Possible controller overheated?

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
I see, I was confused by some posts saying that going slow up hill overheats the motor (no matter what power setting you have). Obviously stalling out the motor will quickly overheat it. They just didn't post it that way.
I've read those too.....

I think some are ex dirt bike riders that are used to having to keep a peaky motor within it's power band. These are electric motors, and if you'll have a look at that Grin chart (again) you'll see where most of the torque is available. My opinion anyway, with no electrical engineering degree to back me. -Al
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Fine. Use this one-

You'll have to request they send you a sine wave. That one will have the sensor wires. It's how I got mine. This one (w/sine wave and sensor wires) is the one I've been running on the MAC 12t. It's mounted on the bike's seat downtube and I've never seen it even get warm.
 

AxialFlux

Member
Ok, another question. Assuming the controller is the only thing that went bad here, and the new one fixes it, how accurate are the watt meters on these displays? I'm thinking if he is going up any questionable hills, he could toggle that on to monitor when he was pulling too much current.
 

harryS

Well-Known Member
The LCD3 always shows the watts. It's probably good to 10%. Just a guess. THe LCD3 also dials up the volts. It's too bad your brother couldn't have done that when the bike was dead. The picture showed the voltage icon had tripped the low voltage icon, but it should still read volts. Now I've never found the voltage to match what my voltmeter says, but it tracks for in-ride monitoring.

I've got a fat tire motor about the same size as your brother, running off a 25A KT controller (much bigger than his), but it's very flat here and I've never sustained 1000W for more than a few seconds, so I've never seen anything get warm.
 

harryS

Well-Known Member
I built many ebikes running off KT controllers, most with LCD3's. THe controllers are 17A. 22A. and 25A peak. One is almost a foot long with 12 Fet's, (S12S), so I never used it. I have used 9 Fet (25A) and the rest are 6 FET, Never had one die after put into use. Had one that didn't work right off the bat though,

I used to buy them from PSWpower, but they sent my last order to Brooklyn and suggested I go over there and get it, only 900 miles away. Despite a lengthy discussion where I produced the DHL documents, Alice at PSWpower scornfully offers me a dollar. I threw up my hands and Paypal gave me the money. Future buys will now have to go elsewhere. I'm sure Alice will remember me and send the next order to Atlanta..
 

rich c

Well-Known Member
Just for the hell of it, I'd crack that motor open and see if the varnish melted on the windings before buying a new controller.
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Troubleshooting to determine exactly what has failed for sure!!!!

Don't start making assumptions and throwing parts at it to see if that fixes it. That's an expensive way to learn - and can be just a little frustrating!
 

tomjasz

Well-Known Member
Troubleshooting to determine exactly what has failed for sure!!!!

Don't start making assumptions and throwing parts at it to see if that fixes it.
unfortunately there are times when having the spare parts to sort by eliminating individual component problems is the quickest path to sorting and bring on the road again. In my first year or do of DIY I found having some key backups invaluable. But I have a few more dollars than patience.
 

AxialFlux

Member
The seller sent me another controller, and I tested it today. No change. The seller is wanting me to verify that I have the parameters set correctly, so I am going to verify that with what they sent me. I do have doubts that it is a parameter issue though.
 

theemartymac

Well-Known Member
I am unclear about slow going uphill overheating the motor.
Is this still a concern if you are going up hill slowly at low throttle settings or helping by pedaling
PS when you say constant full beans, do you mean full throttle or pedaling hard?
Too slow is bad in most any case, although lower throttle settings and more pedal effort will certainly reduce the problem. It is important to remember that any power that is delivered to the motor without conversion to RPM (speed) is converted to heat. So if you have a speed-based PAS setting that is trying to reach say 20kph, and you are crawling along at 8-10kph for a long hill, you are turning a lot of unused power into heat.

On my 750w hub bike, I can overheat it on a long 5-minute moderate/steep climb if I use anything over PAS 2, and fail to keep my speed above 15kph. If I can keep the speed up, I can usually avoid an overheat for some time as long as the PAS setting isn't too high. That bike is a cadence sensor, so each PAS setting is simply providing power until it hits the desired speed (RPM). It doesn't seem to make a difference if I'm 2 kph or 10 kph under that speed, it still pushes significant power until I hit the cutoff speed. Now the further away I am from the target, the more energy is being wasted - turned into heat, but it is still generating heat at any rate.

If you use the GRIN simulator, you can see the "overheat in" field below the graph, and it's not hard to see <10min overheat windows on most settings when the speed is below 15kph.
 

JES2020

Active Member
Too slow is bad in most any case, although lower throttle settings and more pedal effort will certainly reduce the problem. It is important to remember that any power that is delivered to the motor without conversion to RPM (speed) is converted to heat. So if you have a speed-based PAS setting that is trying to reach say 20kph, and you are crawling along at 8-10kph for a long hill, you are turning a lot of unused power into heat.

On my 750w hub bike, I can overheat it on a long 5-minute moderate/steep climb if I use anything over PAS 2, and fail to keep my speed above 15kph. If I can keep the speed up, I can usually avoid an overheat for some time as long as the PAS setting isn't too high. That bike is a cadence sensor, so each PAS setting is simply providing power until it hits the desired speed (RPM). It doesn't seem to make a difference if I'm 2 kph or 10 kph under that speed, it still pushes significant power until I hit the cutoff speed. Now the further away I am from the target, the more energy is being wasted - turned into heat, but it is still generating heat at any rate.

If you use the GRIN simulator, you can see the "overheat in" field below the graph, and it's not hard to see <10min overheat windows on most settings when the speed is below 15kph.
"Too slow is bad in most any case,"

If you said, over amping your motor causes more heat. I would agree, but going slow dos'nt mean you are over amping it. For example if you are going up hill at 5 mph pedaling in low gear AND low PAS or throttle, your peak watts should be well below the watt capacity of the motor and consequently less heat development.
On the other hand accelerating up hill to high speed will push your motor to a high peak amp.

The key is how much time you stay at high peak amps no matter if you are going up hill or in fact down hill.
The issue is to keep the motor away from stalling to improve performance and reduce heat. Stalling is when the load is more than the motor can handle, the result is massive heat build up.

In tests with my controller mod, I purposlly stalled the motor to see what peak amps my controller was now putting out. It didn't take long before the controller wires started to feel warm .

Obviously there are numerous situations where going slow up hill is NOT stalling the motor, many combinations of 0 to max pedal power and power settings. This can easily be verified with the use of a watt meter.
 

theemartymac

Well-Known Member
"Too slow is bad in most any case,"

If you said, over amping your motor causes more heat. I would agree, but going slow dos'nt mean you are over amping it. For example if you are going up hill at 5 mph pedaling in low gear AND low PAS or throttle, your peak watts should be well below the watt capacity of the motor and consequently less heat development.
On the other hand accelerating up hill to high speed will push your motor to a high peak amp.

The key is how much time you stay at high peak amps no matter if you are going up hill or in fact down hill.
The issue is to keep the motor away from stalling to improve performance and reduce heat. Stalling is when the load is more than the motor can handle, the result is massive heat build up.

In tests with my controller mod, I purposlly stalled the motor to see what peak amps my controller was now putting out. It didn't take long before the controller wires started to feel warm .

Obviously there are numerous situations where going slow up hill is NOT stalling the motor, many combinations of 0 to max pedal power and power settings. This can easily be verified with the use of a watt meter.
Certainly sounds fair. I have found with my hub that the only way to completely and reliably avoid overheating on big hills is to drop the PAS all the way to 1 or even 0, and of course, that defeats the whole point of the assist. To throw another generalization out there, I think many if not most riders without temperature sensors are pretty oblivious to how much heat they are generating much of the time unless or until it reveals a problem. And like me, I think many riders just want to ride, and not pay attention to an instrument panel like a pilot! lol
 

JES2020

Active Member
Certainly sounds fair. I have found with my hub that the only way to completely and reliably avoid overheating on big hills is to drop the PAS all the way to 1 or even 0, and of course, that defeats the whole point of the assist. To throw another generalization out there, I think many if not most riders without temperature sensors are pretty oblivious to how much heat they are generating much of the time unless or until it reveals a problem. And like me, I think many riders just want to ride, and not pay attention to an instrument panel like a pilot! lol
To your point, most watt meters will hold many parameters during the ride, including peak amps and peak watt hours. So you don't need to monitor during the ride.
Even so the meter can act as a training aid, allowing the rider to get familiar with how his riding habits effect the motor, and make any adjustments warranted.
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
I constantly monitor how many watts I'm using, so it's easy to see if a display doesn't display watts, I'll be looking for one that does. Next to knowing the battery charge status, that's likely the most critical piece of information available on an e-bike.

As far as rpm running a lot of power through a motor (say it's rated wattage for instance) at an rpm where the motor is nearly stalled, that's a sure recipe for quick heat build up. BUT, if we glance down at our handy watt meter and see we're only pulling about 1/2 the motor's capacity, at that same just above stall speed, it's pretty safe to assume you aren't hurting a thing.
 

JES2020

Active Member
I constantly monitor how many watts I'm using, so it's easy to see if a display doesn't display watts, I'll be looking for one that does. Next to knowing the battery charge status, that's likely the most critical piece of information available on an e-bike.

As far as rpm running a lot of power through a motor (say it's rated wattage for instance) at an rpm where the motor is nearly stalled, that's a sure recipe for quick heat build up. BUT, if we glance down at our handy watt meter and see we're only pulling about 1/2 the motor's capacity, at that same just above stall speed, it's pretty safe to assume you aren't hurting a thing.
"BUT, if we glance down at our handy watt meter and see we're only pulling about 1/2 the motor's capacity, at that same just above stall speed, it's pretty safe to assume you aren't hurting a thing."

Right, that would also mean that you are using half of the motor's capacity.

BTW, that was my situation, before I did the controller mod.
I went from 864 WP @ 48v to 1536 WP @ 48v, and the motor is rated at 1500W. I almost doubled my peak watts.
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
"BUT, if we glance down at our handy watt meter and see we're only pulling about 1/2 the motor's capacity, at that same just above stall speed, it's pretty safe to assume you aren't hurting a thing."

Right, that would also mean that you are using half of the motor's capacity.

BTW, that was my situation, before I did the controller mod.
I went from 864 WP @ 48v to 1536 WP @ 48v, and the motor is rated at 1500W. I almost doubled my peak watts.
Yup. My point was it's not just about rpm. It's about the load on the motor, and how much power if being fed into it.

It might be worth noting for some too, that the fact you doubled your available power to the motor does not mean your battery range is going to be reduced. It's way more about potential power delivery - what you have available at wide open throttle. What you had available at 1/4 throttle originally, hasn't change on bit!
 

JES2020

Active Member
Yup. My point was it's not just about rpm. It's about the load on the motor, and how much power if being fed into it.

It might be worth noting for some too, that the fact you doubled your available power to the motor does not mean your battery range is going to be reduced. It's way more about potential power delivery - what you have available at wide open throttle. What you had available at 1/4 throttle originally, hasn't change on bit!
Yes, I should still have about 80 mile range per charge, it's just that I can get there almost twice as fast.
on second thought...that's not right.
I don't have twice the speed but twice the acceleration an a little more speed due to less sag.
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Yes, I should still have about 80 mile range per charge, it's just that I can get there almost twice as fast.
on second thought...that's not right.
I don't have twice the speed but twice the acceleration an a little more speed due to less sag.
Much better available hill climbing ability is how I look at it!