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

[cajocars]

Hello,

I do not know what I'm doing wrong. But that doesn't look right to me.
My Victrons or the Seplos BMS does not charge my battery as I would like it to.

As can be seen in the graph, the charging power increases up to 100A and then drops down to 10A. This continues until the battery is fully charged.

Since the passive balancing of the Seplos can't keep up, I set the value "Monometer overvoltage protection" to 3,500 V in the Seplos. Otherwise one cell would constantly rise to 3,650 V while other cells are at around 3,400 V.

Anyone an idea what I'm doing wrong?

View attachment 156014

I suspect you might need to "enable" the constant voltage phase as described in this post https://diysolarforum.com/threads/seplos-can-bus-rs485-48v-200a-8s-16s-bms.20051/post-799740
(also read the 2 pages before and after)
Disabling the alarms seems to allow the inverter to go into constant voltage charge

By the way, I've done this and now I can't go back to how it used to work

 

[kingkiwi]

I suspect you might need to "enable" the constant voltage phase as described in this post https://diysolarforum.com/threads/seplos-can-bus-rs485-48v-200a-8s-16s-bms.20051/post-799740
(also read the 2 pages before and after)
Disabling the alarms seems to allow the inverter to go into constant voltage charge

By the way, I've done this and now I can't go back to how it used to work

Thanks for that. I will test it.

 

[duyvietstar]

Hello. I have bms 100A - old version. I have problem when charging. If i charge with big current, some cell will rise over 3.5v and previous cell is 3.2v. See the photo ( cell 2 and cell 3) sometimes is cell 5 and cell 6. I test and check by bms jk, then don't have this problem. So please help me.

 

[houseofancients]

Hello. I have bms 100A - old version. I have problem when charging. If i charge with big current, some cell will rise over 3.5v and previous cell is 3.2v. See the photo ( cell 2 and cell 3) sometimes is cell 5 and cell 6. I test and check by bms jk, then don't have this problem. So please help me. View attachment 158200

Have you top balanced your cells ?

 

[duyvietstar]

Have you top balanced your cells ?

yes, they have balanced. i use another Bms ( JK ) i didn't meet this problem

 

[brum]

If the problem exists only with high current charge/discharge - check your busbar connections. Cells seems pretty well balanced in most log entries, but there are entries with big deviations. So this seems to be either bad busbar connections (high connection resistance) or bad cells (high internal resistance).

If these are caused by busbar issues the problem is wide spread. On the screenshot there are 3 cells with high voltage and only 1 with low voltage. During charging high voltage is sign of bad busbar connection, so most of the cells seems to be with bad connections, not just single one.

Or it may be BMS failure to measure correctly cell voltages. More details are needed for proper analyze.

Is this a new battery? Can you post pictures of it?

 

[duyvietstar]

If the problem exists only with high current charge/discharge - check your busbar connections. Cells seems pretty well balanced in most log entries, but there are entries with big deviations. So this seems to be either bad busbar connections (high connection resistance) or bad cells (high internal resistance).

If these are caused by busbar issues the problem is wide spread. On the screenshot there are 3 cells with high voltage and only 1 with low voltage. During charging high voltage is sign of bad busbar connection, so most of the cells seems to be with bad connections, not just single one.

Or it may be BMS failure to measure correctly cell voltages. More details are needed for proper analyze.

Is this a new battery? Can you post pictures of it?

if you see carefully, you see 1 cell with low voltage when near cell with high voltage. the photo cell 2 low, cell 3 high, another case cell 5 low, cell 6 high. (all cell which use are new.)
i aslo test connect bms JK and seplos ( run together) and monitor by software ( seplos) and phone ( JK) charge with big current then only bms seplos have this problem ( cell voltagle on JK are equal )

 

[Sanwizard]

if you see carefully, you see 1 cell with low voltage when near cell with high voltage. the photo cell 2 low, cell 3 high, another case cell 5 low, cell 6 high. (all cell which use are new.)
i aslo test connect bms JK and seplos ( run together) and monitor by software ( seplos) and phone ( JK) charge with big current then only bms seplos have this problem ( cell voltagle on JK are equal )

Seplos uses a passive balance scheme, which does not work with high capacity cells. Do you have the 2amp active balance JK BMS? If so, that works much better with large cells.
You may want to swap around your cells to see if the problem stays with the cells, or the location. If it stays with the cells, then that would rule out your connections, and you may have to re-top balance. Perhaps swap in new cells if you have spares if a new top balance does not fix it. Or, drop your charge current.

 

[duyvietstar]

Seplos uses a passive balance scheme, which does not work with high capacity cells. Do you have the 2amp active balance JK BMS? If so, that works much better with large cells.
You may want to swap around your cells to see if the problem stays with the cells, or the location. If it stays with the cells, then that would rule out your connections, and you may have to re-top balance. Perhaps swap in new cells if you have spares if a new top balance does not fix it. Or, drop your charge current.

Thank you all. Maybe i find the problem. Today i checked alarm history again, i see not only charging big current but also charge current = 0, this problem still have. I replace voltagle cell sensor and charge, the problem don't have

 

[McSpud]

Guys,
Can any of you tell me why I don't have the usual options available to me in the Seplos Battery Monitor V2.1.9 software?
Most people say the use Sofar battery config here, but I don't see that option?
Trying to get a 16s Seplos BMS (EMU1101 PCBA-V16) to CAN bus communicate with a Solis S5-EH1P5K-L with 3014 / 3D0037 firmware.
Thanks!!

 

[cajocars]

For those who have tried disabling the alarms to get the inverter to go into constant voltage charging, what triggers 100% state of charge? My BMS now triggers 100% before reaching the constant voltage value (56V) and before reaching the monomer overvoltage protection (3.65V). The highest cell when it set itself to 100% was less than 3.5V.
Could it be that it uses Ah count?

 

[brum]

What was the highest cell voltage and the total pack voltage when the 100% SOC was reached?

 

[cajocars]

What was the highest cell voltage and the total pack voltage when the 100% SOC was reached?

Total pack 55.64V, highest cell 3.52V

I think I know what happened: if I look at the SoC reported by the inverter it was 100%, but if I look at the SoC reported by the BMS it was 99.5%.
The inverter only understands SoC as integer numbers, so I think it iterpreted 99.5% as 100% and stopped the charge.

This doesn't happen when the alarms are on because the BMS SoC gets stuck at around 98% and then "jumps" to 100% when the overvoltage is triggered.

 

[brum]

Same here. I don't care for the last 0.5%. What I care about is fully charging the battery. 3.5V per cell is more than enough. Getting this done without the BMS turning on and off the MOSFETs is good enough for me.

 

[cajocars]

Same here. I don't care for the last 0.5%. What I care about is fully charging the battery. 3.5V per cell is more than enough. Getting this done without the BMS turning on and off the MOSFETs is good enough for me.

The problem is that the SoC is based on Ah count, which can drift over time; so today I can reach 99.5% with 56V and some days later I could reach 99.5% with 55V

 

[copec]

Even the most sophisticated SoC algorithms can have significant error at times, I stumbled into a whole mass of scientific literature about it.

 

[brum]

The problem is that the SoC is based on Ah count, which can drift over time; so today I can reach 99.5% with 56V and some days later I could reach 99.5% with 55V

Yep, you may reach 99.5 at both voltages. But this is not a problem. This is still a fully charged battery.

The SOC gets recalibrated at several percentages. 98.2% is also a calibration point. If you are getting to 98.2 and over it on daily bases, your SOC will not drift with time.

 

[cajocars]

Yep, you may reach 99.5 at both voltages. But this is not a problem. This is still a fully charged battery.

The SOC gets recalibrated at several percentages. 98.2% is also a calibration point. If you are getting to 98.2 and over it on daily bases, your SOC will not drift with time.

But I might not get into the balancing stage (I’ve set balancing voltage over 3.45V).
At the moment it stays over 55.2V (3.45V per cell) for only one minute before reaching 99.5%. My active balancer only stays active for one minute per day and it’s not going to do much.

 

[Sanwizard]

But I might not get into the balancing stage (I’ve set balancing voltage over 3.45V).
At the moment it stays over 55.2V (3.45V per cell) for only one minute before reaching 99.5%. My active balancer only stays active for one minute per day and it’s not going to do much.

Can you set it to 3.4V to give it more time?

 

[brum]

But I might not get into the balancing stage (I’ve set balancing voltage over 3.45V).
At the moment it stays over 55.2V (3.45V per cell) for only one minute before reaching 99.5%. My active balancer only stays active for one minute per day and it’s not going to do much.

And what happens after it reaches 99.5% SOC? Does the voltage drop? Or it stays at 55V/56V until you demand energy from the battery?

Mine stays at the configured charging voltage. The voltage drops when the sun goes down and there is demand for energy.