Here's what happened. I bought this Ecotric Cheetah 2.0 folding bike for $80 sight unseen. I was eager to get this bike going so I ordered a beefy controller (KT 25A) And put my EDC 48 volt battery on to it as it didn't come with a battery and couldn't find the right form factor that goes with it. So I put 12 gauge thick stranded wires to the battery prongs that stick up and used connectors that I fit to be snug on the lead to the main power. My battery was too wide to fit where the battery is supposed to sit so for now I strapped it to the frame so it sat between my legs when riding. Wow, this bike blew me away and quickly got up to 28 mph and on a straightaway at full throttle it would get up to 30mph if given the extra time to let it slowly creep up those last two miles an hour. I was zipping across town and to work n back in record times and it just seemed to keep going and going. The one thing i wanna point out is the bottom of the throttle was very jumpy and was hard to get used to cuz it was not smooth at all. Once you got up to a medium speed, it was fine and the jumpiness I attribited to the torque that this bike was able to put out. Then one day I was riding out the gate to my property and the bike jerked from no reason I did knowingly at least and it felt like 80% of the power was sucked out of it in that instant and ever since. I've checked all my connections, swapped out the basic LED display for a S866 so I could see if I could fix it in the settings. That alone was frustrating cuz when I rearranged the DST plug so that the wires matched it's mate, the controller came on every time no problem. But turn the throttle and nothing and 5 seconds after powering up the E10 error comes up with it's corrosponing icon as well. So I checked everything again and thought that I was now using the S866 maybe the communication error was that the PAS wasnt hooked up and that would solve it...it didn't, but after combing thru page after page of troubleshooting there was one guy who said that the wire colors were different than usual. He swapped the display's yellow for the blue and said that was the fix. Nothing else I tried was working so I swapped the same wires and boom, the throttle now does something although it's still only able to go 4 or 5 mph in super slow mode. What causes this? If I blew the controller then it shouldn't do anything right? I've set the P settings to what I usually set them up for for max speed and more throttle than PAS. What is limiting the controller from sending the full power that it did before this happened. Any and all suggestions and guesses are welcomed. Something else to note.... I took apart the throttle to clean it to chec k it off the list and there's a dark grey tapered area on the magnet. It's still magnetized so I dont think it's the problem, but I've been wrong a couple times in my life, so I'm here with an open mind. I don't want to have to get a new controller if I don't have to, but I can at any moment. I wanna work this issue out and find the solution of why this bike can only go super slow and no more when I know it's capable of so so much more. Thanks for reading this far, I like to give the full and nature of the problem i need help with. You got questions? I've got answers for you and welcome all of em. Thanks in advance, Dan
Need help figuring this out. I put a KT 25A to replace the stock Ecotric Cheetah 2.0 500w 48v bike I had fixed but now it only crawls...
- Thread starter djwikkid
- Start date
harryS
Well-Known Member
The KT controller doesn't need a display to run. They usually ship it with this jumper. That gives you throttle and one level of PAS. Is that how you originally ran the Cheetah?
MAybe you burned something out running at 25A and 48V. That's like 1200 watts, and the motor isn't rated to run that high on a steady basis. Maybe just for short periods.
I see the CHeetah did come with an SW900 display. Did you use that? It turns out that displays usually use the same connector. Tis would apply to the S866 and KT displays. I've owned all three.
How they work is the display powers up on battery from the red/black leads. It sends battery power back on the blue lead to power up the controller. Data is sent on the yellow and green leads. The problem is everyone use their own data commands, so you get Comm errors when the display cannot understand the controller responses to its commands. Nonetheless, the KT throttle will be active, as long as the controller powered up.
My guess then is that you ran originally on either the jumper plug or the SW900. Something got too hot and you lost power. Then you managed to get the S866 wired properly so it lit up, but the controller or motor is still fried.
In a situation like this, a bike tech would just plug in a working controller or working motor. They're all compatible if the motor wiring is right, and it would be easy to see which needs to be replaced. In your case, it a lot of labor poking around with a voltmeter. The simplest test I can think of is to see if the motor rotates backward. Should be only mild resistances. If it fights you, then you got a short in the motor, controller, or controller wiring,
You might look at the motor wires. They weren't ended to pass 20-25 amps on a steady basis. Maybe the insulation got soft and broke down.
MAybe you burned something out running at 25A and 48V. That's like 1200 watts, and the motor isn't rated to run that high on a steady basis. Maybe just for short periods.
I see the CHeetah did come with an SW900 display. Did you use that? It turns out that displays usually use the same connector. Tis would apply to the S866 and KT displays. I've owned all three.
My guess then is that you ran originally on either the jumper plug or the SW900. Something got too hot and you lost power. Then you managed to get the S866 wired properly so it lit up, but the controller or motor is still fried.
In a situation like this, a bike tech would just plug in a working controller or working motor. They're all compatible if the motor wiring is right, and it would be easy to see which needs to be replaced. In your case, it a lot of labor poking around with a voltmeter. The simplest test I can think of is to see if the motor rotates backward. Should be only mild resistances. If it fights you, then you got a short in the motor, controller, or controller wiring,
You might look at the motor wires. They weren't ended to pass 20-25 amps on a steady basis. Maybe the insulation got soft and broke down.
First off, thank you HARRYS for replying. I think you are prob right on the money with one of the possibilities you said. I found out last night upon returning from a test run that now with the S866 connected, the throttle worked without the display on. Since now after swapping the blue and yellow wires (something completely illogical to most manuals) and the throttle working for the first time since this started, I'm trying to not only find out if or which module got toasted, but what electrical component can be replaced to fix said problem. If I got that far it would teach me so much about most controllers in general. Now since I swapped out the original "display" which was/is the LED B10 for the S866, it's never got full connection and always has given the E10 code along with the comm icon. So idk if I am even getting one way let alone two way communication. Being that I need this bike back on the road at full speeds, I'm prob gonna order a new controller or see if I can return this one. This is a KT, but only has the weatherproof juilet plug on the motor wire. Everything else is bullet for the power or DST for throttle, brake switchx2, lights x2, 5pin display and PAS.
You are again right on the money with 48v @ 25A being 1200 watts. I didn't even realize in my quest to make my bike faster that I was outputting so much to the hub, which is gonna make me pop that top to inspect the wiring. So far in my speed quest I figured out that the easiest and fastest way to increase the speed is to bump up the battery voltage to the next level only thinking about staying within limits of the caps which are usually 60v on the ones I have worked with so far. Didn't put too much credence into watching the watts as to me with these near-frictionless hub motors, they will always take the current fed to them and spin that wheel for as long as the gauge of the wiring can support it.
Here's what's got me... regardless of which part of the system was fried, I would think that if whatever fried, then it wouldn't work at all and that'd be it. But no, from a dead stop if I turn the throttle for just a second and some the full torque is still there, but then quickly tapers off to a gentle and slow roll about and wont go any higher. But I can def fell the original jolt of power to get it rolling up to it limiting point. If you or anyone jnows why this is happening and what is causing it, I would owe that person a steak dinner with all the trimmings. No joke. So any insight is still welcomed as I need the speed back indeed. Thanks again HARRYS. Hopefully you have more knowledge to gleen and I'm going to pop my hub right now cuz I already inspected the controller inside and out and found nothing abnormal. Dan
You are again right on the money with 48v @ 25A being 1200 watts. I didn't even realize in my quest to make my bike faster that I was outputting so much to the hub, which is gonna make me pop that top to inspect the wiring. So far in my speed quest I figured out that the easiest and fastest way to increase the speed is to bump up the battery voltage to the next level only thinking about staying within limits of the caps which are usually 60v on the ones I have worked with so far. Didn't put too much credence into watching the watts as to me with these near-frictionless hub motors, they will always take the current fed to them and spin that wheel for as long as the gauge of the wiring can support it.
Here's what's got me... regardless of which part of the system was fried, I would think that if whatever fried, then it wouldn't work at all and that'd be it. But no, from a dead stop if I turn the throttle for just a second and some the full torque is still there, but then quickly tapers off to a gentle and slow roll about and wont go any higher. But I can def fell the original jolt of power to get it rolling up to it limiting point. If you or anyone jnows why this is happening and what is causing it, I would owe that person a steak dinner with all the trimmings. No joke. So any insight is still welcomed as I need the speed back indeed. Thanks again HARRYS. Hopefully you have more knowledge to gleen and I'm going to pop my hub right now cuz I already inspected the controller inside and out and found nothing abnormal. Dan
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