Hi

I have a Shoto SDA10-48100, but the 5.12kWh version (16s if I'm not mistaken) along with an Axpert Max 7.2kw inverter.

Very much the same setup and situation as this person: https://powerforum.co.za/topic/9997-3080-soc-battery-settings/

Apparently these two units don't communicate at all...

I'm trying to figure out what the importance is of having the inverter talking to the BMS, other than getting a few parameters setup automatically and I guess getting an accurate State of Charge at any point in time.
I'm also using Solar Assistant, although I still have to get comms working between SA and the battery.

So I guess my question is:  If I'm able to get SA to talk to the battery in order to better check and maintain SoC, is it at all necessary (other than the reasons I pointed out) to get comms going between the Inverter and BMS?  If so why?

I'm still relatively early in my purchase so I might need to look at swapping out one of these units. Hope it doesn't have to get to that point.

Thanks!

7 minutes ago, joe37 said:

Hi

I have a Shoto SDA10-48100, but the 5.12kWh version (16s if I'm not mistaken) along with an Axpert Max 7.2kw inverter.

Very much the same setup and situation as this person: https://powerforum.co.za/topic/9997-3080-soc-battery-settings/

Apparently these two units don't communicate at all...

I'm trying to figure out what the importance is of having the inverter talking to the BMS, other than getting a few parameters setup automatically and I guess getting an accurate State of Charge at any point in time.
I'm also using Solar Assistant, although I still have to get comms working between SA and the battery.

So I guess my question is:  If I'm able to get SA to talk to the battery in order to better check and maintain SoC, is it at all necessary (other than the reasons I pointed out) to get comms going between the Inverter and BMS?  If so why?

I'm still relatively early in my purchase so I might need to look at swapping out one of these units. Hope it doesn't have to get to that point.

Thanks!

You can try RIOT CloudLink - it can interface some inverters and some bms - check first for compatibility before buying a unit.

Inverter <---> CloudLink <---> battery bms

The main purpose is to get an accurate SoC - using Voltage does work, but is less accurate.
You need to ability to configure the inverter with a voltage is 100% SoC and what voltage to stop discharge.
eg. for Band H:
53.6V means 100% SoC
45.5V means 20% SoC
42V means 0% SoC
 

The main reason as mentioned above is to read an accurate state of charge from the batteries, so that the inverter can switch back to grid at an accurate battery SoC, eg 20%. Without it your equipments' capabilities won't be maximised. 

Solar assistant will do this for you since direct comms with the inverter in this setup isn't supported. 

Edited July 14, 20224 yr by Hansa

45 minutes ago, joe37 said:

Hi

I have a Shoto SDA10-48100, but the 5.12kWh version (16s if I'm not mistaken) along with an Axpert Max 7.2kw inverter.

Very much the same setup and situation as this person: https://powerforum.co.za/topic/9997-3080-soc-battery-settings/

Apparently these two units don't communicate at all...

I'm trying to figure out what the importance is of having the inverter talking to the BMS, other than getting a few parameters setup automatically and I guess getting an accurate State of Charge at any point in time.
I'm also using Solar Assistant, although I still have to get comms working between SA and the battery.

So I guess my question is:  If I'm able to get SA to talk to the battery in order to better check and maintain SoC, is it at all necessary (other than the reasons I pointed out) to get comms going between the Inverter and BMS?  If so why?

I'm still relatively early in my purchase so I might need to look at swapping out one of these units. Hope it doesn't have to get to that point.

Thanks!

PS with the shoto batteries we did eventually manage to get it to output some data, solar assistant at that time said 'invalid data recieved'. 

Then pierre did some coding updates to solar assistant, and apparently it should work now as he managed to decode the data recieved, but by then we had changed the batteries (for other reasons) and didn't get a chance to test it out. 

My suggestion is to follow your specific manual that came with your batteries, and set up the dip switches as stipulated, then you'll need the cable from solar assistant as well to connect the RS485 to usb. 

Edited July 14, 20224 yr by Hansa

29 minutes ago, Hansa said:

PS with the shoto batteries we did eventually manage to get it to output some data...

Good to hear.  My cable is on its way.
 

29 minutes ago, Hansa said:

My suggestion is to follow your specific manual that came with your batteries, and set up the dip switches as stipulated, then you'll need the cable from solar assistant as well to connect the RS485 to usb.

Yeah regarding that
(EDIT: To be clear, I'm using the exact same shoto you were using, with the exact same manual and specs)

I'm not entirely certain what the different voltages mean necessarily.  So from the screenshot of the battery specs you posted:

I get what you said about it being prudent to work between the 45V and 56.4V specified, since that translates to ~2.8v to ~3.5V per cell.
I also understand the 30/80% calculation you were doing here.

Your question on whether those calculated values were accurate seemed to go unanswered though, specifically the 54.12V being just above the float voltage and if that can be regarded as 80% SoC.
Did you ever manage to figure that part out or get some answers?

But just in general, from looking at the specs provided in the manual, how would one determine the voltage range that corresponds to 0% - 100% for this battery?
Can you really just take the upper charge voltage and subtract the lower discharge voltage and that's your entire range?  Is this how it works for all LFP batteries?

What does the float voltage actually refer to then?
Because from what I could tell it seems that the measured battery voltage from the inverter, when the battery if fully charged, settles at 54V.  But that would indicated the battery's SoC is 100% at 54V ?  I'm confusing myself here

Hope you get what I'm trying to figure out.

Edited July 14, 20224 yr by joe37

Hi

If you get the comms working then you don't have to worry about any voltage settings on emulated BMS.. 

Emulated BMS is an option on solar assistant when there aren't any comms, so it does something called coulomb counting and estimates the % SoC. 

If there's communication then it won't need to do that, battery will tell it exactly what the SoC is. 

Edited July 14, 20224 yr by Hansa

Thanks, yeah I figured when comms is working I shouldn't have to worry.  Was just wondering in general to further my understanding of relationship between SoC and voltage specs.

Do you know if these inverter settings will also be automatically set by SA once proper comms is established?

If not do you or anyone here know if these settings are optimal given the battery specs? (Mostly curious about "Shutdown", "To grid" and "Back to battery" values)

Ps I can't remember what settings I eventually used as the 30/80 SoC, you can do some research regarding that

3 minutes ago, joe37 said:

Thanks, yeah I figured when comms is working I shouldn't have to worry.  Was just wondering in general to further my understanding of relationship between SoC and voltage specs.

Do you know if these inverter settings will also be automatically set by SA once proper comms is established?

If not do you or anyone here know if these settings are optimal given the battery specs? (Mostly curious about "Shutdown", "To grid" and "Back to battery" values)

Those settings seem fine and as per what my installer had set, those are set on the inverter 

When solar assistant is connected it will take over the back to grid / discharge etc based on the % SoC, so those settings won't affect day to day functionality, however if solar assistant device gets disconnected or something, it will still use those battery settings on the inverter. 

15 minutes ago, Hansa said:

Ps I can't remember what settings I eventually used as the 30/80 SoC, you can do some research regarding that

BTW I see solar assistant doesn't require 30/80 % voltage settings anymore on the emulated BMS option. Just asks for battery capacity and I'm sure it works it out automatically. Cool

11 hours ago, joe37 said:

If not do you or anyone here know if these settings are optimal given the battery specs?

I have the same battery and I have changed the settings slightly to try to be kinder to the lithium as I also have no comms at the moment. Here's what I have from reading about 4 different manuals and some suggestions from Coulomb:

Shutdown: 46V (44V is 1V below the min discharge voltage of 45V) - corrected below

Float: 54V (from a spec sheet)

Bulk/Absorb: 56V (set a little lower to prevent overshoots pushing it higher than 56.4V max)

I can't really comment on the grid settings as I have no grid. If you have grid input then the shutdown voltage might be fine as it probably prevents an alarm already going off at 48V, but there might be a case where there is no grid and the battery could discharge too low, although the bms should prevent that, but I'd prefer the inverter to intervene first. I use a 50V cutoff value, I've read that represents 80% DOD SOC (20% SOC DOD). I've read Coulomb suggest 51.2V back to grid and 53.3V back to batt for 16S lithium in general, you could try those and see how they work for you.

 

Edit: just wanted to correct something on the shutdown voltage: it seems the 15S batteries are designed for 80% DOD and the 16S for 90% DOD which makes reading specs a little confusing. The 15S and 16S both have a min cutoff voltage of 40V, the bms will enter alarm status at 42V and will cut off at 40V, which I would guess is 90% DOD for the 16S model. Your 44V is well within those limits.

Edited July 14, 20223 yr by jumper

14 hours ago, jumper said:

Edit: just wanted to correct something on the shutdown voltage: it seems the 15S batteries are designed for 80% DOD and the 16S for 90% DOD which makes reading specs a little confusing. The 15S and 16S both have a min cutoff voltage of 40V, the bms will enter alarm status at 42V and will cut off at 40V, which I would guess is 90% DOD for the 16S model. Your 44V is well within those limits.

Hi Jumper, thanks for this.  Mind sharing where you got the info for the bms alarm triggering at 42V etc. ?

9 hours ago, joe37 said:

Mind sharing where you got the info for the bms alarm triggering at 42V etc. ?

Sure, I have it from the older version of the manual attached here, on page 16. The 15S and 16S have different over-voltage values, but they have the same low-voltage values. The strange thing is, in the charging table above that they give charging voltages where the typical value (57.6V) will already set off the bms over-voltage alarm (57V).

I've also attached a second document which seems to be the latest battery spec sheet with bulk and float values for the new model with vertical battery connections and CAN port (no RS232). It gives a bulk charge of 57.6V, but I reduced mine as I don't want overshoots to set of any bms alarms until I get comms working and can see what the real settings are.

shoto_sda10_48100_manual.pdf SHO-SDA10-48100-CAN.pdf

On 2022/07/14 at 11:44 AM, joe37 said:

But that would indicated the battery's SoC is 100% at 54V ?

That is correct if you have completed the bulk/absorb stage of charging above 54V and then go to float at 54V, not really when you first reach 54V on the way up. I would guess the battery is about 85%-90% when you first reach 54V and that will increase to 100% as you spend more time above 54V.

With an operating range of 40V-54V with 40V=10% and 54V=100%, I get a very rough calculation of 6.5%/V giving the approximate values below:

54V = 100%

50V = 75%

48V = 60%

45V = 40%

42V = 20%

On 2022/07/15 at 11:35 AM, joe37 said:

Hi Jumper, thanks for this.  Mind sharing where you got the info for the bms alarm triggering at 42V etc. ?

i recently picked up a second hand shoto the 15s model

capacity wise i could only get just under 3kw out of it, and the alarm light came on long before it should 

if i remember correctly it was around 46-47v

and the bms would trip long before the 40v (low voltage on some cells)

i assumed the battery was out of balance, and would correct itself over time

today i gave up hope after running it for 2 months and only a slight increase in capacity

 

opened it up, and as i expected i had 1 cell out of balance

i approximate about 20% ie explaining the lost 1kw

 

i could not get any info on ballance current of the bms of the shoto, assume its low due to the rate of improvement

i assumed a 50ma ,and heaven forbid if it only starts balancing after a certain voltage 

so it would take months, since it goes into standby mode i assume it only balances while charging

 

just saying ,so if others experience the same 

On 2022/07/14 at 8:35 PM, jumper said:

I have the same battery and I have changed the settings slightly to try to be kinder to the lithium as I also have no comms at the moment. Here's what I have from reading about 4 different manuals and some suggestions from Coulomb:

Shutdown: 46V (44V is 1V below the min discharge voltage of 45V) - corrected below

Float: 54V (from a spec sheet)

Bulk/Absorb: 56V (set a little lower to prevent overshoots pushing it higher than 56.4V max)

I can't really comment on the grid settings as I have no grid. If you have grid input then the shutdown voltage might be fine as it probably prevents an alarm already going off at 48V, but there might be a case where there is no grid and the battery could discharge too low, although the bms should prevent that, but I'd prefer the inverter to intervene first. I use a 50V cutoff value, I've read that represents 80% DOD SOC (20% SOC DOD). I've read Coulomb suggest 51.2V back to grid and 53.3V back to batt for 16S lithium in general, you could try those and see how they work for you.

 

Edit: just wanted to correct something on the shutdown voltage: it seems the 15S batteries are designed for 80% DOD and the 16S for 90% DOD which makes reading specs a little confusing. The 15S and 16S both have a min cutoff voltage of 40V, the bms will enter alarm status at 42V and will cut off at 40V, which I would guess is 90% DOD for the 16S model. Your 44V is well within those limits.

Thank-you for sharing these settings. I have a Mecer 5KW and my Shoto 5.12 16S arrived this week. Would you mind sharing your current inverter voltage settings used to manage your Shoto? 

15 hours ago, Vassie said:

Thank-you for sharing these settings. I have a Mecer 5KW and my Shoto 5.12 16S arrived this week. Would you mind sharing your current inverter voltage settings used to manage your Shoto? 

I am still using the basically the same settings and they have been working perfectly since. I have just pushed the float voltage up by 0.5V to make sure it balances properly if not fully charged by the end of the absorb time if solar is bad... I get max 20A charging from my panels and no grid.

Bulk/Absorb: 56V

Float: 54.5V

Absorb/Equalization time: 60mins

On 2022/07/17 at 7:53 PM, Leondavibe said:

i could not get any info on ballance current of the bms of the shoto, assume its low due to the rate of improvement

i assumed a 50ma ,and heaven forbid if it only starts balancing after a certain voltage 

so it would take months, since it goes into standby mode i assume it only balances while charging

This is probably the biggest issue of running without comms.  For these batteries to balance, they must regularly be kept under very slow charge at near 100% capacity.  And the only way for that to happen is for the BMS to manage the charging process.

A very high quality battery with perfectly matched cells can work for years without a proper balance.  For the rest, imbalance will only ever get worse until it chews up a big chunk of available capacity.

6 hours ago, JustinSchoeman said:

This is probably the biggest issue of running without comms.  For these batteries to balance, they must regularly be kept under very slow charge at near 100% capacity.  And the only way for that to happen is for the BMS to manage the charging process.

A very high quality battery with perfectly matched cells can work for years without a proper balance.  For the rest, imbalance will only ever get worse until it chews up a big chunk of available capacity.

yea agree top balanced well matched cell actually stay in balance nicely, heck i have a bms free battery (could not get anything other than dumb daly at the time so skipped it , will fit one soon though on my to do list)

 

it is mixed cells ie different batches and stayed close for months only adjusted the balance once in a few months

 

not sure if any bms does this slow charge notion/balance without human intervention

would love to see an example of this

 

i don't have comms between inverter and shoto

 

i do have coms with a pc so have checked it's behaviour 

ie have seen the shoto charge limit all by it's self ignoring the charge rate happily forcing the charge to go to the other battery

charging tends to go CC CV and then nothing if inverter has a lithium algo

 

so based on battery behaviour i have seen so far i only come to one conclusion the whole battery coms is an oversold feature

 

the only exception is the sunsynk that can actually act on the SOC thanks to shunt in battery ie you could actually set a reserve portion for loadshedding 

 

other than that it is fluff imo

imo any imbalance that becomes  apparent ,with normal cycling going to full regularly

means that  you are stuck with a badly matched cells battery

 

if doing the  20-80  SOC notion will just bring on the drifting quicker imo 

in fact with the lousy balance currents , i see the 20-80 idea as a stupid notion

 

now yes as long as you never get low cell voltages it isn't a problem

as soon as that drift has become enough to cause some cells to go to empty while the inverter thinks you are at 20%soc 

the damage is all but guaranteed how long this takes is dependant on how nicely paired the cells in your battery is

 

just a notion i have i may be wrong 

 

32 minutes ago, Leondavibe said:

so based on battery behaviour i have seen so far i only come to one conclusion the whole battery coms is an oversold feature

Some BMS use a estimate rather than a shunt with a coulomb counter. Some BMSs are simply poorly calibrated and there is no way to fix it under-reading current.

Having an accurate coulomb counter in the BMS makes a world of difference since a LiFePO4 battery can not be measured with voltage without having a 40-50% error as the direction of the current makes a huge difference to the voltage. (Unless you do not place any loads on the battery while charging)

My Daly actually works pretty well (200A Smart BMS). I also use home assistant to step down the charge current as the cells approach 100%. The balance function is a bit of a joke, I probably need to invest in a balancer at some point. In the past I was annoyed with the daly as it seems to reset itself to 100% but that turned out to be a poor contact on one of the busbars, once torqued properly the problem went away (discovered when I started logging cell voltages on a graph) I also discovered that the SOC was out by roughly 20% after 2 weeks where the weather did not permit a full charge, which means that shunt software samples too slow and drifts over time.

Getting a good ROI out of the cells require a good bms, otherwise you will be guessing and using too little or too much of the battery

Edited April 3, 20233 yr by iiznh

10 hours ago, jumper said:

I am still using the basically the same settings and they have been working perfectly since. I have just pushed the float voltage up by 0.5V to make sure it balances properly if not fully charged by the end of the absorb time if solar is bad... I get max 20A charging from my panels and no grid.

Bulk/Absorb: 56V

Float: 54.5V

Absorb/Equalization time: 60mins

Thank-you very much.

1 hour ago, iiznh said:

Some BMS use a estimate rather than a shunt with a coulomb counter. Some BMSs are simply poorly calibrated and there is no way to fix it under-reading current.

Having an accurate coulomb counter in the BMS makes a world of difference since a LiFePO4 battery can not be measured with voltage without having a 40-50% error as the direction of the current makes a huge difference to the voltage. (Unless you do not place any loads on the battery while charging)

My Daly actually works pretty well (200A Smart BMS). I also use home assistant to step down the charge current as the cells approach 100%. The balance function is a bit of a joke, I probably need to invest in a balancer at some point. In the past I was annoyed with the daly as it seems to reset itself to 100% but that turned out to be a poor contact on one of the busbars, once torqued properly the problem went away (discovered when I started logging cell voltages on a graph) I also discovered that the SOC was out by roughly 20% after 2 weeks where the weather did not permit a full charge, which means that shunt software samples too slow and drifts over time.

Getting a good ROI out of the cells require a good bms, otherwise you will be guessing and using too little or too much of the battery

yea the shunt is super accurate but the one thing they can't count is losses

so the visit to top or bottom is what it is needed for it to find its bearings  from time to time

 

as long as the balance isn't out of whack not a big deal

i am thinking of buying an active balancer and have leads on both so i can just plug it in from time to time to just do a top balance again

 

thus only one device is needed

On 2022/07/15 at 8:56 PM, jumper said:

Sure, I have it from the older version of the manual attached here, on page 16. The 15S and 16S have different over-voltage values, but they have the same low-voltage values. The strange thing is, in the charging table above that they give charging voltages where the typical value (57.6V) will already set off the bms over-voltage alarm (57V).

I've also attached a second document which seems to be the latest battery spec sheet with bulk and float values for the new model with vertical battery connections and CAN port (no RS232). It gives a bulk charge of 57.6V, but I reduced mine as I don't want overshoots to set of any bms alarms until I get comms working and can see what the real settings are.

shoto_sda10_48100_manual.pdf 904.6 kB · 3 downloads SHO-SDA10-48100-CAN.pdf 1.5 MB · 3 downloads

if the alarm warning goes off on higher voltages , then you have an imbalance problem, ie as the alarm will flash with individual cell  low voltage

can't recall i think it is on 2.8v per cell , will try and check next time i cycle that deep  

20 hours ago, Leondavibe said:

if the alarm warning goes off on higher voltages , then you have an imbalance problem, ie as the alarm will flash with individual cell  low voltage

can't recall i think it is on 2.8v per cell , will try and check next time i cycle that deep  

We actually discovered, thanks to @jgdt, that the bulk charge voltage broadcast by the BMS is the actual pack overvoltage value which causes the battery to go into protection at the top of charge before it gets a chance to balance. This obviously only happens with comms working and changing that parameter changes the charge voltage broadcast.

I reckon this could cause cell imbalances over time as the balancing will never activate and the battery never reaches 100%.