Need a new 72v controller, any suggestions?

Hello, my brand new 72v kt controller blew up today along with my lcd8h display. Thinking of taking this opportunity to see what else is in the market.
It needs to be 72v, be able to use a display and I need to be able to set the max current. I want 60A max current capability at least but I plan on only pushing 45A max.

I had this in mind, https://www.aliexpress.com/item/32871239603.html?spm=2114.12010612.8148356.12.69a42a23j7hhEF
A little expensive but I'm tired of low quality controllers. However, I can't find much feedback on these, anyone familiar with RisunMotor controllers?

Any suggestions are welcomed, thanks!

Subscribed I'm looking for the same thing, but need sensorless.

05silgto said:

anyone familiar with RisunMotor controllers?

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Some threads and posts about them that may have useful information
https://endless-sphere.com/forums/search.php?keywords=+RisunMotor&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

https://endless-sphere.com/forums/search.php?keywords=RisunMotor+&terms=all&author=&sc=1&sf=all&sr=posts&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

72v x 60a is 4320 watts.

so you need something in that ballpark.

im also pretty sure that most controllers will/should run sensorless. just not as smothly at low rpm.

jimmyhackers said:

im also pretty sure that most controllers will/should run sensorless. just not as smothly at low rpm.

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Not unless they specify that they operate that way.

Most of the controllers I've run across, owned, or worked with or helped people with do not run sensorless, and will not operate a motor without them correctly connected and operating. Not just "not smoothly", but not at all--if you're lucky they'll jerk a bit once, then just stop, and require power cycling to try again, for the same results, or none.

Almost all of the ones that do, all say they are sensorless if they operate that way. Only two exceptions to that so far, that did not say sensorless anywhere on them, and one of them falls back automatically to sensorless when sensored doesn't work, and another is actually suppsoed to be sensored-only yet it must be mismarked, because it won't even use sensors if they are attached, despite having the wires for them. :/


So don't expect a controller to work sensorless unless it says it can. You might get lucky...but more likely not.

i must of been lucky with every cheap chinese controller i bought then.

funny how more expensive versions have less functions.

I bought another 72v kt controller for now. I just built a lithium battery and my bms didn't seem to work correctly with the regen brake option on. However my display recently crapped out since it isn't rated at 72v, so I plugged a jumper at the display plug which I believe turned the regen braking back on and caused some mosfets to blow up. Either that, or it's a crap unit. I only had it for a week.

jimmyhackers said:

72v x 60a is 4320 watts.

so you need something in that ballpark.

im also pretty sure that most controllers will/should run sensorless. just not as smothly at low rpm.

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I'm using 30amps right now but I would like to be able to change the power levels up to 60 in the future. I made my own battery using 2 battery packs I bought from China. Not sure if it can handle much more than 30amps(Not sure how accurate their listed ratings are). While we are on the subject, is there anyway to tell if your pulling too much current from a battery? I have temp sensors on both the bms and on the battery I installed myself with a warning alarm if it hits 50c. If you draw too much current, will the batteries simply start to overheat?

i like to keep a general rule of thumb of 1c discharge rate (maybe 2c at a push)
and upto 1c charge rate.

think of C rating more as a "tollerance" rating than "it can handle this all day every day" rating

they usually give you a constant and then a burst C rating....ignore the burst completely. and take the constant with a pinch of salt.

lipo pouch cells seem to handle higher current better. i wouldnt trust most 18650s past 1 or 2c

despite everyone saying lithium doesnt suffer from the peukert effect like lead acid. it kinda half does.
the higher your discharge rate the less overall available amps from the battery. not to mention more voltage sag.

most lithiums have a optimum operating tempreture.....the closer you can keep it to this the better.
under discharge, cool battery = ok, warm battery = ok/better, hot = bad.
when charging , your want it to be cool/room tempreture.

as for checking cell quality.....most good chargers (my turnigy and isdt models) should have a cell impedence/resistance tester.
you want this value to be even across all cells and as low as possible. any discrepancy will indicate a potential malfunctioning/damaged cell.

they also indicate how many amp hours placed either in or out of a battery. this is usualy a good indication of battery pack health.

a thermal camera is great for noticing a hot cell....as long as the pack design alows viewing of all cells and you can afford the camera, i cant .

I got my new kt controller today and I still seem to be having the same issues. Throttle cuts off occasionally and doesn't work until I reset the display. I have the brake regen option off and even have my brake cables unplugged. Unless it's trying to feed back power regardless when I let go of the throttle. This setup worked perfectly before on my lead acid batteries so it but be something related to my new lithium battery pack and the bms. I'm afraid the controller is going to blow up again. Anyone ever experience this?

im just re reading through......

lets me get this straight......your runninng a 72v battery into a 72v controller but the display is not rated for 72v?
what is it rated to? 48v max?

i get the feeling the display also controls some of the controller functions etc.....
there is potential feeding more volts to the display is making it give out silly/bad instructions to the controller.

there is also a much simpler possibility.....a 4000w load on your battery is sagging it sooooo much that it triggering the LVC.

I was using a 48v display but now I have a 72v display after the 48v one broke. Voltage sag isn't the issue, the low voltage protection on my bms kicks in at about 65v which is 5 volts higher than the controller and once that happens the battery gets cut off completely(display cuts off) until you plug it back in.

I heard that If the contoller requests a certain amount of current and the battery can't supply it the controller enables a safety precaution and cuts off the throttle. Not sure if that makes since though since It can cutoff on pedal assist level 1 but I don't usually have any issues under full throttle. I would have to pay more attention next time I ride. Im waiting on a new motor cover at the moment.

yeah thats pretty much lvc... basically the battery cannot suppply whats needed.

you might not see the voltage sag as this precaution may kick in quickly.

max current draw is usually when your accelerating from a standstill.....uphill this is exacerbated moreso.

once your at or closer to top speed current draw usually tops off.

so if this is happening moreso when your in either of those two max current situations.....its probably controller lvc/lbattery protection.

i dont and never will use a bms, always a balance charger....if your pack is engineered to spec well enough you shouldnt need one.
there is potential your bms is messing things up or adding small inefficiencies that overall may make your battery performance worse than without a bms.

you can always go for a ride without the bms hooked up and see if the problem still exsists to rule it out.

jimmyhackers said:

yeah thats pretty much lvc... basically the battery cannot suppply whats needed.

you might not see the voltage sag as this precaution may kick in quickly.

max current draw is usually when your accelerating from a standstill.....uphill this is exacerbated moreso.

once your at or closer to top speed current draw usually tops off.

so if this is happening moreso when your in either of those two max current situations.....its probably controller lvc/lbattery protection.

i dont and never will use a bms, always a balance charger....if your pack is engineered to spec well enough you shouldnt need one.
there is potential your bms is messing things up or adding small inefficiencies that overall may make your battery performance worse than without a bms.

you can always go for a ride without the bms hooked up and see if the problem still exsists to rule it out.

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That makes sense, thanks for the help. I may try to connect another smaller pack in parallel before removing the bms. The cells are cheap china cells so who knows what they are really rated for.