Charging from a Generator

[mccainc]

Ok, might need an engineer’s perspective on this one. I use a Quick Charge 25A onboard charger that works great when plugged in to shore power. The trouble is I like to take my cart camping and charge from my toy hauler’s Onan 4kw gas generator. For some reason I’m only seeing 2-4 amps of charge current when running of of it. I’ve done side by side comparisons and shore power gives me in the neighborhood of 15 amps (which is about right considering the batteries charge state). The funny thing is if I plug it into my portable Champion 2kw inverter generator it performs the same as if it was on shore power. I’ve contacted Quick Charge and they say the only known problems are from capacitor type generators, of which this is not. The voltage is on point but I haven’t been able to measure the frequency. All other electronics in the camper run fine from the generator. Everything I’ve read seems to indicate that the Onan should produce a clean, true wine wave but I’m thinking that might not be true. I don’t have an oscilloscope to find out. Any thoughts or similar experiences?

[JohnnieB]

Is this one of their chargers that has a transformer on the AC input?
Also, is it designed for lithium batteries?

Obviously it doesn't play well with the 4kW Onan, so what I'd plug it into a "Kill A Watt" meter (or something similar) and then plug the meter into shore power, Onan and Champion and compare the various parameters for differences in Voltage, frequency, Amps, power factor, etc.

This is what I'm referring to: https://www.amazon.com/P3-P4400-Elec.../dp/B00009MDBU

There's similar meters out there and might find a better price.
I've had an earlier version the one linked to that I've used around the house for nearly 15 years and it has been a very useful gadget to have available.

Most recent use was figuring out how big of UPS (battery backup) to get for a new computer system.

[mccainc]

Not sure where the transformer is, everything’s inside a very heavy duty metal case. The model is OB 4825. I had them program it for a lithium profile. Been very happy with it until discovering this issue. Concur on the meter, just sucks because I already have two, albeit cheaper varieties than the kill-a-watt. Thanks.

[JohnnieB]

Originally Posted by mccainc

Not sure where the transformer is, everything’s inside a very heavy duty metal case. The model is OB 4825. I had them program it for a lithium profile. Been very happy with it until discovering this issue. Concur on the meter, just sucks because I already have two, albeit cheaper varieties than the kill-a-watt. Thanks.

Maybe they will provide the info needed. Except for storing data when unplugged, my older unit does all the measurements the newer ones do.

[mccainc]

If I put a load on the generator by turning on the refrigerator it doubles the charger’s DC output current. It has to be something with the shape of the sine wave.

[JohnnieB]

It's a 4kW generator, so put a 1500W heater or hair dryer (Resistive load) on it and see what happen the the charger's output amps.

[mccainc]

Good idea. Don’t have those with me right now on the camping trip so I’ll try when I get home. It’s interesting that the refrigerator produces the best results. The microwave, AC, and to a lesser extent the converter make the output all sorts of wonky. Inductive loads?

[JohnnieB]

I couldn't find any info on an Onan OB 4825. Is it a brushless or a brush type generator?

If it is brushless, it does have a capacitor in the output.

[mccainc]

Sorry, that’s the Quick Charge battery charger model. The generator is an Onan QG 4000.

[JohnnieB]

Oops, that was me mis-reading.

Found some info, but not what I wanted. (didn't identify as brush type or brushless )