Parallax Converter Replacement with Xantrex

SilverGate · 04-17-2009, 02:09 PM

Our Parallax Power Center, Series 7300 (specifically 7355), has a converter that failed during the two year warranty period of our 2007 23’ Safari and was replaced with another Parallax converter by our dealer last September. Last week the replaced converter also failed.

Based on good reports from others here on the forums, we decided to call Randy and order the Xantrex XADC 60A Converter/Charger (Hard wire) from BestConverter.com.

Unlike our two-stage Parallax converter, the Xantrex’s three-stage charging process results in batteries charging faster and more effectively. Xantrex’s 3-Stage White Paper (see link on BestConverter.com) describes the stages:

The first stage, bulk, is a constant current mode that replaces 80% of the battery’s capacity quickly. The charger applies its maximum output current as the battery voltage rises. When the battery voltage reaches a predetermined absorption voltage, operation switches to the second stage.

The second stage, absorption, is a constant voltage mode and replaces the remaining 20% capacity. The charger voltage is held steady while the current falls as the battery approaches full charge.

In the third stage, float, the charger voltage is lowered and held constant at a safe value of 13.5 volts DC, which prevents the battery from being overcharged, while allowing the charger to supply enough current to maintain the battery at a full state of charge.

The Xantrex converter arrived quickly via FedEx from BestConverter.com. Randy steered me to the Parallax 7300 Upgrade Procedure link on their website. This procedure, “Parallax 7355 Converter Replacement with Xantrex XADC-60”, was written by Ernie Hensley of Spokane Valley, WA, who has a 28’ 2005 Airstream Safari. His procedure has detailed instructions and photos, which greatly assisted me. He also kindly answered my questions via email. I downloaded Ernie’s photos into our laptop MacBook Pro, to have nearby as I followed his procedure.

This and following posts will describe and illustrate how I replaced our Parallax converter with the Xantrex. It is not intended to tell you how you should replace yours. It is posted to show what worked for me, which may be helpful to others.

First I disconnected the 30-amp shore power. Then I turned the Battery Disconnect Switch to “Store” and used a voltmeter to ensure that no battery power was reaching the converter. Note, as pointed out by Ernie, it may be safer to disconnect the batteries at the battery terminals, but again, this is what worked for me. Our power center is located in the middle of our trailer under the double wardrobe closet.

SilverGate · 04-17-2009, 02:22 PM

I then removed the face plate revealing the old converter. Again, note the voltmeter which I used to make sure that there was no battery voltage reaching the converter.

(By the way, the original symptom that the converter had failed was that the batteries were not showing 100% when the trailer was connected to shore power and was diagnosed when the voltmeter read that the converter was only putting out 9.69 volts while the Battery Disconnect Switch was turned to "Store".)

SilverGate · 04-17-2009, 02:26 PM

I then disconnected the converter's AC power black wire from the 20-amp circuit breaker and the white wire from the white wire terminal strip.

SilverGate · 04-17-2009, 02:31 PM

Here both of the converter's AC wires are disconnected.

Note the grounding terminal strip on top of the AC side. This will be used by the new Xantrex converter. (The old Parallax converter did not have a ground wire.)

SilverGate · 04-17-2009, 02:38 PM

I then disconnected the converter's DC wires, blue (positive) from the front and white (negative) from the back of the DC board.

The wires were then pulled through the grommets and the Parallax converter was removed.

SilverGate · 04-17-2009, 02:45 PM

The core concept of Ernie's procedure is that the old converter's circuit board can be removed from its metal enclosure and this enclosure can be modified to nicely receive and mount the Xantrex converter.

At this stage the enclosure's top panel is removed by drilling out the rivets. Then the sheet metal baffle inside is removed by drilling out the spot welds.

SilverGate · 04-17-2009, 06:25 PM

And a special thank you to Larry who was my resource when I had technical questions along the way. (He is more talented with using tools than I am... Just see his refrigerator fan switch that he installed earlier this year.)

He did the drilling out of the rivets seen in post #6 and the testing of the voltage in post #11 above as I took photos.

And I thank him for letting me proceed on my own for the most part and get a great hands-on experience and sense of accomplishment.

SilverGate · 04-19-2009, 01:38 PM

Two more variations on the procedure to replace the lower converter/charger section of a Parallax/Magnetek power center to the Xantrex Truecharge™ RV (XADC) multi-stage charging converter are found here:

Magnetek/Parallax to Xantrex (linked from BestConverter.com)

Also see jd's (5cats) complete change-out of the Parallax system's power distribution center and converter/charger here:

XADC Follow-up

(Thanks jd for your fine work and contribution.)

richschafer · 08-29-2009, 02:27 PM

I just finished this upgrade on our Safari 25 FB. We lost our Parallax 1 month after the warantee expired. These instructions were extemely helpful. Thanks SilverGate!

I made two minor adjustments:
1) The fit with the 1/2" mounting rails wasn't tight enough and 5/8" rails were too wide. I had to use a 1/16" L-shaped aluminum bracket between the 1/2" mounting rails and the enclosure. You can see it sitting on top of the mounting rail in the picture below .

2) I used 8AWG wire to connect the Xantrex to the 12V panel instead of reusing the original 10AWG Parallax wire. Xantrex recommends 6AWG, but I couldn't get the fatter wire to fit between the enclosure and the upper section. I compromised at 8.

So far, so good. I'm getting 14.1-14.2 volts DC. I'm just waiting for the batteries to get charged enough for the Xantrex to swith over to float mode. When that happens, I'll call this project complete.

SilverGate · 08-30-2009, 06:50 PM

You’re welcome, richschafer, and thanks for posting your experience and photo here.

As mentioned in the beginning of this thread, I wanted to illustrate my experience in replacing my Parallax converter with the Xantrex unit and that this thread was not intended to be “instructions” per se.

My converter replacement was based, however, on instructions found in the illustrated article, “Parallax 7355 Converter Replacement with Xantrex XADC-60”, written by Ernie Hensley (28’ 2005 Safari) and found on bestconverter.com.

Regarding ½” mounting rails:

Ernie also noted that using 5/8” aluminum channel on both sides was too tight and he ended up using a ½” wide rail on one side and a 5/8” wide rail on the other. In his “Some final thoughts & lessons learned section” he recommends using ½” aluminum channel on both sides and add a washer if necessary to take up any lateral movement. (I did not need to use a washer.)

Regarding wire size:

Xantrex’s Installation Instructions, page 24, Table 2, does show that Xantrex recommends a minimum DC wire gauge of 6 AWG (for XADC-60) running to the battery bank (and a maximum length of 20 feet). It notes that using larger run lengths or smaller gauge wires [to the batteries] than recommended will result in decreased charge/load output performance as well as additional heating and interference effects.

The large red and white wires that Airstream used to connect my OEM converter to my two AGM batteries seem proper and can be seen attached to the DC panel in the enlarged photo in post #5 of this thread.

Table 1 (on page 24 of Xantrex Installation Instructions) lists torque requirements for terminal connections for various sized wires, including 10 AWG.

Upon completion of the installation and connection to shore power, Xantrex put out 14.2 volts as read by my voltmeter (seen in post #11 of this thread), which corresponds to the bulk or first stage charging. This was followed by the absorption or second stage, and finally, once the batteries were fully charged, it settled down to 13.4 volts, the float or third stage of charging.

My Xantrex XADC-60 continues to function perfectly and quietly. I am very happy with it and the service from bestconverter.com.

Quote:

Originally Posted by richschafer

I just finished this upgrade on our Safari 25 FB. We lost our Parallax 1 month after the warantee expired. These instructions were extemely helpful. Thanks SilverGate!

eheffa · 10-02-2009, 12:42 PM

Thanks SilverGate...

This is an excellent resource. Thank you for posting this & the links.

The stock converter on my 25FB unit (Parallax 7300) is quite noisy & has a worrying crackling / buzzing sound when the fan is running. The fan is quite loud & does not inspire any confidence. It has been like this since the beginning but seems to be getting more noticeable.

I was searching to see whether others noticed this & whether they thought it was acceptable... & thus came across your thread.

I think the relative advantage of preserving good battery function would make replacing the Parallax worthwhile in and of itself.

Is your new unit any quieter or cooler than the the old Parallax?

-evan

SilverGate · 10-03-2009, 08:49 AM

Thanks, evan. I also noticed some higher pitched electrical buzzing sounds coming from my old Parallax 7300 series converter, especially when we turned on the ceiling lights.

I do not hear these sounds with the Xantrex and from my experience, the fan runs much quieter than my old Parallax converter. And I believe the fan is more efficient and effective because it is directed in line with the vents of my re-used Parallax converter enclosure.