Planemo Posted March 4, 2022 Share Posted March 4, 2022 Maybe @Seba or someone else can help with this... On the EUCW BMS data for the Z10, what are the + and - mV readings based on? Is it calculated from the average V of the 14 cells? Also, I have seen the icon for one of the cells being green. What does that mean? Cheers! Quote Link to comment Share on other sites More sharing options...
Seba Posted March 4, 2022 Share Posted March 4, 2022 (edited) 1 hour ago, Planemo said: On the EUCW BMS data for the Z10, what are the + and - mV readings based on? Is it calculated from the average V of the 14 cells? Exactly. This shows how much particular cell group is off the average cell voltage of entire battery. 1 hour ago, Planemo said: Also, I have seen the icon for one of the cells being green. What does that mean? This means that this cell group is being balanced (discharged by BMS balancing circuit) at the moment. But even if the cell group isn't displayed green, it doesn't mean that balancing is not active. Seems that some firmware versions doesn't report balancing status. Edited March 4, 2022 by Seba 1 Quote Link to comment Share on other sites More sharing options...
Planemo Posted March 4, 2022 Author Share Posted March 4, 2022 29 minutes ago, Seba said: Exactly. This shows how much particular cell group is off the average cell voltage of entire battery. awesome, cheers 29 minutes ago, Seba said: This means that this cell group is being balanced (discharged by BMS balancing circuit) at the moment. But even if the cell group isn't displayed green, it doesn't mean that balancing is not active. Seems that some firmware versions doesn't report balancing status. Wow, I didn't know the BMS would balance anything whilst not being 'charged'. Sounds pretty smart. That said maybe this is a benefit of the Z10 BMS always being 'live', with the downside being the phantom drain (which is the main reason I keep my eye on it!) Out of interest, what would you say is approaching the 'concerning' level with regards to the mV difference? Quote Link to comment Share on other sites More sharing options...
Chriull Posted March 4, 2022 Share Posted March 4, 2022 6 minutes ago, Planemo said: Wow, I didn't know the BMS would balance anything whilst not being 'charged'. Sounds pretty smart. That said maybe this is a benefit of the Z10 BMS always being 'live', with the downside being the phantom drain (which is the main reason I keep my eye on it!) This was my assumption that the balance resistor are _always_ active once the cell voltage is above 4.2V no matter if the charger is attached. As this makes sense to take care for cells (less time with voltage above 4.2V), increases balancing capability and reduces the need for balancing after green led. Would be great if you could share some observations when and hiw balancing is active. Maybe single cell voltages and balancing state can be logged? 6 minutes ago, Planemo said: Out of interest, what would you say is approaching the 'concerning' level with regards to the mV difference? Imho one main criteria is that by charging and waiting until all balancing resistors are turned off all cells should be in the 4.19 to 4.25V range. So just the measurement accuracy and switching hysteresis "allowed". I'm not sure if the bms have 0/+50mV, -50mV/0 or +/-50mV accuracy? If one regards the chargers voltage accuracy this range could shift a bit down? Maybe best to record/remember values once the battery was new and define these values as good/perfect. The second main criteria would be how much the cells differ discharged. So that no cell gets below 2.5V. First point could be for extended/"repaired" by repeatedly charging until green led shows up. And by discharging the battery less. Which would also help to ensure the second point. Quote Link to comment Share on other sites More sharing options...
Planemo Posted March 4, 2022 Author Share Posted March 4, 2022 (edited) 13 hours ago, Chriull said: This was my assumption that the balance resistor are _always_ active once the cell voltage is above 4.2V no matter if the charger is attached. Well....I had a 'green' cell in BMS2 in EUCW when the cell was showing 4.125v...... Weirdly, I had a cell at 4.137v in BMS1 (also the highest V out of 14) which wasn't green. It also had a higher imbalance than the green cell in BMS2....so I'm not sure whats going on! But I'm still not sure what mV difference would be considered concerning, everything may be fine, it might not, so I'm pi$$ing in the wind at the moment Edited March 5, 2022 by Planemo Quote Link to comment Share on other sites More sharing options...
Chriull Posted March 4, 2022 Share Posted March 4, 2022 1 hour ago, Planemo said: Well....I had a 'green' cell in BMS2 in EUCW when the cell was showing 4.125v...... Weirdly, I had a cell at 4.137v in BMS1 (also the highest V out of 14) which wasn't green. It also had a higher imbalance than the green cell in BMS1....so I'm not sure whats going on! That's not looking nice... At least i'd consider this counterproductive. But as your battery is still alive the possibility of sensor data misinterpretation is very high!? Quote Link to comment Share on other sites More sharing options...
Planemo Posted March 5, 2022 Author Share Posted March 5, 2022 Sorry typo there, I meant to say 'higher imbalance than the green cell in BMS2'. Edited and corrected now. I'm not convinced theres any problem with the cells at all tbh, I think I need to do some research into how much the imbalance in mV is considered 'normal'. 2 Quote Link to comment Share on other sites More sharing options...
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