Purchased a new DuroMax generator (13,000 watt peak / 10,500 watt running) hoping to fast charge with the C8000 charger.
Unable to fast charge when both NEMA 6-20 240v plugs from the C8000 are attached to the pigtail/splitter from the 50 amp service on the front panel of  the Duromax.

The charger seems to start the charging process, then after a few seconds an additional load is applied by the charger (you can hear the generator start to work harder) then beeps from the charger and it recycles to start the charging cycle again.

Fast charging works fine with 2 generators.

Bad sine waves when the additional load is applied? (Triggering errors in the C8000 and causing the reset?)

Received some feedback stating an inverter style generator is required (like the dji 12000i). But I've seen people use the Westinghouse 9500  (12.5/9.5) for fast charging.
Like this... e.g. https://youtu.be/4kRuK4SEuWE?si=FoD9rg3x4DyLTtqD&t=71

I thought this Duromax would work as it seems to exceed the specs of the Westinghouse.

Any thoughts are appreciated.

Thx.

Someone else has said there may be an issue with Dual/Tri Fuel vs. gas only generators? That isn't adding up for me though (I don't see the correlation.)  

It may be just a coincidence that the dual/tri fuel models aren't made as well as the Westinghouse. And these other brands tend to have problems due to the electrical components used - unrelated to the fuel used to turn the shaft. If you use a different fuel, you just lower the HP (when using Propane or Natural gas) so max load (running watts) is reduced. All fuels enter through the same carb.

What generator brands/models do you successfully use to fast charge with a single generator?

Found several likely answers here: https://www.facebook.com/groups/306452727901008/search/?q=generator  

-Check THD for 5% or less
-look at the hz. Some make it to the US at 50Hz not 60Hz
-some of the chargers actually prefer 50hz because they are based on the European/asian standard.
-Check what your frequency is. Mine was 61hz. Lowered high idle until it was 55. Whole different charger now
-Got the voltage regulator replaced. Now I'm charging T40 batteries with a T30 charger and I'm charging batteries from 23% to 100% in 11 minutes and 45 seconds