2x Shoto 5.12kWh SDC10-Box5 charge rates and how to keep temp down

[jgdt]

Hi I have a month old installation consisting of a SunSynk8kW inverter, 2x Shoto 5.12 SDC10-Box5 and 5.4kWp solar array installation.

I've been really struggling to keep the battery temps down under 30 degrees; nevermind the recommended 25 degrees. Typically it reaches about +-31 degrees each day (the highest was 34.5 degrees).

At first I though its the ambient temperature of the west facing garage which get really hot in the afternoon, so I insulated the garage ceiling and doors. But after looking closer into the history graphs (after insulation) I realized the temp jumps are actually in the mornings when the charging occurs at full blast. See screenshot

Typically my SOC is +-55% in the mornings before the sun comes and which point the battery temps is +-25 degrees. Typically they are fully charged around +-10:30 at which point the temps are +-31 degrees. At time of 100% SOC the ambient temp in the garage is typically +-24 degrees.

Would it help if I reduce the charge rate? Currently its set to 80amps (by the installer) even though the BMS' max charge rate is 100A. Interestingly if the charging amps goes over 70 amps it shows as yellow warning on the inverter's LCD display (see photo). This battery is 100A and rated 1C, but looks like on the spec sheet it says recommended charging is 50 amps with max 100A. So should I perhaps down the charge rate to 50A?

Silly question but if you have two batteries and one sets the charge limit to 50A (on inverter's battery settings) is it 50A per battery or 25A each?

Regarding fans: I have noted on a lot of other forum threads people use external fans to cool batteries down. Is there a downside to doing this? The worst thing would be if one cool down the battery temp sensor without really cooling the entire battery, so then it looks like its running cooler but in fact its not. Maybe there's a specific direction or angle at which the fan wind must blow? Is a normal oscillating fan okay or should it be a "pc fan like 12V" type of fan placed at a strategic point? Perhaps I'm just overthinking it.

 

[jgdt]

Any opinions feedback on this will be greatly appreciated. Thanks in advance

[WannabeSolarSparky]

Ideally you should never exceed 0.2C rating for charging and discharging to ensure maximum life of the batteries.

So for a bank of 2x 100 ah batteries your ideal charge point should be closer to 40amps

You should still get the batteries to 100% by midday.

[WannabeSolarSparky]

Keeping in the 0.2C range will also allow the batteries cells to stay nicely balanced

Edited February 28, 2023 by WannabeSolarSparky

[jgdt]

Thank you very much @WannabeSolarSparky, much appreciated. I have set my max charge/discharge according to your advice. What are you using to monitor your batteries on cell level as per your screenshot? I've found the LiBMS info rolled up by the SS inverter over the CANbus from Shoto (Seplos) BMS to be too redactive.

[WannabeSolarSparky]

19 minutes ago, jgdt said:

Thank you very much @WannabeSolarSparky, much appreciated. I have set my max charge/discharge according to your advice. What are you using to monitor your batteries on cell level as per your screenshot? I've found the LiBMS info rolled up by the SS inverter over the CANbus from Shoto (Seplos) BMS to be too redactive.

I removed the builtin bms that the battery came with and replaced it with a JK BMS, I was not happy with how the battery's builtin BMS was working.

[jgdt]

25 minutes ago, WannabeSolarSparky said:

I removed the builtin bms that the battery came with and replaced it with a JK BMS, I was not happy with how the battery's builtin BMS was working.

That's hard core, you can start a DIY channel based on your DIY solar work. Its my feeling as well that the stock BMS on most batteries are mickey-mouse, guess its a cost lowering thing for manufactures and if it shortens the life span of battery its still new business for them so they don't care if the most optimum BMS and optimum settings are not deployed on there batteries. Is this more a less the BMS you used to retro fit? https://www.takealot.com/jikong-bluetooth-4-8s-200a-jk-bms-with-2a-active-balance-and-lcd/PLID91438098

[ShanoMac]

Sorry to piggy-back off this, but reading it RE battery charge rates has me nervous that my shoto batteries are charging too quick. I have the same Shoto batteries as OP.

When the charging happens at midnight (No panels yet, so charged via Grid), I can see the batteries charging at like 1600W, but not sure what is the right setting to adjust on my LuxPower Inverter to make it charge slower.

Is it the 'Charge Current Limit', or 'AC Charge Battery Current'...?

[jgdt]

12 minutes ago, ShanoMac said:

No panels yet, so charged via Grid), I can see the batteries charging at like 1600W

How many batteries do you have? 1600W on DC equates to +-30 amps (depending on voltage) so I think that still more than okay (if you have two, probably still okay'ish if you only have one). And this correlates with the 'AC Charge Battery Current (A)' setting from your screenshot which is set to 30 amps.

I'm not familiar with LuxPower, just extrapolating my limited knowledge from my SunSynk inverter where grid charging is set to 40A (20A each then per battery for 2 batteries) and this typically uses about +-2000W.

The 'Charge Current Limit (A)' setting of 110A probably relates only to DC charging from PV. When you have PV it will again depend on the number of batteries to set this optimally.

Edited February 28, 2023 by jgdt

[ShanoMac]

Just the one battery - so that makes sense then (correlating closer to 30A).

I'm trying to brush up on my knowledge of amps = watts / volts - and the picture is starting to get clearer if I take the 57.4v charge voltage * 30A = 1700W.

I'll chat the the panel installer (who also did my inverter) and get him just to double check it all.

Really appreciate the help, thank you

[WannabeSolarSparky]

49 minutes ago, jgdt said:

That's hard core, you can start a DIY channel based on your DIY solar work. Its my feeling as well that the stock BMS on most batteries are mickey-mouse, guess its a cost lowering thing for manufactures and if it shortens the life span of battery its still new business for them so they don't care if the most optimum BMS and optimum settings are not deployed on there batteries. Is this more a less the BMS you used to retro fit? https://www.takealot.com/jikong-bluetooth-4-8s-200a-jk-bms-with-2a-active-balance-and-lcd/PLID91438098

this is the 1st one I bought
https://www.takealot.com/jikong-bluetooth-8-20s-100a-jk-bms-with-0-6a-active-balance-and-/PLID91438101

got second one bigger at 2amp balance current.

[chrisc]

On 2023/02/28 at 12:28 PM, WannabeSolarSparky said:

I removed the builtin bms that the battery came with and replaced it with a JK BMS, I was not happy with how the battery's builtin BMS was working.

Good day

Have the same battery, connected to an Axpert 5KW inverter, 6 PV panels.  I can never get all 4 SOC lights to display.  Have the bulk charge set to 54.4V and float to 53.5V

Now and then all 4 lights go out and the run light flashes.  No idea what this means.  Several emails to local supplier and factory in China got no response 

We had a 6-hour blackout from 20h00 to 02h00 last week.  The voltage went down to 51.1V and the red light was flashing. 

However, what really interests me was your replacing of the BMS.  Did it improve the batteries performance?  And is it fairly straightforward to install, with no surgery to the battery?  This is something I would really like to do.  I’m quite good fixing electronic devices 

Thanks for your contribution

Edited March 2, 2023 by chrisc

[jumper]

11 hours ago, chrisc said:

Have the same battery, connected to an Axpert 5KW inverter, 6 PV panels.  I can never get all 4 SOC lights to display.  Have the bulk charge set to 54.4V and float to 53.5V

If it is a 16S battery then you can bulk charge to 56V and float at 54V. I have a 16S SDA10 on a 5kw axpert and those parameters charge perfectly to 100%.

11 hours ago, chrisc said:

Now and then all 4 lights go out and the run light flashes.  No idea what this means.  Several emails to local supplier and factory in China got no response

This is just the battery going in to standby mode while charging. This usually happens when it is balancing at the top of charge (3 lights on 4th light flashing) and is normal.

The seplos BMS in the shoto is pretty good and there should be no need to replace it. I would suggest first getting the seplos software and connect to a PC via the rs485 port so you can see exactly what the battery is doing.

Edited March 3, 2023 by jumper

[jgdt]

Stupid question, but how can one know for sure whether ones battery is 15 or 16 cells? The data sheets online for Shoto 5.12 SDC10-Box5 does not explicitly list the number of cells. Or can one derive it from the voltage specs? See photo.

[Kalahari Cruiser]

16 minutes ago, jgdt said:

Or can one derive it from the voltage specs?

Going to guess that it can be derived : nominal voltage of a LiFePo4 cell is 3.2V, and 3.2V x 16 cells gives you 51.2 nominal battery voltage. 

[jumper]

1 hour ago, Kalahari Cruiser said:

Going to guess that it can be derived : nominal voltage of a LiFePo4 cell is 3.2V, and 3.2V x 16 cells gives you 51.2 nominal battery voltage. 

Correct. 15S is 48V nominal voltage. 

[chrisc]

Thanks for the info.  This battery works with Watchpower software via a USB connection.

Is this any good?  

[jumper]

17 hours ago, chrisc said:

Thanks for the info.  This battery works with Watchpower software via a USB connection.

Is this any good?  

Watchpower is not too bad, it gives you all the info from the inverter, but if you don't have comms between the battery and inverter then you will only get the voltage and current. Using the seplos software will give you all the details of the battery down to individual cell level, SOC, SOH and more. You can find more info in this thread:

 

[Raiden2912]

Excuse my ignorance, where do you check the temperature of the batteries on the Watchpower app?  Can you?

[jumper]

On 2023/03/04 at 8:18 PM, Raiden2912 said:

Excuse my ignorance, where do you check the temperature of the batteries on the Watchpower app?  Can you?

I'm not sure watchpower will give you that info, probably just the inverter temp. The battery itself has 6 different temp readings, so I'm not sure which it would choose if it did.

[zivva]

On 2023/03/03 at 3:02 PM, jgdt said:

Stupid question, but how can one know for sure whether ones battery is 15 or 16 cells? The data sheets online for Shoto 5.12 SDC10-Box5 does not explicitly list the number of cells. Or can one derive it from the voltage specs? See photo.

Nominal voltage ...

48V = 15s

51.2V = 16S

[zivva]

On 2023/02/22 at 6:14 PM, jgdt said:

Would it help if I reduce the charge rate? Currently its set to 80amps (by the installer) even though the BMS' max charge rate is 100A. Interestingly if the charging amps goes over 70 amps it shows as yellow warning on the inverter's LCD display (see photo). This battery is 100A and rated 1C, but looks like on the spec sheet it says recommended charging is 50 amps with max 100A. So should I perhaps down the charge rate to 50A?

Silly question but if you have two batteries and one sets the charge limit to 50A (on inverter's battery settings) is it 50A per battery or 25A each?

 

Number in yellow is not a warning, it just means it's close to the limit you set.

if you set max charge current to 100A, number will turn yellow when charging at +80A ...  

if you set max charge current to 40A, number will turn yellow when charging at +30A ... 

Batteries getting to +30 degrees when charging is totally normal : producing energy generates heat.

When decreasing charge current, you slightly decrease the batteries temperature (1 or 2 degrees top) but they generate heat for longer ...

If you want your batteries to stay at 25 degree, you need an AC to keep the room at 20 degrees or less. Anyway, batteries getting up to 35 degrees is perfectly fine : in theory you loose a few hundreds of cycles. You'll get 5000 cycles instead of 5500. 14 years instead of 15 years ... not worth the cost of running an AC 24/7

The recommended operating temperature (the temperature of the room, not the temperature of the batteries) is listed in your data sheet : +15 to +35 degrees. Manufacturers advertise cycles @ 25 degrees (operating temperature, not the temperature of the batteries !) to give bigger numbers but most users operate their batteries at much higher temperatures ...

I'm not sure of the benefits of running a fan to cool the batteries : if the room is hot, fans just move hot air. In a cool room that would make sense, in a room close to the temperature of the batteries it doesn't ...

Edited March 7, 2023 by zivva

[jumper]

FYI from my observation, the actual cell temps are usually 5-7 degrees cooler than the ambient temp, as reported by the BMS. Even on a nice toasty day with 35C ambient, the cells are sitting below 29C:

[jgdt]

11 hours ago, jumper said:

actual cell temps are usually 5-7 degrees cooler than the ambient temp, as reported by the BMS

Thanks Jumper, this is exactly why I want to get Battery Monitor to work on my side as per the other thread you are helping me on. Do you perhaps know what "Battery temp1" through to "Battery temp4" actually refer to?

12 hours ago, zivva said:

stay at 25 degree, you need an AC to keep the room at 20 degrees or less

For now I've decided to built a decent car port in front of my west facing garage, I think this will help a lot keep the ambient temp down in the middle of summer and then at least I have the extra benefit of a carport. If there's an AC in the garage we all might end up living in the garage in summer. Lol. But like you say its not worth the AC buy cost, installation and running costs.

[Antonio de Sa]

11 hours ago, jumper said:

FYI from my observation, the actual cell temps are usually 5-7 degrees cooler than the ambient temp, as reported by the BMS. Even on a nice toasty day with 35C ambient, the cells are sitting below 29C:

@jumper From my custom-made monitoring system, I can see is the ambient temperature going up when SOC is at 100% and the BMS starts to equalize the cells. See attached dashboard, I know I have a cell that is not getting to full voltage, one can clearly see it, it's been like this since day one.