator is connected to the ammeter, your alternator is good, the battery is good........this system has to work properly.

Edited by Sam Buchanan
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I believe the issue is related to the ammeter. I disconnected a wire from the starter solenoid. It was one of 2 wires on that particular post. This stopped the drain. At this point I did not know if the car would crank. It did, and all functions including ignition, lights, heater fan, etc. still work. Except for the ammeter. I now have the alternator wire hooked to the negative battery terminal. It is a terminal with multiple connection points so I was able to use a higher gauge wire than what was there. Would this cause any issues long-term? I can't imagine that it would. I will just remove the VR and throw it in the spare parts bin. I have a feeling a previous owner connected the ammeter separate from the regular harness at some point. Later on, I plan to replace every wire on this thing with new cloth-covered wire, but this lets me drive for now.

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3 hours ago, ozzmonaut said:

I believe the issue is related to the ammeter. I disconnected a wire from the starter solenoid. It was one of 2 wires on that particular post. This stopped the drain. At this point I did not know if the car would crank. It did, and all functions including ignition, lights, heater fan, etc. still work. Except for the ammeter. I now have the alternator wire hooked to the negative battery terminal. It is a terminal with multiple connection points so I was able to use a higher gauge wire than what was there. Would this cause any issues long-term? I can't imagine that it would. I will just remove the VR and throw it in the spare parts bin. I have a feeling a previous owner connected the ammeter separate from the regular harness at some point. Later on, I plan to replace every wire on this thing with new cloth-covered wire, but this lets me drive for now.

 

Glad you found a ground drain....but I'm struggling to visualize what is going on with your wiring....the comment about the starter solenoid is puzzling. I also don't understand the comments about multiple terminals and higher gauge wire.....maybe a photo would help? Do you have a service manual for your car with a wiring schematic?

 

You would be ahead to return the ammeter to the original configuration, it really is a simple hookup. Without an ammeter or voltmeter you are flying blind with no way to see a charging failure in progress. As long as your car has bastardized wiring you will be chasing problems.....get it straightened out once and for all for maximum reliability and ease of maintenance. The original wiring is fine as long as the insulation is intact, some of the wiring firewall forward may be worse for wear and can be easily replaced.

Edited by Sam Buchanan
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11 hours ago, ozzmonaut said:

I believe the issue is related to the ammeter. I disconnected a wire from the starter solenoid. It was one of 2 wires on that particular post. This stopped the drain. At this point I did not know if the car would crank. It did, and all functions including ignition, lights, heater fan, etc. still work. Except for the ammeter. I now have the alternator wire hooked to the negative battery terminal. It is a terminal with multiple connection points so I was able to use a higher gauge wire than what was there. Would this cause any issues long-term? I can't imagine that it would. I will just remove the VR and throw it in the spare parts bin. I have a feeling a previous owner connected the ammeter separate from the regular harness at some point. Later on, I plan to replace every wire on this thing with new cloth-covered wire, but this lets me drive for now.

 

So where did the wire you disconnected from the solenoid go? Sounds like you have a good old fashion short in your wiring. If the previous owner connected the ammeter separate from the regular harness I would wonder why he did that. Plus it says that the wiring harness may have been changed. Trace the wire down that you disconnected and see where it goes, if it goes to another connection then start disconnecting wires from that connection one at a time and see if the voltage draw on your battery goes away. 

Track down exactly where the short is and fix it.

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In addition to the last two posts, the fact that you disconnected the ammeter does not prove it to be at fault.  It was really common to feed other loads off the ammeter, especially aftermarket doodads.  So there may be an added load somewhere.  It would be really helpful for you to draw out the wiring as it exists, and compare to a stock drawing.  I'd almost bet that the problem would become clear once you commit the 'as built' to paper (or computer screen).

 

A true short to ground would result in hot wire and smoke, so my money is on a hidden load. Or, I'm still not clear on what type of alternator installation you have.  One wire, three wire, diode or light bulb to prevent back-feed or???

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