BSLblatt online/offline issues

DIY
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1

Hello All

We have an issue with our BSLblatt battery system - we have three batteries in total that we connected in parallel, for the intercommunication we use the RS485 Ports 4/5 and from the master battery the right cable to our cerbo GX. Basically after starting up all batteries and checking the cerbo, it shows all batteries and says that all three modules are online and 0 offline. Also - when putting the inverter on it keeps on being 3 online and 0 offline. The issue arises from the moment that we connect our pv arrays to our mppt, where it will jump from 3 online to 3 offline (battery being “idle” in the main overview, as its charged to 100% i think? ). After then disconnecting the Pv array again and the inverter starts to pull current from the batteries, it changes to 1 online and 2 offline, meaning that current is blocked from two of the three batteries. I really don’t understand why/what is happening.

Thanks in advance for the help!

2

Could you please give us some information about your system, perhaps with a diagram?

3

Have you followed the setup guide thoroughly?

Batteries will protect if you try overcharge them. Something that shouldn’t be possible on a properly configured system.

You haven’t provided any detail or config, so it is guesswork.

5

ok - i’ll read again through the setup thoroughly and try to find possible errors, i’ll let you know afterwards

6

Great, it is usually something obvious that is missed. These things tend to work if all the steps are followed.

7

Hi - so I indeed missed some configurations (i mainly followed the pdf manual for the 5.1kwh batteries since we have three of those) the only thing I am hesitating about in the whole configuration manual is the float voltage that they tell me to put which is 54.8V. However we have the BSLBATT B-LFP48-100E 3U and on the battery manual it says a float voltage of 54.5. which one do i need to use? the absorption voltage on the manual is also 55 like in the configuration pdf and absorption time i do not find in the battery manual so i put the 1h as told. Thanks again for all the help!

8

The battery will override the manual settings in the inverter/charger

9

Have a few banks running on the bsl and victron recommended settings and they are fine, system is stable, no online offline issues.

The BMS does indeed keep it to the 54.5v.

10

Ok - so I put in the mppt and in the multiplus settings a float voltage of 54.5 - just to confirm, I can leave it as such? I am a bit confused by the answers so a clear yes or no will clear everything up haha :slight_smile:

11

Yes :slight_smile:

12

ok Thanks! I’ll monitor the system now - the batteries are at 90 percent and this afternoon I closed the DC switches to connect the solar panels and it was charging while all three stayed online - so i think it works! — hopefully this will stay even when batteries are fully charged :folded_hands:

13

Hi all - so the same problem occurred today - I do have more information about the status so I made quite a long explanation to not miss any information - it would be amazing if somebody could help!

Update after completing the configuration

Following the advice here, I went through the BSLBATT/Victron configuration again and configured the system according to the documentation for my batteries. After doing this, everything initially appeared to work correctly.

I have three BSLBATT 51.2 V / 100 Ah batteries connected in parallel.

Yesterday evening, when there was no longer any PV production, all three batteries were online and discharged together normally. They remained 3 online / 0 offline overnight.

This morning, when PV production started again, all three batteries remained online and charged together normally. Everything therefore appeared to be working correctly both during charging and discharging.

The strange behaviour started when the batteries reached 100% SOC.

At that point, the batteries stopped accepting charge and eventually the GX showed the batteries as offline. Looking at the LEDs on the individual batteries and comparing them with the BSLBATT user manual, the indication appeared to correspond to overcharge protection. There were no ALM indications.

While there was still sufficient PV production this was not immediately a problem, because the MPPTs were supplying the loads and the batteries were essentially idle.

However, this evening, when PV production disappeared and the system needed battery power again, only one of the three batteries came back online and started discharging. The GX currently reports:

1 battery online / 2 batteries offline

The battery parameters still show the complete 300 Ah installed capacity, but the two offline batteries are shown as blocked from both charging and discharging.

Looking directly at the LEDs on the batteries gives some additional information. The middle battery, which is currently online, shows the RUN-light pattern corresponding to normal discharge operation. The upper and lower batteries show the RUN-light pattern corresponding to normal standby operation. None of the three batteries shows an ALM indication.

What confuses me is that this does not seem like a straightforward DIP-switch, RS485/CAN communication or addressing problem. The exact same configuration successfully had all three batteries online simultaneously, all three discharged together yesterday evening, remained online overnight, and all three charged together this morning. The abnormal behaviour only appeared after the bank reached 100% SOC and entered the protection/idle state.

So my question is: is it normal for individual BSLBATT modules to remain in standby/offline after reaching 100% while another module resumes discharging, or should all three modules normally leave this state and resume discharging together?

If this is not normal, what would you recommend checking specifically? Could this be related to the individual BMS protection/recovery thresholds or cell balancing at high SOC rather than the DIP-switch/communication configuration?

14

No settings are not likely to be wrong.
Dip settings either wotk or they don’t. So if they were and then aren’t then its now a BMS issue.

The clue is when you reach full. There is a protection thatvis being triggered. It is weird that it is both charging and discharge that is being disabled. Usually at full it is just vharge that is disabled/blocked.

Load up the advanced widget for the bms in vrm and check cell voltages there

Sencond thing are they connected daisy chained? Or are they individually connected to a bus bar?

Normally when middle battery stays on and end ones are off it is a current sharing problem.

15

Thanks, that makes sense.

The batteries are connected in parallel using 50 mm² cables in a diagonal/end-to-end configuration: the positive busbar is connected to the upper battery, all positives are interconnected, all negatives are interconnected, and the negative busbar is connected to the bottom battery.

I will check the advanced BMS widget and monitor the cell voltages more closely when approaching full charge.

One thing I have already noticed is that at around 80% SOC, the difference between the highest and lowest cell voltage was very small. However, when the batteries reached 100%, the difference became significantly larger. This seems to fit with the fact that the problem only appears at full charge and that the BMS then enters overcharge protection.

So I am wondering whether one or more cells are reaching the upper-voltage protection threshold before the others, causing the BMS to block the affected modules.

I will monitor the cell voltages during the next charge towards 100% and report what happens.

16

I managed to retrieve the BMS data from VRM for the charging event yesterday. before this event all was working perfectly with three batteries online as already said before.

Around 09:40–10:00 , the maximum cell voltage increased significantly compared with the minimum cell voltage. The maximum reached about 3.55 V, while the minimum was around 3.36–3.37 V, giving a difference of roughly 180–190 mV.

During the same period, the BMS progressively reduced the Charge Current Limit (CCL):

09:42 – 120 A
09:51 – 80 A
09:53 – 40 A
09:56 – 8 A
and shortly afterwards it appears to have gone to 0 A.

The Charge Voltage Limit remained at 55.0 V and the Discharge Current Limit at 300 A.

At approximately the same time, the actual battery charging current also dropped significantly.

EDIT : as a matter of fact - the batteries only block charge when being at full 100% SOC the discharge is not blocked. I interpreted the values wrong. Discharge has not been blocked until now i think. However as said before the upper and middle battery do stay in standby mode and do not discharge.

17

You need to get a call opened with your supplier. They need to get logs from the BMS and see what is going on.

Personally, never been a fan of BSL and the horrid PACE BMS they use, it has had too many issues for the various battery brands that have used it.

CCL=0 at top of charge is pretty common for plenty of batteries, though not the ideal or preferred way of doing it.

The pack shouldn’t go offline though and near 200mv delta is too high, even at top of charge.

In the meanwhile you could force a slightly lower CVL with DVCC.

When I stopped using BSL, they seemed to be incapable of determining an accurate SOC or indeed keeping packs balanced, but they were good value for money and I suppose that comes with compromise.

18

Ok thanks - I will contact the supplier. In the meantime, if no alarms are present in the system, can I just leave it working as is or is it better to only connect 1 battery for now until the problem is resolved ? And what CVL do you recommend that i force onto the system (value now 55)? I’m not sure though that I can change the CVL as this was greyed out, but i’ll check again if i return home.

19

If nothing is complaining, keep calm and carry on.

Make small incremental reductions, if the problem persists, make a bigger one.