generator just to charge batteries

bartlettj wrote:

ktmrfs wrote:
if you have a quality converter that will output 40+ amps, you'll likely find that a 1000-1500W inverter will overload when the batteries are deeply discharged. Converters draw lots more current than one would first guess. As an example, a PD 65A converter draws close to 13A @120V. My advice buy a honda or yamaha 2000W. cost isn't much more than the 1000W, noise level is virtually the same, and you won't risk overloading the generator.
If your converter is in the 45A range then a 1500W would probably work.

40A at 12 V is only 480W. Try again.

your negleting the conversion efficiency and the poor power factor correction and it it's 12V, it's 14.6

so 14.6x40= 580 watts
at 80% effiency thats (580/.8) now we are at 725watts.

now take the typical iota and PD power factor of .7 (725/.7)= 1035VA


so your pushing it with a 1000W generator, since it is VA they care about not watts in most inverter generators.

In reality, a PD 45A converter will draw between 1000 and 1100VA at full output, I know I've verified it. a PD65A converter draws 1300+VA at full output.
So a 40-45A typical converter is often marginal on a 1000W generator, and from experience of fellow campers will usually cause a honda 1000 to overload initally unless you kick it out of boost mode. High temp or high altitude make it worse Given that the honda is rated at about 800 or 900VA continous.

Now, if you have the more recent and common WFCO 55A or bigger converter, run it on whatever you have, more than likely it will never go into bulk mode, so it stays at 13.6 volts at 15A or so and won't draw very much current. Course it will take much longer to charge the batteries.