Author Topic: AC generator causing Schneider 4024 inverter to go to absorb  (Read 771 times)

Duston

  • Newby
  • *
  • Posts: 8
AC generator causing Schneider 4024 inverter to go to absorb
« on: December 02, 2020, 12:54:04 AM »
So I have a midnite classic 150 and the prewired midnite panel with the Schneider 4024 inverter. This is the first winter running the system and the batteries finally got down to 80% DOD while I was away from the off grid yurt. I have crappy gel batteries that I didn’t do enough research on so not concerned about the dod. I have a hand me down 4500w ac generator that I figured was a good time to test it out. Hooked it up fine for 240v, you just plug the 2 phases into the 2 AC in bars. the inverter maxes at 30amps in I believe. I started it up and It ramped up to 30.+ volts. Stopped and I got that figured out by tweaking “custom” batteries so I could set the temperature offset. I got it to 28.7 volts like my batteries call for. My question is the inverter will ramp up the volts to 28.7 then immediately go into absorb like the batteries are almost fully charged. If I turn the generator off the Volts will drop back down to the 80% DOD, around 25v I believe. I can turn the generator back on and same think, right to bulk then immediately to absorb. My absorb volts are set the same as bulk so I don’t know if it’s really a problem. I just know when I am charging from my PV the classic 150 will show the volts increasing and and max amps in  until it hits absorb and then finishing out to float.Never will it immediately ramp up the volts like the batteries are fully charged. The generator is charging as I can see the amps reducing as the batteries are getting fuller. I was able to run it for about 3 hours until I got annoyed with the noise.  I hope that makes sense. I’ve re re re read my Schneider manual and tried the inter webs. I figured this would be my first stop before going to Schneider.

I did chop some trees so I got some more light in there to get the batteries back up to float. Wasn’t about usage. Was I had about 45 minutes of pure sun. That sun drops a lot here in Oregon during the winter!
Midnite Classic 150
Schneider 4024 split phase inverter/charger
6v 260AH gel 24v battery bank
6 Canadian Solar 300w PV panels

ralph day

  • Full Member
  • ***
  • Posts: 121
Re: AC generator causing Schneider 4024 inverter to go to absorb
« Reply #1 on: December 02, 2020, 08:14:05 AM »
IS that an inverter that requires 240vac on it's ACin?  My old Xantrex/schnieder was only 120v.  just the first of many questions likely.

ClassicCrazy

  • Hero Member
  • *****
  • Posts: 3109
Re: AC generator causing Schneider 4024 inverter to go to absorb
« Reply #2 on: December 02, 2020, 12:12:59 PM »
So I have a midnite classic 150 and the prewired midnite panel with the Schneider 4024 inverter. This is the first winter running the system and the batteries finally got down to 80% DOD while I was away from the off grid yurt. I have crappy gel batteries that I didn’t do enough research on so not concerned about the dod. I have a hand me down 4500w ac generator that I figured was a good time to test it out. Hooked it up fine for 240v, you just plug the 2 phases into the 2 AC in bars. the inverter maxes at 30amps in I believe. I started it up and It ramped up to 30.+ volts. Stopped and I got that figured out by tweaking “custom” batteries so I could set the temperature offset. I got it to 28.7 volts like my batteries call for. My question is the inverter will ramp up the volts to 28.7 then immediately go into absorb like the batteries are almost fully charged. If I turn the generator off the Volts will drop back down to the 80% DOD, around 25v I believe. I can turn the generator back on and same think, right to bulk then immediately to absorb. My absorb volts are set the same as bulk so I don’t know if it’s really a problem. I just know when I am charging from my PV the classic 150 will show the volts increasing and and max amps in  until it hits absorb and then finishing out to float.Never will it immediately ramp up the volts like the batteries are fully charged. The generator is charging as I can see the amps reducing as the batteries are getting fuller. I was able to run it for about 3 hours until I got annoyed with the noise.  I hope that makes sense. I’ve re re re read my Schneider manual and tried the inter webs. I figured this would be my first stop before going to Schneider.

I did chop some trees so I got some more light in there to get the batteries back up to float. Wasn’t about usage. Was I had about 45 minutes of pure sun. That sun drops a lot here in Oregon during the winter!
Not sure I am fully following but here are some points to consider.
There is no Bulk setting - at least in the Classic.
When you push a lot of amps into batteries the voltage will shoot up much higher.
Once it gets to the Absorb setpoint then it is going to stay in Absorb until whatever you have programmed to terminate Absorb  - usually Absorb time although some things like the Classic also have Ending amps setting ( used with Whizbang) . When Absorb is done it goes to Float setting.
When in Absorb it does as you mention - holds the Absorb voltage and then reduces the charge current to maintain the absorb voltage .
You need to have both the Classic and the Inverter chargers temperature compensated using their temp sensors that attach on the batteries. The Classic will raise the Absorb and Float setpoints as the batteries get colder ( depending on the temp compensation programmed in ) .
The charger in your inverter probably works in much the same way as the Classic.
So if it was compensating the voltage for colder batteries that is the only way they will charge up fully .

Larry
« Last Edit: December 02, 2020, 12:17:10 PM by ClassicCrazy »
system one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

Duston

  • Newby
  • *
  • Posts: 8
Re: AC generator causing Schneider 4024 inverter to go to absorb
« Reply #3 on: December 02, 2020, 02:03:06 PM »
IS that an inverter that requires 240vac on it's ACin?  My old Xantrex/schnieder was only 120v.  just the first of many questions likely.

Ya I'm that guy. I was telling my wife how do I ask a competent question on something I don't understand? the Schneider 4024 is a split-phase so it can take 120/240
Midnite Classic 150
Schneider 4024 split phase inverter/charger
6v 260AH gel 24v battery bank
6 Canadian Solar 300w PV panels

Duston

  • Newby
  • *
  • Posts: 8
Re: AC generator causing Schneider 4024 inverter to go to absorb
« Reply #4 on: December 02, 2020, 02:39:47 PM »
So I have a midnite classic 150 and the prewired midnite panel with the Schneider 4024 inverter. This is the first winter running the system and the batteries finally got down to 80% DOD while I was away from the off grid yurt. I have crappy gel batteries that I didn’t do enough research on so not concerned about the dod. I have a hand me down 4500w ac generator that I figured was a good time to test it out. Hooked it up fine for 240v, you just plug the 2 phases into the 2 AC in bars. the inverter maxes at 30amps in I believe. I started it up and It ramped up to 30.+ volts. Stopped and I got that figured out by tweaking “custom” batteries so I could set the temperature offset. I got it to 28.7 volts like my batteries call for. My question is the inverter will ramp up the volts to 28.7 then immediately go into absorb like the batteries are almost fully charged. If I turn the generator off the Volts will drop back down to the 80% DOD, around 25v I believe. I can turn the generator back on and same think, right to bulk then immediately to absorb. My absorb volts are set the same as bulk so I don’t know if it’s really a problem. I just know when I am charging from my PV the classic 150 will show the volts increasing and and max amps in  until it hits absorb and then finishing out to float.Never will it immediately ramp up the volts like the batteries are fully charged. The generator is charging as I can see the amps reducing as the batteries are getting fuller. I was able to run it for about 3 hours until I got annoyed with the noise.  I hope that makes sense. I’ve re re re read my Schneider manual and tried the inter webs. I figured this would be my first stop before going to Schneider.

I did chop some trees so I got some more light in there to get the batteries back up to float. Wasn’t about usage. Was I had about 45 minutes of pure sun. That sun drops a lot here in Oregon during the winter!
Not sure I am fully following but here are some points to consider.
There is no Bulk setting - at least in the Classic.
When you push a lot of amps into batteries the voltage will shoot up much higher.
Once it gets to the Absorb setpoint then it is going to stay in Absorb until whatever you have programmed to terminate Absorb  - usually Absorb time although some things like the Classic also have Ending amps setting ( used with Whizbang) . When Absorb is done it goes to Float setting.
When in Absorb it does as you mention - holds the Absorb voltage and then reduces the charge current to maintain the absorb voltage .
You need to have both the Classic and the Inverter chargers temperature compensated using their temp sensors that attach on the batteries. The Classic will raise the Absorb and Float setpoints as the batteries get colder ( depending on the temp compensation programmed in ) .
The charger in your inverter probably works in much the same way as the Classic.
So if it was compensating the voltage for colder batteries that is the only way they will charge up fully .

Larry

ya my fault your not following. For the temp compensation, i understand that pretty good. Schneider does a poor job of defaults for gel batteries that you cant adjust and also shows it as per 24v versus per cell like the Classic. Another member had this issue but I found if you go to custom you can set your temp how the batteries want it. I get what you are saying on the no bulk in the classic. I think that is where I am getting confused. it does say bulk on the classic home screen when it is first charging my batteries, which my understanding is it is sending everything it can to the batteries, then goes to absorb at about 80% and holds that 28.8 voltage I believe, until it hits the ending amp I set up on the Wizbang. I don't think I really was paying enough attention to the amps being pushed into the batteries from the generator. I think I just saw 30+ volt going into the batteries and panic. It is cold in there so I should do a calc on the temp compensation to understand what high volts are ok at that time.

I guess my confusion is the classic reads differently than the inverter when charging and that's probably ok. The good thing is when I have PV power and generator running I could see the classic was throttling correctly, though when the volts were being pushed up by the generator above 30v the classic went to float thinking the batteries were full. Let me do some more diving in and Ill update.
Midnite Classic 150
Schneider 4024 split phase inverter/charger
6v 260AH gel 24v battery bank
6 Canadian Solar 300w PV panels

ClassicCrazy

  • Hero Member
  • *****
  • Posts: 3109
Re: AC generator causing Schneider 4024 inverter to go to absorb
« Reply #5 on: December 02, 2020, 04:48:55 PM »
Does your inverter have a temperature sensor that goes to the batteries ?
So for the Classic you are right -  you put in the temperature compensation value and it knows how many cells to apply it to based on the battery voltage.
Most batteries are usually -3 or -5 mv per cell  and your battery manufacturer will have that info.

Yes you are correct - when in Bulk the batteries will take in all available current until the voltage climbs to Absorb setpoint.
It was probably very gradual with your PV , but with a generator and inverter charger that can put in a lot of power quickly that probably makes the voltage climb very fast.
The SOC state of charge is just an estimate and depends on how you set it up for capacity, efficiency, and it also has a temperature compensation that will change it some in cold weather. But the SOC doesn't have anything to do with charging - just is a monitor basically .

There is some info on the midnite knoweldge base that tells about how to set up ending amps.

Larry
system one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

Duston

  • Newby
  • *
  • Posts: 8
Re: AC generator causing Schneider 4024 inverter to go to absorb
« Reply #6 on: December 04, 2020, 11:16:15 AM »
Does your inverter have a temperature sensor that goes to the batteries ?
So for the Classic you are right -  you put in the temperature compensation value and it knows how many cells to apply it to based on the battery voltage.
Most batteries are usually -3 or -5 mv per cell  and your battery manufacturer will have that info.

Yes you are correct - when in Bulk the batteries will take in all available current until the voltage climbs to Absorb setpoint.
It was probably very gradual with your PV , but with a generator and inverter charger that can put in a lot of power quickly that probably makes the voltage climb very fast.
The SOC state of charge is just an estimate and depends on how you set it up for capacity, efficiency, and it also has a temperature compensation that will change it some in cold weather. But the SOC doesn't have anything to do with charging - just is a monitor basically.

There is some info on the midnite knowledge base that tells about how to set up ending amps.
Larry

Yes, i have temp sensor for the midnite and Schneider. My batteries are -3. That was part of the problem with the default setting for Schneider at -54 which was well over the temp comp that I needed. The custom setting let me set that to -36 (3*4*(-3)). I do have my ending amps set up correctly i believe. I think it is around 3 amps. I feel like after I read stuff, set my numbers, I get it. Then walk away and my head starts spinning. I have been making cheat sheets and posting them on my inverter to help me remember. When I set up the system in the spring I was relying on the wizbang reading and not really paying attention to the battery volts. I'm kinda going backwards and adding fixtures and reading the amps going out so I can get an accurate count on storage need before I put down some money for LiFePo4 batteries. I know its backwards but Budget forced me into a system and I have to work within my inverter output for now. Plus it is 100% off grid so it forces me to really look at my needs vs wants.

Side note I called Renogy, who make the gel batteries i got, when i put the system in place because they really dont have good data sheets on the batteries. I was asking them what the approximate SOC was at different voltages. The person told me "well at 50% your 24v battery bank should be at 12 volts." I said are you just dividing it by 2? I knew at that point I had made a very bad decision on purchasing those batteries.

I think i just need to run everything and calc. out my votltage, amps in and temp compensation. It's probably running as it should. The midnite and inverter are communicating, which is good, as the classic was throttling the PV in when the Gen was running. Thanks for all your input Larry.

Midnite Classic 150
Schneider 4024 split phase inverter/charger
6v 260AH gel 24v battery bank
6 Canadian Solar 300w PV panels

ClassicCrazy

  • Hero Member
  • *****
  • Posts: 3109
Re: AC generator causing Schneider 4024 inverter to go to absorb
« Reply #7 on: December 04, 2020, 01:26:59 PM »
I think you are learning the best way .
It takes a long time for all the technical learning to fit into place and make sense so your observations will reinforce .
All AGM's have similar chemistry so look up a bigger manufacturer for AGM or Gel who has more detailed specs and maintenance and go with that.
You really can't go by voltages for SOC.
And it doesn't matter if  you get the SOC right on - it is just an estimate . if you set it lower than claimed then you just get some insurance that you aren't depleting  your batteries farther than you want to.  The Whizbang knowing all the amps going into and out of the battery is the best way to really know especially for AGM or Gel. 
Some setpoints you may want to tweak depending the season , the temp of batteries, and the age of the batteries.
Much better to learn the way you are on AGM lead acid than on lithiums - mess something up on those and they are bad in a  hurry. Lead acid is more forgiving .

Larry
system one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

Duston

  • Newby
  • *
  • Posts: 8
Re: AC generator causing Schneider 4024 inverter to go to absorb
« Reply #8 on: January 04, 2022, 11:31:47 AM »
Just to close this out for future views, My charge rate was set too high on my 4024 SW Inverter/Charger. It was pushing 30-40 amps and my battery charge rate is 27amps. This was pushing my volts up and causing the system to go into absorb/float.
Midnite Classic 150
Schneider 4024 split phase inverter/charger
6v 260AH gel 24v battery bank
6 Canadian Solar 300w PV panels

boB

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3741
Re: AC generator causing Schneider 4024 inverter to go to absorb
« Reply #9 on: January 04, 2022, 05:30:27 PM »
Just to close this out for future views, My charge rate was set too high on my 4024 SW Inverter/Charger. It was pushing 30-40 amps and my battery charge rate is 27amps. This was pushing my volts up and causing the system to go into absorb/float.

So, are you saying that it is charging OK now ?   I saw your posting about the current limiting today and I posted a PDF about how to get that to work the way you want.

I did not find out though if you let the Classic charge the batteries at that Absorb voltage for a few hours.   I see here that you used "ending amps" and that is usually OK but may possibly end your absorb charge too early.   It really needs to sit there for a time, usually at least a couple of hours at that absorb voltage.

Ending amps may be set too high in which case it would end that charge cycle too early.   Even when the charge current is too high, getting it to Absorb voltage quickly, I would think that the charge current would drop in not too long of a time below your wanted 27 amps and then you could feel good about letting it go for that extra amount of time in Absorb.

But now you should be able to keep that charge current lower by making the setting for the WB Jr. to keep the Classic from putting over 27 amps into the battery even with some of that current coming from a generator if it is still running too.

It used to be, many years ago that there was almost never enough solar to get the batteries charging current above that manufacturers recommended max charge current.   Didn't have to worry about it.   Now days though, solar is cheap enough that this has to be watched more and more.

boB
K7IQ  He/She/It