Yet another battery charger question

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FrankNichols

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Dec 2, 2010
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Hi, my house batteries are not being charged - sort of. Here is what I know so far -

1. We are in a campground with shore power, all our 12V systems seem to be fine (lights, refigerator, etc) when plugged into shore power.

2. This morning I went to start the generator (Kohl 7K) for it's monthly run and the house batteries were too discharged to start it. I used the Aux Start switch to use the engine battery to start the generator and let it run for 30 minutes under load.

3. When I shut down the generator and tried to restart it, the batteries had charged enough to start the generator. This made no sense to me, because I thought the battery charger was connected to shore power not the generator.

4. I checked the AC power to the converter/charger (B&W 3240 40 Amp) and it is shore power (119VAC) - ie. the charger is powered with the generator not running.

5. I measured the DC Voltage at the battery terminals and with the generator off it is 11.9V, with the generator running it is 12.8V.

Point 5 makes no sense to me unless there is another charger running off the generator that has been added someplace that I don't know about. (this is a 1983 HR Admiral I purchased used 9 months ago.) Or somehow the converter/charger "knows" when the generator is running.

Any suggestions on how to trouble shoot this would be appreciated!

TIA,

Frank
 
It sounds like you may have a dead cell in one of your house batteries.  Check the water levels in each cell, then check each cell with a hydrometer.  A battery reading 11.9V after being plugged into shore power is a problem. When you start the gen, the charge you are seeing at the batteries is what the charger is trying to put into it. 

One dead or dying battery will drag all the other connected batteries down to it's level.  It may be time to re-battery.
 
Sarge,

Thanks I will check that next, but I don't understand if the charger has AC from the shore power, why is the generator "charging" the batteries and not the shore power?

Frank
 
It could be that the converter is not doing anything. You might be running off the battery's. Check the converter plug if its not hard wired, also check the fuses on the converter and the output voltage. If you have a battery dosconnect open the switch so as to separate the power source. With the battery disconnected see if you have 12 volt utilities, lights refer and such. That should give you direction.
Jim
 
Jim,

Thanks, To check that I just unplugged the converter/charger from the AC and the house lights flashed and came back on dimmer (I assume because they were then running off the batteries). I plugged the converter charger back in and the lights flashed (I heard a relay click) and came back on bright. So, I assume the converter is working - that of course does not prove the charger is working, which - based on the voltages at the batteries it appears the charger is not working. I am taking the batteries out next to check water levels.

Frank
 
The water level in the batteries looks okay, they are NAPA 65 Month batteries that were installed 14 months ago apparently. The are NOT deep cycle batteries, but I don't expect they have died in 14 months anyway?

Also, when I took the batteries out of the battery compartment I found a loose white wire. I can not find any terminals that appear to be missing a wire yet - any ideas? (Picture attached) Anyone have any idea what the thing on the left with fins is?
 

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One thing we are missing here are the specs on the B&W 3240. Can't find them.

  Sounds to me that it is an old-style converter that has 2 outputs. One for the house lights and a separate one for the charging function.

  The house light function may work ok but the charging function is kaputt.

I found that to be the problem on my old Magnetec 45 amp converter.
Probably not repairable. New converter PD will fix it.

Carson
 
Carson,

Yes, the converter/charger is OLD and is a dual output - I think it is called "regulated" and "charging" on the diagram, I will check again, but I am afraid you are right, it sounds like the charger is not charging. Also, I checked the batteries and the water levels are good, and I tried starting the coach engine and the voltage on the batteries went up to 13.77V - so it appears the engine alternator will also charge the batteries.

I guess the next step is to look for fuses or circuit breakers that maybe blown and to try to measure the charging voltage at the charger and see if it is good there - I could have a bad wire between it and the batteries.

Thanks

Frank
 
The "thing with fins" is your battery isolator.  It is used to divert some of the charge current from the alternator to the house batteries when the engine is running.  It also prevents the house batteries from draining the truck/chassis battery when everything is running on battery power.
 
Lou thank you!

I was just sitting here worrying about the fact the engine was charging the batteries - I was concerned that it might conflict with the battery charger. So, from what you said that part is working correctly, so now I just need to find out why the battery charger is not charging the batteries.

Thanks

Frank
 
Your point #5 doesn't make any sense to me either. The converter/charger is normally powered from the 120vac system, so should get the same power whether on shore or generator. You say the converter has +119 when on shore power, but inadequate 12v output?

I'm not familiar with an 83 HR, but it sounds as though the generator has its own 12v charging system. That isn't typical, but maybe the older Kohlers did that?  That would imply that your main (shore power) charger is not putting out power to the charge feed and only to the regulated feed.
 
Gary,

I agree with your assessment, I think the main (?) converter/charger is only converting and not charging. I will take it out tomorrow and see what I can figure out. I am almost afraid to ask what the price of a new replacement will be, since this is old and a combined converter/charger unit - to replace it I assume I need a converter, a charger and a switch over unit of some kind - smells like money - sigh.

Thanks,

Frank
 
FrankNichols said:
I am almost afraid to ask what the price of a new replacement will be, since this is old and a combined converter/charger unit - to replace it I assume I need a converter, a charger and a switch over unit of some kind - smells like money - sigh.

Thanks,

Frank
Click to expand...

No, you don't need both.  Just connect the regulated output wires to the charge wires and connect them to the output of your new converter.
 
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