When I bought my boat
with a Freedom 25
inverter/charger and a 4.4kw Westerbeke
genset, each on worked fine separately, ie. the inverter/charger worked fine from shore power on the generator provided AC correctly to everything except the charger.
After much testing and trying, I finally could get the charger to run at about 50% from the Genset if I also ran an electric
hair dryer. The final conclusion was that the highly-inductive charger, which had a low power-factor was too inductive for the genset. Some people supposedly solved
the problem by putting motor
capacitors in the circuit, but that didn’t work
for me. Heart said that you needed at least an 8kw Genset for it to work
The final solution was to get rid of the Freedom MSW unit and replace it with a true-sine-wave unit. These usually have a power-factor well above 0.90. That’s worked fine ever since.