esaj Posted March 17, 2017 Share Posted March 17, 2017 2 hours ago, Rehab1 said: Here is the Temperature Data Logger I will be installing on the ACM heat sink. It should be interesting to see the the amount of heat that is being generated and absorbed by the heat sink. Is there a separate heat sensor in that thing or is that it? If the sensor's inside of that device casing, the plastics will probably act as an insulator so it will take a while for the readings to actually match the real temperatures. Don't get me wrong, it's not a bad idea, but mounting an actual heat sensor in direct contact with the heatsink (as close to the mosfets as possible) would probably work better. Link to comment Share on other sites More sharing options...
Rehab1 Posted March 17, 2017 Share Posted March 17, 2017 21 minutes ago, esaj said: Is there a separate heat sensor in that thing or is that it? If the sensor's inside of that device casing, the plastics will probably act as an insulator so it will take a while for the readings to actually match the real temperatures. Don't get me wrong, it's not a bad idea, but mounting an actual heat sensor in direct contact with the heatsink (as close to the mosfets as possible) would probably work better. The temp data logger is self contained! It opens up like a thumb drive and plugs directly into a USB port. The temperature recording is very accurate (tolerance +- 1 degree). Over the past year I have been researching using these on patients with scoliosis braces to determine if they are compliant in their wearing schedule. I set the device at 98.6 degrees so we know the actual time the brace is worn. I have been impressed with the data gathering. I agree that it is best to have the device in direct contact with the heat sink. A data logger with a heat probe where the module could be mounted externally on the wheel's outer shell would be ideal but removing the outer shell is relatively quick so I will evaluate this method first. Link to comment Share on other sites More sharing options...
esaj Posted March 17, 2017 Share Posted March 17, 2017 13 minutes ago, Rehab1 said: The temp data logger is self contained! It opens up like a thumb drive and plugs directly into a USB port. The temperature recording is very accurate (tolerance +- 1 degree). Over the past year I have been researching using these on patients with scoliosis braces to determine if they are compliant in their wearing schedule. I set the device at 98.6 degrees so we know the actual time the brace is worn. I have been impressed with the data gathering. I agree that it is best to have the device in direct contact with the heat sink. A data logger with a heat probe where the module could be mounted externally on the wheel's outer shell would be ideal but removing the outer shell is relatively quick so I will evaluate this method first. One thing that crossed my mind is that I have no idea what the "dangerous" level of temperature is, even if measured from the heatsink. The internals of the mosfets should be kept below 125...150C or so, but what the temperature will be on the mosfet case surface or at the heatsink at that point, I have no idea So... you ride it until the mosfets blow and then take the reading? Link to comment Share on other sites More sharing options...
Marty Backe Posted March 17, 2017 Share Posted March 17, 2017 12 minutes ago, esaj said: One thing that crossed my mind is that I have no idea what the "dangerous" level of temperature is, even if measured from the heatsink. The internals of the mosfets should be kept below 125...150C or so, but what the temperature will be on the mosfet case surface or at the heatsink at that point, I have no idea So... you ride it until the mosfets blow and then take the reading? We know that the current Gotway wheels will tilt-back and stop when the board temperature reaches 79c. So I really don't see how temperatures could destroy a board directly. I don't think we have any direct proof that high temperatures have caused any failures. We surmise that that's the case, but we really don't know. All we know is that cable connections have broken. Is that because of heat or cold solder joints and vibration, or a combination of the two? Link to comment Share on other sites More sharing options...
meepmeepmayer Posted March 17, 2017 Author Share Posted March 17, 2017 12 minutes ago, esaj said: So... you ride it until the mosfets blow and then take the reading? One positive result is that we now have some kind of empiric information instead of guessing. What exactly that information will be is to be seen. Specific to mountain riding (or maybe for GW in general lol?), this might currently be the only option to see what the wheels can do (surely it would be better if they just warn you instead of break but well...). @Marty Backe Haha, a second wheel would certainly be nice. Will you pay if I order one? How about the coming 2000 Wh KS18, or a 16S? You buy two of each and send me one of each Link to comment Share on other sites More sharing options...
esaj Posted March 17, 2017 Share Posted March 17, 2017 14 minutes ago, Marty Backe said: We know that the current Gotway wheels will tilt-back and stop when the board temperature reaches 79c. So I really don't see how temperatures could destroy a board directly. I don't think we have any direct proof that high temperatures have caused any failures. We surmise that that's the case, but we really don't know. All we know is that cable connections have broken. Is that because of heat or cold solder joints and vibration, or a combination of the two? Don't know about the current situation, but in the past we've had numerous reports of mosfets failures, typically in situations where high currents are demanded or high power is used for a longer while. Likely, the temperature at least plays a role here, but of course we can't be sure. Two ways come to mind how the temperature affects mosfet breakdown are the rising Rds(on) (resistance at full conduction, ie. the power loss over the mosfets goes up, causing it to heat more, causing it to resist more, causing it to loose more power and heat more, ie. a self-destructing chain-reaction) and the lowering Vgs(th). The latter is a more complicated situation, the Vgs(th) is the threshold voltage of the gate-to-source where the mosfet will begin to conduct. Usually this is something like 2...4V, but as the mosfet heats up, it goes down. The failure would then be caused by the lowered threshold voltage keeping the mosfet still conducting due to residual gate-charge (the gate acts similar to a small capacitor) while the other side of the half-bridge opens, causing a bridge shoot through. But it's pretty hard to prove without fairly precise measurements from the half-bridge when the breakdown occurs... Also, we don't know where the board-temperature is measured from. Older generation Gotways had the app-data in similar format as what the MPU-6050 gyro uses, and they also used exactly those gyros, so it's possible they read the temperature from the gyro (which is usually relatively far from the mosfets). Link to comment Share on other sites More sharing options...
US69 Posted March 17, 2017 Share Posted March 17, 2017 I have the idea, that melted motor connections had shorted/melt together.and then so burned the board....would explain the locked wheel also! that was exactly what happened to one of zlymex friends on a V3....(first thread december)so same reason for fault...but different/worse outcome as just a disconnection..... we will see... @esaj we did not have one blown mosfet report here from a GW 12 mosfet board....but as long as meepmeep dont open...its. all guessing Link to comment Share on other sites More sharing options...
US69 Posted March 17, 2017 Share Posted March 17, 2017 here it was: Link to comment Share on other sites More sharing options...
esaj Posted March 17, 2017 Share Posted March 17, 2017 27 minutes ago, KingSong69 said: I have the idea, that melted motor connections had shorted/melt together.and then so burned the board....would explain the locked wheel also! that was exactly what happened to one of zlymex friends on a V3....(first thread december)so same reason for fault...but different/worse outcome as just a disconnection..... we will see... @esaj we did not have one blown mosfet report here from a GW 12 mosfet board....but as long as meepmeep dont open...its. all guessing Hopefully it's just a loose connector that's touching the connector of another phase that causes the motor to brake if you try to turn it. Before, when we had no connectors coming loose (), the motor getting "stuck" was a typical dead giveaway of broken mosfets shorting the phases. Link to comment Share on other sites More sharing options...
Rehab1 Posted March 17, 2017 Share Posted March 17, 2017 46 minutes ago, esaj said: Hopefully it's just a loose connector that's touching the connector of another phase that causes the motor to brake if you try to turn it. Before, when we had no connectors coming loose (), the motor getting "stuck" was a typical dead giveaway of broken mosfets shorting the phases. I hope @meepmeepmayer can access his motor connectors. I cannot peal back the inner shells on my ACM to view the motor. The Gotway video on YouTube depicts the shells easily coming loose once the screws are removed. Not mine! Wondering if the 1300 and 1600 models come apart differently? Any suggestions? Link to comment Share on other sites More sharing options...
Hunka Hunka Burning Love Posted March 17, 2017 Share Posted March 17, 2017 Again, you must use the word "good" as an adjective! Did you double check that you got all the screws, even the hidden ones just above the battery? If I had a nickel for every time I tried to brute force something open only to discover oh there's a screw I forgot to undo, well, I'd have me an ACM16 by now. Link to comment Share on other sites More sharing options...
Rehab1 Posted March 17, 2017 Share Posted March 17, 2017 1 hour ago, esaj said: So... you ride it until the mosfets blow and then take the reading? I don't want the title of 'Guinea Pig! You do have a point! I know the FLIR camera has not produced the quantifiable results everyone had hoped for. Mounting the data logger directly on the mosfet heat sink should produce satisfactory evidence based data but what we do with the results after that is a $60k question! Link to comment Share on other sites More sharing options...
esaj Posted March 17, 2017 Share Posted March 17, 2017 8 minutes ago, Rehab1 said: I hope @meepmeepmayer can access his motor connectors. I cannot peal back the inner shells on my ACM to view the motor. The Gotway video on YouTube depicts the shells easily coming loose once the screws are removed. Not mine! Wondering if the 1300 and 1600 models come apart differently? Any suggestions? 1 minute ago, Hunka Hunka Burning Love said: Did you double check that you got all the screws, even the hidden ones just above the battery? If I had a nickel for every time I tried to brute force something open only to discover oh there's a screw I forgot to undo, well, I'd have me an ACM16 by now. Missed screws or those pesky plastic clips you can never get without breaking at least a few do come to mind first... Do they use some sealant or glue when putting them together? Not so long ago, I dismantled one of my displays, breaking quite a number of those plastic clips, and one connector which I then had to replace on the board, while replacing all the capacitors. The end result? The monitor (still) works fine, it turns out the problem is with the motherboard of the actual computer Since the machine is dying anyway (caps going there too, but far too difficult to replace with my current tools), I've got a new workstation sitting on the floor, waiting for re-installing everything from scratch, which is a huge pain with all the of databases, development environments and related software I need with my work and hobbies... Link to comment Share on other sites More sharing options...
Rehab1 Posted March 17, 2017 Share Posted March 17, 2017 10 minutes ago, Hunka Hunka Burning Love said: Did you double check that you got all the screws, even the hidden ones just above the battery? If I had a nickel for every time I tried to brute force something open only to discover oh there's a screw I forgot to undo, well, I'd have me an ACM16 by now. Checked and double check using a huge magnifier and high intensity light. The hang up is the (2) 5x10 cm cosmetic pieces that house the lights and charging receptical. The plastic shell is somehow locked around these pieces. Link to comment Share on other sites More sharing options...
Marty Backe Posted March 17, 2017 Share Posted March 17, 2017 1 minute ago, Rehab1 said: Checked and double check using a huge magnifier and high intensity light. The hang up is the (2) 5x10 cm cosmetic pieces that house the lights and charging receptical. The plastic shell is somehow locked around these pieces. I think I'm going to wait until I have to replace my tire before I attempt to strip everything down to the motor. There's that old axiom, "if it ain't broken don't fix it." Link to comment Share on other sites More sharing options...
steve454 Posted March 17, 2017 Share Posted March 17, 2017 6 hours ago, KingSong69 said: Nope...this startes here in a thread in early december with failure reports of normal V3.....and not just one... As far as i know the fuse only blows in a situation to prevent burning the board....So that in case of a failure you only have to Change the fuse...and not the burned board. So you have the cheaper faceplant ;-) Beside all failure's i am still thinking of buying a ACM 84Volt next.... From my Point of view driving EUC at all is quiet dangerous as Long as there is no real redundancy at least with the board ...and i accept that as the positive's of EUC driving are much better :-) And mostly this fault's occure in a very high amp/torque Situation on steep hills on low Speed ...i am prepared there! Really dangerous it gets for People who are not here in a Forum and are misleaded by whomoever that the EUC is just a normal Transportation device All good points Link to comment Share on other sites More sharing options...
Rehab1 Posted March 17, 2017 Share Posted March 17, 2017 6 minutes ago, esaj said: 16 minutes ago, Hunka Hunka Burning Love said: those pesky plastic clips you can never get without breaking at least a few do come to mind first... Do they use some sealant or glue when putting them together? Clips and glue are a possibly! Who knows what they used being it was manufactured just after the Chinese holiday ended. I was hoping to save @meepmeepmayersome trouble! 10 minutes ago, esaj said: Not so long ago, I dismantled one of my displays, breaking quite a number of those plastic clips, and one connector I am hoping to avoid some of your adroit handiwork Link to comment Share on other sites More sharing options...
Rehab1 Posted March 17, 2017 Share Posted March 17, 2017 7 minutes ago, Marty Backe said: 10 minutes ago, Rehab1 said: I think I'm going to wait until I have to replace my tire before I attempt to strip everything down to the motor. There's that old axiom, "if it ain't broken don't fix it." Marty...with all of your fancy tools and beautiful workbench you should be able to tackle this! If anything do it for the goodness of mankind! Link to comment Share on other sites More sharing options...
esaj Posted March 17, 2017 Share Posted March 17, 2017 8 minutes ago, Marty Backe said: I think I'm going to wait until I have to replace my tire before I attempt to strip everything down to the motor. There's that old axiom, "if it ain't broken don't fix it." I'm the kind who takes things apart out of pure curiosity and then regrets it later... Your method is probably better 2 minutes ago, Rehab1 said: Clips and glue are a possibly! Who knows what they used being it was manufactured just after the Chinese holiday ended. I was hoping to save @meepmeepmayersome trouble! Yet another bullet point for the next designs of wheels: make the shells easily enough to dissamble so that tire changing doesn't involve curse words you didn't know, depression, self-destructive thoughs, uncontrolled rage and alcoholism. Is it that hard? 2 minutes ago, Rehab1 said: I am hoping to avoid some of your adroit handiwork Had to look up "adroit", never heard that word before... I wouldn't call it "adroit" if I end up breaking the clips, though Link to comment Share on other sites More sharing options...
US69 Posted March 17, 2017 Share Posted March 17, 2017 @Rehab1 Btw.: why you want to see the motor and screw the wheel completly open? I thought you only want to visit the board? Link to comment Share on other sites More sharing options...
Marty Backe Posted March 17, 2017 Share Posted March 17, 2017 15 minutes ago, Rehab1 said: Marty...with all of your fancy tools and beautiful workbench you should be able to tackle this! If anything do it for the goodness of mankind! Nice try Link to comment Share on other sites More sharing options...
steve454 Posted March 17, 2017 Share Posted March 17, 2017 2 hours ago, Rehab1 said: Over the past year I have been researching using these on patients with scoliosis braces to determine if they are compliant in their wearing schedule. Have you seen the movie sixteen candles? A girl was wearing one of those braces. When I was in high school, one girl wore one of those. It made me wonder, how long does it take? I actually wish I had one of those, my s curve is called swayback. It seems like one night sleeping in one, (if you could sleep in a brace), would fix everything in the posture. But apparently this girl went through high school with this brace. Major bummer for her, I guess, but not as much of a bummer as the girl who rode a go-cart and her hair got caught in the chain. People said it ripped her hair out. She wore a wig in high school. I liked her, but never asked her to take off the wig. One of my big regrets. I read a science fiction book where the main character was going through training, and at one point was in front of one of the trainers who saw imbalances and just struck him at certain points and that straightened him up, kind of like instant Rolfing. To get back to topic, ride your ACM at slow speed at first, and don't climb any long hills. Link to comment Share on other sites More sharing options...
meepmeepmayer Posted March 18, 2017 Author Share Posted March 18, 2017 I'm really liking @KingSong69's theory atm that it's the motor connectors plus an additional short from that, it would explain everything and it would be an issue under control. Will open as soon as possible and check. -- @Rehab1 Why would you remove the shells from the motor just to check the connectors? You only need to open the side plate. There's also a video "how to assembling ACM" that shows the assembly (there seems to be no difference in construction between 67V and 84V except the bulged side plates). The light and charger panels are screwed to one of the shells, maybe that's your problem? And in your posted video, the last (board side) shell seems to be a bit stuck to the motor at the end. And yep, tire change is really stupid with this kind of construction. Does any manufacturer have a better alternative? Link to comment Share on other sites More sharing options...
Marty Backe Posted March 18, 2017 Share Posted March 18, 2017 7 hours ago, KingSong69 said: <snip> As far as i know the fuse only blows in a situation to prevent burning the board....So that in case of a failure you only have to Change the fuse...and not the burned board. <snip> Yes, I understand why the fuse is there. But I return to my point that it's a cheap solution. Power electronics can be designed to withstand over-current without the need of a mechanical fuse. But it takes extra brain cycles to arrive at that solution (and a few additional parts), so they took the path of least resistance and threw some fuses in there. I fear taking my KS14C to any remote areas because a deeply embedded fuse might blow because I overload the wheel a little. If they are going to use fuses, at least use re-settable ones that can be accessed without any tools. Link to comment Share on other sites More sharing options...
Rehab1 Posted March 18, 2017 Share Posted March 18, 2017 1 minute ago, steve454 said: ve you seen the movie sixteen candles? A It made me wonder, how long does it take? I actually wish I had one of those, my s curve is called swayback. A bit off topic but @Hunka Hunka Burning Love does it all of the time It depends on the magnitude of the curve and skeletal age but empirically they wear the brace until growth terminates. We all have swayback (lumbar lordosis) just some have a greater degree. 20 minutes ago, steve454 said: To get back to topic, ride your ACM at slow speed at first, and don't climb any long hills. That will not happen soon as my ACM is currently in pieces. No desire to ride it until these issues are resolved. Link to comment Share on other sites More sharing options...
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