Help! Inverter dropping one leg with generator input

nobadays

Been snowing for 2.5 days, my 48v mnc lithium bank is down to 43.1v, LBCO is 42v.  Woke this morning to 6*F with frozen water.  We are off-grid and have an insulated water cistern about 30 feet from the house,  heat tape on the plumbing out there but just in case I put a small heater in the pump/plumbing box.  Since the batteries are low I kicked on the generator to help out.  When I came back into the cabin, the SCP was showing a "Dead Battery " fault.  When I went into the mechanical room to check the inverter, noticed the light wasn't working in there, subsequent checking of other circuits we determined one side of the load center was not getting fed. I turned the generator off, and the fault went away and power came back to both sides of the load center.

Tried the generator again, same results.   We have ran this system for over a year and a half with no issues having run the generator several times in the past. It is 120v from the 3500 watt generator feeding the Schneider 4048 inverter.  Just not sure where to look for the problem. 

Thanks in advance! 

nobadays

Talked to NAZWS tech.... apparently when feeding a 120v input the inverter uses the generator input on one output leg and pulls from the battery bank for the other output leg. My fault, dead battery  F86, was saying the batteries were too low to invert and feed the other leg. YET... in the manual it says that point is not reached until >24v.  The tech had no answer why it was doing this at 43.1v.  Is there a setting I'm missing?   Anyone?

Thank you! 

Dave Angelini

I think you are confusing the 4048 dead battery charging ability with a normal LBCO which should be between 42 and 44vdc depending on battery. Normally you feed 120vac only to one leg if you have a 120v genset on CSW.

mike95490

I think it's wrong to expect the inverter/charger to operate with only a single 120V leg from a generator , unless the 4048 was modded to be a 120V only unit.  I always thought it would need 240V to validate the generator.
  but maybe it;s different now

Dave Angelini

Mike, from the factory CSW 4048 can run from 120 or 240 vac. Designed in. The user does have to pick the right winding, L1, for this to work from 120vac.

 It also has the ability to charge a almost completely dead battery. This is often called dark start. The OP should always avoid this as it is an easy way to kill a battery system. LBCO means turn on the genset now! CSW will also give warnings that you are getting close to LBCO.

nobadays

Thanks for the replies... yes the SW 4048 can accept a 120vAC input.  This input is on L1.  I am not confusing LBCO, mine is set at 41v. 

The error was F86, Dead Battery Detected, - out of the manual: Automatic , When only Line 1 is qualified and a dead battery condition is detected. Both Line 1 and Line 2 must qualify to charge the battery.  ** what do they mean by "qualify?"

The Tech told me that incoming AC on L1 is routed to the load center, the invert then draws from the battery bank to energize L2.  Apparently the invert decided 43.1v was too low to draw from to energize L2 so gave me the F86 error. We have recharged/ran cabin from the generator before but maybe not at this low of battery voltage. The snow slid off the main array around 10:30 (we also have 750 watts ground mounted so the snow had been cleared from them, BUT they have shading until 11AM ish) and we started really beginning to charge.  Checked voltage about 11AM  and we had hit 44.9v .... had intended to try to use the generator at 44v but missed that number.  Anyway,  at 44.9v no problem at all, L1 and L2 were energized, everything back to normal. 

The SW 4048 states it has dead battery charging capability on the 4048 to >24v in the bank.  Our Volt meter told us that rather than at 43.1v as the SCP read, we were seeing 43.3v on the meter straight across the board for each of the 6, 2kw modules. So I'm unclear why it threw this dead battery error. I'm also unclear if it was actually charging the batteries or not. According to the above it should have been...  but according to the F86 error code, it would not charge the batteries.  Apparently only a 240vac generator will make that happen. 

My guess is there is another parameter that.... at least I hope... can be set to tell the inverter not to draw anymore juice from the batteries to energize L2 when the generator is running.  Not LBCO but specifically to do with AC output when on generator/AC input. I don't know where this setting is, or if it has something to do with load Sharing/shaving.  I will pour over the manual fir the SCP this evening.   Fortunately we had a blue sky day, because of the snow on the main array charging started late, but nevertheless we hit 47.2v more than enough to get us through until tomorrow when we will top up.

Again, I hope this parameter is set able.

Thank you!

Dave Angelini

I think you are going to have to say this in a different way, at least for me. You have a 120 genset only right? 

Qualify means the input (gen) voltage has to be in the frequency and voltage min/ max spec of CSW.

There should not be any loss charging with a 120v genset on L1. I am guessing that you are pulling more than 22.5 adc (45adc internal charger) and the csw is dropping the genset. This is not good as it will damage the transfer relays if you do this enough. Load shave is one way to stop this along with a few other ways. They did not make this easy as some specs are AC amps and some are DC amps and you have to know what you are setting.

Good Luck and watch the SCP for the gen amps cutting in and out. Do what you have to keep this going until you get the unit configured correctly. Cold Night up here also. Brrrr

BB.

Only question that I can think of--Some LiFePO4 battery BMS can "turn off" the battery if over discharged or over charged...(??).

-Bill

mike95490

BB. said:

Only question that I can think of--Some LiFePO4 battery BMS can "turn off" the battery if over discharged or over charged...(??).

-Bill

I can only guess at how fun that is if you have a solar charge controller active, and the battery "goes away"   !!

nobadays

Dave.... thank you!  Yes 120v generator. So if I read right, and what the Tech told me is correct,  L1 is qualified,  but L2 is not BECAUSE the inverter is saying the battery voltage is too low to draw and invert enough power to feed L2.  What I hear you saying is drawing more than 22.5 amps on L1 and dropping the generator feed.  This is not the case.

The generator IS feeding one side of the load center, no problem,  but, from what I can tell,  some setting in the SCP is telling the inverter to not feed L2 from the battery bank as it sees 43.1vdc as being too low.  I am not sure but I think the batteries were being charged when the generator was on.  The charging light was on.... not blinking as usual but on.  This light also indicates AC input.

This very well may have something to do with amperage draw but I find that hard to swallow.   My MNC Lithium modules will provide as much current as asked for until they hit the "knee" which is about 42vdc +/-.  The generator was performing normally not having any problem providing power, it did not draw down or labor any harder than normal. 

I may give the engineer who helped me design this system a call/email.   In the past he has contacted Schneider when he didn't know the answers.... though he may know more than the tech I talked to yesterday.  The tech yesterday was helpful but just did a search in the digital copy of the manual and pointed me to the pages.  I will do the same in the SCP manual,  plus read all I can that is related.

Today is another blue sky day so we will float no problem. 

BB.... I am using MNC Lithium from Chevy Volt cars.... 6 x 2kw modules.   Yhe BMS i am using is quite simple,  all it does is balance cells.  No over/under charge or temperature cut. I rely on my SCC and inverter for the high/low and manually monitor low temperature.  If we leave the cabin in the winter, the system is shut down... no charging or discharging. 

Dave Angelini

I am still mixing you up on the input side of the inverter and the output side.
I know for a fact that if the genset is qualified on L1 input. It will output on L1 and L2 and should charge the battery.
This is if you are not pulling more the 22.5adc (the equivalent AC is about 15aac)  from the L1 input including your loads.

I asked if you saw the SCP gen input holding the charge amps, or was it cutting out? You would also hear this on the genset rpm.

What genset BTW. You bought the inverter from the store here recently right? Are you at altitude near Flagstaff?

nobadays

Dave... I think I am understanding,  not sure if the Tech gave me correct information, saying L2 is energized from the battery bank.   I just read through the manual and I'm seeing the same thing you are. If using 120v generator L1, if qualified will pass through on both L1 & L2 ... if I read right.  I wish I had paid more attention to the SCP as I can't answer your question,  if it was holding the charge amps or not.  We had shut nearly everything off, and one side of the load center wasn't working... so satellite internet,  was off ascwere thecDish reciever and the refrigerator.... our biggest power consumers.   I don't think there was any way we were drawing 22.5adc, unless the battery charger itself was pulling it.

I do know that the generator rpm did not seem to be as high as it usually is when charging.  Normally I start the generator I let it warm a bit then flip the 30smp breaker to send the power to the cabin. Usually within seconds of throwing the breaker I hear it pulling down, rpm come up. I didn't hear that when this fault occurred i remember thinking it was odd. (HF Predator 3500 inverter/generator  almost 3 years old just less than 600 hours, hours mainly from using it for building projects... in the last 2.5 years we have charged the batteries off the generator maybe 4 times.)

I can only assume.... hate to do that... that the generator was putting out "dirty" power, not capable of being qualified.  That doesn't answer why it did this twice within 10-15 minutes, then an hour or so later, when the battery voltage increased, it worked fine.  I have never had a bit of trouble with the power produced by this generator. 

Not that I totally understand what I read but under Load Support it says for the 48v models... Battery  voltage threshold in order to engage regular AC Support  Mode.  46.0V to  70.0V cannot be  set below Low  Batt  Cut Out  + 2volts.  This is only suspicious as my LBCO is set to 41vdc.... + 2volts is 43vdc... pretty close to what the SCP was reading for battery voltage.   All that said Load Support and Load Shaving are both disabled.

Yes bought the equipment from NAZWS in May of 2019.  It has performed well.  No we are not near Flag... we are at 9500' just over the east side of the continental divide in southern Colorado. 

Thank you for the help! 

Dave Angelini

Try load shave at 14 amps and raise it from there and listen/watch the genset. Without large house loads coming on or off, the genset should sound smooth and consistent as should the battery charge amps. Good Luck.

nobadays

Thank you.... I'll give it a try.