240v genset charging

[BlackWaterPark]

Figured it was time to move out of the introduction section and into deeper waters.  So I'm back at charging the back up once again, trying to figure out how to get higher currents to run through the GS6.  I've got the charge amps maxed out at 99% and I'm metering the hot lead going from the generator to the inverter, and it's clocking in at  ~16.5a.  This current is coming through 10' of 8/3 going to a 240v 4 prong locking plug into the 30a generator outlet. The generator should be able to put near double that out, running on propane.  Am I missing a parameter I'm the inverter to help get the full output through the inverter?

 

Currently 45 amps DC on the main neg directly out of the inverter, and 22.5a DC going to each battery, metered between the busbar add the battery.

Edited January 2, 2022 by BlackWaterPark

[Sid Genetry Solar]

5 hours ago, BlackWaterPark said:

The generator should be able to put near double that out, running on propane.  Am I missing a parameter I'm the inverter to help get the full output through the inverter?

Not necessarily...at the current time anyway 😉.  This is an area that needs work on the firmware.  Hopefully I can get back to the code this week (after all the holiday stuff being over!), and get PFC charging implemented.  Then it'll be up to figuring out what the limits of the inverter are.

Assuming your inverter has a Rev. C control board in it?  If so, there's a lot of work coming in the 1.1r6 update having to do with calibrating the amperage sensors, etc., etc.  We should easily be able to increase the charge amperage (and efficiency).

[BlackWaterPark]

Oh, good then. Kept thinking I was doing something wrong somewhere, or missing some detail.  It works for now as is and pretty good at that albeit a little slower. I was just going nuts trying to figure it out.  And yes, it's rev c board. I like this inverter quite a bit, the more I get to know it.

[Sid Genetry Solar]

Glad you enjoy the inverter; I have major revamps/redesigns and proper implementations of features coming in 1.1r6 which should hopefully get charge working considerably better...plus adding more features.

[BlackWaterPark]

Hey, so I've finally needed to actually charge my bank up via the generator, first time since the new update, and I'm experiencing having the inverter either kick back to "inverter" mode, or actually outright shutdown under an overheat trip. I'm only running the charge amps at like 36%. Prior to the update, I sent to remember a good deal more amperage running through the inverter without a problem. Now, after a half hour or so, it'll kick out of charge mode. Not sure what's going on here.

[NotMario]

After half an hour... Huh... Sounds like temperature.

Sid did say "having to do with calibrating the amperage sensors." Perhaps that 36% doesn't mean what it used to. Did you verify similar amperage with a multimeter? If it's higher, it's going to produce more heat...

And if the amperage is the same, was your ambient temperature colder months ago? If the air around your inverter is warmer, it wont be able to cool as efficiently, so output power would have to be compensated with this in mind.

Nevertheless, as i understand it (i don't use AC-DC charge), increasing temperature should cause the charge to back-off. So this feature seems to be failing you at the moment.

Good luck, friend. Just giving you what little i can that might help you. Sids the actual expert.

[Sid Genetry Solar]

11 hours ago, BlackWaterPark said:

Hey, so I've finally needed to actually charge my bank up via the generator, first time since the new update, and I'm experiencing having the inverter either kick back to "inverter" mode, or actually outright shutdown under an overheat trip. I'm only running the charge amps at like 36%. Prior to the update, I sent to remember a good deal more amperage running through the inverter without a problem. Now, after a half hour or so, it'll kick out of charge mode. Not sure what's going on here.

We definitely need to look into this one.

Prior to the 1.1r5 update, the "charge amps" scale was less than half of what it was set to AFTER the update.  (Before the 1.1r5 update, it was an arbitrary scale; in 1.1r5 I adjusted the "charge amps" scale to be relative to the inverter's rated wattage.)  So there is definitely a change there--the "charge amps" number now looks very small, but likely is MORE than it was doing before.

As far as the inverter doing an overheat trip/shutdown, that's weird.  Because, like @NotMario said, the inverter SHOULD have throttled charge all the way down to 0% BEFORE the overheat ALARM turns on--much less overheat ERROR.  However, if it is overheating very quickly, it's possible the heat inside the transformer core is taking a bit of time to reach the thermistors on the outside--and as such even though the inverter might be throttled to zero (and fans blazing full speed), it still overheats.  Do you know what sensor is causing the overheat?  (i.e. is it transformer, or MOSFET that's overheating?)  I know that charge mode is less efficient than inverter mode (due to hardware limitations)--but you should easily be able to charge at over 50% capacity...

Aborting charge mode (back to inverter I presume) makes it sound more like an outside issue--as apart from normal charge mode exit, the only way this should (!) happen is if the AC input voltage, frequency (or inverter sync) go out of bounds.  If the generator is loading down and physically running slower, the inverter will disqualify the AC input at ~55Hz--and abort charge as a result.  You can verify this from the "OUT" page: during charge, watch the listed frequency on the output (as during charge, AC output is connected to AC input via an on-board relay).  If it's dropping down around 55Hz under load (especially if someone pops on a load in the house!), that will very easily cause a charge abort.

I have to admit that neither Sean nor I do battery charging with the inverters--so we haven't fully tested the capabilities of this function.  There may very well be some needed adjustments.

[dickson]

 If the generator is loading down and physically running slower, the inverter will disqualify the AC input at ~55Hz--and abort charge as a result. 

My 10 year old generator slow down and  the  frequency drop  to 55 hz  under load and I do not know how to fix and can not use now  for L1  N  L2 .     

[NotMario]

@dickson, Adjust the tab that the governor spring attaches to. Just bend it so the spring is tighter. A wee-bit should be enough, do it while it's running and get the frequency up to about 62Hz. After years of service, those springs stretch out, so you could also replace the spring.

I don't think the frequency is his problem because of the "30 minute" time delay. Unless maybe there's a big load being put on passthru power. In which case the inverter is preventing an outage... But that doesn't seem right either because the 6KW inverter should bail if you're taxing a whole generator that most likely handles much more power...

[Sid Genetry Solar]

1 hour ago, dickson said:

My 10 year old generator slow down and  the  frequency drop  to 55 hz  under load and I do not know how to fix and can not use now  for L1  N  L2 .

This is completely a firmware limit; if it's not a problem, and the customer doesn't mind running everything at 50Hz, I can easily remove this protection from the firmware.  It doesn't hurt anything in the inverter--it's just a safeguard in case there are sensitive appliances connected that can't handle 50Hz.

[BlackWaterPark]

The sun came out little later in the day, so i got the charging done via the panels anyway. Then i got hung up with a million other things.  When I've got time, I'll do the whole thing again and see what happens, and try to document it as thoroughly as my abilities allow for.  Oddly enough, in what is absolutely an unrelated but coincidental concurrent event, my neighbors kilovault battery bank balancer for his kilovault lifepo4 bank caught fire while he was generator charging, the very next day.  It actually burned a hole through the top of one of the battery cases, and he's charged in the same manner many times before without issue. I had to go unhook everthing for him and try to get a useful response from kilovault..which is woefully harder that i thought it would be.

[Sid Genetry Solar]

16 minutes ago, BlackWaterPark said:

The sun came out little later in the day, so i got the charging done via the panels anyway. Then i got hung up with a million other things.  When I've got time, I'll do the whole thing again and see what happens, and try to document it as thoroughly as my abilities allow for.  Oddly enough, in what is absolutely an unrelated but coincidental concurrent event, my neighbors kilovault battery bank balancer for his kilovault lifepo4 bank caught fire while he was generator charging, the very next day.  It actually burned a hole through the top of one of the battery cases, and he's charged in the same manner many times before without issue. I had to go unhook everthing for him and try to get a useful response from kilovault..which is woefully harder that i thought it would be.

Main points of interest are what temperature sensor is indicating the highest temp...and what's the listed AC frequency on the "OUT" page.  Beyond that, if we want to watch it/check things during a video call, that might be worthwhile. 

The charge (and inverter) throttle is visible from the "Diagnostic Info" page--I've tested the high-temp throttle-down on my bench (with my soldering iron to heat up the thermistor), and it seems to work as designed there.  I'm not sure what's going on, but we need to find out!

[dickson]

 my neighbors kilovault battery bank balancer for his kilovault lifepo4 bank caught fire while he was generator charging, the very next day.  It actually burned a hole through the top of one of the battery cases

Someone on this forum also had his  lifepo4 bank caught fire .   I  do not use my  generator to charge battery because gasoline  cost too much .    lifepo4 has a flat charging curve and  is easy to overcharge .   

 

[BlackWaterPark]

Yea, his was through a magnum 4840 too... Magnum makes excellent chargers in their inverter/chargers, and i set the parameters according to kilovault recommendations. I'm thinking I'm just going to get 3 or 4 dedicated lifepo4 48v 15a chargers (looking at the Dakota chargers) and run those as a single charger bank. The system I replaced had a discreet charger and i very much preferred that setup over an inverter/charger for a variety of reasons. Running the GS6 as a charger makes all my lights go wonky, like I'm at a rave, likely due to the generator itself I'm sure. With discreet chargers, I could downsize significantly on the genset size and volume as an added bonus.

[Sid Genetry Solar]

26 minutes ago, BlackWaterPark said:

With discreet chargers, I could downsize significantly on the genset size and volume as an added bonus.

Well, remember, the entire load has to be offset by the generator--or you'll just be slowing the discharge rate, and not be actually charging the battery.

 

27 minutes ago, BlackWaterPark said:

Running the GS6 as a charger makes all my lights go wonky, like I'm at a rave, likely due to the generator itself I'm sure.

Worth looking into this; the charge throttle MIGHT be going into an oscillation, which could cause lights to go haywire.  This also needs diagnostics 🙂.

Was it doing the flickering before the 1.1r6 update?

[NotMario]

6 hours ago, Sid Genetry Solar said:

Well, remember, the entire load has to be offset by the generator--or you'll just be slowing the discharge rate, and not be actually charging the battery.

This is what i do. As long as the generator triggers with enough battery to handle the largest reasonable task, with some reserve.
For a typical residential off-grid system, the typical 6-10KW generator is ridiculous overkill.

I use an alternator and back-off the diesel to a RPM to minimize fuel per kwh. If for some reason i would need a bigger task, i can rev the engine faster to get more power at the cost of efficiency.

Of course, for most of us the goal is to not have to use your generator any more than the grid. The generator is just there to supplement, and if you're at that point, you can probably find ways to work within your power limits. (In my case, use a clothes line rather than an electric drier...)

 

[Sid Genetry Solar]

Just for thread continuity...@BlackWaterPark and I did some diagnostics.  The noticeable flickering in the lights while charging appears to be the result of a throttle oscillation in the inverter; this is something that I need to address in code.

The tripping/glitching and errors on the other hand seem to have been caused by generator speed--the genny was running a happy 63-64Hz AC output.  (Adjusting the frequency down seems to have solved the issue.)  Once again, the frequency limits are purely a firmware limit, not a hardware limit--and if this is normal behavior for gensets, I either need to add "alarms" (instead of random tripping), or increase the accepted range.

Inverter temps seemed stable at 36% charge current, and also at 71% charge current.  I know the inverter runs hot in charge mode, but that's normal operation.  Shouldn't be overheating though...

[dickson]

I'm thinking I'm just going to get 3 or 4 dedicated lifepo4 48v 15a chargers (looking at the Dakota chargers) and run those as a single charger bank. The system I replaced had a discreet charger and i very much preferred that setup over an inverter/charger for a variety of reasons.

I  do not have any   lifepo4 48v at this time  but I  would  use a  Dakota  charger  for every  string of  lifepo4 48v  at night  and use solar charger  by day .