EG4 18a 48v Lifepo4 charger and Yamaha ET950 clone 1000w two stroke generator do not work together


Anti-Solar Enthusiast
Nov 11, 2022
Santa Cruz, California
When I test a questionable idea I like to post the results to share with the internet.

I have tested connecting an EG4 18a 48v charger like this:


To a Yamaha clone two stroke generator like this:

And the result is they do not work together. The 18a charger cycles repeatedly enabling and then shutting off, I'm guessing because it doesn't like the voltage is getting on it's input. I tested this directly without any extension cord.

If you let it continue cycling I suppose you'd get some charge out of it, but it's not very nice and I wouldn't like to leave it running that way.
The label on the generator says 800W (Running Watts). It also says 1000W but I can't read the label. I suspect that is a surge rating.

The charger is an 18A charger. At 51.2V that is 18A x 51.2V = 921W. If we assume a 95% efficiency, that means it will draw 921/.95 = 975W.

It looks to me like the generator is undersized. I suspect the generator is cutting out....waiting and then turning back on.
Real world is more like 90% efficiency at maximum output of the charger and LifeP04 charging voltages would be in the mid 50's so that far exceeds the ability of charger and it appears that likely has no voltage control as well.

Take a look at this video and look just how much the rpm drops with just an unloaded drill, zero chance this would ever work, even with a couple of amps it would seem from the video
It does impressively well with some loads like a "3.5 HP" shop vac. It's not the generator that's cutting out, I can see it's the charger that's cutting itself off, but the charger is probably doing so because of the voltage drop from the generator.

I was hoping the charger might sort of "take what it can get" from a lower voltage, and deliver less of a charge, but oh well. Time for a better generator.
I've played around with one of those two stroke generators. Measure the output voltage when you apply a load that size, guarantee you're down in the 90v range. Release the load suddenly and watch the voltage and RPMs spike as the governor can't respond fast enough. 60hz is a vague suggestion.

I know the OP wasn't proposing anyone actually use one of these two stroke generators, just a "here's how this worked out" report. For anyone actually wondering about one of these, the original Yamaha genny might have been great, but these knockoffs are little better than toys. Save your pennies and get any of the small inverter gennies, even used. There's a used 2kw Predator genny in my area for $250 right now. Infinitely better choice.