Growatt tripping Generator

[Groscout]

From Ian's fingers to your eyes

Growatt 48V SPF 3000TL LVM – 3kW 120Vac Stackable Inverter 4.5kW MPPT Charge Controller Split Phase 120V/240V capable with two or more units + free wifi – Watts247 Wholesale

watts247.com

Utility/Generator Charger tips:
The generator charger is a different beast to the solar charger. (Does not utilize the Bulk and Float Charge settings)
It works on a float valve type principle. (triggers when battery voltage drops below that on setting 12 – set the voltage higher than current battery voltage to start charging right away)
Stops charging from Generator when setting 13′ s voltage is reached
Will not start charging the battery again until it drops below battery voltage – in setting 12.
Setting 01 set to SBU to activate setting 12 and 13.
Setting 02, is the Max charging current from Solar + Utility/Generator
Setting 11, is the Maximum Generator/Utility charging current @ your battery voltage (not at 120V)
Setting 14, make sure this setting includes the option to charge from utility/generator (see manual)
Note, setting Setting 11 too high for your generator may cause your generator to falter at startup, and cause the Inverter Charger to lose synchronization with the Generator (58 to 63Hz), if in doubt start small, and work your way up.
If you have any questions, feel free to reach out.

This is a well known annoyance with these chargers. Regardless of what you're seeing on the display, it's behaving as described above.

Ask Ian.

I get the generator charged thing is different between sbu and where I have it set currently but the results are the same.

I have loads of time to kill and the necessary equipment. I think we should poke and prod until everyone knows the answer.

Enlighten me on the float valve principle. That means cc until set voltage is reached?

 

[Jtr042084]

I get the generator charged thing is different between sbu and where I have it set currently but the results are the same.

I have loads of time to kill and the necessary equipment. I think we should poke and prod until everyone knows the answer.

Enlighten me on the float valve principle. That means cc until set voltage is reached?

My response to this is purely off common sense since I can't test this out with no grid power...

If you have Utility set as priority for the AC output, you are using the unit as a UPS, so the utility maintaining the battery levels topped off makes sense.

If you have Solar/Batt as the priority for the AC output, you are trying to avoid using the grid power so float won't make sense. That is when the grid would begin charging your battery at low voltage (and running the loads) until the battery reaches full capacity, then is switches over to Solar/Battery again. (float valve principle)

 

[Jtr042084]

Update: I monitored this last night and found 2 additional details.
-battery low so I start the generator and connect to the inverter
-I have Utility set as my AC priority, so the inverter let the generator pass-through to the load and started charging the battery at 20 amps for 3 hours
-the 4th hour, the inverter lowered the charge current to 10amps
-When the battery reached full, my dimmed LED lights surged in brightness and then the inverter switched to Battery as the generator overload tripped.
Something with the inverter disconnecting the charger to the battery is causing a surge LOL

 

[Jtr042084]

So the generator circuit breaker trip or the GFCI of the generator trip?
"and the final charging load is less than 400watts)"
What do you mean by that, final charging load? If the battery is full then I would not expect the charger to be drawing 400W of power, your other load is only 120W so the whole power consumption is only about 500W pulling from generator. Is this problem repeatable?

It's the overload of the generator, it doesn't have gfci outlets

Sorry for the confusion of the final charging draw, I was stating that in hopes that no one would have the assumption that my generator is being overloaded by the actual draw (load and charging). The last hour of charging drops to 10amps so it tops it off slowly, so a little less than 400w.
Something in the inverter is surging the load when it stops charging the battery, it happens every time. My LED can lights are dimmed to about 10% and they brighten for a split second just before the generator trips off.

 

[sunshine_eggo]

I get the generator charged thing is different between sbu and where I have it set currently but the results are the same.

I have loads of time to kill and the necessary equipment. I think we should poke and prod until everyone knows the answer.

Enlighten me on the float valve principle. That means cc until set voltage is reached?

Simple. Specified current until set voltage reached. Then zero. Bulk only. No absorption or float.

 

[Jtr042084]

I get the generator charged thing is different between sbu and where I have it set currently but the results are the same.

I have loads of time to kill and the necessary equipment. I think we should poke and prod until everyone knows the answer.

Enlighten me on the float valve principle. That means cc until set voltage is reached?

Do you have an amp meter tool?

If so, can you connect to the grid, set your priority as utility, let the batteries charge full, remove solar if you have any, then measure the amps of the battery cables? see if you can read any current going into the full batteries? This will confirm if the utility provides a float charge after the batteries are topped off.

 

[solar8484]

-When the battery reached full, my dimmed LED lights surged in brightness and then the inverter switched to Battery as the generator overload tripped.
Something with the inverter disconnecting the charger to the battery is causing a surge LOL

Measure the peak AC voltage at the generator when this happens. The peak should be < 130Vac. Anything higher could mean that when the charger stops abruptly it causes AC overvoltage that then trips the generator.

 

[Jtr042084]

Measure the peak AC voltage at the generator when this happens. The peak should be < 130Vac. Anything higher could mean that when the charger stops abruptly it causes AC overvoltage that then trips the generator.

I will see if my outlet meter will capture that info and post back onto this thread

 

[Steve_S]

I do not use Growatt but had the same issues, chased it for a few months and the fix was so simple & obvious and I kept going past it. Solution may be similar for you.

Note that this is applicable to my setup at the time, which was 4 Battery Packs in one Bank. 2x280AH & 2x175AH with Samlex EVO Inverter (exceedingly programmable). Generators used for this was both a 4000W Inverter Model & 9000W HD non-inverter model.

Battery Packs would charge up and as expected the 175's hit my designated 100% (3.425Vpc) before the 280's so of course their BMS' would do what they should and cutoff, balance internally etc and that was just peachy as they would level up and top off very nicely even as the amps taken dropped "for them". They would cycle on/off as balancing and toppping off occured and this is Expected in such a config.

The 280's of course take a heap more to hit Full & Top off and as the 175's dropped the amps taken and started cycling the extra immediately goes to the bigger battery packs, again this is normal & expected behaviour and all continues as it should. Then the GOTCHA that kicks the Genset appears ! It all has to do with the EndAmps / TailCurrent and transitioning to FLOAT or NOT.

3 Things are happening here:
1) BMS's reaching full start to cutoff as they should. This shoves the extra amps at whatever pack is still taking the juice, this results in surges and drops as the other BMS's flip On/Off, no genset will like that but within reason it is acceptable. ! BEWARE ! That Inverter Gennies HATE THAT ! They will cycle up & down accordingly but you have to be Very Aware of the watt / amp output limits and DO NOT push them to their spec limits ! FYI: 95% of Inverter Generators are HIGH FREQUENCY they do not take excessive abuse AT ALL ! Not even Honda !
** With the Samlex Inverter/Charger the Max Input Volts/Amps from Genset can be programmed & limited to prevent faults. IE to charge at 75A it takes 120VAC/23A from Genset, so I CAP it to no more than 25A and that still allows Passthrough.

2) Bulk Charging (Constant Current) will NOT get you to 100% SOC, at best it can get you to 95% but more likely 90% with Bulk Grade Cells. Constant Voltage Variable Current (FLOAT) get's you to 100%. THIS IS THE TRICKIEST PART ! Different gear handles the transition differently. One will use the Voltage @ Battery to determine transition to Float while another will look at Amps Taken (EndAmps) to determine the Transition. I am unsure which method is used by GW. End Amps / TailCurrent is based on the Largest Pack in the bank as it will be the last to empty & last to reach 100%. The formula is simple 200AH Battery X 0.05 = 10A. When the Packs reached 10A (collective in a bank it is different) the system should transition to FLOAT (CV). You CAN set the EndAmps to a higher value but too high and you will not have a good transition, meaning BMS' will be cutting off and cyclng.

3) The Inverter Shutdown
Oivey ! the excuses and rationalisations...
Take a genset, have it dump 120V/20A constant and then just drop the line, the genny has a crap and steps down (If Inverter Type) then all of a sudden a BMS opens and takes charge for 30 Seconds and cuts off and the next one opens does teh same & cuts off, then you have 3 or 4 BMS' doing that because the amps pushed are too high triggering Runners etc... The genset will only take that a couple of times and then trigger a fault (pending on brand that can be quick too)
-> Whenever my packs started that cycling the Inverter Genny woudl Fault and go into protect mode and not output AC till reset.
-> Whenever my Industrial Genny was hit with it, it took it & complained but kept pushing BUT the Samlex Charger would then trip & reset and THAT was FUGLY (to be extremely polite).

Some may not like / agree with what I put here but this is real world observation and testing and when I am playing with this kind of thing I can be pushing 200A+ at my bank and doing hard thrash tests. It is what it is.

The arguments over TO FLOAT or NOT TO FLOAT are also due to a lot of misunderstanding and misinformation, partly resulting from the various battery chemistries and how things are addressed for each. LFP REQUIRES CC Constant Current to get to 90-95% and then CV Constant Voltage Variable Current to finish & top off (saturate) the cells.

PS, been down those rabbit holes too often, not going there again...
Hope this helps answer some of the outstanding issues.
You will just have to determine how your Growatt Model handles the endamps/tailcurrent and transition to Float.
Good Luck.

 

[Groscout]

Simple. Specified current until set voltage reached. Then zero. Bulk only. No absorption or float.

Just ran the SBU charging scheme using the generator this morning. I’ll post a video link later today.

Well @sunshine_eggo this time I only get to be partially correct here. Which means Ian is also partially correct. Absorption does happen. Charging amps slowly drop off to 0 over a span of 30 minutes or so.

Yes you are correct regarding SBU and float there is no float when setting 1 is set to SBU. My mistaken testing last year left out trying SBU on setting 1. When I thought I had.
Which leads to a possible solution for our GFCI tripping when charging from a generator.

There was one thing that didn’t happen while charging with the generator using SBU on setting 1. The generator GFCI didn’t trip.

It still trips when using UTI for setting 1.

 

[sunshine_eggo]

Just ran the SBU charging scheme using the generator this morning. I’ll post a video link later today.

Well @sunshine_eggo this time I only get to be partially correct here. Which means Ian is also partially correct. Absorption does happen. Charging amps slowly drop off to 0 over a span of 30 minutes or so.

To confirm - there was NO solar contributing?

If so, this is actually great news. I hope Ian updates the description. That's effectively an absorption phase, which means you actually can get batteries fully charged with a Growatt on AC.

Yes you are correct regarding SBU and float there is no float when setting 1 is set to SBU. My mistaken testing last year left out trying SBU on setting 1. When I thought I had.
Which leads to a possible solution for our GFCI tripping when charging from a generator.

Good. I acknowledge that's the whole damn point.

There was one thing that didn’t happen while charging with the generator using SBU on setting 1. The generator GFCI didn’t trip.

It still trips when using UTI for setting 1.

Hmmm... curious.

Have you tried charging to a lower voltage with UTI... closer to 3.45V/cell?

 

[Ozark Tinkering]

I have loads of time to kill and the necessary equipment. I think we should poke and prod until everyone knows the answer.

Okay here's my guess.

Experience tells me GFCI's hate being powered by other GFCI's. No matter where you try it.

 

[glamsland]

Jtr, I have a similar/same issue. When my growatt reaches float it trips my generator gfi every time…. I called watts247 and the suggested fix was disconnect the ground wire. That didn’t fix it.

I didn’t see this as an issue because my generator isn’t automated and float is where you stop charging LFP. Who’s going to float LFP with a generator anyway?

I’m watching for a solution just in case their is one.

I also have the same issue.. it seems that when the battery hits float, the generator goes in "overload" . wierd..

Did you find a solution for youe problem?