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Split phase generator

I have an Isuzu 3LD1PV-02 motor attached to a Marathon Pancake generator model number 332CSA5204. It is currently wired for single phase 120v 83 amps. I'd like to consider wiring it for split phase and documentation, including wiring diagrams, are limited.

6kw split phase inverter is my potential goal at this time, so would like to switch the generator over to split phase. For times when 50 amp is not available, I will have a 50 amp 48v charger for the batteries.

Anyways, back to the generator.. has anyone on here converted their generator to split phase? What is required to change it?

I've attached some pictures of breaker box on the generator as well as the plaque on the generator.

Also unsure what the small box is inside the breaker box. 
1999 U320 WTFE #5586
2014 Subaru Forester 6sp
4000 watts of solar
650 aH @ 24v

Re: Split phase generator

Reply #1 –
Is your generator a Powertech? These can easily be changed to 240V split phase, contact Powertech for assistance on how to do this.

They will tell you the problem is the voltage regulator only reads one 120V leg, so with unbalanced loads on leg 1 and leg 2, the voltage regulation will not be consistent between legs.

This can be solved by adding a 240V - 240V split phase autotransformer. Unbalanced 120V loads will be absorbed by the autotransformer and the generator leg 1 and leg 2 will always be balanced.

Victron sells 32 amp and 100 amp sizes. Contact Victron for advice on this technique.

Here is the Victron brochure:

Autotransformer 120/240V - 32A and 120/240 - 100A - Victron Energy
https://www.victronenergy.com/upload/documents/Datasheet-Autotransformer-32A-and-100A-EN.pdf

Edit 1: I noticed in your photo "240" was removed from the generator plate, this would indicate 240V capability.

Edit 2: I also noticed the generator plate says 4 leads. I believe this means there are 2 separate armatures that can be either wired in series for 240V with a center tap, or parallel for 120V. Check with Powertech for advice.
Peter and Tammy Fleming
1991 U300 GV 40 - Sold, owned for 4 years
Downsized to Roadtrek Popular 210 class B

Re: Split phase generator

Reply #2 –
Some prior discussion

50amp RV power conversion to 220v household

220v PT10 Generator

There are a few others if you search on generator 220.
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Split phase generator

Reply #3 –
I have a Marathon 322csa3020 generator head that I installed on my generator to replace the PT 10K that died. It came with a regulator that can be switched 120/240. By changing the wire connections it will put out 240. With that said you need to give Jeff at powertech a call as you have a completey different regulator. Have all the information off of the tag on the regulator when you call. I can tell you he will recommend not doing it though. I can also tell you to proceed carefully as wrong connections will let the smoke out of your generator.
My original PT generator ( appears to be a Marathon) was a 10 lead with the same regulator , Jeff can help.  my new marathon is an 8 lead Jeff could not help.
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country

Re: Split phase generator

Reply #4 –
A clarification on the Victron autotransformer for anyone considering this.

The difference between the 32A and 100A units is the "pass through" 240V relay and breakers. The 100A version has a heavier relay and breakers for direct 240V loads, like induction cooktop, electric dryer, baseboard heat, etc. The autotransformer "core" is the same. The maximum neutral current is 32A for unbalanced 120V loads in either version.
Peter and Tammy Fleming
1991 U300 GV 40 - Sold, owned for 4 years
Downsized to Roadtrek Popular 210 class B

Re: Split phase generator

Reply #5 –
Jus to make sure everyone is on same channel. 

The coach has only 120V loads
When running the generator it puts out 120 volts, the 120V is tied to both the black and red wires at transfer switch
L1-L2 = 0
L1-Neutral  = 120 Volts
L2-Neutral  = 120 Volts

Shore power 50 amps is 120/240V 
L1-L2 = 240 Volts
L1-Neutral  = 120 Volts
L2-Neutral  = 120 Volts

On some generators when you are getting 240 volts out of them they do not have a neutral
L1-L2 = 240 Volts
L1-Neutral  = 0 Volts
L2-Neutral  = 0 Volts

When using a generator that has 120/240V you have to make sure your 120V loads are balanced between the two phases.
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago

Re: Split phase generator

Reply #6 –
In looking at the panel (s) in May coach it would take moving some circuits around to achieve any reasonable balanced load.
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country

Re: Split phase generator

Reply #7 –
Quote from: bbeane –
In looking at the panel (s) in May coach it would take moving some circuits around to achieve any reasonable balanced load.

The only thing with balancing the breakers "on paper" is you can't control what is on and/or off at the same time. The only way to always have balanced legs is to add an autotransformer inline with the 240V generator output.

Another option is to use one of the AIMS 240V - 120V/240V split phase inverter chargers (6kw - 12kw). These have a built-in autotransformer and would work well with a converted 240V Powertech generator.

This thread has been interesting. My son and I are planning a 48V all electric coach conversion and will be using the 10kw AIMS inverter.
Peter and Tammy Fleming
1991 U300 GV 40 - Sold, owned for 4 years
Downsized to Roadtrek Popular 210 class B

Re: Split phase generator

Reply #8 –
Good information. Thanks guys.

So, if using the Victron autotransformer, I'd likely just put it inline with the generator to the ATS under the bed. It would be nice if they made a 50 amp but... ah well. My generator usage is about 50 hours a year so spending a whole lot of time and money on the system seems a bit ridiculous.

The other options would be to have two 3000 watt inverters OR a larger 6000 watt inverter with an autotransformer for 240v loads such as a cooktop or mini split. I'm not ready yet but hoping for early next year.
1999 U320 WTFE #5586
2014 Subaru Forester 6sp
4000 watts of solar
650 aH @ 24v

Re: Split phase generator

Reply #9 –
For future reference in this thread there is another source for a balancing autotransformer from Outback. This one is rated at 25 amps per leg. A while ago I saw a listing for a Prevost bus that had 2 of these used together to have a 50 amp system used with a 12kw Powertech. Page 6 has the description for 240V load balancing.

https://www.outbackpower.com/downloads/documents/integration_products/autotransformer/PSX-240_Installation_Manual.pdf
Peter and Tammy Fleming
1991 U300 GV 40 - Sold, owned for 4 years
Downsized to Roadtrek Popular 210 class B