alcatraz Posted May 8 Share Posted May 8 You seem quite enthusiastic about working on the wheel. That's why I suggested the simplest solution of manual periodic balancing. You just need to install balancing wires for it to be convenient without taking much apart. The only problem is you have to keep the wheel. It's too risky to give away. 1 Quote Link to comment Share on other sites More sharing options...
Boris Lämpel Posted May 8 Share Posted May 8 I rode without a working BMS communication for around 1 year. I really cannot advice You replacing the ninebot BMS as long as it tells the firmware everything is ok. You can install the firmware "no BMS" (somewhat like that ist was called) by MRN67. I had it in my ninebot, after the communication between BMS and mainboard did not work anymore. As soon the firmware detects any BMS issue it will make a complete tiltback, so that You can´t ride anymore. With the firmware You can ride again. But with every harder acceleration (and therefore voltage drop) You will get limited because the wheel thinks the battery is empty. Because of the small battery this even happens at full charge. That´s really anoying. I can´t remember anymore: Do you have 2 BMS wire connections (for both batteries)? Then maybe You can flash it to the Z6 firmware (where the wheel has only 1 battery). But with the missing BMS connection You won´t have joy to ride anymore... 1 Quote Link to comment Share on other sites More sharing options...
matthijs Posted May 9 Author Share Posted May 9 On 5/8/2024 at 3:46 AM, alcatraz said: Yes but the broken bms will still possibly handle something depending on how that bms is designed. I didnt understand the difference between a BMS and balancing board, hence my somewhat bad assumptions. However, with the assumption the BMS is okay and still does all the protection (which I somewhat assume, regarding that the statistics of the BMS still read fine), an added 2x 7s balancing board would take care of the balancing. As this option is cheap and allows me to drive with more "peace-of-mind" Ill give this a shot, because as On 5/8/2024 at 11:24 AM, Boris Lämpel said: As soon the firmware detects any BMS issue it will make a complete tiltback, so that You can´t ride anymore. said, having the BMS disabled is kind-of a no-go with the Z10 sadly. If the added balancing board doesn't fit my needs ill consider switching it over to the working BMS, But I hope this will be the end of it and I can start riding again. I thank you for your advice. Ill give an update once it all has come together! 1 Quote Link to comment Share on other sites More sharing options...
alcatraz Posted May 10 Share Posted May 10 Cool. Just one last heads up. The balancing boards can fail so it would be smart to add external balancing wires that cou can probe. Be careful how you install the wires so they don't short out or wear the isolation. These balancing boards do not balance completely, just crudely. So you can expect a 100% charge to yield cells above 4.20v. 4.25v is a safe max voltage. You should figure out how long it takes for the pack to reach 4.25v on ANY cell. When you first install the balancing boards it will look good but over time it'll deviate. Why? Because balancing stops at 0.03v between two cell groups. Not at 0.001v as what we're used to think a balancer does. Your bms screenshots earliet in the thread indicate to me that cell group 14 will exceed 4.25v first. Groups 8-14 will all be at a higher voltage than 1-7 because you're using two bms in series, and 8-14 generally have higher avg voltage (lower capacity/more wear). When you learn which group is your weak group (like group 14) you just measure that one after a 100% charge. If it's over 4.25v then even with the balancing boards, you need to manually balance. This is the problem with 100% charging. On my broken V8 I still have overcharge protection. You do not seem to have it since we saw a group at 4.27v earlier. This is a concern. Monitor after every charge, if ok then every few charges etc. These balancing boards work the best if you don't charge to 100%. If you charge to like 90% you don't have to worry so much. Having an imbalance isn't dangerous while riding unless you're outside the range of 4.2-3.3v. Quote Link to comment Share on other sites More sharing options...
matthijs Posted 9 hours ago Author Share Posted 9 hours ago On 5/10/2024 at 2:53 AM, alcatraz said: Just one last heads up. Hey! I just received the 2 balancing boards, so I will go ahead with the procedure. Thank you for your comments, ill keep them into account. I will keep the Battery attached to the internal Z10 BMS, which is a smart BMS and allows me to keep an eye on the internal voltages after charging even after the balancing board is added. I will alter the output voltage of my charger to prevent any over-charging. The impact on the range will be minimal, but the impact on safety even larger. Thank you for your great advice and help! I will report back once the boards are installed and I have initial results gathered. Quote Link to comment Share on other sites More sharing options...
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