Chriull Posted July 8, 2019 Share Posted July 8, 2019 12 minutes ago, Planemo said: I get the parallel thing. I am just unclear why they are not able to isolate each cell purely for the purposes of monitoring (some sort of gate/diode?) prior to being made up into whatever P is required. One would need to really split the cells from one another - like putting a mosfet inbetween the parallel cells. For measurement they would cut the connection, while riding the connection is established again. Would be a "mess" to wire such a pack up, imho reliability would decrease greatly - so one could monitor the state but decrease overall safety? Afaik the Teslas have some systems like this to disconnect some bad ?strands" from the battery system so they cannot disturb the other cells. But imho making such a thing on a per cell basis is in no way economical. Quote I cant help feeling that stating one knows the voltages of 60 cells from only 20 readings is a bit of a misnomer. Such a splitting up and isolating one not as good cell or just identifying it by monitoring would work out - also imho by now not economicly feasable. Also normaly the cells are tested and presorted by the battery manufacturers - so they should perform good in packs. Just from time to time it happens that one "bad"/not so good cell slips through into a pack. This one then dies together with their paralleled cells. But this is "bad luck" (cell got somehow damaged or slipped through the tests) or some manufacturer who used unmatched cells. For this cases the battery degradation happens quite "fast" and are (should be) covered by guarantee. Normal aging just happens that one parallel cell pack is a little bit weaker than the others - this is the one who gets discharged and charged most (gets highest and lowest voltages) and by this everytime a bit more stressed as the other cell packs. After enough time (charge cycles) all cells of such a paralleled pack are just dead. No need to know individual voltages or other state... Quote Sorry meep I just replied to Chriull, must have gone through just prior to you splitting the thread. Resplit your post again to this topic... 2 minutes ago, ir_fuel said: Unless there is some way in which 3 parallel cells still can push out 4.2V with one cell being dead of course. no. 1 1 Quote Link to comment Share on other sites More sharing options...
ir_fuel Posted July 8, 2019 Share Posted July 8, 2019 5 minutes ago, Chriull said: no. In that case testing per 3 cells seems more than sufficient. Quote Link to comment Share on other sites More sharing options...
Planemo Posted July 8, 2019 Share Posted July 8, 2019 Understood Chriull. So its really a case of packaging/cost/complexity/hoping to notice a problem before it escalates Vs Cost of replacing more than 1 cell/speedy diagnostics/identifying the exact cell/minimizing risk I appreciate your thoughts. In any event, I think ALL wheels should raise an alarm to the user when any voltage irregularities present themselves. Ninebot are sort of halfway there but only because of their odd regen system which shouldnt happen in the first place. At least we have Ninebattery to poke a little deeper. Not sure if other wheels have that ability though.. 1 Quote Link to comment Share on other sites More sharing options...
Jeff Earl Posted July 10, 2019 Author Share Posted July 10, 2019 I think what we need to do is to start a grass roots movement to get Elon Musk interested in EUCs. In addition to industry leading battery technology, Tesla has some interesting patent applications on robust communication systems for BMS control modules. This could be just the ticket for multi-pack EUC battery monitoring/maintenance. Or... We just need an enterprising EUC maker to license (a.k.a "borrow") the tech. Quote Link to comment Share on other sites More sharing options...
someguy152 Posted March 28, 2020 Share Posted March 28, 2020 On 7/6/2019 at 8:50 PM, Chriull said: Here are more than enough reports of 0V cells in battery packs - one has to cut open the packs to verify this! amen to that. can someone help me find a Kingsong 16S bms for my KS18s. ewheels doesn't have them and jason is not supporting the 18s anymore Quote Link to comment Share on other sites More sharing options...
Chriull Posted March 28, 2020 Share Posted March 28, 2020 43 minutes ago, someguy152 said: amen to that. can someone help me find a Kingsong 16S bms for my KS18s. ewheels doesn't have them and jason is not supporting the 18s anymore 1radwerkstatt.de has/announced great new bms with single cell coltage reports for their ?KS18XL?! Did not hear too much of them lately, but they sounded real good. 1 Quote Link to comment Share on other sites More sharing options...
someguy152 Posted March 28, 2020 Share Posted March 28, 2020 interesting i was scrolling thru reports by US69 saying it takes a whole lot of work to get a smartbms on an individual pack because they have to work in conjunction with the other packs, and US69 was saying 1radwerkstatt was the one having pains doing so. Quote Link to comment Share on other sites More sharing options...
Chriull Posted March 31, 2020 Share Posted March 31, 2020 (edited) On 3/28/2020 at 4:57 PM, someguy152 said: interesting i was scrolling thru reports by US69 saying it takes a whole lot of work to get a smartbms on an individual pack because they have to work in conjunction with the other packs, and US69 was saying 1radwerkstatt was the one having pains doing so. If you quote/mention @US69 or @1RadWerkstatt they get notified and can take a position to your statement. Unfortionately it got very quiet after the first reports of @1RadWerkstatt's smartbms I expected many positive reports - bms report of single bad cells is essential for safety and lacking by the normal used bms by now. i have no idea what's going on, if there are props or just no reports/reviews because there are no probs.... Who knows... li ion cells can be dangerous, but they seem to be quite stable by abuse. However every burning EUC battery pack in an apartment building leads to hazardous disaster. So imho we are in dire need ot such such smart bms! Edited March 31, 2020 by Chriull Quote Link to comment Share on other sites More sharing options...
WI_Hedgehog Posted March 31, 2020 Share Posted March 31, 2020 (edited) On 7/8/2019 at 8:14 AM, Planemo said: I get the parallel thing. I am just unclear why they are not able to isolate each cell purely for the purposes of monitoring (some sort of gate/diode?) prior to being made up into whatever P is required. I think the concern is each battery pack would have to be 1P to efficiently use a signal wire for every cell (around 144 or so). The Ninebot miniPro does this on 15S2P=30 cells, and the batteries are ridiculously expensive, though excellent quality... Since EUC battery packs are used in parallel, an economy of scale is realized by putting cells in parallel and reducing the number of signal wires and BMS units required. Average Voltage from each parallel cell bank is reported to the BMS. An improvement could be made wherein a BMS could use one signal wire to send a digital signal to the main board, and the main board would then know the voltage of each parallel bank in each battery. This isn't too complex*, in R/C we previously used one signal wire per servo, and now we use one communications buss for all servos, and "smart" servos. An EUC could similarly use a smart buss from each BMS to the mainboard (with a little filtering the signal could be sent over the DC line and no additional wires would be needed, only logic circuitry). In this manner, monitoring voltage per cell bank will show if a cell in a bank has gone bad and the remainder of the bank is making up for it. EUC World could track pre- and post-ride voltage (not during-ride voltage in order to minimize the amount of data) in order to show if a cell bank is not hanging in with the other banks, and could trigger a battery replacement notice. *This isn't super-simple either. Companies making EUCs service a relatively small market, so for them it's not a trivial undertaking, though it can be done with responsible, reasonable effort. Edited April 1, 2020 by WI_Hedgehog Quote Link to comment Share on other sites More sharing options...
someguy152 Posted April 1, 2020 Share Posted April 1, 2020 2 hours ago, Chriull said: If you quote/mention @US69 or @1RadWerkstatt they get notified and can take a position to your statement. Unfortionately it got very quiet after the first reports of @1RadWerkstatt's smartbms I expected many positive reports - bms report of single bad cells is essential for safety and lacking by the normal used bms by now. i have no idea what's going on, if there are props or just no reports/reviews because there are no probs.... Who knows... li ion cells can be dangerous, but they seem to be quite stable by abuse. However every burning EUC battery pack in an apartment building leads to hazardous disaster. So imho we are in dire need ot such such smart bms! so something i don't get is, for the general population who have these devices who aren't reading these forums but just go out and about with their devices with normal chargers, how would they ever really know that something is wrong with their battery besides noticing less range, cutouts, or the device stops taking a charge (or rarely, fire). I'm wondering if there's enough safeguards that kingsong or any manufacturer has in place for these batteries where for example , if a parallel pack does go to 0v without me knowing, can or will the charger and bms combo still charge the device safely and we can ride normally until the device stops taking a charge or the range is so much less that we investigate. are we just being too anal? I mean the device doesn't exactly need all 67 or so volts and can still run on less, right? Quote Link to comment Share on other sites More sharing options...
Chriull Posted April 1, 2020 Share Posted April 1, 2020 5 hours ago, someguy152 said: so something i don't get is, for the general population who have these devices who aren't reading these forums but just go out and about with their devices with normal chargers, how would they ever really know that something is wrong with their battery besides noticing less range, cutouts, or the device stops taking a charge (or rarely, fire). No. It's just the less range / power - leading to easier overleans. If one looks at the app one sees that it won't charge anymore to 100%. Driving is not too much fun anymore - so mostly people get new battery packs/a new wheel before the risk of fire gets too high? 5 hours ago, someguy152 said: I'm wondering if there's enough safeguards that kingsong or any manufacturer has in place for these batteries where for example , if a parallel pack does go to 0v without me knowing, can or will the charger and bms combo still charge the device safely No. But mostly nothing happens... * keepfingerscrossed* 5 hours ago, someguy152 said: and we can ride normally until the device stops taking a charge or the range is so much less that we investigate. Range will get noticable less. Power for driving should be noticable lower too? Only "real problem" should be second hand buyers who get an EUC with bad cells - they have no comparison and could believe that's normal... 5 hours ago, someguy152 said: are we just being too anal? I mean the device doesn't exactly need all 67 or so volts and can still run on less, right? Yes. As it can drive on low batteries, too. Which are 3.3V*16=52.8V Quote Link to comment Share on other sites More sharing options...
someguy152 Posted April 1, 2020 Share Posted April 1, 2020 7 hours ago, Chriull said: If one looks at the app one sees that it won't charge anymore to 100%. it depends on the app and when someone installs it. my darknessbot app measures 5% below my wheellog app for all 3 wheels. When i first got my wheels, i didn't even know of an app. mabye by the time i install it, i wouldn't be able to tell what 100% means. yes one can look at voltage, but for kingsong S wheels, they already measure 66 at full on the app. I can imagine ppl can look at the numbers and not know what full is. 7 hours ago, Chriull said: Driving is not too much fun anymore - so mostly people get new battery packs/a new wheel before the risk of fire gets too high? I wonder how long that will take to discern. If ur a casual rider, which i imagine most ppl to be, and ur wheel can do 20 to 30mph max, but you only usually go less than 75% of that, then i'd imagine it'll take a long time for you to experience that feeling of not having fun. The demographic of users on this forum I wonder if its representative of all people that buy these devices.. Maybe there's a lot of ppl who just run their devices to the ground instead of selling on the used market Quote Link to comment Share on other sites More sharing options...
WI_Hedgehog Posted April 1, 2020 Share Posted April 1, 2020 Just now, someguy152 said: The demographic of users on this forum I wonder if its representative of all people that buy these devices.. Maybe there's a lot of ppl who just run their devices to the ground instead of selling on the used market I haven't seen many used wheels for sale on eBay compared to the numbers being sold new. For instance, King Song alone said they make about 50 wheels per day, I'd guess Gotway probably double that--with all other manufacturers added in is a reasonable guess 300 EUCs are sold world-wide daily? Conversely, I've mainly found old, unused Ninebot S1 and One wheels and the like on eBay. That seems to suggest many people keep their wheels and ride them until the batteries expire or they break, then throw them away because the cost of repair isn't justified against the cost of replacement. It's unfortunate, as having a healthy and affordable used market would help people buy their first "beater" (learner) wheel and grow the popularity of EUCs. Quote Link to comment Share on other sites More sharing options...
someguy152 Posted April 1, 2020 Share Posted April 1, 2020 yea there's one user who constantly sells refurbished s1's. i have alerts for many of the wheels im interested in on ebay, so yes there arent a lot. Quote Link to comment Share on other sites More sharing options...
Giggi Posted April 2, 2020 Share Posted April 2, 2020 I menaged to buy an used ninebot s2 for 300€ and I am really enjoying riding it, but the app on android and iOS have some weakness I don't know if it's the same for e+ or other models... For example there are no way to turn the lights off and the lift off mode is bugged so it need to be turned off ... I expected more for a company that big software talking ... Quote Link to comment Share on other sites More sharing options...
someguy152 Posted April 2, 2020 Share Posted April 2, 2020 i got my 14s last week for $300, 840wh, 100miles. glad i had my alerts set up... a couple days later another one brand new went from $250 to 430 in the last 5 min of the auction. was very tempted to say the least. it's a phenomenal deal i think Quote Link to comment Share on other sites More sharing options...
WI_Hedgehog Posted April 2, 2020 Share Posted April 2, 2020 10 hours ago, someguy152 said: i got my 14s last week for $300, 840wh, 100miles. glad i had my alerts set up... a couple days later another one brand new went from $250 to 430 in the last 5 min of the auction. was very tempted to say the least. it's a phenomenal deal i think That is a phenomenal deal on both! Congratulations! I picked up a 14M slightly used for $390 shipped 2-day (though only 175Wh) and thought that was a great deal, though admittedly it was more of an impulse buy. I wanted something affordable for learning so I wasn't having that gut-wrenching feeling of dropping a $2,000 wheel. (Not to mention before buying a $2,000 wheel it made sense to get some experience on a wheel...and I may want to buy another older, not-top-end wheel used later on if only occasionally riding...) Back to the BMS, it's 1P, so if a cell fails... I hear 2P requires a firmware re-flash and $150 second battery...don't know if that's really worth it given the money is probably better invested in a newer/faster EUC with 4x the range, as most of the cost in buying one is the batteries. Which really begs the question if used is that great a deal, since the batteries are aged, and the newer EUCs have more safety features, better motors, better batteries... Quote Link to comment Share on other sites More sharing options...
alcatraz Posted April 3, 2020 Share Posted April 3, 2020 We really need a smart bms. Something that is independent from the wheel. It could log all the cell voltages and temperatures, have custom voltage thresholds and triggers for different warnings etc. All connectable through bluetooth. And a manual balance switch. If these bms's could be made compact and rugged enough, we'd never have to buy one. Just harvest ones from old packs. 1 Quote Link to comment Share on other sites More sharing options...
someguy152 Posted April 3, 2020 Share Posted April 3, 2020 this looks compact enough or 16s at least https://www.aliexpress.com/item/4000423794343.html?spm=a2g0o.productlist.0.0.cf811c8bDBsvQ6&algo_pvid=a03b3336-3f1a-4265-a0c9-7d158b68fb86&algo_expid=a03b3336-3f1a-4265-a0c9-7d158b68fb86-9&btsid=0ab6d59515859180575224557ec995&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_ wonder when we will start seeing them Quote Link to comment Share on other sites More sharing options...
someguy152 Posted April 3, 2020 Share Posted April 3, 2020 so if my motor/wheel is rated for 1200W, do i just take 1200/the voltage of my wheel to get the max current and then get a BMS rated for higher than that current? or do these W numbers not equal the maximum/peak W and that's the number i need to find. Quote Link to comment Share on other sites More sharing options...
Chriull Posted April 3, 2020 Share Posted April 3, 2020 3 hours ago, someguy152 said: so if my motor/wheel is rated for 1200W, do i just take 1200/the voltage of my wheel to get the max current and then get a BMS rated for higher than that current? 3 hours ago, someguy152 said: or do these W numbers not equal the maximum/peak W and that's the number i need to find. Exactly. For example the KS16S has a motor rated 1200W, has a 30A fuse (30A*67.2V~2000W) and the BMS most probably (hopefully) an even higher cut off current. BMS current cut off is meant to be a short circuit protection. 2 Quote Link to comment Share on other sites More sharing options...
alcatraz Posted April 4, 2020 Share Posted April 4, 2020 (edited) Ohh, I forgot to add current sensing and logging for that smart bms. I'd rather trust those numbers than those from the euc app. Euc numbers aren't consistent. I would love to know the max temp and max current with time stamps for any given ride. Another feature could be really loud warning piezo elements that you could program to signal you when certain conditions are true. Living in a toasty place worried of heat? Set a heat alarm. Worried about max lean on a climb? Set a current alarm. Worried about those old cells in a certain cell group dropping under a certain voltage sometime during your ride? Set a cell group low limit voltage alarm. Worried about overcharging when going downhill on a charged pack? Set a cell group top limit voltage alarm. There aren't any cutouts here. Just very very very loud alarms and some kind of self diagnostic to ensure the board is functioning normally. Another nice feature would be ability to connect and control a heat element for better winter riding. Edited April 4, 2020 by alcatraz Quote Link to comment Share on other sites More sharing options...
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