Deon Zeelie Posted April 24, 2023 Share Posted April 24, 2023 I needs some info on my BSL 7.2 kwh batteries that's discharging unevenly. my system 2x7.2 bsl' 5&4 months old,connected with comms cable to each other and connected to orange Pi. 8kw Rct max connected to Pi. 16x365 w PV with all the necessary switchgear to connect the system. Normally my system drain to around 30-40%, however on the one day it dropped from 30% to 9 % with no significant load. See Pi data below. What could cause this? Battery 2, the newer now keeps on discharging faster Quote Link to comment Share on other sites More sharing options...
mzezman Posted April 24, 2023 Share Posted April 24, 2023 How are they connected to the inverter? How do the positive and negative cables connect Quote Link to comment Share on other sites More sharing options...
Deon Zeelie Posted April 24, 2023 Author Share Posted April 24, 2023 Parallel to each other then to inverter, running like this since December Quote Link to comment Share on other sites More sharing options...
Deon Zeelie Posted April 24, 2023 Author Share Posted April 24, 2023 Crimped ringlugs, not to sure what you meant Quote Link to comment Share on other sites More sharing options...
mzezman Posted April 24, 2023 Share Posted April 24, 2023 Does the positive from inverter go to battery 1 while the negative goes to battery 2? It seems battery 2 is working harder which could be caused by cabling? If not then it could be a cell or BMS issue zsde 1 Quote Link to comment Share on other sites More sharing options...
Deon Zeelie Posted April 24, 2023 Author Share Posted April 24, 2023 No from inverter both +&- goes to battery 1 and then jumped to battery 2 Quote Link to comment Share on other sites More sharing options...
zsde Posted April 24, 2023 Share Posted April 24, 2023 What @mzezmanis getting at is that you should test by moving either the + or the minus to Battery #2. Quote Link to comment Share on other sites More sharing options...
Deon Zeelie Posted April 24, 2023 Author Share Posted April 24, 2023 Thanks, Just done it after trolling the www, would wait for a full change tomorrow and see how it behave Quote Link to comment Share on other sites More sharing options...
Deon Zeelie Posted April 24, 2023 Author Share Posted April 24, 2023 Also rechecked the parallel cables for possible voltage drops across them 0v, the connections seems 100% Quote Link to comment Share on other sites More sharing options...
P1000 Posted April 25, 2023 Share Posted April 25, 2023 (edited) I think there is possibly more than one issue. What voltage do you charge them to? Edited April 25, 2023 by P1000 Quote Link to comment Share on other sites More sharing options...
Deon Zeelie Posted April 25, 2023 Author Share Posted April 25, 2023 Below my settings Quote Link to comment Share on other sites More sharing options...
Sc00bs Posted April 25, 2023 Share Posted April 25, 2023 11 hours ago, Deon Zeelie said: No from inverter both +&- goes to battery 1 and then jumped to battery 2 That is probably the cause of your issue, the battery that is working harder is the with with the + & - connections to the inverter. You need to move either the positive or negative cable to the other battery terminal (not both). Quote Link to comment Share on other sites More sharing options...
Deon Zeelie Posted April 25, 2023 Author Share Posted April 25, 2023 did change them yesterday and will see what is does after a full charge. i have two exactly the same systems running for 5 months now and this one suddenly did this. will change the other system today as to your sketch just to be safe. Quote Link to comment Share on other sites More sharing options...
Deon Zeelie Posted April 25, 2023 Author Share Posted April 25, 2023 That is probably the cause of your issue, the battery that is working harder is the with with the + & - connections to the inverter. no its the one connected with the links, battery 2 my slave. Quote Link to comment Share on other sites More sharing options...
I84RiS Posted April 25, 2023 Share Posted April 25, 2023 On 2023/04/24 at 9:13 PM, Deon Zeelie said: I needs some info on my BSL 7.2 kwh batteries that's discharging unevenly. my system 2x7.2 bsl' 5&4 months old,connected with comms cable to each other and connected to orange Pi. 8kw Rct max connected to Pi. 16x365 w PV with all the necessary switchgear to connect the system. Normally my system drain to around 30-40%, however on the one day it dropped from 30% to 9 % with no significant load. See Pi data below. What could cause this? Battery 2, the newer now keeps on discharging faster Your one battery likely reached it low voltage disconnect point while the other battery was still above this level. This will explain the sudden drop as that battery will be reporting a near 0% SOC. Generally, while discharging the BMS will report the lowest SOC of an individual battery in the bank to the inverter while discharging (as opposed to the average SOC). Quote Link to comment Share on other sites More sharing options...
Deon Zeelie Posted April 25, 2023 Author Share Posted April 25, 2023 Thank you for the explanation, its a pity Solar Assistant doesn't graph the battery voltages independently, then it would be easy to confirm this. So there might be an issue with the second battery? Tonight it seems fine, will at some stage drain them to below 30% and see if the gap between discharge appears again Quote Link to comment Share on other sites More sharing options...
Deon Zeelie Posted April 25, 2023 Author Share Posted April 25, 2023 This is good news as it protects the batteries. enerally, while discharging the BMS will report the lowest SOC of an individual battery in the bank to the inverter while discharging (as opposed to the average SOC). I only looked on Solar Assistant and it reports the average, the graph and battery tab. Opening the battery tab gives individual values but seems thats not logged (maybe wrong) Quote Link to comment Share on other sites More sharing options...
frivan Posted April 25, 2023 Share Posted April 25, 2023 I found that if you don't charge to 100%, the SoC becomes inaccurate. Perhaps you should discharge and charge the batteries individually to get both to 100%. zsde 1 Quote Link to comment Share on other sites More sharing options...
Deon Zeelie Posted April 26, 2023 Author Share Posted April 26, 2023 6 hours ago, frivan said: I found that if you don't charge to 100%, the SoC becomes inaccurate. Perhaps you should discharge and charge the batteries individually to get both to 100%. Thank yoy.The batteries weren't fully charged as we had a cloudy day. Will now keep an eye on it when it happens again and just swirch to line to complete the charge Quote Link to comment Share on other sites More sharing options...
Deon Zeelie Posted May 9, 2023 Author Share Posted May 9, 2023 BSL updated battery firmware to 2.14, will monitor it for a couple of weeks Quote Link to comment Share on other sites More sharing options...
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