Mono Posted August 18, 2023 Share Posted August 18, 2023 On 8/5/2023 at 9:28 AM, v8nice said: problems with the battery which does not charge to the maximum (between 83.5 and 84v) I am surprised you would think that charging to "only" 83.5V is a problem. On 8/6/2023 at 12:09 AM, Chriull said: Edit: PS: in wheels with not too much cells in parallel single cells were more easily overburdened and by this faster degraded. By this higher p count can give batteries a longer live by less burden. Isn't this completely independent of whether cells are in series or in parallel? 100W is 100W is 100W, after all. Or do you mean that a weak cell when put in series is more stressed when put in parallel? Quote Link to comment Share on other sites More sharing options...
RagingGrandpa Posted August 18, 2023 Author Share Posted August 18, 2023 (edited) On 8/5/2023 at 3:28 AM, v8nice said: problems with the battery which does not charge to the maximum (between 83.5 and 84v) 1 hour ago, Mono said: I am surprised you would think that charging to "only" 83.5V is a problem. No; he meant 83.5V is part of the normal range. Inability to charge to 83.0 warrants investigation. Lower than 82.0 is very concerning. On 8/5/2023 at 6:09 PM, Chriull said: By this higher p count can give batteries a longer live by less burden. 1 hour ago, Mono said: Isn't this completely independent of whether cells are in series or in parallel? 100W is 100W is 100W, after all. Individual cells don't know "power"; only current. An EUC drawing 100W from 20s2p is putting only half the current on each cell, compared to 20s1p. Therefore the 20s1p pack is more "stressed" by this 100W, and ages much more quickly. And then to compare two theoretical packs of the same capacity, 20s2p vs 40s1p, cell current becomes equal again, for the same 100W motor power. But the 40s pack will be more difficult to keep equalized during its lifetime. Cell condition variation in the 2p pack is "averaged" across pairs of cells; but in the 1p pack, any single cell's problem will stand out, with no help from neighboring cells. Edited August 18, 2023 by RagingGrandpa 2 1 Quote Link to comment Share on other sites More sharing options...
mhpr262 Posted August 19, 2023 Share Posted August 19, 2023 22 hours ago, RagingGrandpa said: and ages much more quickly I think that depends entirely on the current, how long it flows and how much heat is generated. Unless you draw so much that the tabs burn through, or you draw so much for so long that the battery overheats the amount of current you draw doesnt affect the lifespan of the battery. Quote Link to comment Share on other sites More sharing options...
rcgldr Posted Sunday at 04:23 PM Share Posted Sunday at 04:23 PM (edited) I just bought an 18XL V2 (spiked pedals, mini-power pads (protrusions at front and back of upper pads), received it on April 25, 2024 , and I used the KingSong app to monitor a full charge with the stock charger. When the stock charger LED turned green, the app showed voltage fluctuate between 84.02 and 84.05 volts, with current mostly at -0.00 amps, and an intermittent pulse of about -0.25 amps every 5 to 10 seconds. I assume this is evidence of the 18XL doing passive cell balancing, reducing current to the pack to near 0 amps, to let the 100 ohm resistors drain the highest voltage cell groups, then intermittently enabling a small current once the highest voltage group drops below some voltage threshold to do a small charge to the entire pack, repeating this cycle as needed to balance the pack. On my V8F with the stock charger, once it shuts off current due to some voltage threshold of some cell group, it slowly discharges over the next 8 hours to 82.5 volts before it reenables charging, taking about 20 minutes to reach that voltage threshold where it shuts off charging and repeats the 8 hour 20 minute cycle. The resistors are 1000 ohms versus 18XL (and other KIngSong EUCs) 100 ohms. It's possible that this is some type of balancing that slowly discharges the entire pack, as opposed to the 18XL where the voltage stays above 84 volts while it s apparently balancing the pack. I think this is the point brought up in Wrong Way's video about Inmotion BMS not having passive cell balancing. I also have an eWheels rapid charger, but it goes into standby and shuts off charging when current transitions below 0.3 amps, which would prevent the 18XL from balancing. What I did for my 18XL was use the eWheels charger to get 18XL to 82 volts, then I switched to the stock charger. Edited Sunday at 04:25 PM by rcgldr Quote Link to comment Share on other sites More sharing options...
Chriull Posted Monday at 07:17 AM Share Posted Monday at 07:17 AM 14 hours ago, rcgldr said: I assume this is evidence of the 18XL doing passive cell balancing, reducing current to the pack to near 0 amps, to let the 100 ohm resistors drain the highest voltage cell groups, then intermittently enabling a small current once the highest voltage group drops below some voltage threshold to do a small charge to the entire pack, repeating this cycle as needed to balance the pack. Bms charge stop happens once a cell groups voltage exceeds some 4.25V and charging is restarted once this cell groups voltage drops below some 4.19 ... 4.2V. This takes more like many hours to a day to discharge than 5-10 seconds. These current pulses are more likely some cpu activity on the motherboard (?capacitor recharging to support the cpu?) 14 hours ago, rcgldr said: also have an eWheels rapid charger, but it goes into standby and shuts off charging when current transitions below 0.3 amps, which would prevent the 18XL from balancing. That's exactly how li ion battery chargers should behave (according to the cell manufacturers ).Prevent endless trickle charging and allow the important final step of balancing once the charger is disconnected! Quote Link to comment Share on other sites More sharing options...
rcgldr Posted Monday at 09:54 AM Share Posted Monday at 09:54 AM (edited) 8 hours ago, Chriull said: Bms charge stop happens once a cell groups voltage exceeds some 4.25V and charging is restarted once this cell groups voltage drops below some 4.19 ... 4.2V. This takes more like many hours to a day to discharge than 5-10 seconds. My main point was that 18XL voltage remained constant, fluctuating between 84.02 to 84.05 volts for 5 or more hours, with the stock charger. 8 hours ago, Chriull said: < Charger shuts off once below 0.3 amp That's exactly how li ion battery chargers should behave (according to the cell manufacturers ).Prevent endless trickle charging and allow the important final step of balancing once the charger is disconnected! Passive cell balancing occurs while the charger is outputting voltage and current, not after charger shuts off. Take a look at Wrong Ways' video again: Edited Monday at 03:38 PM by rcgldr Quote Link to comment Share on other sites More sharing options...
Krb73 Posted Monday at 12:48 PM Share Posted Monday at 12:48 PM Raging Grandpa u seem to know slot I really am new at repairing these euc and I really could use some help Quote Link to comment Share on other sites More sharing options...
Chriull Posted Monday at 07:43 PM Share Posted Monday at 07:43 PM 9 hours ago, rcgldr said: Passive cell balancing occurs while the charger is outputting voltage and current, not after charger shuts off. Seems like a wrong way Quote Link to comment Share on other sites More sharing options...
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