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30/80% SoC & Battery settings


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Hi all,

Been reading quite a bit on here regarding Shoto SDA10 48100 5.12kwh batteries.

We've had an installer do Kodak Max 7.2Kw inverters with these Shoto batteries.

Unfortunately I learnt later that these dont communicate at all. Would have gone the sunsynk + hubble/pylontech route had I known this!

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So now we are trying to get the system communicating to some extent.

For that reason we purchased the solar assistant system.

Have the shoto manual , its a newer design which slightly different terminals (vertically orientated in a line as shown in the manual), CAN comms  and RS485 (no rs232).

Dip switches are also different compared to previous threads which I had seen (for 4 batteries, master has 5&6 up!) . All in the manual which you can see here

With the dip switches correct, and the cascading batteries connected to master RS485B to the battery 2  RS484A, and alternating so on, with the CAN port DISCONNECTED, then ONLY did we get some 'info' being transferred to the raspberry pi. Unfortunately, it says "invalid data recieved". The interesting part is that its at least transferring data now.

SO guys with Shoto batteries trying to get comms, make sure your dip switches are exactly as stated in your specific batteries manual. They seem to be changing things between revisions of the design. And hence confusing people. Hope this helps some of you with Shoto SDA10 batteries.

Pierre has been very helpful in trying to rectify the situation, but for now it seems that the data is in a new format and hence cannot be read.

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Interestingly the RS485 pins listed in the manual are different from other batteries and previous shoto designs, says pin 8 is RS485B.

However, we had used the old cable with Pin 8 as ground, which is providing some data (albeit invalid). According to Pierre this means the manual is wrong. Since if the ground was as per the manual then it would not have worked at all.

THen in 4.2.2. of the manual they contradict themselves by showing pin 8 being the ground. Strange indeed.

 

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Now to the main reason why I'm posting here,

Please see the battery specs below. They no longer specify 15s or 16s so I dont actually know what this battery is. Perhaps they only have one model now. Especially since previous manuals had separated the two. THis manual has only one type. 

 Capture.thumb.JPG.31d31a82c224bf57a6e97d87fe2eba2c.JPG

 

My battery settings on the inverter (USER option selected due to no comms):

Capture2.thumb.JPG.013ae03da6130f817e8ba5c6e0ecb3d2.JPG

 

 

We currently are using emulated BMS to try to maximise benefit from the system, till solar assistant gets the data processing sorted. 

1. What should the 30% and 80% SoC be set to based on the above manual?

2. Do these battery settings look optimised? Especially the 'to grid' and 'back to battery' voltages.

Although I suppose solar assistant will handle this now.

 

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Hi Hansa,

I don't know Shoto Batteries but I do know a 16s config when I see it & can without a doubt tell you that you are dealing with a 16s config.

51.2V is the advertised 16S config as this measures 51.2V ÷16 = 3.2V which is the nominal voltage range for LiFePO4 cells.

In the 15s config like many batteries they are configured for 3.2V nominal & advertised as 48V batteries exclusively & so 48÷15 = 3.2V nominal voltage of the cell. (Pylontech types)

The charge format also has clues as to the 16s arrangement 54V -56.4V.

So you always divide the bulk or even the float by 16 cells to get individual cell voltage provided the cells are top balanced. 

So on your settings bulk at 56.4V ÷ 16 = 3.525V per cell which is the absorption voltage.

So for lithium iron phosphate cells like in anything Solar stay away from the edge of the envelope. So the absolute min voltage is 2.4V & the high is 3.65V per cell. The longer time you spend at these values the more degradation or damaged can be imposed on each cell. 

To lastly answer your question & get to the Crux of the matter. What is the best Charge voltage settings? The one that best suites your desire to make your cells last the longest. Remember take whatever you want to set & ÷ that numbed by 16s in your case. That value is what will make you sleep better at night.

87

 

 

 

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By the way Pierre is a Top man & I appreciate that he spends so much time to help where he can to get things working. Sorry just a general shout out to him as his dedication and individual attention to customers is what is so sorely lacking in so many businesses let alone solar. 

87

 

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4 hours ago, Hansa said:

I learnt later that these dont communicate at all.

I haven't looked at the Max removable display firmware, but in the King/VM III removable display firmware, there is a battery type SH for SHoto (and also type BAK). These two are disabled at present, but there is code that responds to those battery types.

So my guess is that either these are still in development, or they were planned, found too hard, and have been disabled (there is code to skip over those options) rather than deleted in case they get around to finishing it.

So it's possible that Voltronic will come out with Shoto support at some point in the future.

Of course, that doesn't help you now 🙄. But perhaps keep it in mind for the future.

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7 hours ago, 87 Dream said:

Hi Hansa,

I don't know Shoto Batteries but I do know a 16s config when I see it & can without a doubt tell you that you are dealing with a 16s config.

51.2V is the advertised 16S config as this measures 51.2V ÷16 = 3.2V which is the nominal voltage range for LiFePO4 cells.

In the 15s config like many batteries they are configured for 3.2V nominal & advertised as 48V batteries exclusively & so 48÷15 = 3.2V nominal voltage of the cell. (Pylontech types)

The charge format also has clues as to the 16s arrangement 54V -56.4V.

So you always divide the bulk or even the float by 16 cells to get individual cell voltage provided the cells are top balanced. 

So on your settings bulk at 56.4V ÷ 16 = 3.525V per cell which is the absorption voltage.

So for lithium iron phosphate cells like in anything Solar stay away from the edge of the envelope. So the absolute min voltage is 2.4V & the high is 3.65V per cell. The longer time you spend at these values the more degradation or damaged can be imposed on each cell. 

To lastly answer your question & get to the Crux of the matter. What is the best Charge voltage settings? The one that best suites your desire to make your cells last the longest. Remember take whatever you want to set & ÷ that numbed by 16s in your case. That value is what will make you sleep better at night.

87

 

 

 

Your message is highly appreciated, and has clarified many aspects for me.

Thank you for the detailed response and your time. 

We would want a good balance between battery longevity and maximising benefit, as everyone else. 

Hence it seems prudent to use the 45v to 56.4v values as suggested in the charge /discharge voltages of the manual, rather than anywhere near to 2.4V & 3.65V per cell. 

 

I'm trying to work out 30% and 80% SoC for input into solar assistant emulated BMS for now. 

Would it be these 45 and 56.4 values that I work within? 

According to my calculations this would be 48.42v and 54.12v. My concern is that 54v is the float charge so is that suitable to apply for 80% SoC...

Edited by Hansa
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17 minutes ago, Hansa said:

I'm trying to work out 30% and 80% SoC for input into solar assistant emulated BMS for now. 

Would it be these 45 and 56.4 values that I work within? 

According to my calculations this would be 48.42v and 54.12v. My concern is that 54v is the float charge so is that suitable to apply for 80% SoC.. 

Absolutely no sweat at all Hansa. Happy to help & share stuff with anyone whom might ask or need the assistance.

The values you have their are quite good. These should not stress the cells. What I will say about the Solar Assistant battery emulator is that it doesn't do a bad job at all to guestimate the SoC. As a final & a little more costly resort you can connect a Victron Smart Shunt on the negative side on your battery in series. Then connect a VE direct to USB cable into the Pi. This will count the Coloumbs on the way in & on the way out. This works as an accurate SoC with Solar Assistant. The Smart Shunt & cable will cost in the region of +-R3K. But then you have solved the problem for good.

87

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Yes, the shunt is in series on your negative terminal on your battery bank. Your options are the smart shunt or the Victron BMV or battery monitor. So doesn't matter how many batteries are in Parallel. There is only one connection going to the inverter neg so it plugs in on this terminal before the input to the inverter. It's a glorified ammeter. Counts the amps in & out. It's also rated up to 500A. Don't think you will exceed this number though 🤣

87

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52 minutes ago, Hansa said:

Just to confirm, if the batteries are in parallel the victron shunt would also work? 

If we don't get things sorted here after a few months, may end up going that route. Thanks for the suggestion

PS it's a 3 phase system, with 3 inverters. And 4 batteries in parallel 

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A single Axpert Max 7.2kW can draw 165A. So with 3 in parallel & in 3 phase that limit of 500A will not be exceeded but only just at 495A. But don't think that you run all phases at 7.2kW extensively. I would think that the 500A limit is safe only unless you plan an upgrade. Any upgrade or additional inverter added & you are over that limit. A price comparison between the 1000A & 500A model should be done here to make sure that you get the best value. 

87

 

 

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