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Seplos CAN BUS RS485 48v 200A 8S-16S BMS

Righty. Finally got comms. Turned out my first new lead was faulty ( no continuity on the blue wire ) so that’ll teach me to check my leads even if they’re new. Think everything is running ok now and guessing the software is defaulted to Pylontech as it’s not in the drop down
What can I actually do with this Seplos software or is it more a monitoring/ fault finding thing?

Soz for this double post, not sure how to delete it.
 
testtenor said:
Hi all. Can anyone recommend the best settings for 280ah, 200A BMS. My cells stop discharging at 24% at the moment. I'm getting the Monomer Low Pressure Alarm. Any ideas?
Click to expand...

What are the lowest cell voltages at that point? Did you do the top balance of the cells?

The "Monomer Low Pressure" alarm likely means that there are cells below 3V (likely close to 2.5V). The cause for this is either a lack of top balance or your weakest cell is 24% short of the 280Ah capacity. But 24% lower than the 280Ah capacity is ~210Ah. Where did you get that cells from? Did you test the capacity for some of them?
 
brum said:
What are the lowest cell voltages at that point? Did you do the top balance of the cells?

The "Monomer Low Pressure" alarm likely means that there are cells below 3V (likely close to 2.5V). The cause for this is either a lack of top balance or your weakest cell is 24% short of the 280Ah capacity. But 24% lower than the 280Ah capacity is ~210Ah. Where did you get that cells from? Did you test the capacity for some of them?
Click to expand...
Thanks for answering. Yes I top balanced. I didn't check the capacity, but the supplier was reputable and I've had cells which have been tested at 100% capacity from the same seller.

Lowest cell is 2.8V which is what's confusing me. Voltage difference has run quite high though. I'm wondering if a bad cell?!

16747681822281262815131528676348.jpg
 
The highest cell voltage is at 3.03V and the lowest is 2.8V. This does not look like unbalanced cells. And also doesn't look like a major capacity deviation.

Did you charge the battery to the point where the BMS disables the charging to protect the battery from overvoltage? The BMS needs that to calibrate the 100% charge point.
 
It's been running for a few months charging at night up to 100%. That's why I want to check settings to make sure nothing is wrong or incorrect
 
Charging to 100% according to the BMS or charging until the BMS disables the charging? These are not the same if it has never marked the 100% charge point correctly.

My inverter will stop charging when the BMS reports a 100% charge. Even if the cells are at 50% actual charge.

To do the calibration you need a proper charger that does not communicate with the BMS, but terminates charging based on the voltage. Or a power supply capable of delivering 60V.
 
brum said:
Charging to 100% according to the BMS or charging until the BMS disables the charging? These are not the same if it has never marked the 100% charge point correctly.

My inverter will stop charging when the BMS reports a 100% charge. Even if the cells are at 50% actual charge.

To do the calibration you need a proper charger that does not communicate with the BMS, but terminates charging based on the voltage. Or a power supply capable of delivering 60V.
Click to expand...
I'm running a Sofar ME3000SP. I could maybe pull out the comms cable? I don't have a 60V charger
 
If your inverter can work in "open loop" mode you can likely do that. Set proper charging voltage limit. 57.6V should do the job. Monitor the moment when the cells start going over 3.4V to confirm your pack is in good balance. If it is - all cells will quickly go to 3.5V and the to 3.6V. And somewhere at that point, the BMS will disable the charging and set the SOC to 100%.
 
brum said:
If your inverter can work in "open loop" mode you can likely do that. Set proper charging voltage limit. 57.6V should do the job. Monitor the moment when the cells start going over 3.4V to confirm your pack is in good balance. If it is - all cells will quickly go to 3.5V and the to 3.6V. And somewhere at that point, the BMS will disable the charging and set the SOC to 100%.
Click to expand...
I'll have to investigate. I'm not sure what would happen if I pulled the Comms cable. I'll try to charge tomorrow without it and see what happens!
 
testtenor said:
It's been running for a few months charging at night up to 100%. That's why I want to check settings to make sure nothing is wrong or incorrect
Click to expand...
What has been the lowest SOC over the months you have been running?
Did you previously go down much lower or has this 24% lower limit alarm been a regular thing since commissioning?

As @brum mentioned, you need a proper full charge and top balance to happen.
I would suggest that you run the logging tool in the SEPLOS software and capture the data for the hours it takes to charge up completely, then create some graphs from that to see for sure what is happening.
 
Mariner62 said:
What has been the lowest SOC over the months you have been running?
Did you previously go down much lower or has this 24% lower limit alarm been a regular thing since commissioning?

As @brum mentioned, you need a proper full charge and top balance to happen.
I would suggest that you run the logging tool in the SEPLOS software and capture the data for the hours it takes to charge up completely, then create some graphs from that to see for sure what is happening.
Click to expand...
No it's been down to 15%. This is why I am just flagging it now, as it's a new thing
 
testtenor said:
No it's been down to 15%. This is why I am just flagging it now, as it's a new thing
Click to expand...
Right. It could just be a single rogue cell which is hitting the upper kneepoint early on the charge cycle. Get the data logged and have a look or post the file here.
 
I suppose it won't work just by pulling out the cable. The inverter will require a configuration change.

You may try an alternative approach directly to the BMS.

Option 1) Set the Ah capacity of the battery to a high value. Instead of 280Ah to 400Ah. This will prevent the BMS from stating that the batteries are charged at the old level and will lead to charging until the high voltage disconnect alarm pops up. The BMS will calibrate the 100% SOC point. Once the battery goes to low voltage disconnect this will calibrate the 0% SOC.

Option 2) Likely won't work, but you can try to set the SOC level when the battery is at 2.8/3V per cell. Set it to 1% and if you see that value on the display of the BMS you are good to go. It didn't work for me - the specified SOC value in the settings had no effect on the actual SOC that the BMS was calculating.
 
If the BMS cuts off on a SoC threshold, disable that in the checkboxes session of Upload Parameters. I did that.
 
Last edited:
More likely if the inverter cuts off on a SOC threshold. The Seplos BMS will cut on voltage levels only as far as I have seen.
 
brum said:
More likely if the inverter cuts off on a SOC threshold. The Seplos BMS will cut on voltage levels only as far as I have seen.
Click to expand...
So do you think it's worth trying @brums idea and setting it to 300ah+? Tricking both the BMS and the inverter to fully charge?
 
Are you asking me if my idea is worth trying? It looks like a simple and cheap approach to trick the system into fully charging the battery.
 
I can only check that in the evening, but it was a toggle near the bottom, with "SoC" in the name. Also use BatteryMonitor V2.1.9 just in case.
 
CrossStreet said:
I can only check that in the evening, but it was a toggle near the bottom, with "SoC" in the name. Also use BatteryMonitor V2.1.9 just in case.
Click to expand...
Ah. I'm not sure I can use 2.1.9 let me check. I'm logged in on 2.1.8 at the moment
 
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