I was reading through the past posts and really can't find anything on this. Does anyone know how hot the hub motor should or can get? I started this new thread because I am curious to know what other user are experiencing, since we have several user doing different voltage and controller mods with.
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Support V is for Voltage
With most permanent magnet motors, brushed or brushless, it is good to operate them below 100 degrees C. or less than 212 degrees F.(boiling point of water)-- Some series wound motors, with no permanent magnets, can survive higher temperatures, but such operation is not generally desirable. High operating temperature hastens magnetization loss of permanent magnets, and if temperature get too high, generally above boiling, the insulation, or epoxy inside the motor may weaken and fail, resulting in magnets loosening, or windings/power leads shorting, with disasterous effects. Generally, if a motor is consistently running too hot to hold your hand on it, it is not operating efficently, and changing its size, voltage, or gearing would provide an improvement for the application. Traveling at cruise speed, on level ground, a vehicle motor should just be warm, but may normally become somewhat hot after climbing a long hill with a passenger or other heavy load.-Bob
Robert M. Curry
Thanks for the quick response. I see what you mean about the hill. I felt the motor after I had rode about 3 miles and it was only warm. Then I felt it after I climbed a hill that is pretty steep for florida. It made the bike slow down about 2mph versus the flats speed. When I felt it again it was hot. I could hold my hand on it but only for a few seconds before it became uncomfortable. What is a good way for me to measure the motor temp?
So if 212 degrees or boiling point of water is the the hottest a motor should get then I don't believe I reached that point since I could still touch the motor for a few seconds without it burning me. I know I couldn't do that with boiling water.
Hub motors are notorious for poor cooling. If you are seeing 130deg temps on the outer surface, the coils down in the middle are MUCH hotter. OTOH, the tiny power leads are probably protecting the motor from literally melting. I've also never seen any notes here about burned up motors.
So I check the outside temp for a 130 degrees? Are you also saying that the tiny power wires are limiting the amount of current being delivered to the motor?
If that is the case then it should be only a matter of time before I burn something out. Correct? (wires or motor)
I have felt the wires right at the hub motor and they are not hot to the touch. The motor was a little hot on the brake side after a 6 mile ride. Where on the motor can I measure the temp?
Probably.
Probably not, unless you go doubling the current passed by the controller with a shunt (and NO one would do that 8-0). Even then, according to anecdote, the most likely failure is a pack meltdown triggered by an unbalanced pack. I wouldn't worry too much about motor temperature. If you DO worry about it, I'd advise getting one of those non-contact thermometers and developing a history of typical temperature readings. Then, if a hot day and a heavy load occurs, you'll be able to anticipate an overload.
The wires are so fine they probably radiate their heat pretty fast. As for a measuring point, I'd say it was more important to have a consistent place rather than one magical place. If you were going to run the motor to the ragged edge of failure, the place to measure the temperature is at the coils inside the case. This is done, in fact, with more sophisticated hub motors.
This is fun, isn't it?
Thank you for the info on the thermometer that is a good idea. I have thought about hooking up a cycle analyst to measure the current as I stated in another post. I have to wire a 6 pin connector to the new controller as the only down fall to that. I am getting about 29mph now and I read that one of the other members that has gone to 72v is getting 28mph top speed out of modified stock controller. So I am thinking that the new controller is similiar in curreent draw to the stock modified controller.
Could the motor be the reason 2 different 72v controllers are basically have the same top speed even though mine is capable of 45 amps or is it as you said the stock wires are limiting both of the controllers. Maybe the stock shunt mod controller at 72v is also capable of 45 amps (max)?
I don't believe that my controller as hit the max amps with this motor because I have a 40 amp fuse now instead of stock 30 amp. It would have blown already correct?
Pretty much the deciding factor on top speed is nothing more than the Voltage of the pack supplying the controller.
Roughly each 12V battery you add will give u +5mph top speed regardless of what controller you are using. Amperage is what controls the torque/power of the motor, not top speed. IE acceleration and speed up a hill.
48V ~ 19mph
60V ~ 24mph
72V ~ 29mph
84V ~ 34mph
Just one question hguido1.... Where do you live? The reason I ask is because running the bike at 72V pretty much disqualifies it from being considered an e-bike in most states I know of. Meaning that you would need to register it, tag it, insure it, and have a license to operate it. Just warning you ahead of time in case it applies to your state.
As far as the fuse goes.... it CAN take a little over 40amps and not blow, more than likely though, you have not gone over 40amps yet. A 45 amp draw would most likely be going up a long steep hill or a lot of acceleration with a rather LARGE person/s on the bike.
Dave ; Tennessee
XB-600.
Yes, any speed over 20 mph disquialifies you. I am aware of that and most of my riding is on flats so I am probably not pulling the max amps of the controller. I weigh around 170 but sometime I have my son on and he is 100 pounds. I haven't had a problem yet but I have only taken short trips to the store with the combined 270 pounds. I usually see a speed around 26 to 27mph with a 270 pound load and full batteries. I rode today with 14 miles on the pack since last recharge and the combined weight of 270 pounds yielded a speed of 23mph. I need to recharge the pack but I am trying to get a total distance before I do.
So if I understand your post sixpax then my bike will possibly accelerate faster to the same max speed as a modified stock 72v controller ?
Yes that would be correct. The whole "shunt" mod is a way of tricking the controller to use more current, thus increasing power and acceleration. So more current = faster acceleration + power/torque
Dave ; Tennessee
XB-600.
I read on another forum that my controller has 3 shunts now instead of two. when it had two it was a 28amp max controller at 72v. I have not opened mine to see but if this is true anyone who has a xb-600 and is worried about the 45 amps max of this controller could remove a shunt.
That would basically be a "reverse shunt mod" :)
Instead of increasing current you reduce it. Almost not worth the new controller and time. Unless you actually measured out what to replace the shunt with the limit the current to your liking. It is basically calculating how long of a given wire you need to create a certain resistance across the shunt, thus limiting the current.
If that is true... it looks like controllers use 1 shunt per 15amps for measuring and limiting. Interesting in the least. Unless I am mistaken xb-500 controllers have 1 shunt.
Dave ; Tennessee
XB-600.
Sixpax2k9 if that is the case one shunt per 15 amps then the 60v shunt mod takes the stock controller to around 30amps. Which is close to what others have said they are seeing when testing. My suggestion of removing a shunt from the 72v controller is for people that feel it might be easier to remove the shunt instead of adding caps and fets to increase to 72v with the stock controller. That way people wouldn't have to worry about the 45amp max being to much for the motor and wires. Mine seems to be running fine with the max 45amps but only time will tell I guess.