Growatt 6000 Low DC Cuttoff

AW1511

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Joined
Aug 8, 2021
Messages
5
I have hooked up a growatt SPF6000T DVM. This is connected to 2kW of panels on the PV input(90V when loaded), 2 banks of 48V 200Ah flooded golf cart batteries, and then I have the AC input connected to a Kohler 6kW generator with a 2-wire auto-start system.
The solar and battery charging portions are working excellent.

I am having 2 issues:
1. I can not change the low DC cut off voltage (setting 21). MAIN ISSUE
-This results in the inverter not cranking up the generator until the default 42 volts(Lower than I would like for my Flooded lead acid batts). I want to raise this to 46-48V. I am doing this because I only want the generator too kick on for an hour or so while we are asleep to run the air conditioner when the batteries run low.

2. The generator auto start function does not work how expect it too. When the batteries get to 42V the dry contact signal will connect the NO pair. This functions as expected. The issue is the NO lines will re-open as soon as the generator shows up to the inverter. This shuts off the generator and is creating a looping generator on/off which is not acceptable obviously haha

Settings Below:

1: SBU
2: 50A -- 400Ah/8 = 50A
3: APL
5: FLD
6: LTD
8: 230V -- Generator Outputs 230 @60Hz, Air conditioning rated for 230V
9: 60Hz
11: 30A -- Trying to slightly limit generator loading current for charging the Batts
12: 48.0V -- My understanding is this should override the 42V default of setting 21???
13: 54.0V -- From my understanding this should be where the generator cuts off(NO pair returns to open)
14: SNU
15:bON
16: LOf
17: AON
19: 58.4V
20: 54.0V
21: 42.0V -- CANT MODIFY, but seems to be overriding setting 12
22: 001
23: Dis

With these settings I can watch the batteries fall past 48.0V and drop all the way too 42.0V before the NO pair closes.
 

AW1511

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Joined
Aug 8, 2021
Messages
5
Also if I manually tie the gen auto-start wires together the generator will crank, supply the load and charge the batteries. This seems to tell me it is something with my settings on the cut off and on voltages.
 

AW1511

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Joined
Aug 8, 2021
Messages
5
Okay, I think I may have found a way to solve issue 1 - not sure how it will affect the second auto start problem. I will change to the "User-Defined profile and then setup new self defined settings for 19, 20,21.

Changes here:
5: USE
19: 58.4V
20: 54.0V
21: 48.0V

My question here is how do settings 12,13 come into play?

I will test these settings and update here.

Please don't let this update stop you from commenting. Any thoughts or tips on this would be greatly appreciated because I am so new to this inverter.
 

AW1511

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Joined
Aug 8, 2021
Messages
5
Hi Bob,

I was able to modify setting 21(low bat cutoff) by switching to USE. I am still not able to get the generator to stay on. It is still looping on and off.
I think this may be from the generator frequency going out of sync when it is first loaded. I am going to try to reduce the utility charge current from 30A to 10A soon and see if that makes a difference. Although that low of a utility charge current will be really annoying.

Are you having the same issue?

Thanks,
Andrew
 

Roswell Bob

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Joined
Dec 5, 2020
Messages
433
Location
Warner, NH
Hi Andrew.

I don't have Growatt. I just took a lightning strike last week and thinking of a Growatt inverter to replace the AIMS. Probably SPF6000T DVM. It seems reasonable price and will get my well pump started. It is annoying that I have to start the Kohler backup when I want to run the well. My wife has been a good sport so I have little to complain about. I was just poking around and found your notes. If you can point me to a manual I will take a peek at it and see if I can figure out what the generator relay is doing. I'm going to have to get familiar with manual anyway. Did you get your inverter off of Ebay?
 

AW1511

New Member
Joined
Aug 8, 2021
Messages
5
Here is the link to the inverter at signature solar where I got it.
I live close enough that I went and picked it up at there east Texas location. They seem to be good people. The manual is at the link as well.
It seems to me that the SPF6000T DVM is quite a good value. If I could get the generator auto start working it would be perfect for me.

Here is a link to the MPV version at watts247. They have a few good tips in the description of there devices. I've heard good things about them too. The MPV version allows up to 250V from the panels on the MPPT charger.

Regards,
Andrew
 

Short_Shot

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Joined
Jul 13, 2021
Messages
1,811
Is it shutting the generator off because the charge voltage comes up and it detects this? I'm not familiar enough with it to know how the generator auto start logic works, if it has any, or if it's just an on-off switch.

If so, just put an off-delay relay in place and set it for the time you want the generator to run.
 

schmism

Solar Addict
Joined
Jul 13, 2020
Messages
1,014
Location
Central IL, USA
My question here is how do settings 12,13 come into play?
12 - "setting voltage point back to utility (in your case generator) when selecting SBU or Solar first in #1

13 - "setting voltage point back to battery mode when SBU or solar in #1

14 - charger source priority

In my case I use SBU in #1 so my
#12 - 47.0v
#13 - 52.0
#14 - OSO (only solar) you likely want CSO - solar first then utility (-which for you is genset) ONLY when sun is not shining

In my system runs like this - staring on battery, the battery voltage drops to 47v and I transition to grid, as I only want the battery charged off solar, it stays on grid till the sun comes up and starts charging the battery to 52v then transfer back over to the solar/battery.

In your case if the grid is the generator, then you likely want the generator to charge 50+ % of the battery before shutting off. (my high voltage cut off Hvco - #18 is 57.0v) so something like 55.5v (for my system)

If 12 and 13 are separated by only a few volts (like mine) then your generator (grid) will start, charge to #13 and shut off. but because the sun is not up, the system is running on battery and "quickly" draws back down to #12 (switch to grid, in your case genset) and the cycle starts again.

instead make #13 half your pack voltage or something. (were half here is tough because lithium batteries have such a flat discharge/charge curve)

Note I have Lvco set at 45 volts a few volts lower than #12. This is so if i lose grid overnight and already "out" of battery then I have a short time that I can rig up a generator to charge the battery before power goes down. Or for the sunny months it means the power goes off in the house for only a few hrs before the sun comes back up and we start over. My system is sized to get me through one night on battery. charge durring the day and rinse and repeat. I do not have "days" of battery backup with my normal "critical" loads. If SHTF then i could pair down consumption to get a day perhaps 2 out of it but thats theoretical at this point.

As a side note, I wish there were some more software settings.
- winter mode as defined by dates in the software. in winter mode i expect a fraction of the sun i get in the summer so I dont expect to be able to recharge my pack much off sun. so i want the generator to run for recharge to like 80% charged before shutting off. Summer mode, i likely want that to be like 30% because i expect to have more than enough sun to charge the pack the rest of the way up durring the day.
- storm mode, I have a tornado/thunderstorm/icestorm warning. Hit the button to temporarlly charge the battery to 100% full off the grid and keep it there for 24hs. If the grid goes down i have good battery, in 24hs the system reverts back to normal settings.
 
Last edited:

Jamsolar876

New Member
Joined
Apr 27, 2021
Messages
9
12 - "setting voltage point back to utility (in your case generator) when selecting SBU or Solar first in #1

13 - "setting voltage point back to battery mode when SBU or solar in #1

14 - charger source priority

In my case I use SBU in #1 so my
#12 - 47.0v
#13 - 52.0
#14 - OSO (only solar) you likely want CSO - solar first then utility (-which for you is genset) ONLY when sun is not shining

In my system runs like this - staring on battery, the battery voltage drops to 47v and I transition to grid, as I only want the battery charged off solar, it stays on grid till the sun comes up and starts charging the battery to 52v then transfer back over to the solar/battery.

In your case if the grid is the generator, then you likely want the generator to charge 50+ % of the battery before shutting off. (my high voltage cut off Hvco - #18 is 57.0v) so something like 55.5v (for my system)

If 12 and 13 are separated by only a few volts (like mine) then your generator (grid) will start, charge to #13 and shut off. but because the sun is not up, the system is running on battery and "quickly" draws back down to #12 (switch to grid, in your case genset) and the cycle starts again.

instead make #13 half your pack voltage or something. (were half here is tough because lithium batteries have such a flat discharge/charge curve)

Note I have Lvco set at 45 volts a few volts lower than #12. This is so if i lose grid overnight and already "out" of battery then I have a short time that I can rig up a generator to charge the battery before power goes down. Or for the sunny months it means the power goes off in the house for only a few hrs before the sun comes back up and we start over. My system is sized to get me through one night on battery. charge durring the day and rinse and repeat. I do not have "days" of battery backup with my normal "critical" loads. If SHTF then i could pair down consumption to get a day perhaps 2 out of it but thats theoretical at this point.

As a side note, I wish there were some more software settings.
- winter mode as defined by dates in the software. in winter mode i expect a fraction of the sun i get in the summer so I dont expect to be able to recharge my pack much off sun. so i want the generator to run for recharge to like 80% charged before shutting off. Summer mode, i likely want that to be like 30% because i expect to have more than enough sun to charge the pack the rest of the way up durring the day.
- storm mode, I have a tornado/thunderstorm/icestorm warning. Hit the button to temporarlly charge the battery to 100% full off the grid and keep it there for 24hs. If the grid goes down i have good battery, in 24hs the system reverts back to normal settings.
Hey just curious, what happens if it hits the lvco . Does the inverter turn off all together (including grid bypass)?

I found that I had two days of storm and though my Growatt switched over to grid the standby power draw was still like 1.5amps DC. So over night it was pulling battery way down (lifepo4). I got scared and switched over to Utility charge priority just to get some juice back in the battery.

If I wasn't home my BMS would go into battery cutoff of it for there though
 
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