Growatt + Daly, constant pain

Mondo

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Joined
Dec 7, 2020
Messages
29
This is my 3rd set of DIY LiFePo4 batteries, and I cannot believe the problem is my cells anymore.

I have a Growatt SPF 3000TL LVM 24V, 8S 280AH Grade A (Eve I believe) cells, and a Daly 8S 100A BMS with bluetooth. I top balanced my cells inside on a bench-top charger, and again after a fews days of settling... so I'm 99% sure it was fully charged when I started the setup. No matter what settings I put in, it goes from 27-27.2V down to 26.3 within an hour or two. If I power cycle the system (kill switch), then it starts charging again, but no more than 8-10A even though I have solar and utility charging on. Within an hour its back to 27V, and either the BMS turns off the Charging MOS (in which case 50% of the time the Growatt Shine app still says its providing charging), or the Growatt stops providing charge and the BMS says Charging MOS is still on (and again 50% the Growatt Shine app might even say its supplying power). At first I could flip the Discharge MOS manually, or worst case the main battery kill switch, and it would start charging again. But now either of those methods or resetting the BMS leads, are kicking it back into charge. I can't figure out what is drawing 2A all the time with everything off... but even with that constant, it should take days to drain as much as it has in hours. Even if I turn everything in my van on, I should only be pulling 10-12A (tested). All switches were off, so the only phantom draw should be the inverter, which is supposed to be 1A or less.

The only other thing I noticed is that the voltage at the battery terminals is 26.6, but at the posts in the Growatt it 27.3, which I imagine means it's reading the PV contribution at the Growatt, but not the BMS... perhaps I need to separate on where it ties in.

Essentially, I'm looking to keep the batteries topped-off, or even better, un-used, while sitting in the driveway on shore power.
When I'm on the road, I'd like the Solar to handle as much as possible, so I know I'd switch Growatt Setting 01 to SOL at that point.

Looking for any advice to get some consistency. This has been over a year of frustration, and way too much wasted money. Let me know what other info might be helpful.

My settings:

BMS SettingBMS ValueGrowatt SettingGrowatt Value
cell volt high protect3.4V01UTL (home) and SOL (Road)
cell volt low protect3.10V02140
sum volt high protect27.20V03UPS
sum volt low protect25.60V04SEN
diff volt protection0.30V05US2
Chg overcurrent160.0A06LHE
dischg overcurrent180.0A07THD
type of batteryLFP/liFeP0408120
rated capacity280.0AH0960
cell reference volt3.2V102
sleep waiting time3600s1130
SOC set100%1226.8
balanced open start volt3.200V1327.4
balanced open diff volt0.050V14SNU
chg low temp protect5°C15bOF
disChg low temp protect-20°C16LOF
diff Temp protect15°C17AOF
18BYE
I removed a few which are definitely not related1927.2 <-- Won't let me change
2027.2 <-- Won't let me change
2126.6
22SbE


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hipringles

Solar Addict
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Jan 31, 2021
Messages
194
Trying to understand exactly your problem here...

your saying that the battery capacity seems way low from this comment:

I can't figure out what is drawing 2A all the time with everything off... but even with that constant, it should take days to drain as much as it has in hours.
Is your inverter on? If so that's your 2A right there. These inverters are ~50w idle, so 2A on 24v, or 1a on 48v. If not, turn off all DC loads, and re-add from your fuse-panel 1 at a time.

Regardless, I think your cell voltage protect is *way* too low. If I am charging my 560ah 48v pack with high amp (say 50a), it will hit 3.4 on a cell pretty fast ish (well well below 100%), then as soon as you take off power it will taper down to much lower. I would set this at 3.55 or 3.6 to give buffer room for floating during charge.

Same thing on inverse, when your in the lower half of the pack, and pulling heavy amps, it will sag down more than "resting" voltage. Remember that the voltage % capacity charts are for resting voltage.

IMO I would setup this:

BMS: Cell protect 3.6 high, 2.5 or 2.6 low
Growatt: 28V high, and ~22-23 volts lot.
 

Mondo

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Dec 7, 2020
Messages
29
Trying to understand exactly your problem here...

...

BMS: Cell protect 3.6 high, 2.5 or 2.6 low
Growatt: 28V high, and ~22-23 volts lot.

Yeah, sorry, pretty long winded.
The problem is getting BMS and Growatt Start/Stop Charge limits in sync... and not having to manually reset circuit just to get it charging again.

My next step was to push the Growatt higher, and let the BMS cut it off. Then figure out why solar and utility is keeping the circuit charged, but not going back to battery.

So at 3.6V are looking at 28.8V on BMS. So maybe set my Growatt to 30V to account for solar?

Also seeing this chart: https://diysolarforum.com/threads/lifepo4-24v-voltage-chart.22388/#post-264611
And this one: https://footprinthero.com/lifepo4-battery-voltage-charts#elementor-toc__heading-anchor-1

Is that suggesting charge up to 29.2V and let it go back to 27.2V when not being powered?
 

hipringles

Solar Addict
Joined
Jan 31, 2021
Messages
194
Yeah, sorry, pretty long winded.
The problem is getting BMS and Growatt Start/Stop Charge limits in sync... and not having to manually reset circuit just to get it charging again.

My next step was to push the Growatt higher, and let the BMS cut it off. Then figure out why solar and utility is keeping the circuit charged, but not going back to battery.

So at 3.6V are looking at 28.8V on BMS. So maybe set my Growatt to 30V to account for solar?

Also seeing this chart: https://diysolarforum.com/threads/lifepo4-24v-voltage-chart.22388/#post-264611
And this one: https://footprinthero.com/lifepo4-battery-voltage-charts#elementor-toc__heading-anchor-1

Is that suggesting charge up to 29.2V and let it go back to 27.2V when not being powered?

The Growatt ideally should be doing the battery disconnect on both the high/low end. The BMS is the monitoring at the cell level incase you have a runaway, or in the rare event the growatt fails to do so.

I would set the BMS to as high as you want a cell, 3.6 or 3.65, then the growatt about 0.1V/cell *lower*. So if you want the BMS at 3.65 (which is common), you can set the growatt at 28.4V. For reference, I have my 48V growatt at 56.4.

The way the charger will work is to go up to this voltage (28.4), then will 'float' at whatever the float voltage is once the cells settle.

And do the opposite for low end. BMS at 2.5 or 2.6 per cell, then growatt around 22-23
 

Mondo

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Dec 7, 2020
Messages
29
The Growatt ideally should be doing the battery disconnect on both the high/low end. The BMS is the monitoring at the cell level incase you have a runaway, or in the rare event the growatt fails to do so.

I would set the BMS to as high as you want a cell, 3.6 or 3.65, then the growatt about 0.1V/cell *lower*. So if you want the BMS at 3.65 (which is common), you can set the growatt at 28.4V. For reference, I have my 48V growatt at 56.4.

The way the charger will work is to go up to this voltage (28.4), then will 'float' at whatever the float voltage is once the cells settle.

And do the opposite for low end. BMS at 2.5 or 2.6 per cell, then growatt around 22-23
Hmm. Then I have to figure out the voltage discrepancy between Growatt and Battery, else it’s going to shutoff 1V early
 

Mondo

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Dec 7, 2020
Messages
29
What gauge wire? Length? And what's the amp load and charging amp?

I'll check again in the morning, but I'm pretty sure its 4 AWG (worst case 6 awg) welding cable, and no more than 18".
I set the Growatt to a combined 120A charge limit, but with Sun out, I get 8A at max (300W of panels on roof)
 

Mondo

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Dec 7, 2020
Messages
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@hipringles confirmed its 6 AWG.

So far it seems to charge, hit the cut off, and now settles on a much better spot. Though it drains much faster than it should considering the load is only 2A. So it'll go from 26.8 to 26.5 within an hour. I've set the "Battery -> Mains point" on Growatt to 26.6, just to force it to go back to charging, and its gone down to 26.3 twice and still not kicked in. It only goes back to charging mode if I hard reset it by using the battery kill switch.

Two questions:
  1. How to get it to consistently kick back into charging mode without manual intervention
  2. How to get it to supply more than 2A - 4A charge when in charge mode, and the A/C load is 25% or less.
 

Struc

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Sep 20, 2021
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Location
Oconomowoc / Land o Lakes WI
@hipringles Though it drains much faster than it should considering the load is only 2A. So it'll go from 26.8 to 26.5 within an hour. I've set the "Battery -> Mains point" on Growatt to 26.6, just to force it to go back to charging, and its gone down to 26.3 twice and still not kicked in. It only goes back to charging mode if I hard reset it by using the battery kill switch.

Any voltage way at the top of the curve is going to drop off fairly quickly. These are 3.2v batteries (25.6v in 8s) I wouldn't worry about it. There is so little capacity at the higher voltage that it is normal for it to draw down quickly. If you keep a constant load on them, they will drop to a certain point and then stay there for a VERY long time. Then, when they are getting near depleted you will see the voltage start to drop again.
 

Mondo

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Dec 7, 2020
Messages
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Any voltage way at the top of the curve is going to drop off fairly quickly. These are 3.2v batteries (25.6v in 8s) I wouldn't worry about it. There is so little capacity at the higher voltage that it is normal for it to draw down quickly. If you keep a constant load on them, they will drop to a certain point and then stay there for a VERY long time. Then, when they are getting near depleted you will see the voltage start to drop again.

Is 27 -> 26.4 (70%) considered the top? 🤷‍♀️
I have noticed it's been on 26.4 all night though, that that is definitely reassuring. I see what you mean on the curves, and I guess I had only looked at that from a Charge perspective, and not discharge. Makes sense now.
 

hipringles

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Jan 31, 2021
Messages
194
Is 27 -> 26.4 (70%) considered the top? 🤷‍♀️
I have noticed it's been on 26.4 all night though, that that is definitely reassuring. I see what you mean on the curves, and I guess I had only looked at that from a Charge perspective, and not discharge. Makes sense now.
Fwiw resting full voltage should be near 3.35-3.4
 

Mondo

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Dec 7, 2020
Messages
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Ok. So 26.4v (3.3v) isn't too terrible to sit on since its been all day. Hooked-up my DC/DC charger, and that was working well, and consistently.
Still can't understand why Growatt isn't honoring my Battery->Mains Point setting and kicking into charging again while on shore power. I'm going to try and call them.
 

derekisastro

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Jan 27, 2021
Messages
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Ok. So 26.4v (3.3v) isn't too terrible to sit on since its been all day. Hooked-up my DC/DC charger, and that was working well, and consistently.
Still can't understand why Growatt isn't honoring my Battery->Mains Point setting and kicking into charging again while on shore power. I'm going to try and call them.
As has been suggested, LiFePO4 batteries will always 'settle'. They will not hold 3.6, 3.65, hell even 3.45 they do not hold. They will settle to a lower voltage; understand this is not a representation of the SOC (state of charge). I'd be content with mid 26 volts once it's been fully charged. If you are worried about it, and you have a Daly Smart BMS, you can charge the batteries to 3.6 or 3.65 per cell and then reset the 'capacity' on the Daly BMS to 100%. When the voltage settles and you think you've lost 20-30% capacity, you can check the Daly BMS, it should measure the amps out of the battery when it reports the % capacity left (based upon you setting 100% and you telling the BMS that you have 280ah batteries).

As to the second issue, I too have struggled with the charging of the batteries but have discovered how the Growatt I have seems to work.

With Solar and AC charging, the parameters of 'float' and 'bulk' charge, which for you, you cannot change (the two 27.2 settings), is ONLY for solar charging. It has no relation to AC charging. As a side note, most here run the 'USE' setting for DIY lithiums, not the USE2. It will allow you to set the 27.2 settings to what you want, as well as have some other benefits/work better for some people. Your choice.

IN my experience the AC charging is totally dependent (with 1 caveat) upon the 'back to battery' (setting 13 I think) setting and the 'switch to utility' (setting 12 I think) setting. When the battery is being used and hits setting 12, the AC begins charging the battery AND carrying the load. It does this until it hits setting 13, then the utility stops charging and the battery takes the load (when using the battery to provide power). It does not matter what I set my float and/or bulk too, the AC charging always functions based upon the settings in 12 and 13 for me. It does kind of make sense, though can be frustrating if you want to get the AC charger to 'top up' the batteries for whatever reason. This is when the caveat above, resetting the system will usually get the AC charging back on, as long as the battery is below setting 13.

I hope this helps in your situation, understanding how to get the best out of your system. As has been suggested, use the BMS only as a safety. If it is disconnecting your battery then something should have gone wrong. I cannot answer the voltage differences you're measuring, I'm going to measure my system now and see if it's similar.
 

gdpetti

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Oct 15, 2019
Messages
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Ion at GW explained to me that the BMS's we use is the biggest problem.... I finally agreed after frying mine.... the GW doesn't seem to need it... I have them inside the vacampervan setup)... same batteries in self build.... all new to me.... GW worked fine without the BMS... I have one cell (#8) that fills up faster than the other 7 in 8S setup.... so I set the GW at 27.5... it usually stops at 27.6.... I don't need to push it higher... Heck, I probably rarely go below 80% charge.... only when using the microwave, induction stovetop etfc..... the reading on the GW reads down to 25.8 or so on that draw, but once off, it's back up to 26.6 as usual.... as that's where it settles after charging up to 27.5/6.
Ion was right about the BMS's.... doesn't seem like they share the same setup as the AIOs.... but I have no problem with that lower charge setting. I can top off every 6 months as Will suggested. As I'm never on AC, I don't have that issue.... my 280AH 24v battery is more than I need, same with the 930watt solar panels on the roof... which is what I wanted... more is better when you need it... mostly weather related... not a problem now that I'm in the SW, but when going north/NE, the lack of sunlight sure will change that... but I also put in tilt on the panels... using gas struts... haven't used them yet... but makes a big dif if needed... I've only been on the road FT for 5 weeks... still in shakedown mode.... wanted to do before, but didn't have time before I wanted to head out for something else. Learning the basics on these AIOs, batteries etc, has been the most important thing.... especially when you are starting from zero.

No BMS hasn't been a problem... batteries and AIO in van, I don't like hot or cold weather, so the temp issue won't be affected.... lower charge setting prevents the other problems... I can now see what Ion at GW meant.... couldn't understand it before... the BMS I had was the problem.
 

Zwy

Photon Sorcerer
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Jan 3, 2021
Messages
1,697
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Timbuktu
Yeah, sorry, pretty long winded.
The problem is getting BMS and Growatt Start/Stop Charge limits in sync... and not having to manually reset circuit just to get it charging again.

My next step was to push the Growatt higher, and let the BMS cut it off. Then figure out why solar and utility is keeping the circuit charged, but not going back to battery.

So at 3.6V are looking at 28.8V on BMS. So maybe set my Growatt to 30V to account for solar?

Also seeing this chart: https://diysolarforum.com/threads/lifepo4-24v-voltage-chart.22388/#post-264611
And this one: https://footprinthero.com/lifepo4-battery-voltage-charts#elementor-toc__heading-anchor-1

Is that suggesting charge up to 29.2V and let it go back to 27.2V when not being powered?
Don't use USE2, set GW to USE.

Set bulk at around 28.0V, float 0.5V below that. Then monitor cell readings on BMS to see if you get a runner to 3.65V at the 28.0 bulk. BMS set high disconnect at 3.65V. low disconnect your choice around 2.5V to 3.0V.

I'd have to look where I set back to battery but it's not that big a deal as I only plug in occasionally.
 

mikefitz

Photon Sorcerer
Joined
May 28, 2020
Messages
1,268
Unless I missed the comment, the problems you are having may be due to the strange BMS upper and lower protection limits shown in the first post. Is it possible to review actual settings for cell and pack protection upper and lower values.

Mike
 

derekisastro

Solar Enthusiast
Joined
Jan 27, 2021
Messages
65
Ion at GW explained to me that the BMS's we use is the biggest problem.... I finally agreed after frying mine.... the GW doesn't seem to need it... I have them inside the vacampervan setup)... same batteries in self build.... all new to me.... GW worked fine without the BMS... I have one cell (#8) that fills up faster than the other 7 in 8S setup.... so I set the GW at 27.5... it usually stops at 27.6.... I don't need to push it higher... Heck, I probably rarely go below 80% charge.... only when using the microwave, induction stovetop etfc..... the reading on the GW reads down to 25.8 or so on that draw, but once off, it's back up to 26.6 as usual.... as that's where it settles after charging up to 27.5/6.
Ion was right about the BMS's.... doesn't seem like they share the same setup as the AIOs.... but I have no problem with that lower charge setting. I can top off every 6 months as Will suggested. As I'm never on AC, I don't have that issue.... my 280AH 24v battery is more than I need, same with the 930watt solar panels on the roof... which is what I wanted... more is better when you need it... mostly weather related... not a problem now that I'm in the SW, but when going north/NE, the lack of sunlight sure will change that... but I also put in tilt on the panels... using gas struts... haven't used them yet... but makes a big dif if needed... I've only been on the road FT for 5 weeks... still in shakedown mode.... wanted to do before, but didn't have time before I wanted to head out for something else. Learning the basics on these AIOs, batteries etc, has been the most important thing.... especially when you are starting from zero.

No BMS hasn't been a problem... batteries and AIO in van, I don't like hot or cold weather, so the temp issue won't be affected.... lower charge setting prevents the other problems... I can now see what Ion at GW meant.... couldn't understand it before... the BMS I had was the problem.
I'd love to understand why Ian thinks the BMS's are the problem? From my understanding, the BMS essentially should never come into play. It should largely be invisible to the system. If it does come into play, it's because there was an issue that needed intervention.

I can only assume that Ian means they are a problem if you are using the BMS as cut-offs for managing the charging of the Growatt. This should NOT be how BMS's are used.

I'm not sure how you know you have runaway cells if you don't have a BMS, how are you monitoring individual cell voltages? You seem to imply you are monitoring individual cell voltages (one of the main jobs of the BMS).
 

gdpetti

Solar Enthusiast
Joined
Oct 15, 2019
Messages
112
Yes, I have repeatedly check the individual cells... one of mine charges up faster than the other 7... not really a problem if I set the charge lower... currently have it set at 27.5, so the GW always shuts off about .1 above that, as the reading goes up and down some while charging, which could be the issue that affects the BMS as Ian said.... SInce I'm overpowered in panel and battery for my needs, by design for any future need or weather issues since I'm FT in the campervan now, this isn't a problem... I did the Chinese purchase of the cells and didn't notice in time the one cell issue compared to the others... this is the problem when you order stuff before you really need it or before you're ready to set it up.... that was my problem... and too late to return the one cell... but it isn't off by much and the price was good... Will mentions the stack now, but as always, the real price is with shipping....and that seems to only get worse. The BMS I had, a Daly, had present cutoffs... it wasn't ... can't remember the terms... the simple one like mine you can't change the parameters, while the more complicated ones, you can. Since I couldn't change them, they conflicted with the GW settings, especially with that one cell issue always going too high while the others were fine. Reduction in the charge level fixed that... again, I hardly ever go below 80% charge... the GW charge comes on in sunlight hours if the inverter is turned on.... so in this SW sunlight, it's always testing the charge limit at 27.5 currently (.6 in reality).
 

derekisastro

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Joined
Jan 27, 2021
Messages
65
Yes, I have repeatedly check the individual cells... one of mine charges up faster than the other 7... not really a problem if I set the charge lower... currently have it set at 27.5, so the GW always shuts off about .1 above that, as the reading goes up and down some while charging, which could be the issue that affects the BMS as Ian said.... SInce I'm overpowered in panel and battery for my needs, by design for any future need or weather issues since I'm FT in the campervan now, this isn't a problem... I did the Chinese purchase of the cells and didn't notice in time the one cell issue compared to the others... this is the problem when you order stuff before you really need it or before you're ready to set it up.... that was my problem... and too late to return the one cell... but it isn't off by much and the price was good... Will mentions the stack now, but as always, the real price is with shipping....and that seems to only get worse. The BMS I had, a Daly, had present cutoffs... it wasn't ... can't remember the terms... the simple one like mine you can't change the parameters, while the more complicated ones, you can. Since I couldn't change them, they conflicted with the GW settings, especially with that one cell issue always going too high while the others were fine. Reduction in the charge level fixed that... again, I hardly ever go below 80% charge... the GW charge comes on in sunlight hours if the inverter is turned on.... so in this SW sunlight, it's always testing the charge limit at 27.5 currently (.6 in reality).
That makes sense.

I am still confused about what Ian thinks the issue is though. The non-smart BMS's usually aren't worth it. Usually though, it's because the parameters are set way outside safe voltages not because the values are tighter than what you would have on the inverter (sometimes less than 2.5V and sometimes up to 3.75V for cells for the non-smart BMS's).
 

gdpetti

Solar Enthusiast
Joined
Oct 15, 2019
Messages
112
I can't remember exactly what Ian said about it, but you're probably right on the 'non-smart' BMS that I had, as the 'smart' ones can be programmed better around the needs of the GW. I just know he was right.... first, as a newbie, I had the basic issues, but my 'non-smart' non-programmable BMS was the problem.
 
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