Cloud Posted November 30, 2015 Share Posted November 30, 2015 i was just thinking, since the kingsong wheel overheats easily during multiple acceleration/ braking, and i understand that the heat comes from the battery, it is the padding on the sides of the wheel covering the battery that must be keeping all that heat in. Why not remove the soft pads and replace them with a few strips of padding at certain spots only. Lets assume that my ankles will be fine. shouldnt this help a lot with the wheel overheating? Unless the heat from the high current is generated not by the battery? opinions? Link to comment Share on other sites More sharing options...
SlowMo Posted November 30, 2015 Share Posted November 30, 2015 I was also into RC jets (tiny ones) and what we normally do is place the battery and speed controller in an area where there would be more air flow. But for EUC's, adding more air flow would mean creating air vents which will be bad in the rain. Link to comment Share on other sites More sharing options...
Cloud Posted November 30, 2015 Author Share Posted November 30, 2015 8 minutes ago, SlowMo said: I was also into RC jets (tiny ones) and what we normally do is place battery and the speed controller in an area where there would be more air flow. But for EUC's, adding more air flow would mean creating air vents which will be bad in the rain. I was thinking about making openings for air flow and rejected this idea for this same reason - water protection. But i think if i just remove the padding, this should have a huge effect, no? Link to comment Share on other sites More sharing options...
SlowMo Posted November 30, 2015 Share Posted November 30, 2015 Maybe not. Once you remove the rubber padding, you will just find the plates that covers the battery and the main boards which is still enclosed tight. One idea that comes to my mind is adding a dc fan inside. Link to comment Share on other sites More sharing options...
Cloud Posted November 30, 2015 Author Share Posted November 30, 2015 5 minutes ago, SlowMo said: Maybe not. Once you remove the rubber padding, you will just find the plates that covers the battery and the main boards which is still enclosed tight. Yes there are plates there, but the plates cant keep the heat in as much as the padding does. The heat has to dissipate faster through the plastic cover than it does through the cover and the padding on top of it. the padding looks to have a low heat conductivity - this is why it never appears warm to touch. The plastic, on the other hand, does. Link to comment Share on other sites More sharing options...
SlowMo Posted November 30, 2015 Share Posted November 30, 2015 Well, there's no harm trying, but the beautiful padding will be destroyed. It will look ugly as my MCM2S as in this photo. Link to comment Share on other sites More sharing options...
Cloud Posted November 30, 2015 Author Share Posted November 30, 2015 6 minutes ago, SlowMo said: Well, there's no harm trying, but the beautiful padding will be destroyed. It will look ugly as my MCM2S as in this photo. I think your wheel actually looks cool and quite futuristic:) i was thinking the padding doesnt have to be destroyed. I can carefully remove it and keep it. I could always place it back! i just want to make sure that the heat actually comes from the battery itself. I just dont know enugh about it. Maybe it comes from the connections/ mosfets on the control board when the higher current goes through them? If the experts confirm it comes from the battery, i should probably try to remove the padding. p.s. Three head lights? I like the way you roll:) Link to comment Share on other sites More sharing options...
SlowMo Posted November 30, 2015 Share Posted November 30, 2015 Our moderators @esaj and @Gimlet are the experts in this field. Link to comment Share on other sites More sharing options...
Cloud Posted November 30, 2015 Author Share Posted November 30, 2015 Yes , i am waiting for them to wake up and chime in:) Link to comment Share on other sites More sharing options...
SlowMo Posted November 30, 2015 Share Posted November 30, 2015 I still prefer the Kingsong 14C even with this issue. The 14C never had a burned motherboard like this. Link to comment Share on other sites More sharing options...
Cloud Posted November 30, 2015 Author Share Posted November 30, 2015 Yes, i remember you mentioned the burned motherboard in a different post. I prefer kingsong too, this s why i am trying to fix the issue rather than switch over to other brands. On the other hand, i dont know if you ever experienced much of this issue. Having to stop and wait every 5 minutes of riding can really take the wind out of your sail) Link to comment Share on other sites More sharing options...
EUC Extreme Posted November 30, 2015 Share Posted November 30, 2015 Gotway 18 Link to comment Share on other sites More sharing options...
Cloud Posted November 30, 2015 Author Share Posted November 30, 2015 7 minutes ago, vee73 said: Gotway 18 I guess we have drifted from the subject of overheating into the subject of the battle of the motherboards:):) or are these some kind of heat fins under the board to dissipate heating? Link to comment Share on other sites More sharing options...
EUC Extreme Posted November 30, 2015 Share Posted November 30, 2015 Increasing the surface area to enhance the cooling. These are available from the shop. Between the pasta and heat evaporates more efficiently. Link to comment Share on other sites More sharing options...
SlowMo Posted November 30, 2015 Share Posted November 30, 2015 Yes, @vee73's heat sink solution seems to be a great idea coupled with a small dc fan to dissipate the heat. Link to comment Share on other sites More sharing options...
Cloud Posted November 30, 2015 Author Share Posted November 30, 2015 So i can order these? That would be cool I dont know if there is enough room inside the casing to add a heat sink.. The board seems to be right under the the plastic cover... Link to comment Share on other sites More sharing options...
esaj Posted November 30, 2015 Share Posted November 30, 2015 @Cloud Thanks for the vote of confidence, but remember that I'm not an expert... Still, my guess is that most likely the overheating is happening in the mosfets on the mainboard, not the batteries. I don't think the temperature of the batteries is even monitored by the mainboard, some BMSs do have over/undertemperature protections, but they work like all the other BMS-protections: they cut the power if the temperature drops too low or goes too high... Removing the padding around the mainboard compartment could help a bit, but probably not very much (is the KS mainboard even behind either of the pads or on the top of the compartment sideways?). DC-fan can help with moving the heat off the heatsink, but if the heated air cannot leave the mainboard compartment, it will only slow down the heat build-up, not totally prevent it, although eventually the heat (both as infrared radiation and heated air) will go through the plastics and small holes etc, so it could be even enough (it's not like the compartment itself is heat-insulated and of course shouldn't be). Larger heat sink would probably also help, if you can find one that fits, or if you can attach another heatsink to the current heatsink (with thermal paste or such in-between to help with heat conduction). The best option I can think of would be a heatsink that's partially outside the compartment, so it can transfer the heat outside (you could cut a hole for the heatsink to come through the plastics and then seal off the sides with silicone or some other elastic stuff, so it won't come off due to heat expansion/contraction). @vee73's large heatsink with fins to add the surface area for emitting the heat away looks very efficient for cooling, as long as the heat conducts properly from the mosfets to the heatsink, and preferably the heat from the heatsink itself can be moved outside the mainboard compartment, by using the heatsink as one of the "walls" of the compartment so the fins are outside. Should you choose to replace the existing heat sink, one of the problems that must be taken into account in the cooling is that the mosfet "body" (the large metal part that best conducts the heat off the component) is also connected to one of the legs: So basically you want to connect that to a heat sink so it conducts thermally as good as possible, but at the same time, you must take care to insulate it electrically to avoid any short circuits. Usually there's some sort of thermal pad or thermal tape between the mosfets and the heatsink (also the screw must be insulated so that it won't act as a conductor between the metal in the mosfet and the heatsink). The yellow/orange stuff in @SlowMo's picture of the Ninebot mainboard is some sort of thermal pad/tape that electrically insulates the mosfet bodies from the heatsink, while allowing heat to transfer. At least 3M produces such tapes and pads. Does anyone know if all the King Songs suffer from this heat problem, or if it's just some (older?) models? I'm wondering whether they've changed the mainboard or cooling between the models, or used different mosfets or if the motor driving itself is somehow altered so that the mosfets produce less heat (smaller losses in mosfets)... Link to comment Share on other sites More sharing options...
Keith Posted November 30, 2015 Share Posted November 30, 2015 Esaj is correct, the MOSFET's mainly and the motor itself to a lesser extent is where heat is generated, virtually no heat is generated in the battery until it's voltage has dropped to near empty. If the battery is ever getting hot it is being overdischarged or is near the end of its useful life. MOSFET's have incredibly low internal resistance and are operated with several in parallel, reducing that even further. Unfortunately they are also being switched on and off umpteen times per second to drive the phases of the brushless motor and limit the current to that motor. On/Off doesn't happen instantaneously which causes them to pass through a period of higher resistance - that's when the heat is produced. Link to comment Share on other sites More sharing options...
Gimlet Posted November 30, 2015 Share Posted November 30, 2015 The KingSong board is mounted to a fairly heavy gauge aluminium plate with heat paste in the mosfet connections to it. Also the plate is centred over and sealed to a square opening to the top of the wheel so it benefits from the draft caused by the passing tyre so it's difficult to see an easy way to improve the heat dissipation. There's not enough clearance to add cooling vanes to the bottom of the plate and besides they'd soon get clogged by muck flicked up from the wheel. You could possibly make the cooling plate longer and maybe enlarge the square hole through to the wheel but that's the best idea I have for an easy improvement. I would upload a picture but I've reached my limit. Link to comment Share on other sites More sharing options...
esaj Posted November 30, 2015 Share Posted November 30, 2015 29 minutes ago, Gimlet said: I would upload a picture but I've reached my limit. I've switched over to use http://imgur.com/ for posting pictures in the forums... I don't know if there's any limit to how much pictures you can put up there, but at least so far I haven't hit it (and I could always remove old unnecessary pics). It's fairly easy to use and you can get direct links to your pictures for posting on the boards. Link to comment Share on other sites More sharing options...
UKJ Posted November 30, 2015 Share Posted November 30, 2015 @Gimlet As I see you have a KS14c 800W, 680Wh, have you experienced any over heating issues? And as I am seriously considering this same model, how does one know of this over heating, if and when it happens? App? I also just received info that the newer models do not have this problem? Thanks, ukj Link to comment Share on other sites More sharing options...
Gimlet Posted November 30, 2015 Share Posted November 30, 2015 As I have one of the first batch off of Jason it did have a couple of problems. First was that it would go into tilt back at 55volts which is was able to induce by riding around my local circuit which is between 3 and 4km. Then Sam Clegg visited a after a pleasant local ride where we were swapping wheels around for comparison he tried some fairly violent idling which burnt out a mosfet or two. The replacement board that Jason sent me has a lower threshold of 50volts before it tilts to stop you riding and has a higher ampage tolerance has has worked without any problems since I fitted it. It is still different to the present board as it doesn't have iPhone connectivity or adjustable tilt back warning speed. That's the downside of being in at the launch but as I don't have an iPhone and I have no wish to lower the speed of tilt so I'm happy. Link to comment Share on other sites More sharing options...
Cloud Posted November 30, 2015 Author Share Posted November 30, 2015 3 hours ago, UKJ said: @Gimlet As I see you have a KS14c 800W, 680Wh, have you experienced any over heating issues? And as I am seriously considering this same model, how does one know of this over heating, if and when it happens? App? I also just received info that the newer models do not have this problem? Thanks, ukj Overheating should only occur if you ride with a lot of acceleration and braking and is more likely t hapoen if you are heavy. If you are riding normally, on even surface it should be happening. When the wheel overheats at 70 degress C, it will tilt back and forth and beep making you dismount the wheel and turn it off. Upon cooling in a coupke of minutes you can turn it back on and ride normally. I dont know if the latest batch has addressed this or not Link to comment Share on other sites More sharing options...
Cloud Posted December 1, 2015 Author Share Posted December 1, 2015 14 hours ago, esaj said: @Cloud Thanks for the vote of confidence, but remember that I'm not an expert... Still, my guess is that most likely the overheating is happening in the mosfets on the mainboard, not the batteries. I don't think the temperature of the batteries is even monitored by the mainboard, some BMSs do have over/undertemperature protections, but they work like all the other BMS-protections: they cut the power if the temperature drops too low or goes too high... Removing the padding around the mainboard compartment could help a bit, but probably not very much (is the KS mainboard even behind either of the pads or on the top of the compartment sideways?). DC-fan can help with moving the heat off the heatsink, but if the heated air cannot leave the mainboard compartment, it will only slow down the heat build-up, not totally prevent it, although eventually the heat (both as infrared radiation and heated air) will go through the plastics and small holes etc, so it could be even enough (it's not like the compartment itself is heat-insulated and of course shouldn't be). Larger heat sink would probably also help, if you can find one that fits, or if you can attach another heatsink to the current heatsink (with thermal paste or such in-between to help with heat conduction). The best option I can think of would be a heatsink that's partially outside the compartment, so it can transfer the heat outside (you could cut a hole for the heatsink to come through the plastics and then seal off the sides with silicone or some other elastic stuff, so it won't come off due to heat expansion/contraction). @vee73's large heatsink with fins to add the surface area for emitting the heat away looks very efficient for cooling, as long as the heat conducts properly from the mosfets to the heatsink, and preferably the heat from the heatsink itself can be moved outside the mainboard compartment, by using the heatsink as one of the "walls" of the compartment so the fins are outside. Should you choose to replace the existing heat sink, one of the problems that must be taken into account in the cooling is that the mosfet "body" (the large metal part that best conducts the heat off the component) is also connected to one of the legs: So basically you want to connect that to a heat sink so it conducts thermally as good as possible, but at the same time, you must take care to insulate it electrically to avoid any short circuits. Usually there's some sort of thermal pad or thermal tape between the mosfets and the heatsink (also the screw must be insulated so that it won't act as a conductor between the metal in the mosfet and the heatsink). The yellow/orange stuff in @SlowMo's picture of the Ninebot mainboard is some sort of thermal pad/tape that electrically insulates the mosfet bodies from the heatsink, while allowing heat to transfer. At least 3M produces such tapes and pads. Does anyone know if all the King Songs suffer from this heat problem, or if it's just some (older?) models? I'm wondering whether they've changed the mainboard or cooling between the models, or used different mosfets or if the motor driving itself is somehow altered so that the mosfets produce less heat (smaller losses in mosfets)... Thanks a lot esaj, this is very helpful. I am still undecided if i want to introduce a heat sink or modify the existing one. however, today the wheel was overheating especially often ( i really dont know why its not consistent day to day, but some days its better than others), so when i felt the plastic with my habd on top of the control board it was warm. Then i stuck my hand under the padding where the battery is and it was warm also. This means that whether the battery produces the heat or the mosfets, there is a heat in the battery compartment and it cannot escape because of the padding and adds up to the control board pverheating. So i removed padding on both sides and continues riding. It didnt fully resolve the problem but i believe it got better. I will try to do a test standing on a slope with and without padding and will measure the delta in the time it takes the wheel to overheat. Once thing is clear - the ambient temperature has little to no effect on overheating ( unless the ambient is so high its close to the overheating temp). Link to comment Share on other sites More sharing options...
Gimlet Posted December 1, 2015 Share Posted December 1, 2015 Have you checked up inside the casing above the wheel with a torch? If the alloy heat sink plate that is open to the wheel has a coating of dirt/mud then it could be affecting the cooling a lot. Batteries need to be warm to give their best performance. Tesla heat their car battery packs and performance is limited when the batteries are cold. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.