Popular Post Marty Backe Posted June 15, 2019 Author Popular Post Share Posted June 15, 2019 6 minutes ago, US69 said: You know ...i dont want to „bash anything“.....as you have no problem crapping on Gotway , i also have no problem of praising them, lately for example for thor very nice MOS 247 boards on the MSX and Monster.....but now pushing this hole problem to a tiny bit of plastic eveidence and say it was workmanship of the one putting the board together......hmmh......who of us knows if this tiny plastic part is not just coming exaxtly from these mosfets blowing.....just partly melting a layer „off“ of from the other „heat conduction“ stripe thing? Just one question, which then i really would like to have explained: What about the totally steady and ongoing over Amperage warnings you received? You said yourself that you never, never ever before, received such ongoing warnings of beeing always over 90Amps on ANY wheel at all at overheat hill, not even on other Gotways, while with the Nicola it allready started at „baby test hill“....the very first heavy climb? Isnt that alone piece of evidence enough? Alone in the video...as you over and over said „please dont blow a Mosfet“ ....i guess you already sensed that the ongoing vibration on your pebble and the steady „over 90amps“ beeps from the bluetooth were not „normal“.... so why now trying to overly protect this blow as „poor workmansship“? For Me the poor workmanship was in the decission to step back to the small mosfets...and that even while on a wheel that seams to be needing a lot more amperage than even the bigger size wheels like MSX..... I inspected the board and thermal conduction material very closely. You're just going to have to believe me when I say it is extra material. It did not melt from any other parts of the control board. I firmly believe that this is a failure of workmanship not design. It's coincidental that the wheel is also apparently using a lot of current. Maybe it's my engineering background that leads me to follow the evidence. We will have to agree to disagree on this. Peace 7 1 Quote Link to comment Share on other sites More sharing options...
Dzlchef Posted June 15, 2019 Share Posted June 15, 2019 1 hour ago, Rama Douglas said: Well, if you wanna burn some mileage, I get off work around 4:30 today from Beverly Hills...I'll be riding a bit after...hit me up! 😎 I wish. All of my managers are out and the last remaining is sick so I'm here until late. I do have my Nikola so it'll be an evening light show on way home tonight! 1 Quote Link to comment Share on other sites More sharing options...
Dzlchef Posted June 15, 2019 Share Posted June 15, 2019 19 minutes ago, Marty Backe said: I inspected the board and thermal conduction material very closely. You're just going to have to believe me when I say it is extra material. It did not melt from any other parts of the control board. I firmly believe that this is a failure of workmanship not design. It's coincidental that the wheel is also apparently using a lot of current. Maybe it's my engineering background that leads me to follow the evidence. We will have to agree to disagree on this. Peace If there is a foreign object that is the path of failure then I totally agree with Marty. If it wasn't under that stress then it would have failed at a different time. He's lucky for the slow speed failure. 2 1 Quote Link to comment Share on other sites More sharing options...
Popular Post Mrd777 Posted June 15, 2019 Popular Post Share Posted June 15, 2019 56 minutes ago, Rainu said: Hey guys, does anyone know, has only the nikola plus the better mosfets or also the 100v 1230wh nikola (not plus)? Or in other words, has only the 84v nikola the poorer mosfets? I have the 1230wh 100volt Nikola. I should open it up this week to inspect the board. Do we have comparative photos of the To-227 board, to the 84v version? 5 Quote Link to comment Share on other sites More sharing options...
Popular Post US69 Posted June 15, 2019 Popular Post Share Posted June 15, 2019 17 minutes ago, Marty Backe said: I inspected the board and thermal conduction material very closely. You're just going to have to believe me when I say it is extra material. It did not melt from any other parts of the control board. I firmly believe that this is a failure of workmanship not design. It's coincidental that the wheel is also apparently using a lot of current. Maybe it's my engineering background that leads me to follow the evidence. We will have to agree to disagree on this. Peace Peace as always.....yeah, just disagreeing on that.... my -software engineering- background leads me to follow the -not coincidental- other evidence....steady high amperage alarms on small mosfets... 6 2 Quote Link to comment Share on other sites More sharing options...
Marty Backe Posted June 15, 2019 Author Share Posted June 15, 2019 27 minutes ago, Mrd777 said: I have the 1230wh 100volt Nikola. I should open it up this week to inspect the board. Do we have comparative photos of the To-227 board, to the 84v version? The bigger MOSFETs are huge in comparison. But I don't have a Nikola picture. Quote Link to comment Share on other sites More sharing options...
Chriull Posted June 15, 2019 Share Posted June 15, 2019 1 hour ago, US69 said: but now pushing this hole problem to a tiny bit of plastic eveidence and say it was workmanship of the one putting the board together. For instance PET has about 20-50 times the thermal resustance than thermal paste - leading to 20-50 times the temperature drop per Watt... 1 hour ago, US69 said: What about the totally steady and ongoing over Amperage warnings you received? You said yourself that you never, never ever before, received such ongoing warnings of beeing always over 90Amps on ANY wheel at all at overheat hill, not even on other Gotways, while with the Nicola it allready started at „baby test hill“....the very first heavy climb? Did not get this point to this full extend before - higher currents more often with "smaller" mosfets... Poor mosfets! Additionally with prevented/hindered cooling... @Marty Backe - got the nikola so much more "aggressive/reactive? Just top speed motor power did not make such a big leap compared to the last models? Another explanation for much higher currents could be a higher lift cut off speed and/or a bit slower driving speed? The smaller Mofets can not be the readon for the current, they just fry earlier... ... or by some new firmware version the reported current is a bit more off than it was before? 1 Quote Link to comment Share on other sites More sharing options...
Popular Post eddiemoy Posted June 16, 2019 Popular Post Share Posted June 16, 2019 1 hour ago, US69 said: You know ...i dont want to „bash anything“.....as you have no problem crapping on Gotway , i also have no problem of praising them, lately for example for thor very nice MOS 247 boards on the MSX and Monster.....but now pushing this hole problem to a tiny bit of plastic eveidence and say it was workmanship of the one putting the board together......hmmh......who of us knows if this tiny plastic part is not just coming exaxtly from these mosfets blowing.....just partly melting a layer „off“ of from the other „heat conduction“ stripe thing? Just one question, which then i really would like to have explained: What about the totally steady and ongoing over Amperage warnings you received? You said yourself that you never, never ever before, received such ongoing warnings of beeing always over 90Amps on ANY wheel at all at overheat hill, not even on other Gotways, while with the Nicola it allready started at „baby test hill“....the very first heavy climb? Isnt that alone piece of evidence enough? Alone in the video...as you over and over said „please dont blow a Mosfet“ ....i guess you already sensed that the ongoing vibration on your pebble and the steady „over 90amps“ beeps from the bluetooth were not „normal“.... so why now trying to overly protect this blow as „poor workmansship“? For Me the poor workmanship was in the decission to step back to the small mosfets...and that even while on a wheel that seams to be needing a lot more amperage than even the bigger size wheels like MSX..... I think the smaller mosfets with proper cooling they added might be fine. It is when they don't get rid of the excess heat they blow up. with the plastic not removed from the silicone thermal sheet, those mosfets are isolated since plastic is a poor conductor. The problem is we don't know now for sure if it would have blown a mosfet even with the more aggressive algorithm. Looks like @Marty Backe should try the over heat hill again after making sure the new board is kosher. 4 Quote Link to comment Share on other sites More sharing options...
Popular Post US69 Posted June 16, 2019 Popular Post Share Posted June 16, 2019 22 minutes ago, Chriull said: Did not get this point to this full extend before - higher currents more often with "smaller" mosfets... Poor mosfets! Additionally with prevented/hindered cooling... @Marty Backe - got the nikola so much more "aggressive/reactive? Just top speed motor power did not make such a big leap compared to the last models? Another explanation for much higher currents could be a higher lift cut off speed and/or a bit slower driving speed? The smaller Mofets can not be the readon for the current, they just fry earlier... ... or by some new firmware version the reported current is a bit more off than it was before? Just to make it clear... The Nikola in comparison to other wheels he Tested has been nearly on all hills, even the small ones, over his 90amp warnings. No other GW wheel did this on these hills. So my point is that the Nikola -for the nice torque it has- produces/needs more amps than for example the MSX....and because of that steady high amperage blow a Mosfet...my opinion at least! And yeah, thats what a lot of people report...great torque on the Nikola for such a „big“ tire size. So that’s exactly the point i make...Because of the higher amount of torque-amps the relative smaller type Mosfet is a design mistake. 6 1 Quote Link to comment Share on other sites More sharing options...
Popular Post meepmeepmayer Posted June 16, 2019 Popular Post Share Posted June 16, 2019 (edited) 1 hour ago, Mrd777 said: Do we have comparative photos of the To-227 board, to the 84v version? Here's a picture of the TO-247 package in the MCM5 (on the bottom right). They're so big, you can't confuse the different types. The black casings nearly touch each other. 25 minutes ago, eddiemoy said: Looks like @Marty Backe should try the over heat hill again after making sure the new board is kosher. I wasn't going to ask as I guess Marty has no interest in doing this. But since you mentioned it... - I'm too wondering if it was only a build quality problem, or if the wheel would have fried anyways due to design. That unusually high current needs to be explained. Edited June 16, 2019 by meepmeepmayer 4 1 Quote Link to comment Share on other sites More sharing options...
wheelr Posted June 16, 2019 Share Posted June 16, 2019 1 hour ago, US69 said: Whatever: It was clearly a mistake to use the small MOS again..... 2 hours ago, Marty Backe said: I firmly believe that this is a failure of workmanship not design. Gentlemen, your observations aren't mutually exclusive. And I hope Marty will repeat this test with a correctly assembled version of the Nikola. Sorry Marty but you have become our go to test dummy 3 Quote Link to comment Share on other sites More sharing options...
Dzlchef Posted June 16, 2019 Share Posted June 16, 2019 And to think that he tried to get me to ride with him on Friday. That would have answered the question of workmanship versus design but I enjoy riding my Nikola and don't have a stable with 11 wheels to choose. 1 Quote Link to comment Share on other sites More sharing options...
Marty Backe Posted June 16, 2019 Author Share Posted June 16, 2019 47 minutes ago, eddiemoy said: I think the smaller mosfets with proper cooling they added might be fine. It is when they don't get rid of the excess heat they blow up. with the plastic not removed from the silicone thermal sheet, those mosfets are isolated since plastic is a poor conductor. The problem is we don't know now for sure if it would have blown a mosfet even with the more aggressive algorithm. Looks like @Marty Backe should try the over heat hill again after making sure the new board is kosher. Unfortunately I'm not sure if this is something that can be inspected without disassembling the board - something I have no interest in doing. But I may take it up the hill again 3 Quote Link to comment Share on other sites More sharing options...
Popular Post Marty Backe Posted June 16, 2019 Author Popular Post Share Posted June 16, 2019 13 minutes ago, wheelr said: Gentlemen, your observations aren't mutually exclusive. And I hope Marty will repeat this test with a correctly assembled version of the Nikola. Sorry Marty but you have become our go to test dummy Maybe I should take donations 5 3 Quote Link to comment Share on other sites More sharing options...
Marty Backe Posted June 16, 2019 Author Share Posted June 16, 2019 3 minutes ago, Dzlchef said: And to think that he tried to get me to ride with him on Friday. That would have answered the question of workmanship versus design but I enjoy riding my Nikola and don't have a stable with 11 wheels to choose. If you had joined me it would have been a mellow Glendora Mountain Road ride But in hindsight I'm glad I found the weak point in my wheel. When I get the new board I should be good for anything 1 Quote Link to comment Share on other sites More sharing options...
Marty Backe Posted June 16, 2019 Author Share Posted June 16, 2019 46 minutes ago, US69 said: Just to make it clear... The Nikola in comparison to other wheels he Tested has been nearly on all hills, even the small ones, over his 90amp warnings. No other GW wheel did this on these hills. So my point is that the Nikola -for the nice torque it has- produces/needs more amps than for example the MSX....and because of that steady high amperage blow a Mosfet...my opinion at least! And yeah, thats what a lot of people report...great torque on the Nikola for such a „big“ tire size. So that’s exactly the point i make...Because of the higher amount of torque-amps the relative smaller type Mosfet is a design mistake. Yes, the excess current will blow the MOSFET if the MOSFET does not have a proper heatsink. Quote Link to comment Share on other sites More sharing options...
maltocs Posted June 16, 2019 Share Posted June 16, 2019 9 hours ago, Afeez Kay said: Get the Gotway Tesla.. simples 😁 I'm looking for a 1600WH+ wheel, unless you know of bigger battery Tesla that I don't know about. Quote Link to comment Share on other sites More sharing options...
LZMutant Posted June 16, 2019 Share Posted June 16, 2019 5 hours ago, Marty Backe said: Unfortunately I'm not sure if this is something that can be inspected without disassembling the board - something I have no interest in doing. But I may take it up the hill again I'm sure you'll be so curious you'll want to take it back up, but... This is your personal wheel as well as your personal skull. As an observer I'm certainly curious as to what would happen if you took your Nikola 84V back up but you know what? You've done enough, IMO. I'll survive if I never learn the answer to the burning question, "Will Marty climb Overheat Hill on his rebuilt Nikola without self-immolating?" And if you do decide to return to the mound maybe it'll be after some more empirical evidence throughout the web-o-sphere suggests that your issues were a one-off. Perhaps some other intrepid Nikola owners will challenge similar summits successfully, confirming your diagnosis of a one-off shoddy tear-off of some plastic? Anyway, looking forward to the video of you doing the climb on your Nikola again next month... 2 Quote Link to comment Share on other sites More sharing options...
esaj Posted June 16, 2019 Share Posted June 16, 2019 8 hours ago, meepmeepmayer said: Here's a picture of the TO-247 package in the MCM5 (on the bottom right). They're so big, you can't confuse the different types. The black casings nearly touch each other. You do know that TO-247 is the "medium"-size? Plus probably there are some more special case / less standardized packages that are even bigger. Not that that big packages would be needed (at least yet), outside this incident, the mosfets frying on overheating have been very few in the last couple of years, or at least I don't remember that much cases compared to before that (when boards sometimes seemed to be popping left and right ). The paralleled (12 mosfet) setups have been criticized by power electronics designers before, saying that a single larger package and/or better rated mosfet should be used instead. Likely it's all about the $$$, cheaper to add a couple of smaller and/or poorer rated mosfets than one larger and/or with better specs. 2 1 Quote Link to comment Share on other sites More sharing options...
LucasD Posted June 16, 2019 Share Posted June 16, 2019 It is simply both the design and poor workmanship. Poor workmanship - all 3 blow up mosfets has this plastic leftover, whereas others don't. So high current made them overheat and finally blow-up. Poor design because it seems Nikola demands more amps so better to have bigger mosfets, they by size alone would also survive longer. Yet there was still a high chance if left with this plastic insulator they would blow up few minutes later... 1 1 Quote Link to comment Share on other sites More sharing options...
Popular Post Chriull Posted June 16, 2019 Popular Post Share Posted June 16, 2019 Just made it through the topic, since i got things like the often high current alarms a bit late, to look for maybe other points missed... Here some points gathered On 6/11/2019 at 8:02 PM, Mike Sacristan said: Nikola 1600: 100km Nikola 2100: 131km Nikola 1230: 76km Nikola 1845: 115km For the 100V version, especially the 1230Wh - does anyone know how the battery configuration is? 24s4p with ~3500mAh cells or 24s6p with ~2300mAh cells? Especially with the high current demand reported hopefully it's a 24s6p configuration - 4p could already be borderline by too much voltage sag? On 6/15/2019 at 10:19 AM, Seba said: You're right. It also seems that there is no temperature probe near the radiator or MOSFETs. This is a major design flaw, as PCB temperature where temp probe is apparently located in Nikola, being additionally cooled by the fan located on wrong side, doesn't reflect MOSFET tab or package temperature. This is why @Marty Backe got misleading, very low temperature readings. For example, in KS-18L/XL there is a temperature probe located close to the heatsink and MOSFET that is farthest from the cooling fan. This is why L/XL may be perceived as a "hot running wheel". Nikola wasn't "cold running wheel", it was just a "very hot running wheel with low temp readings". 23 hours ago, meepmeepmayer said: MSX: didn't even get hot. Robust beyond all doubt, as seen from @EUC GUY's videos (car push test + mountain test like Marty's hill, but longer).. MCM5: didn't even get hot. 18S: juuuust made it to the top without overheating. 18XL: overheated shortly before the top. Runs quite hot in general. V10F: overheated shortly before the top. Z10: I forgot, but I believe it overheated. I hope I remember correctly. Thank you again Marty for all the tests. Gotway seem to have some way/tradition of "hiding" their Mosfet/heatsink temperatures and by this seem to be the most "performant" at the hill test - until the mosfet fuse blows. V10F is the other extrem - imho the only one measuring the heatsink temperature and giving an overheat alarm before every other wheel. 20 hours ago, Rehab1 said: Yes it appears that GW is using thermal pads instead of paste. Most experts state that paste is more effective than the pads as it fills in all of the microscopic pores between MOSFET and the heat sink. I hate thermal paste as it is messy to work with. For paste and pads the thermal resistances vary with about a factor of 10 (over maybe even more - did just a quick check...), depending on the "quality" choosen. With the paste one has to use some insulation plate (mica plate/disc) and apply a continously _as thin as possible_ paste film on _both_ sides of the mica disc, or the thermal conductivity is not guaranteed. 20 hours ago, Rehab1 said: The additional downside for the thermal pads is they need to be replaced each time the MOSFETs are unscrewed from the heatsink or the heat transfer properties will be diminished. This is true for thermal paste and insulation, too. 18 hours ago, Seba said: You can't use paste in this case, because metal tab of each MOSFET is electrically connected with center pin (so called "drain"). You can also notice a plastic insulation sleeves used to insulate thermal tab from the screw (that is electrically connected to the radiator). As written above - mica plates (as i was used too in "ancient" times) would be a possibility. But with the manufacturering quality control probs that's no possibility - imho thermal pads (of good quality) are sufficient and the best choice with at least some chance to be applied correctly. As it seems by now there exists pads with protective (?plastic?) foil - so they found a way to even spill this easy method... 20 hours ago, Jon Stern said: Thermal gap pads are very effective, but only if sufficient compression force is applied. The thermal resistance quoted by the manufacturer is with a certain amount of compression. That's the next "problem" - the right compression is needed in any case. Too low of a force and there is no good contact, too much force and the mosfet "bends up" at the body part, were good contact would be most important! Most manufacturers recommend spring clips to prevent this problem and get a good, sufficient and evenly distributed pressure - especially at the most important points! Spring clips have the additional advantage, that no plastic insulation parts are needed to insulate the screws - as (some) plastic could "creep" over time and the pressure gets "lost". 18 hours ago, Marty Backe said: Thanks :-) Unfortunately I did not have WheelLog configured for logging. I'll try to remember to turn on logging on my future wheel tests. That's a pity - would be great to have logs of all tested wheels at overheat hill! 18 hours ago, Marty Backe said: I don't think there's much to learn from opening the wheel. To get access to the MOSFETs is pretty much a destructive process. All of the wiring on mine looked great. 12 hours ago, eddiemoy said: Looks like @Marty Backe should try the over heat hill again after making sure the new board is kosher. 11 hours ago, Marty Backe said: Unfortunately I'm not sure if this is something that can be inspected without disassembling the board - something I have no interest in doing. But I may take it up the hill again As one sees on Rehabs foto below, at least the "outside" row of mosfets should be easy to inspect. One could even peek under the thermal foil if there is some plastic foil forgotten. Just the "inner" row hidden by PCB and heatsink will be tricky to inspect - but maybe using some flashlight and peeking inside (?with a mirror?) could reveal some "reflections" of forgotten plastic foils? 20 hours ago, Rehab1 said: 3 3 Quote Link to comment Share on other sites More sharing options...
Harold Farrenkopf Posted June 16, 2019 Share Posted June 16, 2019 (edited) That plastic sheet looks like there were two pulls of the plastic in the process of removal. One pull from one side and they noticed it ripped and then they went to the other end and pulled it and it ripped again but the thought that they got it all when in fact they left a piece in the middle. Just extremely poor training/workmanship or care. They likely pulled it too fast. The assembler needs to be better at quality control and realize that is a critical component that needs to be done right. they likely have the boards sourced out and the final assembly process did the error of pulling the film off too fast. I’d be concerned that this may not be a one off error with this assembler. What was the production number? Edited June 16, 2019 by Harold Farrenkopf 2 1 Quote Link to comment Share on other sites More sharing options...
Mike Sacristan Posted June 16, 2019 Share Posted June 16, 2019 1 hour ago, Chriull said: For the 100V version, especially the 1230Wh - does anyone know how the battery configuration is? 24s4p with ~3500mAh cells or 24s6p with ~2300mAh cells? Especially with the high current demand reported hopefully it's a 24s6p configuration - 4p could already be borderline by too much voltage sag? I asked this question in the speed reduction thread and @meepmeepmayer answered that the 1230Wh is 24s4p. This holds true for the MSX as well and we have an MSX rider on the forum who is experiencing beeps at around 35mph on his 100V 120Wh MSX. He seems to ride very fast and aggressively though. This is in line with the 53 km/h "minimum speed" for the 100v MSX. 1 Quote Link to comment Share on other sites More sharing options...
Popular Post Boogieman Posted June 16, 2019 Popular Post Share Posted June 16, 2019 (edited) Regarding thermal paste/pads. Wouldn't ordinary high grade CPU paste (silver) be great. On Cpu's you only apply a, small Central Dot and apply pressure to have a thin layer. Why all the mica yada yada layers and stuff? Heat trans is the goal right? On the other hand, if Gotway made an error, return wheel and Sue their asses. You guys shouldn't be "free developers" because they are lazy and want to make quick bucks. Not to mention the danger. I like EUCs but not that some Chinese firm want to push their product to make cash, playing with the buyers "health". Thank God we have this forum. I normally wait one year to make sure initial flaws are gone. Thanks to all the heroes here that take the blow and try this out to push manufacturers to stop making shortcuts. Edited June 16, 2019 by Boogieman 4 2 Quote Link to comment Share on other sites More sharing options...
Popular Post esaj Posted June 16, 2019 Popular Post Share Posted June 16, 2019 (edited) 10 minutes ago, Boogieman said: Regarding thermal paste/pads. Wouldn't ordinary high grade CPU paste (silver) be great. On Cpu's you only apply a, small Central Dot and apply pressure to have a thin layer. Why all the mica yada yada layers and stuff? Heat trans is the goal right? The mosfets need to be electrically insulated from the metallic heatsink, as discussed at least a couple of times already, last time maybe a couple of pages ago... Quote On the other hand, if Gotway made an error, return wheel and Sue their asses. You guys shouldn't be "free developers" because they are lazy and want to make quick bucks. Not to mention the danger. I agree otherwise, but good luck suing a Chinese company out-of-pocket from abroad. Hope you have very deep pockets Quote I like EUCs but not that some Chinese firm want to push their product to make cash, playing with the buyers "health". Thank God we have this forum. I normally wait one year to make sure initial flaws are gone. Thanks to all the heroes here that take the blow and try this out to push manufacturers to stop making shortcuts. Yeah, it's not a bad idea to wait for a few batches so the initial, ahem, "mishaps" get sorted out. Then again, if nobody ever bought a new model, the manufacturers wouldn't make them... Plus even a "proven" model that has faithfully carried you for a long time can fail on you out-of-the-blue for a multitude of reasons. Gear up. A vehicle with a single wheel totally dependent on a bunch of electronics and batteries to keep you from hitting the pavement any instant can never be 100% safe. It's a risk every rider needs to factor in and decide whether it's "worth it". Edited June 16, 2019 by esaj 5 2 Quote Link to comment Share on other sites More sharing options...
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