Carlos E Rodriguez Posted June 29, 2017 Share Posted June 29, 2017 On 6/27/2017 at 7:12 PM, Carlos E Rodriguez said: Also remember that if the cables already have lower temp solder, it will reduce the capabilities of the better solder. But it will be better regardless. Assuming the motor wires are getting 200 to 300 deg C then I still would not trust it. I almost think it would be better to twist the wires together and solder or use a in-line screw terminal. On otherb userb testedn theb insulation odb theb wires going to the motor and they melt easier I and going to replace my connectors with this lineman splice. Might leave one regular of three and put sensors on both to see results. Link to comment Share on other sites More sharing options...
Hunka Hunka Burning Love Posted June 29, 2017 Share Posted June 29, 2017 4 hours ago, zlymex said: Is Linnea a she? I thought Jane Mo is. Over the period of about one year, the local riding group where I am in is the most notorious for frying MOSFETs of the new generation GW EUCs(namely ACM, V3) among GW community, because there are a lot of hills here, and 'wild riding style'. The way GW handles this is quite simple: send us new boards, we ourselves exchange them, and send the bad ones back. I'm now still in possession of two V3 boards, one is bad waiting for repair/return, the other is new waiting for somebody the moment. The first ever incident happened here was an ACM of one of my fellow last August when we were climbing a hill together at night. His ACM just stopped, smell and smoke were coming out, and we opened the cover on site to exam, here are some photos As can be seen that at least one MOSCFET burned, cable fastener melted, and outer tube of the motor cable also burned. Fortunately, nobody was hurt because of those(may be ten) incidents. Among these incidents, there are three exceptions: one is the shorting connector(result to burnding of MOSFET anyway), the other two were not related to burning MOSFETs(one is the bad 5V, the other is mine showing on the right of the first photo that unable to switch on) But why these MOSFETs burn before any warning? I had a conjecture that drive circuit/firmware is mulfunction in some rare situations resulting the direct shortage of the 3 phase bridge. Yep, I'm pretty certain Linnea is female. I don't know if she is related to the owner of Gotway, Mr. Lin as they have the same last name. It's good to see that Gotway has a local group stress testing their wheels. You guys look to be on the front lines of discovering weaknesses in these wheels and reporting them back to Gotway. Have you asked them about the possibility of increasing the axle and bearing size on their wheels to allow thicker and cooler wiring to avoid future problems? I wonder if the MOSFETs could be burning out due to shorts in the wiring as we have seen that as well. Looking at your photos those wires are putting out huge amounts of heat, almost like an electric oven in order to melt the cable sheaths, looms, and insulation. If that is happening, shorts may be occuring which lead to the MOSFETs blowing. Maybe Gotway might listen to your suggestions more than ones from North America as you guys have the larger market share over there. Could you see if they would be willing to increase axle sizes and bearings to allow heavier gauge wiring to be used? We know they did improve the thickness a little bit, but I think the axle diameter is the main limiting point. I bet if they increased it getting rid of the bottleneck and used thicker wiring we would likely see fewer control boards burning out? Take for example electrical power transmission towers. They have very large wires to transmit large amounts of electricity. Now imagine if they used super tiny wires to do the same thing. All that current trying to make it through gives off heat in the process, and you can bet things will end up failing. I think these wheels need to have wires sized appropriately to the large current draws demanded of them to avoid failure. Link to comment Share on other sites More sharing options...
Marty Backe Posted June 29, 2017 Share Posted June 29, 2017 54 minutes ago, Hunka Hunka Burning Love said: Yep, I'm pretty certain Linnea is female. I don't know if she is related to the owner of Gotway, Mr. Lin as they have the same last name. It's good to see that Gotway has a local group stress testing their wheels. You guys look to be on the front lines of discovering weaknesses in these wheels and reporting them back to Gotway. Have you asked them about the possibility of increasing the axle and bearing size on their wheels to allow thicker and cooler wiring to avoid future problems? I wonder if the MOSFETs could be burning out due to shorts in the wiring as we have seen that as well. Looking at your photos those wires are putting out huge amounts of heat, almost like an electric oven in order to melt the cable sheaths, looms, and insulation. If that is happening, shorts may be occuring which lead to the MOSFETs blowing. Maybe Gotway might listen to your suggestions more than ones from North America as you guys have the larger market share over there. Could you see if they would be willing to increase axle sizes and bearings to allow heavier gauge wiring to be used? We know they did improve the thickness a little bit, but I think the axle diameter is the main limiting point. I bet if they increased it getting rid of the bottleneck and used thicker wiring we would likely see fewer control boards burning out? Take for example electrical power transmission towers. They have very large wires to transmit large amounts of electricity. Now imagine if they used super tiny wires to do the same thing. All that current trying to make it through gives off heat in the process, and you can bet things will end up failing. I think these wheels need to have wires sized appropriately to the large current draws demanded of them to avoid failure. Great points and questions @Hunka Hunka Burning Love I did want to point out that your transmission power analogy doesn't quite hold up. Sorry, it's the engineer in me. The transmission towers use relatively small wires because they transmit power via extreme voltages and relatively small currents. This is why some of us think that high voltage wheels may be better, reducing the amount of current (and thus heat) flowing thru the cables. A ~200 volt wheel would be awesome. They wouldn't have to increase the axle size, could use higher gauge (thinner) wire, and everything would run cooler. Link to comment Share on other sites More sharing options...
US69 Posted June 29, 2017 Share Posted June 29, 2017 1 hour ago, Hunka Hunka Burning Love said: I wonder if the MOSFETs could be burning out due to shorts in the wiring as we have seen that as well. Looking at your photos those wires are putting out huge amounts of heat, almost like an electric oven in order to melt the cable sheaths, looms, and insulation. If that is happening, shorts may be occuring which lead to the MOSFET Zlymex allready said that... If the wires are shorted, yes, you are right, the Mosfets will blow anyway ;-) Link to comment Share on other sites More sharing options...
Hunka Hunka Burning Love Posted June 29, 2017 Share Posted June 29, 2017 5 hours ago, Marty Backe said: Great points and questions @Hunka Hunka Burning Love I did want to point out that your transmission power analogy doesn't quite hold up. Sorry, it's the engineer in me. The transmission towers use relatively small wires because they transmit power via extreme voltages and relatively small currents. This is why some of us think that high voltage wheels may be better, reducing the amount of current (and thus heat) flowing thru the cables. A ~200 volt wheel would be awesome. They wouldn't have to increase the axle size, could use higher gauge (thinner) wire, and everything would run cooler. I'm no engineerologist. I was just trying to pick an extreme example in terms of wire size. If transmission towers used 14 gauge wiring, the wire would probably burn up pretty quickly (or would they? ). Instead they use bundles of wires like these for strength, flexibility, and ability to not heat up too much as to cause problems. The wire size is matched to optimize the energy transmitted so I would hope if Gotway wires are melting, rather than cover them up with thermal sheaths, they might change them up to an appropriate size to match the demand after they increase the axle sizing. Car batteries have pretty thick wiring going to them. If they used super thin wires there probably would be some issues as well from them melting most likely. I think wires need to be large enough to withstand the current drawn across them. Evidence of melting insulation and damaged exterior coverings is definitely a sign of trouble, I think we can both agree! (Or can we? ) Link to comment Share on other sites More sharing options...
Rehab1 Posted June 29, 2017 Share Posted June 29, 2017 33 minutes ago, Hunka Hunka Burning Love said: The wire size is matched to optimize the energy transmitted so I would hope if Gotway wires are melting, rather than cover them up with thermal sheaths, they might change them up to an appropriate size to match the demand after they increase the axle sizing. I totally agree! Unfortunately in order to increase the wire diameter for better 'electrical energy transmission' the conduit ( motor shaft) needs to be larger. I see no reason why the motors can't be built with a greater diameter shaft to accept larger awg wires or at least replace the standard wires with a silicone version containing high heat insulation and a greater strand count! Both wires below are 14 awg! Which one would you prefer in your GW? Yes the initial retooling costs to create a new motor might be high but GW needs a major break through in R&D that concentrates on safety not just performance! They can brag about having the fastest wheel on the market but who cares if it fails all of the time and causes injury! I sincerely hope GW's upcoming firmware tweak solves all of the problems associated with oscillations, melted wires and burned Mosfets. We will know shortly. Link to comment Share on other sites More sharing options...
steve454 Posted June 29, 2017 Share Posted June 29, 2017 9 minutes ago, Rehab1 said: I totally agree! Unfortunately in order to increase the wire diameter for better 'electrical energy transmission' the conduit ( motor shaft) needs to be larger. I see no reason why the motors can't be built with a greater diameter shaft to accept larger awg wires or at least replace the standard wires with a silicone version containing high heat insulation and a greater strand count! Both wires below are 14 awg! Which one would you prefer in your GW? Yes the initial retooling costs to create a new motor might be high but GW needs a major break through in R&D that concentrates on safety not just performance! They can brag about having the fastest wheel on the market but who cares if it fails all of the time and causes injury! I sincerely hope GW's upcoming firmware tweak solves all of the problems associated with oscillations, melted wires and burned Mosfets. We will know shortly. I like the larger wires, they seem more sturdy. The fine wires go pftt. but the fine wires are great! Link to comment Share on other sites More sharing options...
steve454 Posted June 29, 2017 Share Posted June 29, 2017 On 6/29/2017 at 2:04 PM, Carlos E Rodriguez said: I and going to replace my connectors with this lineman splice. Might leave one regular of three and put sensors on both to see results. Small wires cause fires Link to comment Share on other sites More sharing options...
The Fat Unicyclist Posted June 30, 2017 Share Posted June 30, 2017 1 hour ago, steve454 said: Small wires cause fires And matches... Don't forget matches! Link to comment Share on other sites More sharing options...
Rehab1 Posted June 30, 2017 Share Posted June 30, 2017 1 hour ago, steve454 said: My understanding is that current moves along much easier when there are more strands. Current travels along the surface of the conductor so the fine multistrand silicone wire have a lot more surface area than the standard strand wire. Also silicone wire is much more flexible and heat resistant. If I can pull (3) 14 awg silicone wires up through the ACM axle GW could do the same. Link to comment Share on other sites More sharing options...
Carlos E Rodriguez Posted June 30, 2017 Share Posted June 30, 2017 5 hours ago, Marty Backe said: Great points and questions @Hunka Hunka Burning Love I did want to point out that your transmission power analogy doesn't quite hold up. Sorry, it's the engineer in me. The transmission towers use relatively small wires because they transmit power via extreme voltages and relatively small currents. This is why some of us think that high voltage wheels may be better, reducing the amount of current (and thus heat) flowing thru the cables. A ~200 volt wheel would be awesome. They wouldn't have to increase the axle size, could use higher gauge (thinner) wire, and everything would run cooler. Nice try @Marty Backe but it does not work that way. When the high voltages are transmitted then they are put through step down transformers to get the desired volts and amps. The motror does not work the same way. The only thing that matters is amps period, no exemption , no if's, no maybe. Amps amps amps. Ahhhhhhhhh! Amps. Reparat after me. Amps amps amps. Link to comment Share on other sites More sharing options...
Marty Backe Posted June 30, 2017 Share Posted June 30, 2017 12 minutes ago, Carlos E Rodriguez said: Nice try @Marty Backe but it does not work that way. When the high voltages are transmitted then they are put through step down transformers to get the desired volts and amps. The motror does not work the same way. The only thing that matters is amps period, no exemption , no if's, no maybe. Amps amps amps. Ahhhhhhhhh! Amps. Reparat after me. Amps amps amps. My power tools, that run cooler when wired for 220 vs 110, use half the current in the process. I really don't understand your statement, but probably just because it's not fully flushed out. Clearly I"m not a motor engineer. Your "amps amps amps" statement implies voltage has nothing to do with how a motor functions with regards to performance. That can't be true. Is it possible for you to better explain this as succinctly as possible. Maybe a few sentences minus the charts and diagrams? I'm genuinely interested. Link to comment Share on other sites More sharing options...
Carlos E Rodriguez Posted June 30, 2017 Share Posted June 30, 2017 2 hours ago, steve454 said: Small wires cause fires The wires are just a picture for the method on how to join them. I will use the original not smaller. You guy are just amazing! Lol. Link to comment Share on other sites More sharing options...
The Fat Unicyclist Posted June 30, 2017 Share Posted June 30, 2017 2 hours ago, Carlos E Rodriguez said: Nice try @Marty Backe but it does not work that way. When the high voltages are transmitted then they are put through step down transformers to get the desired volts and amps. The motror does not work the same way. The only thing that matters is amps period, no exemption , no if's, no maybe. Amps amps amps. Ahhhhhhhhh! Amps. Reparat after me. Amps amps amps. Assuming the objective is "energy consumption" wouldn't the key be Watts? And as Watts = Volts × Amps, then higher voltage should mean lower amperage, shouldn't it? Link to comment Share on other sites More sharing options...
Chriull Posted June 30, 2017 Share Posted June 30, 2017 6 hours ago, Rehab1 said: My understanding is that current moves along much easier when there are more strands. Current travels along the surface of the conductor so the fine multistrand silicone wire have a lot more surface area than the standard strand wire. Also silicone wire is much more flexible and heat resistant. If I can pull (3) 14 awg silicone wires up through the ACM axle GW could do the same. Normal braided/multistrand wires do not help against the skin effect - they just make the wire more flexible. But there are special braided wires that can reduce the effect - with insulated strands and a specially designed strand pattern: (from https://en.wikipedia.org/wiki/Skin_effect) " Mitigation[edit] A type of cable called litz wire (from the German Litzendraht, braided wire) is used to mitigate the skin effect for frequencies of a few kilohertz to about one megahertz. It consists of a number of insulated wire strands woven together in a carefully designed pattern, so that the overall magnetic field acts equally on all the wires and causes the total current to be distributed equally among them. With the skin effect having little effect on each of the thin strands, the bundle does not suffer the same increase in AC resistance that a solid conductor of the same cross-sectional area would due to the skin effect.[10] " 5 hours ago, Carlos E Rodriguez said: Nice try @Marty Backe but it does not work that way. When the high voltages are transmitted then they are put through step down transformers to get the desired volts and amps. The motror does not work the same way. The only thing that matters is amps period, no exemption , no if's, no maybe. Amps amps amps. Ahhhhhhhhh! Amps. Reparat after me. Amps amps amps. The amps are respobsibly for the torque with a motor constand k. With higher voltages the motor can be designed with different k, so that less amps are needed for the same torque as with a low voltage motor... (with the max speed staying about the same) So lets say amps, amps, volt, volt, amps, amps, volt, volt.... Link to comment Share on other sites More sharing options...
steve454 Posted June 30, 2017 Share Posted June 30, 2017 8 hours ago, Carlos E Rodriguez said: The wires are just a picture for the method on how to join them. I will use the original not smaller. You guy are just amazing! Lol. I know, I was just joking. That does look like a very good way to join the wires together so they never come apart. Link to comment Share on other sites More sharing options...
steve454 Posted June 30, 2017 Share Posted June 30, 2017 9 hours ago, The Fat Unicyclist said: And matches... Don't forget matches! Link to comment Share on other sites More sharing options...
Carlos E Rodriguez Posted June 30, 2017 Share Posted June 30, 2017 16 hours ago, Marty Backe said: My power tools, that run cooler when wired for 220 vs 110, use half the current in the process. I really don't understand your statement, but probably just because it's not fully flushed out. Clearly I"m not a motor engineer. Your "amps amps amps" statement implies voltage has nothing to do with how a motor functions with regards to performance. That can't be true. Is it possible for you to better explain this as succinctly as possible. Maybe a few sentences minus the charts and diagrams? I'm genuinely interested. Ok. v=ir. Is the basic equation. So let's say just for simplicity that the motor wires have a resistance of 0.5 ohms. Then i=v/r so 67/0.5 = 130 amps. For 84/.5?is 162 amps. Now that been said obviously we don't run at those currents. So that is where the PWM chopping determines the actual current at the commutation point. So now let's say it takes 10 amps to go 10mph. There you see I don't refer to volts because it is not important for this scenario. It takes 10 amps to go 10mph. It does not matter as long and v/0.5 produces 10 amps. And is not battery volts. V is the integrated v* duty-cycle. In theory 100% dutycycle will give max current but we never go there. So your battery volts do not determine current in the motor. Is not that simple. There are other reasons to need higher battery volts. The most important one is have a battery with enough volts to be greater or equal than the back emf at the desired max speed. And yes a higher voltage will produce a higher max theoretical amps but that is not the main reason. Link to comment Share on other sites More sharing options...
Marty Backe Posted June 30, 2017 Share Posted June 30, 2017 24 minutes ago, Carlos E Rodriguez said: Ok. v=ir. Is the basic equation. So let's say just for simplicity that the motor wires have a resistance of 0.5 ohms. Then i=v/r so 67/0.5 = 130 amps. For 84/.5?is 162 amps. Now that been said obviously we don't run at those currents. So that is where the PWM chopping determines the actual current at the commutation point. So now let's say it takes 10 amps to go 10mph. There you see I don't refer to volts because it is not important for this scenario. It takes 10 amps to go 10mph. It does not matter as long and v/0.5 produces 10 amps. And is not battery volts. V is the integrated v* duty-cycle. In theory 100% dutycycle will give max current but we never go there. So your battery volts do not determine current in the motor. Is not that simple. There are other reasons to need higher battery volts. The most important one is have a battery with enough volts to be greater or equal than the back emf at the desired max speed. And yes a higher voltage will produce a higher max theoretical amps but that is not the main reason. That's a bit of tap dancing there. I understand what you've written but it really doesn't negate my posit that a higher voltage system can reduce current loads through the cable harness. IMHO. Link to comment Share on other sites More sharing options...
Carlos E Rodriguez Posted June 30, 2017 Share Posted June 30, 2017 25 minutes ago, Marty Backe said: That's a bit of tap dancing there. I understand what you've written but it really doesn't negate my posit that a higher voltage system can reduce current loads through the cable harness. IMHO. 10 amps is 10 amps. How do you figure less load. If the motor uses 10 amps to maintain 10 mph it a higher battery volts won't change anything. If I do it in reverse 10 amps and 0.5 ohms using v=ir then 10*0.5 is 5 volts. So 5 volts is the theoretical battery volts. But because it is commutated and we can not do 100% dutycycle we need slightly more volts. So let's say we really only need 10 battery volts to maintain 10mph. SERIUOSLY. Now don't jump all over this. This does not cover acceleration and starting from zero and getting up to 10mph. All I am saying is a higher battery volts or lower but not too low does not matter as long as it can deliver 10amps. Link to comment Share on other sites More sharing options...
Carlos E Rodriguez Posted June 30, 2017 Share Posted June 30, 2017 11 hours ago, Chriull said: Normal braided/multistrand wires do not help against the skin effect - they just make the wire more flexible. But there are special braided wires that can reduce the effect - with insulated strands and a specially designed strand pattern: (from https://en.wikipedia.org/wiki/Skin_effect) " Mitigation[edit] A type of cable called litz wire (from the German Litzendraht, braided wire) is used to mitigate the skin effect for frequencies of a few kilohertz to about one megahertz. It consists of a number of insulated wire strands woven together in a carefully designed pattern, so that the overall magnetic field acts equally on all the wires and causes the total current to be distributed equally among them. With the skin effect having little effect on each of the thin strands, the bundle does not suffer the same increase in AC resistance that a solid conductor of the same cross-sectional area would due to the skin effect.[10] " The amps are respobsibly for the torque with a motor constand k. With higher voltages the motor can be designed with different k, so that less amps are needed for the same torque as with a low voltage motor... (with the max speed staying about the same) So lets say amps, amps, volt, volt, amps, amps, volt, volt.... Agreed Link to comment Share on other sites More sharing options...
WARPed1701D Posted June 30, 2017 Share Posted June 30, 2017 The way I see it. For two motors of the same power (800W say) if one runs at 100V and one at 200V the 100V one will require twice the current (amps) to operate. The 200V motor and associated cabling (assuming the cable gauge (ergo resistance) is unchanged between the two) should run cooler as a result of less amps. No step up or down required as long as the power source and motor are paired for voltage. I'm probably wrong but that is my take on it. Link to comment Share on other sites More sharing options...
Carlos E Rodriguez Posted June 30, 2017 Share Posted June 30, 2017 5 minutes ago, WARPed1701D said: The way I see it. For two motors of the same power (800W say) if one runs at 100V and one at 200V the 100V one will require twice the current (amps) to operate. The 200V motor and associated cabling (assuming the cable gauge (ergo resistance) is unchanged between the two) should run cooler as a result of less amps. No step up or down required as long as the power source and motor are paired for voltage. I'm probably wrong but that is my take on it. I give up. I just won't engage in this discussion anymore. I which you guys would know how motors works before questioning the people that do. So I will just surrender. You don't know how frustrating hear conversations are. I bring facts and science other think refuting with opinion is cool. But it's not. So I give up. I won't comment on motors anymore. Link to comment Share on other sites More sharing options...
Hunka Hunka Burning Love Posted June 30, 2017 Share Posted June 30, 2017 Kinda regretting the whole electrical transmission line example here. How about we all agree that big wires good and small wires that burn/melt/self-destruct bad. Here's a quote I found (I don't know if it's accurate or not as I'm no motorologist): Effects of high voltage. An assumption people often make is that since low voltage increases the amperage draw on motors, then high voltage must reduce the amperage draw and heating of the motor. This is not the case. High voltage on a motor tends to push the magnetic portion of the motor into saturation. This causes the motor to draw excessive current in an effort to magnetize the iron beyond the point where magnetizing is practical. http://www.ecmweb.com/design/highs-and-lows-motor-voltage http://poweroptimisa.com/uploads/documents/Electric motors & Voltage.pdf Link to comment Share on other sites More sharing options...
Pasi Posted June 30, 2017 Share Posted June 30, 2017 I understand @Carlos E Rodriguez is a little bit frustrating. Let say we have 67V and we need 10A to go 20km/h. If we make battery to 670V, who think, it need only 1A to go 20km/h? Maybe, but it needs just another motor! Now I think it is almost the same motor (of course I am wrong *#?), but the current (Amps) make that torque and power ( it is never that DC 67V over that motor (*#). Sorry, too many beers. Link to comment Share on other sites More sharing options...
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