Genny HZ erratic with PD Converter charger load

Sagecoachdriver · 04-17-2021, 05:59 PM

My Onan 4000 was surging but with Seafoam/gas and slight governor adjustment it worked fine until the only load was a heavy charge of the Lithium house batteries. If another load was applied, the Hz stabilized around 60Hz. Otherwise, it fluctuated between 45 and 60Hz. Still showing 45-50amps going into Lithium house batteries. The Converter charger is the original PD 4560 and not the Lithium only upgrade. I was told by BB and PD that I just need to hit the charge wizard to get into boost mode bringing the voltage up to 14.3 volts.

Sagecoachdriver · 04-18-2021, 10:54 PM

So I guess nobody out there has ever had the generator frequency Hz hunting. Will make the call tomorrow to Progressive Dynamics. They will probably say I need the Lithium mode charger.

JLeising · 04-19-2021, 12:00 AM

A guess - it sounds like the converter is varying the load on the generator faster than the generator governor can track.

Sagecoachdriver · 04-19-2021, 12:28 AM

Quote:

Originally Posted by JLeising

A guess - it sounds like the converter is varying the load on the generator faster than the generator governor can track.

So do you think a Lithium converter charger will solve the issue? I'm going to try the normal mode of 13.6 volts instead of the boost at 14.3. But I noticed that the boost starts out at 13.6 and not 14.3 and it's not until 95%+ charged that the voltage goes up to 14.3v. Not sure what to expect and it's not going to be anywhere near the 50amps going into the Lithiums.

JLeising · 04-19-2021, 01:26 AM

My guess - and it is only a guess - changing to a lithium PD converter will not make any difference. My suspicion is that the PD converters use the same basic voltage conversion circuitry and differ in the charge mode change logic and final voltage.
If so, a different manufacturer’s converter may behave differently (or not).
Not sure the frequency variance is a problem for the converter. Maybe PD can answer? Since it stabilizes when something else is on, may not be a problem...
Alternatively, maybe add a load that comes on with the converter sufficient to stabilize the generator...

Sagecoachdriver · 04-19-2021, 01:36 AM

Quote:

Originally Posted by JLeising

My guess - and it is only a guess - changing to a lithium PD converter will not make any difference. My suspicion is that the PD converters use the same basic voltage conversion circuitry and differ in the charge mode change logic and final voltage.
If so, a different manufacturer’s converter may behave differently (or not).
Not sure the frequency variance is a problem for the converter. Maybe PD can answer? Since it stabilizes when something else is on, may not be a problem...
Alternatively, maybe add a load that comes on with the converter sufficient to stabilize the generator...

Thanks. Going to see if just turning on the stove vent makes a big enough load difference. Taking it in later this week to the shop and hopefully they will know what's going on. Never had this issue with lead acid batteries, but who knows. Never checked it specifically. I'm hoping it just low rpm. Service manual said no load voltage should be typically 125v with no load and mine is 122v. I don't want to mess with the speed control anymore. Turned it up from 120.4v. Plus frequency should be 62.5Hz no load and mine is 61.5Hz. Definitely needs professional adjusting.

JLeising · 04-19-2021, 02:11 AM

I’ll be interested to hear the outcome.

The stove vent on mine is 12 volt. Suspect you will need to add some 120 volt load.

Sagecoachdriver · 04-19-2021, 08:17 AM

Quote:

Originally Posted by JLeising

I’ll be interested to hear the outcome.

The stove vent on mine is 12 volt. Suspect you will need to add some 120 volt load.

You're right! Not thinking, it was bedtime. Electric mode on water heater works fine, but once the water is heated the hunting starts again. Maybe the Dish receiver left onor space heater on fan only?

Sagecoachdriver · 04-19-2021, 03:44 PM

Spoke with Progressive Dynamic about converter charger and Hz hunting while on high battery recharge. He said to check voltage and current at battery and converter charger and look for fluctuation in Boost mode and normal mode. If none, then it is just HARMONIC and is of no concern. If there is fluctuation then things can get damaged. going out to test now.

TitanMike · 04-19-2021, 08:03 PM

When a non-inverter generator's motor speed fluctuates like described, frequency will change correspondingly.

I have founs that in most cases this is caused by sticky carburetor linkage and throttle shaft.

A quick cure in every case with any of my generators doing this was to clean linkage and shaft first with carb cleaner then followed with a dry lube spray.

This allows the "governor" and related moving pieces to respond more quickly to engine speed changes.

From the description this is not an electrical issue but rather a mechanical issue with engine and governor in generator.

If it was an inverter generator then it would be an issue with inverter circuitry that controls frequency regardless of engine speed.

Sagecoachdriver · 04-19-2021, 09:08 PM

Quote:

Originally Posted by TitanMike

When a non-inverter generator's motor speed fluctuates like described, frequency will change correspondingly.

I have founs that in most cases this is caused by sticky carburetor linkage and throttle shaft.

A quick cure in every case with any of my generators doing this was to clean linkage and shaft first with carb cleaner then followed with a dry lube spray.

This allows the "governor" and related moving pieces to respond more quickly to engine speed changes.

From the description this is not an electrical issue but rather a mechanical issue with engine and governor in generator.

If it was an inverter generator then it would be an issue with inverter circuitry that controls frequency regardless of engine speed.

I cleaned all th linkage with carb spray and dry lube and it's working fine. I checked the voltage and Hz at converterc harger and at batteries and they all seemed to have a few tenths of fluctuation. I don't know about it being harmonics.
Still have an appointment thursday.. The technician is going to thinking I'm nuts and should have left it alone.

Sagecoachdriver · 04-21-2021, 12:19 AM

Going to adjust the genny tomorrow following Onan's service instructions. I believe the issue is caused by the droop being too small as I don't see much drop in Hz with heavy load. Backup is going into Onan shop Thursday morning, regardless.

Wes Tausend · 04-22-2021, 01:22 AM

...

Sage,

Maybe some of what you are saying is just beyond me, but the first thing I would suspect is that the carb is still plugged. Like mine was.

If any gas engine surges, it's not getting enough fuel. I think yours just shows up at a certain load, a carb setting chosen by the governor. Granted, there are some hunt issues that could appear from a screwed up governor setting, but they are different, not really a fuel "surge", but a true "hunt". You shouldn't need to re-set the governor for the correct rpm (Hz/sec) after the carb is cleaned because the gov normally hasn't moved from correct factory.

I had trouble with my gen after running it for A/C in my driveway on an extremely hot day (107°F I think) and I fear I didn't let it run in cool-down long enough. The gas can boil out of the carb bowl from intense residual heat after shut-down and leave a nasty residue in the bottom and where the jet is. On very hot days since, I've been taking the outside cover off near the end of a longer cool-down, then shutting down from the exterior control right after. The carb bowl is then immediately exposed to cool outside air instead of the residual enclosed-hot-iron after-bake effect.

At first, mine ran fine from just Sea Foam too when unloaded, but then still surged like yours on my heavy A/C load. These carbs are actually easy to disassemble and clean the right way. The left-over gunk after Sea Foam is quite visible when open. For simplicity, there is no idle jet, just the main, because they never run at idle.

In case it happens again, I left the plastic EPA clip off to allow just quick unscrewing the brass jet adjustable needle, for a quick spray-clean with the carb in place. But the plastic EPA stop snaps right back in place if I ever want it back on there.

An important point: I carefully set the bare needle precisely where it was originally, which happens to be about 1 1/2 turns out like usual. EPA is still good for test. A shop may not be willing to legally do this, hence the usual Onan recommended new-factory-carb-fix.

The gen frequency will never be exact in my opinion. Mine never was from new, using a small meter I have. But it is darn close. Your 61.5Hz-62.5Hz range sounds passable to me. Everything should run as perfect on it, as utility line power (except a synchronous clock). Surging rpm definitely makes the A/C voltage waver as the gen never gets to settle to the load on steady throttle... until the carb is clean.

I'll be pretty interested in what you find. In the future, I'm planning a part wet-cell/part lithium arrangement myself. I want a single big lithium on the fridge inverter, if the combo works out.

Good luck,
Wes

Sagecoachdriver · 04-22-2021, 02:32 PM

Took the MH in to an authorized full service onan shop. The tech made adjustments to the carb, governor speed and sensitivity screws and choke. No more Hz hunting with only the converter charger pumping 45+v into the Lithium batteries. Carb is fine and it runs smooth. He wasn't a fan of Seafoam and suggested using a stronger professional carb cleaner but didn't recommend one by name.

Wes Tausend · 04-24-2021, 02:01 AM

Quote:

Originally Posted by Sagecoachdriver

Took the MH in to an authorized full service onan shop. The tech made adjustments to the carb, governor speed and sensitivity screws and choke. No more Hz hunting with only the converter charger pumping 45+v into the Lithium batteries. Carb is fine and it runs smooth. He wasn't a fan of Seafoam and suggested using a stronger professional carb cleaner but didn't recommend one by name.

Sage,

Good to hear! Thanks for getting back. The Sea Foam must have worked.

How did all the other stuff get out of adjustment, or did he just peak it out with some fine tuning?

After seeing how the needle and black plastic EPA stop is put together, I've thought about just popping it off with a couple of jack-knives to get behind it. The brass needle then simply unscrews by finger. In that case, I think a guy could spray-clean it in about 5 minutes, put it right back together and nobody would be the wiser.

I used carb cleaner and brake cleaner from Walmart. They're cheap and in big cans. The carb cleaner will remove paint if it gets on it, so I usually get by with brake cleaner, which is probably mostly just alcohol. Once the carb is off and apart, it's easy to use carb cleaner which cuts much faster.

Wes

Sagecoachdriver · 04-24-2021, 09:24 PM

\I have started the genny up each morning and I am amazed at the fact that with 5 seconds of priming, it start right up with no cracking sound. Before, it would crack for 5 or more seconds before starting. It is hardly a noticalble when a load is applied. The tech did a fantastic job of tuning it. He says with all the bouncing and use , they tend to eventually go out of adjustment.

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