Progressive Dynamics PD4045

[Carl G]

As part of my 1987 Lil Bigfoot renovation, I'll be installing a PD4045 converter/charger. I just about have all of the supplies, tools, etc., but have a rookie question. The PD4045 has 12 positive DC wire leads coming out of the back and postive and negative 10 AWG wires leads that go to the battery. I plan to run the 12 postive DC leads to a barrier terminal block similar to the one in a picture that Matt found on the Airstream forum (the converter/charger in this picture is a PD4045)and then run the positive lead to a terminal block, where I will step it up to 4 AWG wire to run to the battery (needed to avoid voltage drop). I will also be installing a ground (negative) bus bar (smilar to the one that you see intalled near the wall in the picture below) for all of the negative 12v wires coming back from trailer systems. My questions deals with the white 10 AWG negative wire that is supposed to run to the battery. In the picutre below, it is the wire that runs from the top of the converter/charger, is spliced in the middle, and then runs to the bus bar located along the wall. Is this correct? Should I run this lead to this bus bar and then run my 4 AWG wire from the bus bar to the battery to complete the circuit? And, then should I run my ground wire from this same bus bar to a disaster fuse and then to the frame?

In RV Electrical Systems, Moeler writes, "Converters with a built-in charger usually have two separate outputs: one supplying the power for the RV's 12-volt equipment, the other going to the battery for charging purposes." That does not appear to be the case with the PD4045. How do the 12v systems get power when the trailer is not connected to shore power. Does the power come back through the postive battery lead through the converter/charger and then to the 12v leads running to the various lights and other systems?

Thanks for the help. I want to be sure that my thinking is correct before I begin.

P.S. In the picture, you can see 2 small terminal blocks just above the long barrier terminal block containing the postive 12v wires. I can trace the one with red heat shrink; it is the positive wire to the battery. Can anyone tell me about the other terminal block? It appears to have one return wire with yellow heat shrink, but the other terminal is empty.

Thanks,

Carl

[Orcus79]

I think the two small erminal blocks are actually automotive circuit breakers, though I culd and have been wrong in the past. There is a second wire attached to the one with the yellow crimp, its dark red (in a shadow?) making it hard to see against the dark plywood.

As for how to wire it, I have no clue, sorry.

[Matt in SV]

Yes this plan sounds correct, although I don't believe you need to fuse the ground. Those do appear to be fuses or breakers on the 12vdc positive. My convertor has just one positive screw terminal, but it does have 2 fuses. There should be some fuse on the convertor output, and a fuse on the tow vehicle's charge line somewhere. I would also expect to see a big fuse on the battery positive. I put mine right on the positive pole using a special fuse holder. I'll try to grab a picture of that. The size of that fuse depends on whether you are running an inverter. It could be 100 amps or more if you have a 1kw inverter for example, or it could be much lower, like 50 amps if you don't plan to use one.

How far is the run to your battery? If it's short like four feet I would think you could get away with six gauge wire.

[Carl G]

Originally Posted by Matt in SV

Yes this plan sounds correct, although I don't believe you need to fuse the ground. Those do appear to be fuses or breakers on the 12vdc positive. My convertor has just one positive screw terminal, but it does have 2 fuses. There should be some fuse on the convertor output, and a fuse on the tow vehicle's charge line somewhere. I would also expect to see a big fuse on the battery positive. I put mine right on the positive pole using a special fuse holder. I'll try to grab a picture of that. The size of that fuse depends on whether you are running an inverter. It could be 100 amps or more if you have a 1kw inverter for example, or it could be much lower, like 50 amps if you don't plan to use one.

How far is the run to your battery? If it's short like four feet I would think you could get away with six gauge wire.

Thanks Matt,

The idea for the disaster fuse came from Moeller's book. He writes, "An important item--usually missing--is a fuse or circuit breaker to protect the RV from possible destruction in the event of a major electrical problem. A fuse to prvent these occurrences is aptly named a disaster fuse." He continues, "The disaster fuse should be mounted in the negative line going from the battery bank's minus post to the chassis ground post."

But, I realize that some of the ideas in the book are a bit outdated. If you don't think it is necessary, it will save me some money and time.

[Matt in SV]

I believe this is intended to protect your 12VDC system from something going weird on the chassis ground, as opposed to the other way around. Like if you were to connect up to some 30A circuit that had earth connected to hot, or maybe your battery gets loose in a crash and rattles around some, or a powerline falls on your trailer.

I took a look at the scamp manual and it appears they have just the one fuse on the positive rail. This link may work:

Google Image Result for http://scamp.n0kfb.org/manual/electrical.jpg

I found a page of the Moeller book on Disaster Fuses here, for anyone else who's following along:

http://books.google.com/books?id=y97...20fuse&f=false

Regards,

Matt

[Matt in SV]

I found that Fuse Holder at West Marine. It's a Blue Sea Systems product. The holder and fuse are sold separately. The fuse is that plastic pillow mounted under the threaded stud. The hole at left is at least big enough to accommodate the smaller 5/16" post on the battery. I held that down with a wing nut because I am still sorting things out.

it could just as easily connect up to a 1/4" lug or an battery switch somewhere in your circuit.

Here's a link to the battery fuse holder at West Marine. It was around $20 for the holder and about $17 for the fuse. I guess you could use a second one on your chassis ground if you want that Disaster Protection.

Battery Terminal

http://www.westmarine.com/webapp/wcs...classNum=11287

Fuses

http://www.westmarine.com/webapp/wcs...4&ci_sku=17333

Regards,

Matt

[Roy in TO]

I used one of those in my boler American.
Great fuse system, but make sure you have a spare fuse on hand. Not everybody carrys them. One is not always close to a marina.

[Carl G]

Looks like the trick. Now, should I place one of these in the battery compartment and one at the other end of the positive lead just as it is about to connect to the converter -- larger amp unit by the battery and slightly less amp model in the trailer?

Thanks,
Carl

[Roy in TO]

I used the one Matt pictured in the battery box and the one below inside.
BLUE SEA SYSTEMS Fuseholder at West Marine

[Matt in SV]

Originally Posted by Carl G

Looks like the trick. Now, should I place one of these in the battery compartment and one at the other end of the positive lead just as it is about to connect to the converter -- larger amp unit by the battery and slightly less amp model in the trailer?

Thanks,
Carl

The converter output may already be fused. If not you can add a fuse there. Your converter probably does have an automotive style fuse inline with it's output. My progressive dynamics convertor has 2 fuses, I think they're 20 or 30 amps each, one on the charging circuit and a second one I think on the dc output.


I took a peek at the pd4045 and it says it has two 30 amp fuses, so I think you're covered on that end. I don't know if they're on the power supply or collocated with the other 10 fuses under the panel cover, but see if you can find them!

[Carl G]

What about using thermal resettable circuit breakers like those from Blue Sea? You wouldn't have to worry about keeping a spare, $15-$20 fuse around.