Converter 3-stage

[Grumpy Grampa]

Hi . I have a 2017 Thor Miramar. My question what is the difference between a regular converter compared to a 3-stage converter?

Which one is the better choice, and if I don’t have a 3-stage in my coach now, can I upgrade to a 3-stage?

Thank you

 

[Bob Nodine]

Hi . I have a 2017 Thor Miramar. My question what is the difference between a regular converter compared to a 3-stage converter?

Which one is the better choice, and if I don’t have a 3-stage in my coach now, can I upgrade to a 3-stage?

Thank you

I suspect your coach already has a 3-stage converter. The three stages are Bulk charging at 14.4 volts, Absorption charging at 13.6 volts, and Float charging at 13.2 volts. The converter will start out in Bulk mode if your batteries need charging and you just connected to shore power or start the generator. Most chargers will limit the Bulk charging time to about 1 hour. The converter will then fall back to Absorption mode to bring the batteries to full charge. Once the batteries reach full charge the converter will go into the Float mode to maintain the charger.

 

[DavidEM]

I suspect your coach already has a 3-stage converter. The three stages are Bulk charging at 14.4 volts, Absorption charging at 13.6 volts, and Float charging at 13.2 volts. The converter will start out in Bulk mode if your batteries need charging and you just connected to shore power or start the generator. Most chargers will limit the Bulk charging time to about 1 hour. The converter will then fall back to Absorption mode to bring the batteries to full charge. Once the batteries reach full charge the converter will go into the Float mode to maintain the charger.

All true.

But the converter in my 2021 Axis would only charge at 5-10 amps, even when discharged to 70% SOC. It was a WFCO 8955.

I replaced it with a Progressive Dynamics charger and the charging current jumped to the 30s under similar conditions.

I concluded that the WFCO charger was a fixed voltage type, not a three stage.

David

 

[Grumpy Grampa]

Thanks when you put in the 3-stage. Did you have to do different wiring? And is the battery Isolation sylinode inside the unit, or still separate?


Thank you

 

[ghnl]

I don't know the details of your specific charger. Our prior MH (2004 Thor Class C) did not have a 3 stage converter. It would overcharge the coach battery if I left it connected to Shore Power for weeks. I replaced the original converter with a "Smart Charger" (3 stage) from Progressive Dynamics (same maker as the old one) and it was a simple swap - label all the wires (& take pictures, too) and the new unit's connections were all in the same locations. No more overcooked batteries.

 

[16ACE27]

Thanks when you put in the 3-stage. Did you have to do different wiring? And is the battery Isolation sylinode inside the unit, or still separate?


Thank you

A regular converter is a 3 stage converter. I don't think there is an RV converter made in the last 15 years that was not at least a 3 stage converter. The problem is. many cheap 3 stage converters lose their "smarts" and start acting as a single stage charger.

Replacing itis easy, wire for wire/

The battery isolation latching solenoid is completely separate from the converter and Power Center.

 

[DavidEM]

Thanks when you put in the 3-stage. Did you have to do different wiring? And is the battery Isolation sylinode inside the unit, or still separate?


Thank you

Progressive Dynamics, the manufacturer of the charger that I bought to replace the OEM WFCO, makes two types: a charger with a 120V plug and one with bare wires. The latter is the one made to replace the OEM charger. As Ted notes above it is a wire for wire installation.

It is possible that the OEM WFCO was designed as a three stage charger but failed as Ted notes above and became a single stage charger. That really turned me off to WFCO products.

And as Ted also notes, the battery isolation system is entirely separate from the charger.

David

 

[Grumpy Grampa]

Thanks. Looking on Amazon they now have a 4-stage converter any idea why 4-stages now instead of 3-stages?

 

[Mark54]

Thanks. Looking on Amazon they now have a 4-stage converter any idea why 4-stages now instead of 3-stages?

Extends battery life longer- read this:
https://www.progressivedyn.com/chargewizard/
This is for mostly for wet cells, from what I have read.
The one thing I see that is different is no 'float' charge- replaced with "storage" and added desulfation phase, or 'equalization' charge to desulfate the battery, that doesn't happen in LFP's anyways.
I use Battery Minders or Noco chargers for winter storage of chassis wet battery b/c they have desulfation phase charge to knock the sulfur off the plates, lengthening battery life.

So if you still have a single stage- best to replace with a 3 or 4 stage unit. I'd do the 4 stage if you're charging wet-cell batteries. Easy to do- just wire for wire as others have said.

For LFP, take indoors or have in heated storage disconnected, and cycle 50-65% to 100% and drop back to 50-60% every 3 months.

 

[dkoldman]

I bought based on profile types I needed to maximize my desired batteries.

I had OEM Progressive Dynamics for FLA ( 3 stage) and I upgraded to this BEFORE I actually bought new batteries.

https://www.amazon.com/Inteli-Power...cphy=9192225&hvtargid=pla-2280825311422&psc=1

My current batteries are Lithium and I just changed the profile. Only 2 stages are needed for my Lithium battery.

My install was 120vac plug and play. Had the exact same mounting holes as my OEM.

Note: I know some will say the converter upgrade is NOT required, but I wanted to get the maximum possible from my new new lithium battery. A side benefit in my case, I was able to sell my 5 year old Progressive Dynamic 45amp converter for $100. So the upgrade only cost me $150 plus it came with remote pendant that tells you the current charge stage