Here another BMS issue:

My laptop is fitted with 3 Li cells in series. Some times ago I noticed that they did not anymore get charged. The net adapter works fine as I could work with the laptop when connected. I suspected the charging circuit at fault and brought the laptop to a repair specialist. After investigation he announced that not the charging circuit is at fault but the BMS prevented charging. Since battery and BMS are an integrated unit, the whole unit must be replaced. That cost me a lot of money. I have these cells now at home and could very well charge them bypassing the BMS. I intend to use them in another application without BMS.

9 hours ago, Beat said:

Here another BMS issue:

My laptop is fitted with 3 Li cells in series. Some times ago I noticed that they did not anymore get charged. The net adapter works fine as I could work with the laptop when connected. I suspected the charging circuit at fault and brought the laptop to a repair specialist. After investigation he announced that not the charging circuit is at fault but the BMS prevented charging. Since battery and BMS are an integrated unit, the whole unit must be replaced. That cost me a lot of money. I have these cells now at home and could very well charge them bypassing the BMS. I intend to use them in another application without BMS.

Interesting that you indicate the battery cost a lot. The last time I replaced my older laptop I thought the price was very reasonable. 

A new issue with a BMS.

Some time ago I added an additional LEOCH 48100TB pack. It looks like an upgraded version as the BMS shows 103.8Ah capacity versus 100Ah on the 3 others. Also I noted a considerably lower internal resistance that results on higher de- and recharge currents.

Now its BMS goes havoc. While the other BMS i.e. show 36% SoC, this one shows 3%. While the packs are full on float voltage, 100% SoC, this one shows around 60%. On the other hand it correctly goes into cell balancing mode when voltage is at bulk level. I do not worry too much as I think the battery itself is OK. The current readings check out with a clamp DC Ammeter. I tried the BMS reset at full charge but no change.

Does anyone have a clue what make of BMS it is and how to solve the problem?

Here are the identity readings trough PmodbusToos:

SN 05921140018Z, Version P15S100A-0529-1.10

The 3 others have version P15S100A-8293-1.40

 

11 minutes ago, Beat said:

A new issue with a BMS.

Some time ago I added an additional LEOCH 48100TB pack. It looks like an upgraded version as the BMS shows 103.8Ah capacity versus 100Ah on the 3 others. Also I noted a considerably lower internal resistance that results on higher de- and recharge currents.

Now its BMS goes havoc. While the other BMS i.e. show 36% SoC, this one shows 3%. While the packs are full on float voltage, 100% SoC, this one shows around 60%. On the other hand it correctly goes into cell balancing mode when voltage is at bulk level. I do not worry too much as I think the battery itself is OK. The current readings check out with a clamp DC Ammeter. I tried the BMS reset at full charge but no change.

Does anyone have a clue what make of BMS it is and how to solve the problem?

Here are the identity readings trough PmodbusToos:

SN 05921140018Z, Version P15S100A-0529-1.10

The 3 others have version P15S100A-8293-1.40

 

The P15S100A looks like a hardware number. It then looks like the same hardware. 

How about connecting only the new battery now that there is no LS. See if it reaches 100%. I suggest disconnecting the old 3 when they show 100% and the new one 60%.

Then do a good discharge down to 15-20% or as close to disconnect as possible. Then recharge back to 100% before connecting the old 3 again. No need to keep at 100% because it seems the cells are balanced. 

Just a suggestion. 

Edited April 20, 20242 yr by Scorp007

22 hours ago, Scorp007 said:

Just a suggestion. 

Thank you for your considerations. That total discharge already happened accidentally together with all packs. Noting changed.

Some time ago I observed when its SoC suddenly switched from about 60% to almost 100% while approaching full charge voltage. But that didn't happen again. It looks like the SoC accounting is screwed up. I just don't pay attention to it, the inverters act on battery voltage. And the pack currents tell what's happening.

I thought it looks like a pace bms if I remember from reading this threaf months ago. Don't have time to reread now.

I run 3 LEOCH 48100TB packs in parallel for almost 5 years. So far no problem. Cycle count over 1500 on the oldest one, SoH still 100%.

Last year I gradually added 3 packs of the new type 48100S. They come with a different make of BMS.

It is not unexpected that they come with lower internal resistance. They discharge and charge with higher current than the older ones. However their BMS go weird. At instances they show SoC more than 30% lower than the older ones. These are in contradiction with the terminal voltage. As they all are connected in parallel they have the same terminal voltage. The SoC is related to the terminal voltage by the specific curve of LiFePh batteries. Readings could differ some % points due to measuring inaccuracies but not that much. Either readings are wrong - or both. I'm getting goose bumps by the idea of letting such BMS talk to the inverter.

There could be another explanation. It could mean that the packs real capacities are significantly higher than the specs indicate. Assuming the packs have 130Ah but the BMS is set for 100Ah. At discharge the BMS starts discounting Ah from 100 rather than from 130. This way its SoC reading remains about 30% lower than real SoC. That assumption would mean good news what battery capacity is concerned, but disturbing.

What do the experts think about this?

I would never estimate SOC on Voltage, it's very inaccurate due to the charge curve of batteries.

mV difference in voltage can be a massive difference in SOC.

On 2024/04/20 at 1:23 PM, Beat said:

A new issue with a BMS.

Some time ago I added an additional LEOCH 48100TB pack. It looks like an upgraded version as the BMS shows 103.8Ah capacity versus 100Ah on the 3 others. Also I noted a considerably lower internal resistance that results on higher de- and recharge currents.

Now its BMS goes havoc. While the other BMS i.e. show 36% SoC, this one shows 3%. While the packs are full on float voltage, 100% SoC, this one shows around 60%. On the other hand it correctly goes into cell balancing mode when voltage is at bulk level. I do not worry too much as I think the battery itself is OK. The current readings check out with a clamp DC Ammeter. I tried the BMS reset at full charge but no change.

Does anyone have a clue what make of BMS it is and how to solve the problem?

Here are the identity readings trough PmodbusToos:

SN 05921140018Z, Version P15S100A-0529-1.10

The 3 others have version P15S100A-8293-1.40

 

It is a PACE BMS.