NO 12 volt off of battery, but all 12 volt and AC works off of shore power

[Step5575]

Hello, I have a head scratcher. '93 Lance Squire 3000 camper. New battery, with power to the inverter/converter (Magnetek Series 6300, 25 amp model 6325 with a Parallax 7345 Power Supply), and to the test panel on the wall, but only to the test button . No power from the battery feed is fed to the water pump switch on the test panel. There is NO 12v output to any of the lights or other 12v accessories from the battery feed. But when I hook up shore power, all 12 volt, and AC functions work properly. According to the manual, the inverter is automatic, with no need to switch between AC or battery . I fear the inverter was fried by PO. I did find a pair of wires coming off of the fuse panel that were bare at the ends and they could have shorted. However, the fuse to that circuit was pulled. I removed the wires, and replaced the fuse, but still no 12v off of the battery to the 12v circuits. 
 My questions  are  these. Why would the 12v functions work when connected to 120v shore power, and not when only powered by the battery. Shouldn't all 12v be dead ? I mean, a 12v power source should route 12v without interruption, shouldn't it ? If the inverter was damaged, shouldn't the 120v to 12v have the same issue of no output ? Also, why is the 12v output ran through the inverter, and not directly from the battery to the 12v sources anyways ? Is this done to prevent shorting of the 12v battery feed and the 120v shore power feed ? To keep them isolated from each other ? If that's so, why does the test panel have battery power, and additional 12v power to the water pump switch when ran off of shore power 120v ? Is the inverter repairable ? Or do I need to swap out the unit ? 

Any advice to help me out is appreciated.
Stephen

[Just Lou]

Others with specific knowledge of your Magnetek converter will be along to make a diagnosis and suggestions, but my limited knowledge of that unit says that your symptoms are not all that uncommon.

Some older converters had separate outputs to feed the in-house loads and to charge the batteries.  The unit depends on a relay point transferring to feed the battery voltage back to the loads when no shore power is present.  I suspect that is your problem.

Be prepared for suggestions to replace that converter with a newer and better model.

[Step5575]

Thanks for the heads up ! Replacement is what I fear. I did see a replacement relay for a Magnetek 7345 on Ebay, along with whole 7345 units. $27 for the relay, and $220 for a whole 7345 . I may have to see if I can get the 7345 apart without a complete teardown. $27 sounds better than $220 any time. And it sounds like a relay problem. Maybe the relay is not switching back to allow the battery 12v to flow through. Stuck in the 120v position, which would allow the 120v to work as it should.

[John From Detroit]

In your case there are many possible mess ups.. First the Magnetek 6300 it is both a converter.. sort of,  and power distrubution panels (both 12 and 120 volt).  The converter part is very poor, not well regulated, single stage and known to kill batteries.  But it is not just a converter, it is a "converter and charger" two different devices with a cross over relay.  If this was removed, and the job not done right, that's your problem.

If it was not removed, a relay could have failed.

Not the parallex 7300 (Without the letter "T" on the end) is very slightly better, it has slightly better regulation but is still single stage and thus should be upgraded.   Parallex, bought Magnetek.

Then we get to the posibility of blown fuses, or tripped breakers, and the disconnect switch.

In short, you need to take a test light and track it down.

[Step5575]

Already took my meter to the converter, and that's where the problem resides. All of the fuses, breakers, and the trip switch in the battery box checked out fine. I suppose I'll just tear into the piece, as it doesn't sound like I have much to lose anyways.

  If I decide to replace the piece, does anyone have a specific piece they could recommend ?
Thanks, Stephen

 

[Gary RV Roamer]

As others have said, the charging and 12v converter functions are somewhat separate in your 6325/7345 set-up. Clearly the 7345 is working - that's what is providing 12v from shore power. Your problem seems to be with the battery feed, so I would be checking the wiring from battery to the 12v distribution panel. I don't have a schematic or any recent experience with the 6300, so can't offer more detailed advice.
 
 Possibly this schematic will help.  http://www.parallaxpower.com/6300/6300.PDF
 
 This brief tech description also has some clues:
 
 

The DC output of the Magnetek 6345, option A, has three possible voltage sources: the converter output, the battery output and the charger output. The battery charger has a voltage sensing circuit which toggles the output between maintenance and charge.
 
 With the shore power plugged in, there are always two voltages available from various combinations of the three sources. The converter output is isolated from the other outputs by relays when on shore/generator power and available on fuses 1 thru 6. Battery output is available on fuses 7 thru 9 and is affected by the state of the battery and the battery charger. High demand on the battery fuses pulls down voltage and causes the charger to kick in yielding, guess what?, 15 1/2 VDC! There is a lag between removing the load and the voltage returning to normal.
 
 Addendum: There is an Option C that has a 6A charging section that supposedly senses battery condition. Option CC is a 12A solid state charger.
 

[Jim Dick]

Most units have fuses that prevent problems if the DC leads are hooked up backwards. They are 30amp fuses. They will blow and isolate the battery from the charger. Perhaps one or both have failed for some reason. I'd check them if you haven't already.