Damaging the Converter

It is hoped that the following information may prevent your becoming an unhappy camper.
This information based on a conversation with a fellow TrailManor owner who discovered the hard way how simple it is to damage the charger side of the converter. This can occur if the following conditions are in place at the same time:
1- the trailer battery(ies) are low in charge
2- the trailer is plugged into 120volts, and
3- the electric tongue jack is activated.

“.........My experience was with a model 6332 MagneTek converter but believe same thing could happen to all 6300 series. The entire converter doesn't fail, just the battery charging section which has a capacity of 10 Amps. If the battery is a little low and you are plugged into 120V while using the electric jack, the battery charging circuit can be asked to supply more than 10A and therein is the problem. A high wattage resister burns out which isn't hard to replace but you can't pick one up at any corner emporium (or Radio Shack)

The output of the 6300 series converters is a raw full wave rectified sine wave with no regulation. (Output voltage varies in direct proportion to variations in 120V input). Lights and motors don't care but electronic devices do and must be connected to the fused battery circuits of the distribution panel. (See Owner's Manual). You must have a battery to use antenna amp and 12V outlets.

With the 7300 series converters, the output is well filtered and regulated and everything can be operated without a battery if necessary. There is no concern about overloading because they have an electronic current limiting circuit. A much better converter but comes at a price. Most people will find the 6300 series satisfactory but since I had trouble l am happy to have the 7300 upgrade.”

[Bill]

I'm surprised that the converter doesn't have a fuse in the output. Perhaps the addition of an in-line 10 or 15-amp slow-blow fuse would be a good precaution. Given what your friend describes, I'm also surprised that the converter doesn't hurt itself when it is attached to a totally dead battery. This could result in a charge current well over 10 amps.

My 2002 2720SL is in the garage, so I can't open it up, but the RV Data Card says I have a 6332 converter. When I get to open it up, you may be sure I will be paying attention to what I do, and I will check out the configuration. But the Owner's Manual, the slick-paper advertising brochures, and TrailManor.com all say that it has a 30-amp converter. If the 30-amps isn't available for battery charging, what is it?

Bill

[RickNewcomb]

Searching around the web I found this webpage which describes the MagneTek converter.

http://www.mastertech-inc.com/converters.htm

On this page was the following:

MagneTek 6300Q Series Linear Converters offer a total electrical package, with output ranges from 25 amps to 50 amps. Each model has a 30 amp, 120-volt AC panel board, 12-volt DC distribution panel, and a converter/charger with optional line generator transfer switch.

The 6332Q has 12v 30 amp Output and a 12 amp converter/charger.

Based on that, I would guess that the 12v 30amp output is seperate circuit from the 12 amp charger. ???

More from E. D. (via Hal)

Hi Hal,
I'm surprised that the 6332 converters did not have a breaker or fuse in the charging circuit too. Been lead to believe that some did but mine did not and if I kept it there would have been a fuse. The 30 Amps is the output capability of the main section of the converter which feeds the lighting circuits directly when plugged into 120. When unplugged a relay switches these circuits over to the battery. My source of information for the converter is packed in the trailer so I can't give a detailed explanation the converter operation.
Incidentally the lighting circuits do have fuses.

[Bill]

I got into my TM. The diagram in the owners manual shows two output lines from the converter - a blue one (the filtered output to the 12v loads) and a black one (to the battery). The diagram shows a 20-amp fuse in the black line, but doesn't say where it is located. In my TM, there is an inline fuseholder right at the battery. I find a 30-amp fuse installed there. If this is the only fuse, and if the converter's charger has a 10-amp capability, I can believe that the combination of a low battery and an electric tongue jack would overload the converter.

I sure would like to find a schematic diagram for the 6300-series converter. I am an electrical engineer by profession, and could evaluate the circuits and make recommendations. Anybody got one?

Bill

Bill,
You might try http://www.mastertech-inc.com/converters.htm
or www.magnetek.com to see if folks at either site would provide you with a schematic.

Bill, me again... for information on the Magnetek Converter, you should go to www.brwholesale. I just reverified their site and found that they are presently rebuilding it. Even though, you can dl their full color catalogue. It takes about 7 minutes to dl it. Their phone # is 1-800-900-2468. Camping World (and maybe other RV stores) also distributes this product. Maybe they would make you a copy of the schematic.

Hal

Hal,

I wonder if the person with the damaged converter has the electric tongue jack connected to one of the three accessory circuits to his 6332.

In addition to the six 12v circuits powered by the converter output, the 6332 has 3 12v accessory circuits connecting full time to the battery. It's apparent that the battery charging section cannot sustain a high current surge by a high demand appliance without a full battery to support in spite of the appearance of a 15 amp circuit.

I'm betting the problem would be solved if the electric tongue jack is powered by one of the six converter powered circuits. Here the 120v to 12vdc converter would handle the current when plugged in to AC {where the problem occurred} and, of course, powered by the battery when not plugged in.

[Bill]

CJ - Your theory makes sense to me.

I rummaged around in my converter last week, looking at connections (I am an electrical engineer). I haven't actaully pulled the converter and traced out the schematic yet, but I believe that the hookup is as shown in the .gif diagram attached. [Would like to hear confirmation or other info from anyone who has any.] The natural reaction (including mine) of someone buying an electric jack would be to connect it right up to the battery. But if my diagram is right, it shows just what you describe. It should be hooked up to the converter output.

Bill

Hi Bill,

I am also a EE. Your circuit looks right on. I'm guessing that the converter section might use an SCR and that the battery charging section [and cleaner power] uses a transformer, full wave rectification, with a series resistor to regulate battery charge as that is what burned up with the original problem.

Also, I found out the AC outlets in our camper share a 15amp GFI circuit breaker which we popped last week by running a space heater and a micro-wave simultaneously.