# Kelly Controller Choice



## ratchet6900 (11 mo ago)

Hello all, I'm trying to decide between a Kelly KLS6030N and a KLS6018N for my electric ATV (a Venom E-Grizzly, 48V, 1500W stock controller and 3000W BLDC motor according to the vendor). I wish to replace the stock controller as I am not happy with the control of acceleration in the high speed range - it is extremely abrupt off the line even with v low throttle opening, hard to control at low speeds and IMO unsafe especially for younger or inexperienced riders.

The KLS6018N at first glance seems more than adequate for this application as it is rated at 220 A (30 second surge) and 80 A continuous (48V * 80 A = 3,840 W). The KLS6030N is rated at 270 A and 90 A respectively (and $50 more expensive). The reason for my uncertainty is that the Kelly tech support person (Fanny) says the 6018 is too small for my application, quote:

"The current rating is based on the motor phase side. The 48V is on the battery side.
Anyway KLS4812S is mini controller. It can not support 3KW motor. The controller will be overloaded by 3KW motor for running a period."

Can anyone explain this in clearer terms? I don't understand if the stock 1500 W controller gives more than adequate performance, why the smaller Kelly controller won't work as well or better. What I'm thinking is that the controller's output current may be much higher than the input from the battery (at a lower voltage). Could that be the case??

Thanks much for any assistance....


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## gunnarhs (Apr 24, 2012)

Hi one of the best things at Kelly is their technical support Fany so you should trust him with this.
The rating of a Kelly controller, which is given in max voltage / max current (and not in power) assumes that the most current is drawn at low voltage and the least current at highest voltage.
So in above example the 48V / 80A rated controller does put out (motor side, low speed ) 80 A at maybe10 -20 V.
At 40V motor side (high speed) the current will be about 20-40A. So the power of the controller is probably about 1000 W continuous and the maximum power 1600 W.
I do not know about the Venom Grizzly Controller but if it is given up at 1500 W power and used for a 3000 W Motor it's 1500 W is most likely continuous power rating.

In the motors I have used from Kelly (120-140 V, 400-600 A ) the continuous power has been about 20 kW and the maximum 30 kW for a short time ( minute).
That is actually pretty good for an air cooled controller for 1000 USD 

The software can be configured easily so that the controller can drive in pure torque mode (which is aggressive but not so efficient) and also in mixed mode which is better for less experienced drivers.
(voltage /speed mode only , which also can be set does not work for a vehicle with variable torque requirement).

But I would go for 48V /100 A (continuous) in your case if you can find one. The 48V / 90A is also rather low according to my real world experience with these controllers.


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## ratchet6900 (11 mo ago)

Hey gunnarhs, thanks for the informative reply. I was not aware that Fanny was a guy (not that it matters much) but you are right about how useful he is - I have asked several email questions and he has always replied quickly, some times within less than an hour.

I kinda expected my calculation of wattage might not be accurate as you point out (lower voltage on motor side). As well, the 6018 and 6030 are rated at 60 V so would it be downrated for operation at 48V? 

Anyhow, it looks like the 6030 would be the better choice but even so, maybe not enough (Fanny seems to think though it would be OK)?


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## gunnarhs (Apr 24, 2012)

The 6030 is the obvious choice if you are running with a 60V Batterie-Pack (then less current is drawn). If you are running with lower voltage batterie-pack (48V for example) then (continuous) current will be higher. The question is how well the controller handles that and you are safer with a bigger controller.


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## ratchet6900 (11 mo ago)

OK, thanks again. The 6030 it is!.

BTW, if anyone else is contemplating buying one of these units, Fany tells me the contactor is not necessary - I think I will try it that way and maybe just add a manual switch if it results in too much battery drain.


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## Serjeo (Mar 25, 2019)

stay away from the controller if you got a problem with, they won't help you, i mean Fany or Kelly 
i have issue with KLS 8080I and they says "you have to buy a new motor or blah blah blah"
very dissatisfied with Kelly tech support.


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