'69 - Replacing Univolt

[Jamespio]

I got my '69 without a Univolt and without a battery. The whole rear service center is in some disarray because of an ongoing bath overhaul. But I just got my new converter/charger (Powermax PM3-35 I got on clearance). So, a few questions:

1. The powermax wants to be plugged in via a standard duplex receptacle, but the original wiring did not seem to include an outlet in the area where I think(?) the Univolt used to reside (behind the rear outside access door). I see a 12AWG 2 conductor with ground cable in the area, black sheathing; would that have been 110VAC heading into the Univolt? I also see what looks to be a pair of 10AWG (not sure) conductors (one red, one white) that seems to lead to the 12VDC distribution panel. Obviously, I'm not sure about all this, and am wondering if anyone who has done this repalcement in a '69 can help tell me what to look for.

2. Once I get the converter installed, will I be able to use 12V fixtures while attached to shore power even though I don't have a battery? I'd prefer not to buy a battery since this trailer is still at least months and possibly years from being towed, and I'd like to avoid that expense until I'm actually ready to hit the road.

[idroba]

It sounds like the original 120 volt power came from the #12 two conductor with ground cable you found. You can just put a 120 volt outlet in a surface mounted box on that wire and plug your new converter/charger in.

The #10 wires you see most likely came from the battery and converter/charger to the distribution panel. The battery and converter/charger (original Univolt) would have been connected in parallel, probably with 50 amp fuses in the lines going to the distribution panel.

Most converter/chargers can be used without a battery, but check the information on your Powermax. I don't know what they say about it. But, if allowed by the manufacturer, you can most likely just connect the Powermax output to the red (+) and white (-) lines you have found and you will power your 12 volt circuits.

I think I would test the red and white lines first, prior to hooking up the Powermax by connecting them temporarly to a charged 12 volt battery (put at least a 30 amp fuse in the + line) and see if the interior 12 volt things such as lights and fans work. If they do, then you can substitute the Powermax for the battery, again assuming that is allowed by the Powermax people. At a later time you can put a battery in the system.

That is my best shot at your problem.

[TouringDan]

I agree with idroba.

[Jamespio]

Thanks for the input.

[rayandre]

I just changed out our 69 Univolt today with a Pwermaxx Boondocker 45 amp converter and a PPL PB-9 fuse panel because the old Univolt had an integrated glass fuse block. Took about 4 hours to do it. If your looking at one pair of 8AWG red and white cables they could be one of two things: the red could be either the positive from the trailer battery or the positive from the car battery. The white could be either the negative from the trailer battery or the ground load from all the of the 12 V. In my case, the new fuse panel had three positive distributions to take both battery inputs and the positive from the converter. The only two wires I can't figure out what to do with are a red and black for the ammeter-not sure what to connect those to because our new fuse block doesn't have a shunt. I was told by Randy at Best Converters that our Boondocker has limiting circuit technology and would not need the 40 amp fuses for the batteries but other sources seem to disagree with this. I'll probably add them tomorrow for ease of mind. I can take pictures of mine if it would help. The black is definitely your 120v feed. Simply duplex like idroba mentioned. Good luck getting it back to operational.

[Calltheball]

Originally Posted by rayandre

I just changed out our 69 Univolt today with a Pwermaxx Boondocker 45 amp converter and a PPL PB-9 fuse panel because the old Univolt had an integrated glass fuse block. Took about 4 hours to do it. If your looking at one pair of 8AWG red and white cables they could be one of two things: the red could be either the positive from the trailer battery or the positive from the car battery. The white could be either the negative from the trailer battery or the ground load from all the of the 12 V. In my case, the new fuse panel had three positive distributions to take both battery inputs and the positive from the converter. The only two wires I can't figure out what to do with are a red and black for the ammeter-not sure what to connect those to because our new fuse block doesn't have a shunt. I was told by Randy at Best Converters that our Boondocker has limiting circuit technology and would not need the 40 amp fuses for the batteries but other sources seem to disagree with this. I'll probably add them tomorrow for ease of mind. I can take pictures of mine if it would help. The black is definitely your 120v feed. Simply duplex like idroba mentioned. Good luck getting it back to operational.

Where did you put the fuse block. Am getting ready to replace the original Univolt in my '70 Caravanner. Thanks

[Jamespio]

My set up was exceptionally easy.

The 12AWG or 14-AWG wires in nonmetallic sheating now lead to a duplex receptable mounted on the floor of the area where the Univolt used to sit. The PM3-35 plugs into that. The 10-AWG wires (red and white) are connected to the PM3-35. Still no battery, as the trailer is not towable at the moment, but everything inside works just as one might expect. 110V receptacles work (which makes it much easier to plug in a drill), lights and fans all work. Far as I can tell, everything that is still conneted, actually works properly, which is pleasantly surprising for a 40 year old trailer.

[rayandre]

well, to make it quicker and slightly easier I simply used the existing space where the Univolt was-a side compartment next to and through a closet on the other side of our shower. I mounted the fuse block, converter and one 4x4 gang box to the back wall. the gang box aloud me to extend the original 110v wiring so I could create the necessary plug the converter needs and move it farther away-wires were too short. I do want to move all of this inside and under the twin bed on that streetside area so it's a little more direct to check it all out of the weather but that would mean I would have had to extend the 12v wires and change the battery cables out too. Since I only had a half day to get this all done and tied up I decided it would work fine where it was and still give me twice the room in that compartment than I had before due to the newer equipment being so small compared to the old beast.

[Calltheball]

Replacing old Univolt with built in DC load fuse block. Old fuseblock has 40amp fuses for TV battery input + and RV battery +. New Parallax fuse block only has 20amp fuses. New converter is a Power Max PM3-35 35amp. What do I do about the TV input wire and the RV battery + input wire that are 40amp fuses in the old fuse block. '70 Caravaner

[rayandre]

My Powermax has (2) 30amp fuses on it so Randy (at Best Converter where I purchased it) said it wasn't necessary for me to separately fuse the TV and battery the way it had been done originally. Some people take their old fuse blocks and reuse that portion along with a new blade fuse block so they can maintain the 40 amp and the shunt. I didn't have to because the Powermax Boondocker is already fused before the fuse block whereas the Univolts weren't. The only thing I never resolved was loosing the 1 or 2 amp fuse for the panel light which I don't care about but there is a work around for that too online at Best Converters web site. We drove this new system this summer cross country through 9 states, 5 national parks and over 6300 miles in 4 weeks without one problem (related to this upgrade) so it worked really well and maintained the battery perfectly. In fact we were dry camping most of the time and I was checking my battery levels with a meter quite often and it was a very happy and healthy battery. I'm not sure but I would guess your new Powermax is fused as well. Good luck-it's well worth it to get this part of your rig up to (at least) 20th century technology! My next move it to get my battery closer to the converter and start thinking about a solar set up.