Dewey Battery Charging Aux Power Unit - PTO Shaft

Does anyone else have one of these? I'm curious what PTO shaft option the Yanmar has on it. I've tried decoding the part number, but the PTO option digit doesn't match any of the known PTO option codes. I've also tried calling Yanmar, but they had no clue.

When mine gets here, I plan on removing the DC alternator and putting on a 120/240V gen head so I'll have a lightweight ~5kW diesel gen.

I take it that you have a MEP501 being delivered? Handy unit for 24v applications or charging up MVs. You want to convert it to 120/240V? That will take a little bit of engineering. What you want is a MEP 531, 120/240 3KW. They work well. The 531 has a completely different control panel and is equiped w/ AC outlets. Basically, the two units share the frame, engine and fuel system. Other than that they are unque. It may be easier to source a 531 than convert a 501.
If interested, I know of a surplus source that has several running 531s for sale. I have two of each model, they are handy and a little noisy.

It's similar to the 501, but has the larger L100V engine instead of the L48. This one doesn't have a fuel tank and has a cool remote start box. There's been a bunch of them coming up on certain websites...


The alternator on it is undersized for the amount of power the engine can put out. My thinking is if I can adapt a new gen head to it, I'll have something like the 531 in terms of weight and size but with a lot more power.

From what I've read in other threads there's a spider coupler between the PTO shaft and the alternator which is a b1tch to get off. This leads me to believe its a tapered shaft. I'm just hoping its the E-DG variant as this is the standard SAE J609-B setup for mounting a gen head.


Oh and for anyone else who has one of these, I got a hold of the user's manual from Dewey...
View attachment LVPS Manual Revision B.pdf

OK, got it, yes those L100 engines are stout. I've been off the auction sites fore a while. What are the going bids for a nice one? Might have to start looking again.

They've been going between $400-700. The engine alone is worth more than that and they are all brand new/unused units.

Oh no, I might have to take a tickle.

I finally got my generator in and confirmed it's got the right shaft for J609-B gen heads. I've got a 6kW unit from Northern Tool on order and will put together a thread showing how to convert this unit over to 120/240 AC when it get here.

I have one as well haven’t fired it up yet. Any sources for the cool remote start box?

Dewey will sell you the box (I checked), but its $350. Check out the last page of the manual I posted above. There's a full schematic for the box and its dead simple. I plan on wiring up directly to the circular connector on the local control box to start the unit up.

I just picked up one of these, and have not got it running yet.

Does anyone know what the connectors on the fuel lines are? I dont recognize them, and would like to get some matching fittings to hook up to the generator

Good thread. Look forward to hearing about this head swap!

Light in the Dark said:

Good thread. Look forward to hearing about this head swap!

Click to expand...

Check out yertnamreg's thread here:
https://www.steelsoldiers.com/showt...y-Charging-Aux-Power-Unit-Generator-Head-Swap

Scar59 said:

I take it that you have a MEP501 being delivered? Handy unit for 24v applications or charging up MVs. You want to convert it to 120/240V? That will take a little bit of engineering. What you want is a MEP 531, 120/240 3KW. They work well. The 531 has a completely different control panel and is equiped w/ AC outlets. Basically, the two units share the frame, engine and fuel system. Other than that they are unque. It may be easier to source a 531 than convert a 501.
If interested, I know of a surplus source that has several running 531s for sale. I have two of each model, they are handy and a little noisy.

Click to expand...

Believe the 531s are 120V only, so that makes this endeavor perfect.