Wonky Fuse Box: PowerMax Converter

[sandgrubber]

The PO of my 1970 Overlander replaced the original converter with a PowerMax 45 Amp converter. He seems to have kept the original fuse box; a pretty simple unit with two 40 amp fuses and four 20 amp fuses.
I'm now having trouble with DC current cutting out. No lights, no fan. Then you go wiggle the fuse box a bit and the power comes back on, at least until it cuts out again.

Personally, I'm a dunce about electricity. I'm working with a handyman who is fairly good with DC circuitry. He says he thinks there are loose connections in fuse box, and it would be good to replace it. Problem is, I can't find anything that will take two 40 Amp fuses and four 20 Amps. Vintage trailer supply has a fuse box . . . http://www.vintagetrailersupply.com/...-p/vts-146.htm ...but they don't say whether it will serve the existing circuit lay-outs and some of the reviews mention that it has no 40 amp circuits. Bestconverter at http://www.bestconverter.com/12-Posi...l#.VvW-p0e4Z6w has a similar unit, but, again, I can't see that it can be adapted to the existing wires, specifically, 40 amps.

I think I'm missing something. Would be most grateful if someone could fill me in, or direct me to documentation that offers a solution.

p.s. I intend to take the Airstream with me when I move to New Zealand, which will mean a conversion to 220V wiring, or perhaps total conversion to off grid. I'd prefer not to invest a lot in patching up the current system only to have to do it all over again. Quick and dirty would be good enough for now.

[featherbedder]

Mine started to do the same thing other day so I ordered fuze panel from vintage trailer supply this afternoon. Google out of doors mart, they have a diagram how to hook up new fuze panel, it is very simple to do, also I did not find the 2 large fuzes in pics. but I don't think they are needed. The fuzes are for 12 volt not 110 so only thing you would worry about is 220 to converter, but there is a power converter that drops 220 to 110 volts as I had one in Germany to run my us items, so may be no big deal for 220. I think they come in various sizes but I lived there 60 yrs. ago. They plugged into 220 and us plugged into other side of it. No worry about voltage rewiring.

[lewster]

Blue Sea Systems has a variety of fuse panels that will accept any fuse up the the panel's rating.

I'll try to link later when I'm at a computer.


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
ABYC Certified Master Marine Electrician
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center*AMS Lithium Batteries
Lifeline AGM Batteries**Magnum Inverters
541-490-6357

[sandgrubber]

Thanks, guys.
I'm still confused about the 40 Amp circuits. There are several nice looking fuse boxes out there, but they all max at 30 Amp circuits. Plus two @ 40 Amps + four @ 20 Amps comes to a total of 160 Amps. That's higher than most of the units people seem to be using. What is it that I'm not getting?

[Bob Cooke]

I did the same thing years back. My original set was yielding blinking lights on
12 volt when using 120 shore power. It's 1970 25 ft trade winds and had a 40
12 volt system. I isolated input to the converter and piggy backed the new 45 amp
Converter under the origional fuse box system Replaced the main 30 amp fuse
With an automotive type circuit breaker with automatic 're set. No more problems
Hope you have good luck with yours Best wishes I am Bob Cooke

[DKB_SATX]

This is a total guess, I don't know much about the older original converters, but since the old fuse block was integrated into the converter itself, the 40A fuses may have fused the leads that went to the battery. I don't have any 40A circuits in my '70s Argosy trailers, for example, and have never blown a fuse.

The PowerMax has a pair of big fuses built in for reverse-polarity protection, and you can fuse the battery leads inline if you want more protection there, but I have the VTS fuse block and it has no problem supplying all the 12v I need to run the trailer's systems.

[lewster]

Here's a high amp Blue Sea fuse block that will accept much higher ratings than 40 amps: http://www.amazon.com/Blue-Sea-Syste...sea+fuse+block

I too don't know why you would want 40 amp fuses in your circuit. Do you have anything running on 8AWG wire? Remember, you fuse to the ampacity of the wire, NOT the device.

[A W Warn]

Originally Posted by featherbedder

Mine started to do the same thing other day so I ordered fuze panel from vintage trailer supply this afternoon. Google out of doors mart, they have a diagram how to hook up new fuze panel, it is very simple to do, also I did not find the 2 large fuzes in pics. but I don't think they are needed. The fuzes are for 12 volt not 110 so only thing you would worry about is 220 to converter, but there is a power converter that drops 220 to 110 volts as I had one in Germany to run my us items, so may be no big deal for 220. I think they come in various sizes but I lived there 60 yrs. ago. They plugged into 220 and us plugged into other side of it. No worry about voltage rewiring.

This is the link to the wiring diagram at ODM.
http://odmrv.net/ConverterChangeOver...ChangeOver.php

If those 40 amp fuses are inline, in (+) and (-) wires, between the battery and the fuse block, you could substitute an inline breaker like this:
http://odmrv.com/catalog/index.php?m...roducts_id=706
I know this link shows a 20 amp, but they are available in different sizes. My Excella has 50 amp inline breakers protecting the battery circuit that look exactly the same as these.

add edit:
another option: http://www.oreillyauto.com/site/c/de...0227&ppt=C0335

[sandgrubber]

Originally Posted by A W Warn

This is the link to the wiring diagram at ODM.
http://odmrv.net/ConverterChangeOver...ChangeOver.php

If those 40 amp fuses are inline, in (+) and (-) wires, between the battery and the fuse block, you could substitute an inline breaker like this:
http://odmrv.com/catalog/index.php?m...roducts_id=706
I know this link shows a 20 amp, but they are available in different sizes. My Excella has 50 amp inline breakers protecting the battery circuit that look exactly the same as these.

add edit:
another option: http://www.oreillyauto.com/site/c/de...0227&ppt=C0335

BINGO! That's what I was missing.

Yes, those are the battery leads. They are even labelled BATT on the fuse box. As I said, I'm a dunce when it comes to electricity. So it's ok to separate them out and use some ordinary box for the 20 Amp circuits. Excellent.

[featherbedder]

In my 76 AS there are 2 = 50 amp glass fuzes at top rt. side of panel that are both hot they are in batt. circuit . Why are they needed as convertor has 2 = 30 amp and indiv. circuits on panel are fuzed, also odm diagram does not show any large cap fuzes in hook up pics. for batt. circuit.