Battery incorrectly reports SOC as 100% once grid returns

[Confucius]

Use timer is unticked, under battery settings there is a disable float charge that is unticked. So float charge is enabled

Never seen that setting before but mine is also disabled.

 

[ovisser1]

Feels to me like the inverter is using the wrong settings for the battery, purely because the libms screen settings are different compared to both the spec sheet and the battery settings page.

Will replace the cable for sanity, and maybe try rs while im at it.
See if one of those helps

 

[Phoenix Energy]

I see you don’t have an earth neutral bond relay. ☹️ not related to your problem but just an observation.

He might have one, probably the installer forgot to tick that option.

 

[valiente]

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I would also suggest checking the BMS_Err_Stop setting.

This basically throws an error when the Battery BMS is not reporting anything.

 

[ovisser1]

This basically throws an error when the Battery BMS is not reporting anything

Wanted to, but would have been even worse off.

An update on this; got a pm from another carbie with the same battery; and he was having the same issues I did, and more...

His other issue is that the battery is also draining faster than it should be, and when I do the math, mine is doing the same.

2 hour loadshedding, battery starts at 100%, sunsynk app shows 150w(+-) draw. After the power comes back; battery was at 86-88% soc. Even including inefficiencies; it means the battery used 600wh+ which is way too high. Literally more than double the app suggests.

So said PM told me to unplug the bms cable, and see if it improves. So I double checked the settings on the inverter for the voltages and unplugged the ethernet cable.

No more problems. Latest loadshedding the battery only dropped to 93% on a 150w+- load. Which is roughly 350wh used - makes way more sense.

And when the power restored, the battery showed incremental SOC.

Am i right in assuming the bms is either fucked faulty or useless?

 

[el3venth]

If the BMS is not somehow directly connected to the inverter then you're going to need a shunt or similar device to monitor the SoC based on current in & out. Battery voltage is rarely accurate.

Disclaimer: I know nothing.

As an engineer with 15+ years in the renewables and inverter design field, you are 99.94% correct!
The biggest problem is that it is more than just current in and current out. You also have to deal with self-discharge, chemical/conversion inefficiencies, electrical losses, etc. And then add device aging to that equation.

So the technique that most BMS use that they know the following: After keeping a battery at a certain voltage for a certain time, the charging current should drop below a certain point, and the battery is considered full for practical purposes. Then afterwards it uses educated guesstimates to figure out how much goes in and out and determines what it think the current state of charge is.
Also, once in a while you should take the battery from a close to zero point to full for the BMS to guesstimate the total amount of power that the battery can take.

If you just use voltage, then all the above calculations are not done, and you are at the mercy of a really crap guess by the inverter.

 

[el3venth]

Wanted to, but would have been even worse off.

It could be that that the cable between the inverter and the battery is not correctly configured.

Both CAN and RS485 requires 120ohm impedance cable with a 120ohm termination resistor at both ends of the cable. Otherwise you will end up with weird comms issues.

The termination resistor may or may not be pre-terminated at either the battery of the inverter. Or you might need to just manually wire one in.

Also note that the cable must technically be 120ohm impedance cable. You can try substitute with CAT5 cable that has an impedance of 100ohm. But if you use some shit like CCA CAT5, then the impedance will be totally wrong and you will have comms issues.

 

[Qui_Illustrati]

To me, sounds like a fix potentially addressed by firmware. I've seen many posts regarding my inverter (not Sunsynk) and incorrect SOC reporting, not dissimilar to your issue, that the inverter manufacturer addresses with a logged call and a techie remotely connecting and pushing a firmware tweak/update which resolves the issue. Maybe worth logging a call with Sunsynk and get their take on it?

 

[ovisser1]

It could be that that the cable between the inverter and the battery is not correctly configured.

Both CAN and RS485 requires 120ohm impedance cable with a 120ohm termination resistor at both ends of the cable. Otherwise you will end up with weird comms issues.

The termination resistor may or may not be pre-terminated at either the battery of the inverter. Or you might need to just manually wire one in.

Also note that the cable must technically be 120ohm impedance cable. You can try substitute with CAT5 cable that has an impedance of 100ohm. But if you use some shit like CCA CAT5, then the impedance will be totally wrong and you will have comms issues.

Thank you, will check the cable tonight and see what it is, might be onto something.

To me, sounds like a fix potentially addressed by firmware. I've seen many posts regarding my inverter (not Sunsynk) and incorrect SOC reporting, not dissimilar to your issue, that the inverter manufacturer addresses with a logged call and a techie remotely connecting and pushing a firmware tweak/update which resolves the issue. Maybe worth logging a call with Sunsynk and get their take on it?

I've got a strong feeling sunsynk will simply say not their battery they dont want to deal with it - general SA lack of service has my hopes very low.

Going to try see if the cable is up to spec, if not will try the firmware update route.


One guy that I know of is currently trying to RMA the battery because of the issues, will like to know the outcome of that. Maybe he finds the solution before I do.

 

[el3venth]

To me, sounds like a fix potentially addressed by firmware. I've seen many posts regarding my inverter (not Sunsynk) and incorrect SOC reporting, not dissimilar to your issue, that the inverter manufacturer addresses with a logged call and a techie remotely connecting and pushing a firmware tweak/update which resolves the issue. Maybe worth logging a call with Sunsynk and get their take on it?

Oh, that is something that I have not even considered. Typically you would only pair an inverter and battery together if both manufacturers have certified their products for working together.

If they have not given their thumbs-up, you might have warranty issues. Most inverters/batteries include some sort of clause stating that they are only to be used with approved products.

 

[Qui_Illustrati]

Oh, that is something that I have not even considered. Typically you would only pair an inverter and battery together if both manufacturers have certified their products for working together.

If they have not given their thumbs-up, you might have warranty issues. Most inverters/batteries include some sort of clause stating that they are only to be used with approved products.

Typically. Yes. But with these batteries from Scott they essentially mimic, replicate (or whatever the correct term is) from the BMS the Pylontech type. So essentially they should work on any inverter that accepts Pylontech and be able to accurately communicate. There are nuances though as I found out as well.

I have a Solis Hybrid and it too only has profiles for a specific list of batteries. For the longest time I did not have SOC reporting in my app because of the 'custom' battery. What Solis eventually did is connected to my inverter, loaded a new firmware and all was good since. No questions asked. I just told them battery not communicating well with inverter, they fixed it. That's why I'm inclined to think that with some firmware fuckery on the Sunsynk it can be made to work properly together.

Or @ovisser1 , maybe you can get in touch with Scott and have some logs sent through to his battery techs. Maybe they can pick up the issue and resolve from the BMS side (?)

 

[el3venth]

Typically. Yes. But with these batteries from Scott they essentially mimic, replicate (or whatever the correct term is) from the BMS the Pylontech type. So essentially they should work on any inverter that accepts Pylontech and be able to accurately communicate. There are nuances though as I found out as well.

I have a Solis Hybrid and it too only has profiles for a specific list of batteries. For the longest time I did not have SOC reporting in my app because of the 'custom' battery. What Solis eventually did is connected to my inverter, loaded a new firmware and all was good since. No questions asked. I just told them battery not communicating well with inverter, they fixed it. That's why I'm inclined to think that with some firmware fuckery on the Sunsynk it can be made to work properly together.

Or @ovisser1 , maybe you can get in touch with Scott and have some logs sent through to his battery techs. Maybe they can pick up the issue and resolve from the BMS side (?)

Ah. But here is where it gets complicated. I am aware of the Pylontech CAN protocol. (If you want it, I am happy to send some of it to you. Some stuff would still be under NDA I think. If you have a uC with a CAN hat or even a USB-CAN adapter you can read some cool stuff on the battery.) If I can recall correctly, Pylontech is the same as SMA, but you theoretically have to send a keep-alive response request every once in a while.

But just because it sends the same info packets using the same addresses, does not mean that it responds in the same way.

But you should be able to at least read the name of the battery and get the correct SoC/SoH. If you are not getting those, I would look at checking the cabling and the software setup. To my knowledge Sunsynk has supported Pylontech forever and I am pretty sure that any firmware from the last two years should include the Pylontech/SMA tables.

EDIT: Ooo. Solis Hybrid. I have the MODBUS tables for that one and can help you intergrate that into Home Assistant or any other home automation system quite easily if you ever need to. Will have to check the NDA on that but I think I have the public tables for that.

 

[Qui_Illustrati]

EDIT: Ooo. Solis Hybrid. I have the MODBUS tables for that one and can help you intergrate that into Home Assistant or any other home automation system quite easily if you ever need to. Will have to check the NDA on that but I think I have the public tables for that.

I've been having it 🤣 Had it HA integrated for a while and then ripped out all smart home integrations and totally dumbified my life. Don't need all that complexity in an already complex life. Now I'm more than happy to just use native apps and set and completely forget and have basic controls when needed.

 

[ovisser1]

Oh, that is something that I have not even considered. Typically you would only pair an inverter and battery together if both manufacturers have certified their products for working together.

Indeed, I found that out a bit late, call it school fees if you will.

Or @ovisser1 , maybe you can get in touch with Scott and have some logs sent through to his battery techs. Maybe they can pick up the issue and resolve from the BMS side (?)

Going to PM him again now, I did before starting the thread asking for help, but he said (and I quote)
"That's very odd reporting behaviour. Unfortunately I've got no idea what's causing it"

Thank you both for the help though.
In order I'll try proper cable, scott then sunsynk if all else fails

 

[aiccc]

Why do you have 'activate battery' ticked?

 

[ovisser1]

Why do you have 'activate battery' ticked?

Thats how the installer set it up - haven't researched it myself.

What does it do and why should it not be on?
Got a sunsynk approved installed for the exact reason that I dont know inverters well enough/at all

 

[ovisser1]

Okay google answered it for me.

Turning it off now

 

[ovisser1]

No

Why do you have 'activate battery' ticked?

Now that I'm sober, know what its for and reading this again,

we did need it, installer was right to tick it.
There were some battery charging and discharging issues when it was installed.
Scott said it was a imbalance between the cells that locked the battery.

So we had to fully discharge the battery before it worked.

 

[D3TTOL]

@ovisser1 learning lessons the hard way

 

[el3venth]

In order I'll try proper cable

Make super sure the pins are going to/from the correct spot.
CAN cable is not a LAN cable. So it might be wired differently. Also ensure that the pairs are used correctly. You want the CANH/CANL to be twisted together, otherwise you will be subjected to noise and interference.

 

[Confucius]

Got a sunsynk approved installed for the exact reason that I dont know inverters well enough/at all

It doesn’t really take much to become a sunsynk approved installer so that point is actually worthless.

 

[Qui_Illustrati]

It doesn’t really take much to become a sunsynk approved installer so that point is actually worthless.

Raises the question - would a Sunsynk approved installer go ahead and install a Scott battery if the battery isn't on an 'approved' list and then sign off the install as compliant? Or was the Scott battery after the initial install and signoff @ovisser1 ?

Next inverter when the Sunsynk is laid to rest- get the new Solis S6 Hybrid Superior and more cost effective.

 

[JG_RSA]

So regarding the Activate Battery setting, should it be off by default?
After reading this, I've noticed that it's ticked on my two week old installation with (presumably) new Deye inverter and 2x Hubble batteries at a weekend home. There's no loadshedding there and batteries are set to maintain 70% SOC when on grid, just so that there's a backup in case of cable theft or some other unforeseen event.
It should be off then, no? Can it cause any harm in leaving it ticked or does it use more power to constantly trickle charge the battery, if I understand the purpose correctly?

 

[madness_inc]

Raises the question - would a Sunsynk approved installer go ahead and install a Scott battery if the battery isn't on an 'approved' list and then sign off the install as compliant? Or was the Scott battery after the initial install and signoff @ovisser1 ?

Next inverter when the Sunsynk is laid to rest- get the new Solis S6 Hybrid Superior and more cost effective.

The Solis is brand new and hardly any reviews of it anywhere (besides a short term one posted on powerforum recently), so curious how you're so confident it's superior?

 

[Qui_Illustrati]

The Solis is brand new and hardly any reviews of it anywhere (besides a short term one posted on powerforum recently), so curious how you're so confident it's superior?

The Solis brand is not new at all. Been running the previous generation Solis Hybrid for ages - I feel the older generation Solis Hybrid is superior to the Sunsynk. The newer generation, going on the datasheet, is superior to their older generation so by deduction superior to the current Sunsynks. Based on my personal experience with Solis features, lack of issues prevalent with Sunsynk/Deye users and the Solis technical support and their efficiencies, and my opinion of course. And pricing comparisons are freely available. Makes sense getting more bang for buck and Solis certainly offers a whole lot more back for buck.

 

[madness_inc]

So just ann opinion then. 6 months ago everyone was on the Deye/Sunsyk bandwagon. Time will tell

 

[Qui_Illustrati]

So just ann opinion then. 6 months ago everyone was on the Deye/Sunsyk bandwagon. Time will tell

Sure. But also there is actual data available to support most opinions. Datasheets. Those exist. The problem with bandwagons is they are usually a horrible association. But you're absolutely right - time will tell. Always good exploring options though.

Anyway - apologies for the derail @ovisser1 .
Hope you're winning this battle with the battery.

 

[aiccc]

So regarding the Activate Battery setting, should it be off by default?

Yes, the manual explains it well.

One needs it only when the battery is fully discharged.

From manual (activate when the battery (alone) will not power on the inverter or the inverter can not charge the battery)

 

[JG_RSA]

@aiccc
Thanks. I'll untick the option.
I don't know why the installer had it ticked. I assume the default setting would be off(?)
I just wanted to make sure I wasn't missing something, like if it is a good thing to do for a while on new installation or something.

 

[ovisser1]

Raises the question - would a Sunsynk approved installer go ahead and install a Scott battery if the battery isn't on an 'approved' list and then sign off the install as compliant? Or was the Scott battery after the initial install and signoff @ovisser1 ?

Was not done after the fact, They did install it

It doesn’t really take much to become a sunsynk approved installer so that point is actually worthless.

That is also actually very sad. The market is already so flooded with overnight installers, hard to know who actually knows what they're doing.
And what the right way is without eventually just doing it yourself anyway.