US69 Posted March 21, 2017 Share Posted March 21, 2017 6 hours ago, jrkline said: I've seen the pics.I'm just speculating that high resistance at one or more of his connectors created enough heat at the point where the wires were pinched or bunched together causing the insulation compromise resulting in the short between the wires.Of course it could also be that one or more of the wires had the insulation compromised which led to an arc fault and the connectors had no impact whatsoever.I would be very curious to know if any of the connectors on his wheel exibit abnormal resistance and thus possibly leading to the fault. Before: Yes I could trust the wheel then,I even trust it now without removing the motor connectors.I have put my wheel under extreme stresses of heat,hill climbing,tumbling down a 330ft.cliff etc. and that is all with the extra weight of 1360wh's of batteries and side boxes added.If my motor connectors were defective,I'm sure it would have revealed itself by now.And all of the defects people are experiencing such as yourself involve the motor connectors only,not the wires themselves or where they are soldered to the control board.So if you illiminate the motor connectors altogether,then you illiminate the source of all the reported failures!I No offense meant, but I would say that your upgraded 67 Volt Acm and the new 84 Volt Acm's are not comparable! I also upgraded my 67 volt Msuper to nearly 1200wh....but it is still not an 84 volt machine. This Watthour upgrade just made the voltage drop lower and increases the range, while it not changes the firmware and so can not draw generally more power from the board. As i have heard the 67 Volt machine boards are more or less limited to about 120 Amps, while the 84 Volt Powerhorses are about 180amps. Even if this numbers are not absolutely correct, fact is the 84 volt machines deliver more power and so also seam to need a higher amperage at all, as the 84V machines are not delivered in smaller batteries versions..... i also said/thought before that a high resistance of the connector could be the reason for this fault, but then the heat would be the greatest at the connectors itself. Here we see that the melted cables were really far away from the connectors... So my conclusion here is that perhaps the whole time the cables have been the culprit...in the cases/faults before they just attacked the weakest point, which was the soldered connector. When this conector stays strong, the next seams to be the cable insulation which melts... Link to comment Share on other sites More sharing options...
esaj Posted March 21, 2017 Share Posted March 21, 2017 16 hours ago, Hunka Hunka Burning Love said: I'd be curious to see what @esaj thinks of my arcing theory. Well, again my first reaction would be "not likely", but who knows? I know that motors/coils can produce very high voltages in spikes when a coil turns off, still, to strike through the cable sheaths, it would likely need to be somewhere in the kilovolts (thousands of volts) range... Then again, I've seen a small DC-motor run with 9V kick back around -100V in short spike with the scope, so... At least it cannot be common, otherwise stuff like this would be happening all the time. "Just" heating would seem more plausible (or a combination, where the sheaths first start melting, and once the cables got close together with the sheaths melting away from between them, at some point the isolation was thin enough for a strike-through to happen). But it's all speculation. Link to comment Share on other sites More sharing options...
Radislav Posted March 21, 2017 Share Posted March 21, 2017 4 hours ago, KingSong69 said: As i have heard the 67 Volt machine boards are more or less limited to about 120 Amps, while the 84 Volt Powerhorses are about 180amps. Even if all the three phases share this "180A" maximum value equally, then we have 180 / 3 = 60 A on each wire. Do we have 3.6 mm diameter motor wires? No. In reality each wire should be able to carry even more because the current has to return to a controller board somehow. Plus we need gilded wires because of the skin-effect. Link to comment Share on other sites More sharing options...
esaj Posted March 21, 2017 Share Posted March 21, 2017 5 minutes ago, Radislav said: Even if all the three phases share this "180A" maximum value equally, then we have 180 / 3 = 60 A on each wire. Do we have 3.6 mm diameter motor wires? No. In reality each wire should be able to carry even more because the current has to return to a controller board somehow. Plus we need gilded wires because of the skin-effect. Only two of the phases are carrying current at a time, the third is "floating". The same current goes "in" through one phase and "out" the other, so two of the wires carry the same current at the same time, it's not "distributed"/"shared" between them. Here's an old post of mine about the basics of 3-phase BLDC-motor drive, although there are probably better sources in the internet and people who know more about them in these forums too: Link to comment Share on other sites More sharing options...
Radislav Posted March 21, 2017 Share Posted March 21, 2017 5 minutes ago, esaj said: so two of the wires carry the same current at the same time, it's not "distributed"/"shared" between them Great article, thanks! It reminds me what I've learned in Moscow radio-electronics university The worst case - each wire must be ready to carry 180A if duty ratio is 100%. I even fear to imagine the diameter of wires for this current. The starter in a car eats ≈100A and we all remember how thick the battery wires are! Link to comment Share on other sites More sharing options...
esaj Posted March 21, 2017 Share Posted March 21, 2017 14 minutes ago, Radislav said: Great article, thanks! It reminds me what I've learned in Moscow radio-electronics university The worst case - each wire must be ready to carry 180A if duty ratio is 100%. I even fear to imagine the diameter of wires for this current. The starter in a car eats ≈100A and we all remember how thick the battery wires are! I've used this table in many occasions to pick (minimum) wire-sizes: http://www.powerstream.com/Wire_Size.htm It also lists the maximum frequencies for the 100% skin depths, but one thing to keep in mind is that the wiring usually hasn't got only a single conductor, but multiple smaller ones (multiple strands/conductors per wire), so for the skin-effect, you'd need to take into account the amount and thickness of each conductor. Also, the skin depth frequency is for AC (single sine-wave) frequencies, the square(ish) wave used with PWM is different, since square-wave is actually a sum of multiple (theoretically infinite amount of) harmonic sine-waves, and of course, as usual, there are many more factors in play (stray capacitance and inductance of the wiring and circuits, back-EMF, electrical noise, the complex magnetic and electrical field effects in the motor etc.) So I guess the safest bet would be to use thick cables made of multiple smaller conductors..? Link to comment Share on other sites More sharing options...
Radislav Posted March 21, 2017 Share Posted March 21, 2017 16 minutes ago, esaj said: So I guess the safest bet would be to use thick cables made of multiple smaller conductors..? Higher sine-waves are weaker than the first one... And the motor coils give an inductive load, so when we feed it with a squared voltage, the current will take some time to rise to its maximum and I suspect at this frequency it will look more like 1-st sine-wave Due to thermal issues I would bet on 10-15 strands in a 5mm wire and each of them should be gilded. But the axis of the wheel is not wide enough for it. So if I had a GW, I would never let the temperature go higher than 68°C (at this temp my Ninebot doesn't let me do anything else than to slow down and stop). At this stage the wires temperature can be even twice as high but the maximum for the isolation is 200°C which is written on it. Link to comment Share on other sites More sharing options...
Rehab1 Posted March 21, 2017 Share Posted March 21, 2017 I peeled back the shrink wrap of the wire connectors and compared them to the picture Linnea from Gotway posted. They appear similar My connectors will be completely eliminated as I proceed with my modifications and the wires will be soldered together followed by aviation shrink tubing. Link to comment Share on other sites More sharing options...
Xima Lhotz Posted March 21, 2017 Share Posted March 21, 2017 I think this has little to do with skineffekt and all to do with to small wire for the current (and heat). It might contribute a bit but its all about the amps. In bends, only thing that protects the copper is the insulation and when in a bend the cables (copper) are "pressed" against the pvc. Even without heat you can get "cold short" due to bending the cable more than the minimun specified diameter over time. All tables look reasonable but the cables are in free air, surrounding temp of 20 to 30 degrees, not bundled and no type of isolation of the copper is specified (pvc, pex, silicon etc) and also no heat sources are accounted for. This example is for 1 phase 230V AC Swedish installation rules (but its all the same, almost but the connection to temperature is clear): And this is for continuous 24/7 situations and a design temp of 70 degrees (for the cable) constant with PVC insulation. The conductor in that cable will be 70 degrees when 10A goes through it. 10A calculation with pvc 70 degree insulation. If i was to design a cable that should hold 10A then usual cable is 1,5mm2 (16+ AWG) with sourrunding temp of 25 degrees C. If the surrounding temp is increased to 60 degrees then i would need a 4mm2 (11 AWG) cable for 10A! 30A calculation 25 degrees C = 6mm2 cable (9 AWG) 60 degrees C = 25mm2 cable (3 AGW) *This is not saying this is the requirement for a ecu only to show the current / heat relation. To sum up, the resistance in the cable creates heat and the cable is designed around the max temp of that cable. If we increase the surrounding temp then we must decrease the heat generated by the cable with a bigger mm2 to account for that external heat generated so the cable doesn't get to hot. Link to comment Share on other sites More sharing options...
Rehab1 Posted March 21, 2017 Share Posted March 21, 2017 28 minutes ago, Xima Lhotz said: I think this has little to do with skineffekt and all to do with to small wire for the current (and heat). It might contribute a bit but its all about the amps. I totally agree. Transitioning from a 14 awg wire initiating from the PCB down to a 16 awg wire coming from the motor is just asking for trouble. The 14 awg is rated at 200 degrees C but the 16 awg wire has no visible temperature rating. Once I open up the metal housing allowing me direct access to the motor I am hoping there is room to increase the wire size. @meepmeepmayer we will gets this figured out sooner or later Link to comment Share on other sites More sharing options...
Xima Lhotz Posted March 21, 2017 Share Posted March 21, 2017 12 minutes ago, Rehab1 said: I totally agree. Transitioning from a 14 awg wire initiating from the PCB down to a 16 awg wire coming from the motor is just asking for trouble. The 14 awg is rated at 200 degrees C but the 16 awg wire has no visible temperature rating. The important thing here is that 200 degrees is not the surrounding temp, its the temp of the conductor in the cable. And this is the maximum temp and should never be used for design. @Rehab1 Its really fun looking at the dismantling of your wheel Do you have a photo of the engine cable markings? It would be fun to find the specs of that cable. A single, silicon, 16 AWG cable, in free air, at 30 degrees C, with a current of 30A has a conductor temp of 200 degrees. (according to this specific table but its all about the same (silicon insulation with copper conductor) http://catalog.connectronicscorp.com/Asset/WIREMAX-conductor-CURRENT--2-.pdf Adding 3 cables, bundled, overheat alarm with surrounding temp of 70+C = Not fantastic. Link to comment Share on other sites More sharing options...
Rehab1 Posted March 21, 2017 Share Posted March 21, 2017 14 minutes ago, Xima Lhotz said: Rehab1 Its really fun looking at the dismantling of your wheel Do you have a photo of the engine cable markings? It would be fun to find the specs of that cable No markings on the engine ( motor) wires. I need to start my own thread as I move into further disassembly and modifications so I don't muddy the waters any further here. What stated out as an inquiry into @meepmeepmayer's issue has turned into a full blown autopsy. Link to comment Share on other sites More sharing options...
esaj Posted March 21, 2017 Share Posted March 21, 2017 Vee's old "I plan to test"-topic has a ton of pictures of his mods, including replacing/adding the motor wiring with thicker ones: But I think that at that point he also had custom-made his own "sleeve nut" or whatever it's called for the motor, as the original had broken or something, so the extra wiring might not fit with the original (plus that was an MSuper V2, the newer ones are probably different). Link to comment Share on other sites More sharing options...
Marty Backe Posted March 21, 2017 Share Posted March 21, 2017 1 hour ago, Rehab1 said: I need to start my own thread Great idea Link to comment Share on other sites More sharing options...
EUCMania Posted March 21, 2017 Share Posted March 21, 2017 To measure the highest temperature achieved, use Non-Reversible Temperature Recording Labels SMALL SELF-ADHESIVE TEMPERATURE RECORDING STRIPS TURN BLACK AT 38°C TO 260°C (100°F to 500°F) I found it at http://www.telatemp.com/c/186/temperature-tags-labels-irreversible-labels Or http://www.omega.com/pptst/TL-8.html and there are others. I do not know how big the labels are. If it is small enough to put on the wires, then we can get a reading of the highest temperature there. Then we can decide whether actionc are needed. Link to comment Share on other sites More sharing options...
meepmeepmayer Posted March 21, 2017 Author Share Posted March 21, 2017 @Rehab1 Just be careful not to make the insides of the motor (coils?) the weakest point, because if you ever stress the wheel enough to break that.... you're ******. That's really how a wheel should be designed. Design your electronics so there's a clear weakest point, and monitor that. offtopic: How big is the actual diameter of the motor? I was wondering how much "easier" (less current/voltage etc) and possibly more efficient (use of battery capacity) it would be if the motor was designed to utilize the full tire diameter. Link to comment Share on other sites More sharing options...
US69 Posted March 21, 2017 Share Posted March 21, 2017 6 hours ago, Marty Backe said: Great idea Hey Marty, i just wanted to write you a PM... "Marty" kann not receive personal message.... Is your Inbox full? Link to comment Share on other sites More sharing options...
Marty Backe Posted March 21, 2017 Share Posted March 21, 2017 46 minutes ago, KingSong69 said: Hey Marty, i just wanted to write you a PM... "Marty" kann not receive personal message.... Is your Inbox full? Yeah, it was full - I deleled a bunch of messages Link to comment Share on other sites More sharing options...
US69 Posted March 21, 2017 Share Posted March 21, 2017 yip...now it worked ;-) Link to comment Share on other sites More sharing options...
Rehab1 Posted March 21, 2017 Share Posted March 21, 2017 1 hour ago, meepmeepmayer said: @Rehab1 Just be careful not to make the insides of the motor (coils?) the weakest point, because if you ever stress the wheel enough to break that.... you're ******. That's really how a wheel should be designed. Design your electronics so there's a clear weakest point, and monitor that. offtopic: How big is the actual diameter of the motor? I was wondering how much "easier" (less current/voltage etc) and possibly more efficient (use of battery capacity) it would be if the motor was designed to utilize the full tire diameter. I will be careful but if something happens you will be one of the first to find out! The biggest issue will be feeding 3 larger AWG wires up through the axle. Here is a photo of the motor. Link to comment Share on other sites More sharing options...
meepmeepmayer Posted March 21, 2017 Author Share Posted March 21, 2017 Oh wow, just realized you opened the motor cover. Cool! More in your topic: Link to comment Share on other sites More sharing options...
Rehab1 Posted March 22, 2017 Share Posted March 22, 2017 13 hours ago, esaj said: Here's an old post of mine about the basics of 3-phase BLDC-motor drive, although there are probably better sources in the internet and people who know more about them in these forums too: Your superbly written EUC Motor Drive post should be proudly positioned front and center under (your) the Electric Unicycle Terminology topic! I am so impressed with your knowledge! Link to comment Share on other sites More sharing options...
Duf Posted March 22, 2017 Share Posted March 22, 2017 On 3/19/2017 at 3:23 PM, Marty Backe said: That's why I was disappointed to learn that the Monster has two fans. I hope they don't break. I was riding my Monster in the mountains yesterday (low 25c's temperature) and the internal temperature climbed as high as 65c. I have a feeling the Monster is not going to do so well when I start riding it in the mid-30's. My ACM, with no fans, rarely gets in the 60's even when I'm riding at it's 33c outside. Oh wow I had no idea your Monster got that warm. If it gets that hot with two fans, damn. I have never seen the temp on my Msuper out of the 40's but flat Florida helps me there. Link to comment Share on other sites More sharing options...
US69 Posted March 22, 2017 Share Posted March 22, 2017 20 minutes ago, Duf said: Oh wow I had no idea your Monster got that warm. If it gets that hot with two fans, damn. I have never seen the temp on my Msuper out of the 40's but flat Florida helps me there. The fan's on the Monster are more or less useless and totally misdesigned. These weak Standard fans with small Diameter do nothing more than shifting the warm air in the closed chamber a bit around .... That is not only my opininon, one of the French sellers said their repair-specialists are loughing about that fans and titled them useless as well.. Link to comment Share on other sites More sharing options...
Marty Backe Posted March 22, 2017 Share Posted March 22, 2017 28 minutes ago, Duf said: Oh wow I had no idea your Monster got that warm. If it gets that hot with two fans, damn. I have never seen the temp on my Msuper out of the 40's but flat Florida helps me there. Yep, it definitely consistently runs hotter than my other wheels. What I'm curious about is whether it'll actually overheat, but I'll have to wait for the summer months to find out. Link to comment Share on other sites More sharing options...
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