How Big a Gen to Run a Converter? Some Info.

MrWizard wrote:
These are not constant voltage device?
13.6v at max amps and 14.4v when finishing the charge
What we need to know is at what amps point will they reach and carry 14.4v
I don't know the math formula for that
The 70 amp PD was 64.7amps at 14.2v at the converter, did not go around the RV and measure at the batteries

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A constant amps in bulk converter is putting out say constant 100 amps during bulk, while battery voltage rises to Vabs (14.4 eg) The highest output va using battery voltage is just before amps taper at the start of the absorption stage. Once the absorption stage starts and amps taper, power required to run the converter drops off too.

What I do not know, is during the bulk stage, what the converter's output voltage really is except that it must be more than the battery's voltage. From listening to the generator, mine revs right up as soon as you turn on the 100 amper and it stays revving like that until amps taper. This suggests converter output voltage is 14.4 (or whatever it is set for) from the start. I don't really know.

It shouldn't matter, since at some point you will want to have that max output of 100 x 14.4, so the gen will have to supply enough power to do that when the time cones.

Note--The PD converter is not really a constant amps in bulk converter, from most accounts and charging plots we have seen, so amps are tapering somewhat from the start. (Should still be 70, not 64 at 14.2v)

Perhaps this would make them less demanding of the generator since their output is below rated amps except for the first minute. When battery voltage rises to near 14.4 then amps really start to taper, same as with any other charger, so you can tell you are now in absorption for sure compared with the PD's slower tapering during bulk.

The PD still gets the job done and the extra time it takes in bulk by not doing constant amps is trivial for most folks. Only mentioning it here because of the possible effect on generator demand.