750W 60v motor cuts out with throttle

[Dollabeel02]

Hello, I have a 60 volt 750 watt fat tire E-bike from hardcore ecycles that I use for hunting. Used it one morning and it worked great, finished hunting and started heading back and if I hit the thumb throttle motor drops out instantly. Also on pedal assist level 5 it drops out instantly, level 4 it will run some on pedal assist but still drops out. Level 3 it runs better but doesn’t seem to have the power it had. Bike manufacturer sent me a new controller and display and still does the same. I ohmed out my cables from display to controller, and controller to motor and they all ohm good. My battery voltage fully charged is 71.5 volts. I have unhooked thumb throttle, and brake sensors and it still does it. Does anyone have any idea what it could be or what I need to check?

thanks

[wisk9ice]

When you say "drops out" powers off? or you have to cycle switch back on? I suspect something with the BMS on the battery Check voltage during battery Draw and see what happens?

[Dollabeel02]

The display stays on just the motor stops working, motor watts go to 0 most of the time I can drop pedal assist back down to level 3 and it will pick back up, but as soon as I switch to level 5 or press throttle when it’s hooked up motor cuts out again

[wisk9ice]

Is it possible to unhook the power to the motors and test each one individually. See if one or both Individually gives same results?
What type of display is it? Is it capable of wattage draw? Hope this helps I'm not well versed in dual systems or how they are wired but maybe other more knowledgeable individuals have some ideas.

[Dollabeel02]

its just one 750 watt hub motor. KT-LCD3 is the model for the display, and it is what come on the bike originally.

[Dollabeel02]

[wisk9ice]

I still suspect it is your Battery/BMS- The wattage draw exceeds the capability of your battery. What is the age of the battery? They will decline over time.

[Dollabeel02]

Battery is almost 2 years old, bike/battery has around 200 miles.

[wisk9ice]

Curiosity was it cold when you went hunting that day? Also does it act the same when you have a full charge on it? How did you charge your battery when it was not used for a long time?
Here is a you tube link on maintaining a e bike battery: https://www.youtube.com/watch?v=WVcFytLYOIQ

[Dollabeel02]

The 1st time it happened it was a “cool” day but it has been pretty warm lately and it does it still. The video I shared was before charging my battery, it’s fully charged now and still doing it the same. After hunting season I charged my battery completely and stored it inside.

[stts]

Naw its not the battery. If the BMS dropped out, then the whole display would shut off. The controller is cutting the motor off for some reason. A malfunction reason. With higher wattage numbers, more heat is being generated. It could be something in the controller is getting too hot and cutting off. The motor takes lots of time to get hot and also to cool off. But the controller cools off much quicker. Like the time it takes to drop down a few PAS levels and a few seconds more. So something in the controller has failed so it gets hot pretty quick. I would open mine up and just fix it. Your pretty much stuck with getting a replacement controller.

Dang. You already got a new controller. Thats bad news. They got these thermal circuit breakers that are wired into the motor when they get too hot. Its looking like that has gone bad inside the motor and it now opens up with just a little bit of heat. That sucks. I would tear it apart and just rip that little bugger out of there. But again, your stuck with getting a new motor...

The power steering on my car did the same thing. It just quits and suddenly my car wont turn on the curves. Yikes. Surprised the hell out of me when it first happened. Electric power steering. And that little thermal breaker is going bad on all those GM steering motors. And theres no official recall. Unofficially they replace them for free if they cant convince you that you broke your own steering. I dont fall for those deceptive games. I told them fix it or Ill wreck and I will sue. Those basterds kept my car for 3 weeks fixing it. I could have fixed it in an hour.

[stts]

Yup, put the bike up on a stand and start running it till it warms up and see if it cuts off. Or just ride it around till it cuts off, then put it up on a stand and run it at higher pas till it shuts off again. Then lower pas till it starts up. Feel the motor to make sure its not really hot. Then use a hair dryer on the motor on various places to try to get it to shut off. Even try to find the spot the hair dryer shuts it off the quickest. Its hard to get a hair dryer to shut these motors off, but if it does, then you know that device in the motor is faulty. Use a thermometer on the motor after it shuts down to see what the motor temperature is while it is not running.

[Dollabeel02]

I can put it on a stand, turn it on and press throttle and it cuts out almost instantly (it will run longer with tire off the ground but most of the time if I go 0-full throttle it will cut out even with tire off the ground). Or I can start off on PAS 5 and pedal and it will cut out almost instantly.

[stts]

Yea, full throttle means full current and the thermal contacts cant deal with full current. Run it pas 4 on the stand and watch what the watts reading on the right side of the display says. In the video it was below 800 while you were riding it. I figure on the stand it will be WAY lower. I also figure pas 5 would also be way lower than 800 watts, since no weight is on the tire. Note what numbers you see for watts and how long it will run in those pas levels before it cuts off. Also see if you can get pas 3 to cut off.

[wisk9ice]

I thought thermistor would not cut out that quick unless there was other underlying condition that would cause this? I still go back to battery capability. stts you are correct on BMS,; since he replaced display and controller process of elimination is battery.

[stts]

Well if its a thermister problem, then it went sensitive and cutting out with very little heat. And all it could do would be to shut off the hall sensor in the motor. Then the controller would react to loss of hall sensor by cutting off current. Like whats going on. But it seems to be more sensitive to the higher current setting, which suggests worn contacts of a thermal breaker on one of the coil legs. Contacts still allowing low current, but heating up quick when current hits the higher level. Then breaker opens a winding and the controller again shuts off the motor. If it was a battery issue, the BMS would simply shut everything off. Including the display. There is only 2 battery wires. They either have voltage or they dont. I assume the display doesnt have a separate battery supply inside of it. There is no point to that extra expense that would allow water entry into the electronics.

[Dollabeel02]

I have noticed when using throttle the temperature on display goes off then comes back on, but it doesn’t do that when using PAS. I am going to try running it with tire off the ground when I get home to see if it will cut out on 3 and 4 and how long it takes.

[wisk9ice]

stts is a wise fellow and I see what he is talking about. I hoped it was a simpler solution but A motor tear-down may be required.

[stts]

I found something. Right in the sweet spot. Its a video of a motor like whats on hardcore ecycles. Its gutted and you see the innerds. Its got a few white tubes with wires going in. The same tubes used to cover wire connections and even thermal breakers. Theres a surprise thats been discovered. One tube has burnt wires going into it. That means wires getting really hot. Wires that are trying to be failures. If a thermal breaker is inside that tube, its also getting hot even if the rest of the motor is pretty cool. And that breaker will eventually start going off. If too much heat hits the breaker, it will even be damaged by loss of metal anneal. And then the breaker will go off more often at lower heat. I am pretty sure this is what going on here. I suspected this was a problem and now I found a video of somebody else with this very problem. His motor has not actually shut down yet. He's replacing the shaft he tore up. But I bet there are lots of these type motors out there with this internal wiring failure from faulty manufacturing process. So there you go. I can fix stuff like this no sweat. But the average joe is kinda stuck with getting new hubs all over America. Hopefully you can talk the bike shop into doing the right thing.

So heres the youtube video and watch the whole thing for education, or just watch from 5:26 to see the surprise discovery.

https://www.youtube.com/watch?v=Tb3mXqU1CJs

Anyways, Im outta here. My best bud of 30 years just died and I got to get over the denial. His family will be needing my help. Ill be back when everything is done.

[Dollabeel02]

Sorry to hear about your friend.

I did put the bike up and ran it on PAS 3, the watts ran 75-100. I did notice right off the bat that I could get it started with PAS and stop pedaling for a brief second and then start back and it would make the motor cut out even on level 3. This happened not even 45 seconds into running the bike and I can repeat this scenario just about every time.

I did manage to run it without it cutting out for prob 4-5 minutes non stop. Stopped the wheel and felt motor and there was no noticeable heat felt.

[stts]

Yea, that was a bad week. Shit happens then you die. But it was partly his fault. People need to wake up when trouble shows and take better care of themselves. Being afraid of doctors gets nothing done. That ass Faucci really screwed up so many people in the head. Anyways, yea, where theres a burnt wiring issue going on, things could still be working, but performance will balk when the loading is heavier. And as the burnt wiring issue gets more burnt, the performance gets even poorer until the wiring finally burns in half. That guy in the video actually stumbled on his burnt wiring issue but didnt understand what he found. He just put glue over it. Hah. He will eventually have the same issues you are having when he is out in the boonies on a hard ride. And he could end up with a total failure without much warning. And with a bad wiring connection issue going on, the motor will be cutting out without time for the motor to heat up.

[Dollabeel02]

update on my issue… I did get a new motor from the e-bike manufacturer under warranty. And my bike is working great now!

thanks everyone for the help!

I was able to keep my old motor. Are there any places that fix/rebuild these hub motors? Since I did not have to send old one back I would like to get it fixed if possible so I will have a spare if I was to ever have another issue.

[stts]

Well that is great news. In this inflation economy it's harder than ever to get warranty on things that screw up. As for fixing the motor, it's all about time and technical know how. Both cost a ton of money these days. They didn't even want it back because the business of shipping is also very expensive. So taking advantage of that bad motor is mostly a DIY type of thing. Or it ends up costing more than it's worth.