controller parameters

[chris_akez]

Hello everybody
My ebike has a 1000w motor and a 48V controller with a current limit of 18A.
If I multiply 48 * 18 = 864 Watt. Is this controller suitable?
The controller has already been destroyed once and the company sent to me a new one exactly the same.
Can I make some adjustments to the controller current limit parameter (P14 1-20) so that it does not burn out?

 

[AHicks]

Chris, your question, without knowing a LOT more about the controller, is pretty much impossible to answer. I can tell you that a 1000w motor would normally have a controller of 25 amps minimum. A little "headroom" provided by something like a 35a controller isn't a bad plan.... -Al

 

[alphacarina]

Would an 18 amp controller try to supply 25 amps to a big motor, or are they self limiting?

Don

 

[AHicks]

Would an 18 amp controller try to supply 25 amps to a big motor, or are they self limiting?

Don

That's a good question. In my experience the controller manf. will allow themselves a little "overhead" on their amperage rating. In other words, a controller with an 18 amp max capacity will likely be internally limited to 15 amps max. From a practical standpoint, the controller is acting as a bottleneck. This is because your battery, which is able to deliver say 20 amps (round numbers), cannot possibly supply the full amount your motor, which is rated to use up to 20 amps (again round numbers) is able to use, as the controller is internally capped at 15 amps.

That's actually a pretty common scenario.... -Al

 

[kongrui1984]

Chris, you can't just modify the parameter only by display, the controller have it's own current limit , it means even you adjust the option on display, the controller will goes along by itself. not exceed the 18 amper. the controller will cut the electricity when the amper surpass the "overhead" parameter which have set inside it.

 

[chris_akez]

Chris, you can't just modify the parameter only by display, the controller have it's own current limit , it means even you adjust the option on display, the controller will goes along by itself. not exceed the 18 amper. the controller will cut the electricity when the amper surpass the "overhead" parameter which have set inside it.

so you say that if I change the limit amper parameter (P14) to 10A the maximum power of the motor will be 48 * 10 = 480 Watts. I do not mind, I am looking for a way to protect the controller because it has already burned once.
If not, what is the purpose of parameter (P14)?

 

[kongrui1984]

so you say that if I change the limit amper parameter (P14) to 10A the maximum power of the motor will be 48 * 10 = 480 Watts. I do not mind, I am looking for a way to protect the controller because it has already burned once.
If not, what is the purpose of parameter (P14)?

If you set the parameter under the value of controller, it will work, the current limit is according to the lower one.

 

[chris_akez]

If you set the parameter under the value of controller, it will work, the current limit is according to the lower one.

Τhank you for the replay, I think the bike has little space for the 25A controller and they have put 18A because it is smaller in size.

 

[AHicks]

Chris, no idea what you are working on or what limitations are involved (a couple pics might help?), but if that controller is buried in a place without good air circulation, it could be overheated pretty easily. That might explain multiple failures pretty easily.....

 

[harryS]

48V is only about half charge, by the way, The battery starts out near 54V, which puts you at 970 watts initially.

They use a shunt resistor to monitor and limit the current. It's just a loop of wire, looking like a low soccer goal here in this picture. How well they control the length of that wire is how well they can control the current. One common trick to increase the current is to solder a length of thin wire across it, to lower the resistance,, or they will thicken the wire by adding solder to it. It would be harder to do the opposite. I'veused KT controllers the most. When they say 17A or 20A peak, that's what I get using my current meter, give/take an amp.



If you don't want to burn out the controller, don't ride slow up long hills. Burns out motors too,

 

[chris_akez]

If you don't want to burn out the controller, don't ride slow up long hills. Burns out motors too,

Thanks for the advice, I will try it even though I live in a city with many uphills.
Do you know if the transistors screwed to the box burn out? ( about the electronic circuit the question)

 

[chris_akez]

Chris, no idea what you are working on or what limitations are involved (a couple pics might help?), but if that controller is buried in a place without good air circulation, it could be overheated pretty easily. That might explain multiple failures pretty easily.....

The bike is the mx-01 Gunai and you can view a video about replace the controller

 

[AHicks]

Too bad you couldn't fasten the controller to the outside of that box for better cooling. Maybe lead the wires up through the bottom of it so the connections are out of the elements for the most part. Or you could even seal that hole for the wires with some non hardening plumber's putty to minimize water intrusion.

Paint the controller flat black to minimize any distraction to the bike's appearance.

 

[chris_akez]

Too bad you couldn't fasten the controller to the outside of that box for better cooling. Maybe lead the wires up through the bottom of it so the connections are out of the elements for the most part. Or you could even seal that hole for the wires with some non hardening plumber's putty to minimize water intrusion.

Paint the controller flat black to minimize any distraction to the bike's appearance.

Very good idea, to get a bigger controller 25A and install it externally. The cables will be inside so that they are not visible and I will seal the hole. Thanks for your answer.

 

[AHicks]

I was thinking of the original controller, to keep it from frying again, but the same plan for a bigger controller is an even better plan! If you go KT controller and display, and take the time to install it properly (which will likely involve some tedious wiring work), betting you'll get a completely transformed bike out of the deal, set up to your personal 'druthers!

Down side will be you will be spoiled forever, as I am. You will see/experience what CAN be done, rather than something that just works, kinda. -Al