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Old 05-23-2016, 10:26 AM   #1
3 Rivet Member
2016 28' Flying Cloud
The Plains , Ohio
Join Date: Dec 2015
Posts: 134
Question Parallax converters

The general opinion on these forums is that the original equipment Parallax converter should be replaced with a multistage converter. On the other hand, here is a quote from the Parallax website:

Q: Does my Converter/Charger completely shut-off when the battery reaches full charge?
A: When the battery reaches full charge, its internal resistance will stop, or resist the current being provided by the converter and current entering the battery is between 20 and 25 milliamps. Fully charged batteries will self-discharge themselves and will always accept some small amount of current to offset this self-discharge

They then go on to say:

Q: Can I leave my Parallax converter system constantly connected to 120VAC power? Will this damage my batteries?
A: Parallax converter models deliver a nominal "float voltage" output of 13.2 -13.8 volts DC. Leaving the RV connected to 120VAC and the converter output connected to the battery should present no problems as long as this "float voltage" is between 13.2 - 14.1 volts DC and recommended battery maintenance is performed.

(Does that mean constantly refilling battery water?)


Q: My friend has a "smart charge controller" that plugs into his converter system. Why hasn't Parallax offered a "smart" charger option for my unit?
A: The issue we have with "smart charger technology" (when used in an RV) lies more with the application of the technology than the technology itself. In a typical RV 12 volt electrical system, the converter/charger and the battery or battery bank is connected in parallel with the rest of the 12 volt distribution system. In "parallel" means where the charging source (converter/charger) positive and negative output is electrically connected to both the battery bank positive and negative, and the 12-volt distribution system positive and negative, at the same time. The voltage output of the converter "smart charger" is based on a "detected" battery voltage. The converter "smart charger" claims to "monitor" and respond to battery condition while connected to the entire 12 volt system. Unless the charging source (converter) has a separate or isolated charging output, we do not agree that a converter or charger can effectively differentiate requirements of the batteries from other 12 volt loads while simultaneously connected to the rest of the 12 volt distribution system in the RV.

Detected use or voltage change on the RV 12-volt load system (i.e. lights, pumps, etc. being turnedon) generally keeps these devices at a 13.6 -13.8 "float" voltage. This raises the question whether any real additional benefit is being provided to the battery bank unless the coach remains in a "non-use" storage condition. If a converter "smart charger" is only connected to the battery bank and can therefore monitor only battery voltage or current, and is not also connected "in parallel" with the 12 volt distribution system, we have no problem with the application of "smart charger technology".

So I'm confused. Is Parallax blowing smoke? Or can I sleep at night and not worry about my batteries without changing out the converter?

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Old 05-23-2016, 10:53 AM   #2
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Tyvekcat's Avatar
2014 28' International
Blacksburg , Virginia
Join Date: May 2014
Posts: 185

Well there is a lot of information on the Parallax, distilled down, its a good power supply for you to power projects & radios, but not to proficient as a 4 stage charger. It will boil your wet cell batts. Here are a couple links to discussion and replacement.

and a project for the Parallax:

you can search, there are more and tons of info,
Have a good one

Ra, Chelle & Natasha
For my next trick, I will use my new Airstream & Dodge Ram 2500 CTD to make this pile of money disappear.
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Old 05-23-2016, 11:49 AM   #3
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2008 25' International
Broomfield , Colorado
Join Date: Apr 2009
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Ditch that piece of junk parallax converter… It boiled one set of my batteries and killed the second set. Spent a couple hundred bucks on a progressive dynamics replacement converter and haven't looked back.
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Old 05-23-2016, 01:43 PM   #4
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2014 25' Flying Cloud
Cuddebackville , New York
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If my Parallax convert ever bites the dust, I'll replace it with a 3 stage. But until then it works fine for me. My first set of batteries with a Parallax lasted 7 years.
2014 25' Flying Cloud Rear Twin
2012 Dodge Durango Hemi/AWD
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Old 05-23-2016, 02:05 PM   #5
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2015 23' International
2013 25' FB International
Apache Junction , Arizona
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The single stage OEM Parallax converter unit was on my list of things to replace on our new 2013 25FB International Serenity along with the GYM tires as soon as I got the unit home from the dealership in October of 2012.

While the replacement multistage unit fit as advertised, the relocation of the incoming wire connection posts on the new board required some creative efforts to gain several more inches of "loose" wire in order to make those connections under the cross frame queen bed.
WBCCI Life Member 5123, AIR 70341, 4CU, WD9EMC

TV - 2012 Dodge 2500 4x4 Cummins HO, automatic, Centramatics, Kelderman level ride airbag suspension, bed shell

2014 31' Classic model 30 twin beds, 50 amp service, 900 watt solar system, Centramatics, Dill TPMS, disc brakes, 16" tires & wheels
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Old 05-24-2016, 08:02 AM   #6
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2013 25' Flying Cloud
Middleton , Idaho
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I have a PD4655 sitting on my bench, waiting for me to install it. The reason I am changing out the stock converter is to be able to charge faster from my generator, when needed. From what I have read, the stock converter does not put out enough volts to quickly or properly charge the batteries. For storage, I have been using a Battery Tender or Ctek maintainer, so I was not concerned about the stock Parallax overcharging the batteries.

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