AKM100

[harrys]

We own three 20" bikes with the Q100H 260 rpm motors from BMS battery, All powered with 20A KT 6-FET controllers (two are sinewave), I built a fourth one this year, using an AKM100 from topbikekit..I pulled out an old BMS Battery P06 17A square wave controller to run it, but it would stall on throttle starts, So I tried on the 20A sinewave controller and it was fine,

About a month ago, I realized the AKM was 320 rpm. No load spreed of about 25 mph instead of 20 mph, and in the real world with a rider, maybe 2 mph faster at 21-22 mph,

So this weekend, I put in a 25A KT 9-FET controller, 12 continuous amps instead of 10. I was worried my battery (10S-3P GA) wouldm't support 25A, but it did. It might have a litte more top speed too, Haven't really tested, The controller does draw 130W in level 1 assist though, whereas the smaller model drew 90-100W, That means my wife will have to pedal a little faster to keep up. She won't like that. Probably have to reduce the current via the LCD3.

 

[vfr400]

You'll strip the gears running that motor with 25A. It's not 12A continuous. That'sthe controller's rating, that you'll exceed with a high speed motor. It'll be 25A mainly continuous with the throttle or on level 5 because of the motor's high speed. That will also overheat the controller if you use high power for too long. I serviced one that had been running at 20A, and the teeth on the gears were about 30% worn away. Personally, I wouldn't go any higher than 17A with a Q100/AKM100. Get yourself a Q128 if you want to run with that sort of current.

 

[harrys]

Thanks for the caution! We're slow riding though. Average speed is under 12 mph, these being 20" folders ridden by seniors.

The AKM already has 2076 miles on the 20A controller in 2020. The Q100h's are from 2017, and have about 2300-2400 miles over that time.I did wear out the pawls on a DNP 11-34 freewheel at 3098 miles. I started with it in 2017 and put it on the AKM100 where it got those 2076 miles, but that's a known condition with DNP parts. In fact, if the DNP hadn't failed I would never have looked at the AKM label to discover its true rpm.

Nonetheless, it's possible I could melt the gears on a long hill if I got too exuberant. I've never tried to open a Q motor. I have a Q128 with a burned out speed sensor, I hear they assemble like Martian cannon shells from War of the Worlds, with big threaded covers,

 

[Nealh]

The current draw as you should know is higher at low speed, many on ES stripped the gears at 20a using 48v though . High current is the 100's Achilles heel.

 

[harrys]

It's always the nut behind the wheel that breaks a vehicle. My nutty days are far in the past. Maybe.

 

[vfr400]

I have a Q128 with a burned out speed sensor, I hear they assemble like Martian cannon shells from War of the Worlds, with big threaded covers,

You can use an external speed sensor.

 

[harrys]

I have used an external one several times. Twice when the motor didn't have a sensor and once when the internal sensor failed.

WHat is odd is that when I used the LCD3, the speed would be stable when coasting, but sometimes jitter under power, almost like the controller was reading the external sensor and the Hall sensors. Maybe the sensor was picking up motor or controller RFI,

 

[harrys]

You'll strip the gears running that motor with 25A. It's not 12A continuous. That'sthe controller's rating, that you'll exceed with a high speed motor. It'll be 25A mainly continuous with the throttle or on level 5 because of the motor's high speed. That will also overheat the controller if you use high power for too long. I serviced one that had been running at 20A, and the teeth on the gears were about 30% worn away. Personally, I wouldn't go any higher than 17A with a Q100/AKM100. Get yourself a Q128 if you want to run with that sort of current.

Today I discovered the drawback with my 25A controller. It runs about 140-150W in PAS 1, vs about 100-110W on my 20A model. Felt good, but I kept outpacing my wife. While waiting for her to catch up, I dialed C6 down from 10 to 7, which makes it a 20A controller again.

When I get a chance, I'll swap it back with the 20A model. And then I'll shuffle the 25A into a bigger bike.