House batteries not charging

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Hotdawg22

Member
Joined
Aug 20, 2015
Posts
21
Hello everyone. Back again with a big problem with my house battery charger which is a BW MFG converter.
This is an older model motor home and is a 1983 Holiday Rambler Imperial.
It has the BW MFG. converter MD 3240UL which seems to be working very well.
I have checked the output and am getting 13.3V output for the house fuse panel and the leg that charges the batteries.
House lights and pump DO NOT work on converter power only. I have to use an external charger to keep the battery up so the house system will work.
I have checked all the wiring in the battery bay (with all batteries removed and the converter plugged in) and can not find ANY wire that has power.
So, this tells me there is a break in that line somewhere, but where.?? The number of wires and locations of the many wires on this MH is mind bending. LOL
I have tried to trace the wire from the converter to see where it goes and that is impossible cause it goes into the floor cavity and i have no idea where it surfaces.
ANY help on this will be greatly appreciated. I have spent hours on the net looking for wiring diagrams, likekind issues , etc without any success.
So, given that, maybe somebody out there has had this same problem and can help me out.
I know that somewhere between the converter and the battery bay there must be a fuse or switch? I have already checked everyplace i can think of, but no sign of the culprit.
Thanks for any help.
 
Is it practical to run a new wires from the converter output to the 12V distribution panel? Might be the easiest fix.

I don't know who could help you except for another vintage Imperial owner who has found and fixed a similar wiring problem.
 
Hotdawg22 said:
Hello everyone. Back again with a big problem with my house battery charger which is a BW MFG converter.
This is an older model motor home and is a 1983 Holiday Rambler Imperial.
It has the BW MFG. converter MD 3240UL which seems to be working very well.
I have checked the output and am getting 13.3V output for the house fuse panel and the leg that charges the batteries.
House lights and pump DO NOT work on converter power only. I have to use an external charger to keep the battery up so the house system will work.
I have checked all the wiring in the battery bay (with all batteries removed and the converter plugged in) and can not find ANY wire that has power.
So, this tells me there is a break in that line somewhere, but where.?? The number of wires and locations of the many wires on this MH is mind bending. LOL
I have tried to trace the wire from the converter to see where it goes and that is impossible cause it goes into the floor cavity and i have no idea where it surfaces.
ANY help on this will be greatly appreciated. I have spent hours on the net looking for wiring diagrams, likekind issues , etc without any success.
So, given that, maybe somebody out there has had this same problem and can help me out.
I know that somewhere between the converter and the battery bay there must be a fuse or switch? I have already checked everyplace i can think of, but no sign of the culprit.
Thanks for any help.
A 1983 BW MFG converter (MD 3240) would most likely be a clone of the infamous Magnetek 3240 series.  The converter shares an enclosure with the AC and the DC distribution panels. 

The symptoms suggest a problem with the relay on the converter output.

(see statement in red)  If the lights work with an external charger on the batteries, there couldn't possibly be an open wire between the battery and the distribution system.

(see statement in green)  Are you sure you weren't checking these points while you had the external charger hooked up?
 
OK. Thanks to all for feedback. I been out there scratching my head for the lack of action to take.
Gary, i did think about running a wire from converter to battery box but problem is, I have no idea where to connect it in the box. There are about a millon (lol) wires and connections in that box so i do not know if i should connect it to the isolater or to that solenoid that belons to the house batteries. I just know there is a fuse or switch somewhere between the converter and the box and i just have to locate it.
Lou, you are right. That BW is same as a Magnetek.
No, i had no power of any kind except the converter at the time i tested it. NOW, a surprise!! I just re-tested the DC system with the converter going (no battery or charger) and I DO have power to that system without a battery present. Guess the original test was flawed somehow. (Actually, the 2 , 12V lights i originally tested were burned out) LOL
SO in summary: with shore power plugged, the converter working, i get 13.3 volts on the red wire coming out of the converter to the DC fuse box.
I get 13.3 volts from the blue wire coming out of the converter that goes to the house battery box. But voltage never reaches the battery box. This means no charge is getting to the house batteries.
 
SO in summary: with shore power plugged, the converter working, i get 13.3 volts on the red wire coming out of the converter to the DC fuse box.
I get 13.3 volts from the blue wire coming out of the converter that goes to the house battery box. But voltage never reaches the battery box. This means no charge is getting to the house batteries.
Are you now saying that even with the charger on the battery, you don't get any 12V power to the lights and/or appliances?
 
No. Here is how it stands.
Plugged into shore power:
!) no batteries hooked up,
    a) the converter is putting out 13.3V to the DC and panel, interior 12V lights work, water pump does NOT work. normal??
    b) converter is putting out 13.3V on line that is supposed to charge house batteries. No power is getting to the battery box.
2) with installed batteries:
    a) converter is still putting out 13.3v and Interior lights work, as well as water pump
    b) converter is still putting out 13.3v and batteries still get no charge.
 
I understand, but you said earlier, that with the battery installed, the converter unplugged, and the external charger on the batteries, the batteries would light the lights.  Is that now true or false?
 
To clarify. With house batteries (charged up) installed. No shore power or generator running, motor not running...everything works exactly as it should. The house batteries will eventually run down.
I can hook up the external charger directly to house batteries and everything works as it should and as long as the charger is connected, the house batteries will stay charged.
Sorry for the confusion.
 
Voltage at the battery with the converter on OR off is 12.97 = or - a volt or two. So converter has no effect on voltage at the battery.
Been out there doing several tests and here is what i have discovered.
1) discovered that when house battery is connected the converter stops charging on the line that goes to the batteries. The line that feeds the house DC panel stays at 13.3
2) the red wire on the converter that charges the house batteries connects to 3 black wires, 2 large ones and 1 very small one. Tested with the converter OFFhouse battery connected: , I separated these black wires from the red one and with the battery connected i tested each wire.
1 large black wire had  12.97v
1 large black wire had 9.45 v
1 small black wire had 12.97v
So this tells me that the wires from the converter to the battery box are OK?? They have current flow from the battery backwards to the converter. Have no idea why one wire has 9 + volts. I wonder if there might be a resister in that line for something.
3) with the house battery still connected, the converter on, i tied the red wire and all the black wires back together and tested for volts and it was zero!!
OK. Now that i am completely lost (lol) does anybody have an idea or two? Why did the converter lose the charge when i connected the wires?
Tomorrow i will do a continuity test on those black wires and see where they are connected in the battery box. It almost seems like they have a diode in the line somewhere.???
 
Hard to say without some hands-on diagnosis, but I would be inclined to trash that old 3240 and replace the converter portion with something worth working on. Best Converter has a kit for swapping out the converter/charger portion. There are alternative that a capable DIYer can use that might be a bit better, but the kit is decent and I think not too hard for very basic electrical skills.
http://www.bestconverter.com/MagnetekParallax-to-Ultra-III_ep_8-1.html
 
Well, it could be the converter, but the mystery here is why it has output, under certain conditions, but as soon as i load it up with the battery connection, it stops charging.
SO, before i go buy another converter i wil do one more test.... Tomorrow i will hook up an external charger to those black wires and check the battery box to see if i am getting voltage. If i get voltage "BINGO" new converter in order. If i DON'T get voltage... BACK to the drawing board.
Thanks again.
 
It only takes two wires to charge a battery - one each to plus & minus terminals. You keep talking about three, and also mention a red wire. I don't have an adequate mental picture of what you have, so remain somewhat mystified by the numbers you report. Any chance of a photo?

The old 3240 is an unfiltered DC power converter, so loads that are sensitive to variations in the power are usually wired to the battery, which acts as a filter and smooths things out. The variations are sometimes called "noise" or "AC ripple". I think it has separate outputs for charging and for direct power to the 12v distribution panel (fuses).
 
Here is a diagram that is very much like your unit.  It should explain the two outputs. 

Yours may not actually have all the charger circuitry.  It may only have the SCR and the wire wound high wattage resistor (R1), but the logic of the connections is the same.  The adjustable charger was an option on those converters. 
 

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This output layout is almost exactly like my converter.
The REd wire marked "battery" is the one that has 3 black wires connected to it.
I will try to post some pics today.
The BLUE wire is for the house DC and is connected to a red wire.
 
Gary B-D is the Magnetk line/design.. I just scrapped out a trailer that has one.. It has a red wire and a blue wire for output one (Blue I think) goes to the battery and does a triple P job of charging (Piss Pot Poor). as you well know.

He may have mistaken it for black if it was dirty.

To the O/P.. Upgrtade the converter evfen if it's not bad.. that design was bad coming out of the factory.. ALso your meter readings are rather meaningless on that device unless you spend a whole lot on memters.
 
OK, mystery solved. The converter has to be bad. I hooked up an external charger at the converter location (converter unplugged) to the 3 black wires and tested for voltage at the battery box and there it was.
So even tho the converter is putting out voltage that should charge the batteries, it fails when the batteries are hooked up.
I am off to the market to get a converter. Am looking at a 3 stage 55 amp one that i am sure will do.
Some pics attached in case anyone else needs to know.
Thanks to all.
 

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Any replacement will not have separate wires for charging and direct house DC power, so there will be some modest wiring changes.  Basically the converter output will be just two wires, all nicely filtered and well-regulated.  You will be pleasantly surprised that the new one charges the batteries better/faster, provides cleaner DC power, and the battery life will be at least 2x what you have previously experienced.
 
Hotdawg22 said:
OK, mystery solved. The converter has to be bad. I hooked up an external charger at the converter location (converter unplugged) to the 3 black wires and tested for voltage at the battery box and there it was.
So even tho the converter is putting out voltage that should charge the batteries, it fails when the batteries are hooked up.

Aha, I had one that did the same thing and finally found it the same way ... with a charger temporarily ... good job!

Howard
 
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