Roadpower Posted May 30, 2021 Share Posted May 30, 2021 Thank you for the explanations. Quote Link to comment Share on other sites More sharing options...
Chriull Posted January 27, 2022 Author Share Posted January 27, 2022 As i just had a glimpse at the "Cycle satuator universal charger" manual from grin technologies/ebikes.ca There the state for lithium akkus a threshold for charge completion: "Once the current gets close to zero amps and falls below the Complete Amps threshold, the battery is full and the charger says Charge Complete." and their handling/explanation for cell balancing considering packs like we use for EUCs: "Cell Balancing With lithium packs, it can happen that the battery stops charging abruptly because the BMS circuitry has tripped from a cell overvoltage fault. If the battery's management circuit does cell balancing, then this high voltage cell will be bled down to a release voltage and then the charging will resume again. This process can sometimes repeat many times, especially if the pack was largely unbalanced. Even though the charger says "Charge Complete", it will still resume the top up charges as the BMS circuitry allows so that the pack can fully balance out." Quote Link to comment Share on other sites More sharing options...
goatman Posted January 27, 2022 Share Posted January 27, 2022 (edited) you can ask Grin for the factories seconds Satiator ( they failed the waterproof test) for a considerable savings if you dont need waterproof Edited January 27, 2022 by goatman Quote Link to comment Share on other sites More sharing options...
alcatraz Posted January 29, 2022 Share Posted January 29, 2022 Don't know if this has been mentioned but there are max/min voltages not only for the pack as a whole but at the cell group level as well. My V8 doesn't turn on if a cell group is below 3v. I manually charge it above 3v and the wheel turns on. Another thing I'd like to point out is that the weak groups might not have different capacity, but different self discharge (internal resistance). While other groups stay at their voltage, the weak group always pulls downward even when just idling. The longer the time between balancing, the greater the imbalance. I have two such groups in my V8 and this wheel is reliable. It's just that I need to manually balance that pack. The bms can't do it no matter if I keep it 24h on the charger. (I suspect it doesn't balance at all). This wheel is not a fire hazard. The cells have never been over 4.25v or below 2.5v. They just have different self discharge imbalances. Quote Link to comment Share on other sites More sharing options...
RagingGrandpa Posted January 29, 2022 Share Posted January 29, 2022 13 hours ago, alcatraz said: This wheel is not a fire hazard. All cobalt-type Li-Ion cells are a fire hazard. Your self-discharging cells even moreso. 13 hours ago, alcatraz said: self discharge (internal resistance) Cell resistance and self-discharge are separate things. Resistance affects the cell only during loading. Self-discharge affects the cell during storage. Your EUC may work normally and last a long time, but don't kid yourself that it's risk-free. 2 Quote Link to comment Share on other sites More sharing options...
alcatraz Posted January 30, 2022 Share Posted January 30, 2022 (edited) No packs are risk free sir. With monitoring you're essentially safe. We've grown accustomed to having zero insight to what's going on inside our packs. That's what you should be critisizing, not minor imbalances. The self discharge has not accelerated at all in 3 years. I feel safer with this pack than a brand new mystery pack because with this one I know what's going on. I suspect the self discharge is a result of corrosion. I discarded a few cells with slight corrosion before I rebuilt the pack. I even did the self discharge test before assembling the pack. (Charged to 4.20v and let them sit for 2 months. Discarded anything that stood out.) 👍 If anyone says "my wheel is reliable", I need to remember that trick you just did = "Don't kid yourself". Because no pack is risk-free. Which is true. I guess in some eyes I'm like a bomb de-arming technician. Do you think people that keep their wheels outside or in unheated space realize the temperature changes ensure moisture slowly going into their wheels? Then they sell it to some poor guy after years of that going on. We all kid ourselves basically. Minimize risk is a good aim. Eliminate risk is just a dream. Edited January 30, 2022 by alcatraz 1 Quote Link to comment Share on other sites More sharing options...
goatman Posted January 31, 2022 Share Posted January 31, 2022 if you store your pack at 3.2v its less likely to start the self discharging process than at 3.7v, its a shame your wheel wont let you go to 2.5v theres less capacity per 0.1v from 2.5v to 2.7v with an active cell balancer it more accurately balances down low than you could ever get up high at 4.2v. trying to balance older cells at 4.2v throws the pack out of balance and shouldnt be done. if youre worried about corrosion spray the nickelstrip with plasti=dip, works great Quote Link to comment Share on other sites More sharing options...
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