Parallax 7355 Converter Replacement with Xantrex XADC-60
I own a 28 foot 2005 Airstream Safari which came with two Interstate Megatron Type 24 batteries. After taking a trip through several national parks and doing mostly dry camping last summer, I was disappointed with the lack of battery capacity and the amount of time I had to run my generator every day, even though we were using minimal heat and lights.
I was told that keeping my coach plugged in during the off-season probably cooked my batteries, even though I periodically made sure the electrolyte levels were topped off. The Parallax 7355 converter in my coach was strictly a single stage charger and pumps constant voltage and amperage into the batteries, whether they needed it or not.
I started to read the various internet forums and articles about battery power and concluded that I wanted to install two 6-volt golf cart batteries with the best amperage ratings that I could reasonably get into my battery box. My research led me to the Trojan T-145 batteries, which had a footprint that would fit, but were physically too tall for my battery box. After discussing this with the folks at Airstream of Spokane, they told me they had an idea of how to modify the battery box. Using aluminum “C” channel, they extended the height of the box and relocated the door so the Trojan batteries would fit. The following photos show the final results of the battery installation, and I was pleased with how it came together.
Reading the maintenance literature from Trojan about the charging of the batteries brought me to the conclusion that I was not going to get optimal life and capacity out of these batteries with the Parallax converter. More research brought me to BestConverter.Com and a phone conversation with Randy. We talked about my project and he explained the various options available for putting a 3-stage charging/converter system in place to get what I wanted. I decided to go with the option to install a Xantrex XADC-60, so I placed my order and went for it. When it arrived, I unpacked it and was immediately impressed with the quality and rugged feel of the converter. Further, I could see that it was going to be a great fit into the Parallax power center enclosure. The installation turned out to be very straightforward and I was extremely pleased with the result, especially after I heard the fan run for the first time and noted that it was quieter than the Parallax unit. So here’s the step-by-step of how I did it:
Note: Before working on the power center, ensure that the shore power is disconnected and that the battery cables are disconnected at the battery terminals. You could either injure yourself or damage your equipment!
1. Remove the power center face plate and expose the existing converter.
The cover is held on by four Torx screws and removing them exposed the converter section of the power center. I removed all of the screws in the A, B & C order shown below.
2. Disconnect the AC power side from the terminal strips and the circuit breaker.
The Black wire will be connected to the screw terminal of the circuit breaker and the white wire will be connected to the terminal strip. In my installation, there was no ground wire to the grounding terminal strip. In the following photo, the white wire has been removed from the terminal strip and the black wire is still connected to the breaker.
3. Disconnect wires from the DC side
4. Pull the wires through the grommets and remove the Parallax converter unit
5. Drill out the rivets and spot welds on the enclosure
The rivets on top are obvious and all need to be removed. The spot welds are found on the right side and bottom and hold a sheet metal baffle that will need to come out.
6. Remove all mounting screws and remove the circuit board and baffle plate.
The metal standoffs should remain intact and the nylon standoffs in the center should be trimmed to match their height.
7. Use Xantrex deck-mount brackets as a template to make new mounting rails
I used ½ inch aluminum channel from Ace Hardware to make my mounting rails. I drilled 1/8 inch holes through both sides and ¼ inch holes on one side for screwdriver access. Use bracket mounting screws to attach to the sides of the Xantrex unit.
8. Put the Xantrex converter into the enclosure on the standoffs and ensure a snug fit laterally, using washers on the rails if necessary. (I don’t know what the manufacturing tolerances are for the enclosure or the converter, but I didn’t need any.) Drill a hole through one side of the enclosure and put in a sheet metal screw through the outer edge of the rail.
9. Before mounting the top of the enclosure, locate and drill a 1 inch hole in the enclosure over the AC side of the converter. It will line up quite nicely with the existing access holes in the power center. Put in a grommet, pull the AC wires through and remount the top with sheet metal screws on the sides. The one on the back will be obstructed by the Xantrex case. Additionally, I clipped the DC wires out of the old Parallax unit and installed them into the DC side of the Xantrex prior to remounting the top. Here’s what it all looked like installed in the enclosure on the standoffs and rails. It is well grounded to the enclosure and has air gaps all around. (I noted that using the deck-mount brackets would have created an air gap under the unit, which I believe is important for cooling any power supply.)
10. Feed the wires through the power center access holes, reinstall the enclosure. and terminate the wires to their respective positions. On the AC side, the black wire goes to the screw terminal on the breaker, the white goes to the white terminal strip and the green goes to the ground terminal strip. On the DC side, the blue and the white are reattached to the DC board to the terminals from which they were removed. Remount the DC Panel and close up the breaker panel side. Here it is, all finished.
Some final thoughts & lessons learned:
I believe with instructions such as these, I could do this job in about an hour. It went in easier than I thought and I am thoroughly happy with the result.
I opened the top of the Xantrex unit because I wanted to see where the grounding lugs were connected. I was impressed with the internal construction of the Xantrex and it has the look and feel of a very quality product. I noted that the ground lugs are connected only to the case itself and not to the circuit board. Therefore, installing it as I have, the unit is fully grounded through the power center. The Xantrex is designed to be a deck-mounted unit and if the case is electrically isolated through a mounting on plywood or through double-sided adhesive tape, it certainly should have a ground wire from the lug to the chassis. However, in this installation, I concluded that a chassis ground to one of the lugs would be redundant like putting on a belt to go along with suspenders. My meter tells me it’s fully grounded as installed.
Regarding the securing of the unit to the enclosure, I originally had one round head sheet metal screw on each side, but the clearance for the enclosure into the power center was too tight for both screws to be present. I could have pulled them out and countersunk the heads, but I concluded that one screw was sufficient to secure the unit. Also, when I measured up the internal clearance, I thought I should use 5/8 channel instead of ½ inch, however after mounting the first 5/8 inch rail, it would have been too tight. I switched over to ½ inch channel for the second rail. This is why I would recommend going with ½ inch on both sides and use a washer if necessary to take up any lateral movement.
All-in-all, this was a fun project that is fairly easy to do with basic tools and a fundamental understanding of wiring. When I first powered up the coach and checked the voltage, my heart momentarily sank as I checked the battery voltage and it was at 11.2 (I had all the lights on and the furnace going). I had connected the shore power, reconnected the batteries and only the battery power was happening. Then I realized that I hadn’t flipped the circuit breaker back on at the power center. The joke was on me! With the flip of the switch the lights immediately got bright as the voltage jumped up to 14.1, the first stage of the multistage charging capabilities of this unit. I checked again in the morning and it had adjusted to 13.2, as expected.
So here’s my last photo:
If you read this and have any questions, please feel free to contact me.
2023 S. Sonora St.
Spokane Valley, WA 99037