Kelly Controller power ratings

builder7

100 µW
Joined
Sep 16, 2021
Messages
9
When I look at Kelly controllers I see voltages and amperage rating that suggest a much higher power rating than advertised. Does anyone have any insight?

Example KLS7218S
Voltage 24 - 72v
Amps
80 continuous
200 burst

They advertise this as a 2000w controllers and those numbers suggest a much higher power capability.
 
That is much better than the other way around.

The specifications as laid out by manufacturers in data sheets specify absolute maximum / minimum limits of acceptable ranges only, not recommendations intended for normal functioning, operating conditions for day-to-day cycling.

These are "stress ratings", to which the gear can only be subjected for short times, without causing irreparable damage.

Frequent exposure to such stressful conditions, or for extended periods, can adversely affect reliability and will greatly reduce lifespan.
 
builder7 said:
Voltage 24 - 72v
Amps
80 continuous
200 burst
Treat these as separate ratings.

Max voltage really should not be approached unless trusted members have tested and proven it is indeed very conservative.

Current is more nebulous, very much depends **how long** continuous means, might be only twenty minutes might be two hours

and burst (peak, pulse) might be only 2sec might be 20sec

Also ambient temperature changes everything, 77°F usually is standard.

The wattage rating is least nailed down, probably means "can handle the normal usage range of motors called 2000W rated"

https://ebikes.ca/learn/power-ratings.html
 
From what I have heard, Kelly current ratings are phase current, not battery current, so the numbers will be much higher for a given power rating. This makes comparison with other controllers difficult. Phase current can be 3x the battery current.
 
If you do experiment with going to high amps/watts

and you do not want to test to destruction

use a temp sensor and cut power when you see internal temp rising quickly above 90°C or so, ideally earlier
 
From a rating perspective phase current is the important one, battery current is kind of irrelevant.

Phase current is what the motor and MOSFETs see. For bldc at max speed phase = battery current, for sinusoidal there's some sqrt3s in there.

At zero speed, battery current can be tiny and phase huge.
I2R=VbatIbat
R is in Milli ohms so go figure...
 
But if you want to compare to other controllers that are rated by battery current you have to divide by about 3.
 
I know how this works.

I can tell you absolutely, I think.,. Tractive effort ( curve ) load, battery ability, RPM rang and kV, all have an effect. Time, current demand, whats what... On how Kelly lays out the power.

For instance: Here is a KEB72801X: 2018 controller.

8Kw rated by Kelly. 350A peak, 165A continuous is the datasheet.

I pulled 280 amps out of the battery.. 18kW battery horsepower.

Explain that "its phase amps" people. Well.. It is.. The waay phase amps and battery amps interact with load and speed... for one thing.. but.. With a good homemade pack. I also ran this bike on a Top of the line hobbyking Lipo.. and it was much much 3worse. 1/2 the power was al the lipo could hack... Lipo complied and that was that.

I just sold a 459$ Kelly for 180$ and it was a " 450A " controller .. with a 160A continuous.. Rated 12kW by kelly.. a heavy golf catr type controller.. It was listed as " 450A for 10 sec, 400A for 30 sec, and 160 A contin." A very large controller (massive).

Basically the controllers peak at start ( when maximum tractive effort is neccesaryon a traction system, prime mover) and igf you have it setup rihgt it will haul inthe RPM rangeyou need..

Lufgging and loping do not do well, the 10 sec is up,revert to controller max rating.. contin...

18kW.jpg

JunkLipo vs Goodlipo.JPG


.....here is another log. KEB 72330

: Somewhere from 2012-2013.. I think. At least before 2015.

It is a 3.3kW rated controllr.
1min.JPG7Kwlog.JPG20sec7Kwpeak.JPG


I pulled 7980w and 107.2A out of it. I heat this one up.. I have ALL the tractive effort with this level of power and do pull full controller phase amps.. and battery amps from that.

BIG BUT.. It tries 100a, 8kW... BUT.. after 30 seconds it REVERTS to a current throttled state where it will only put out the ( half) amps of the rating.. So I cruis alot at 40-50A contin ( max contin,.. ) but if I can peak here or there.. it WILL.... given how speed and phase amps are related.. It is a 3.3kW controller and puts out 3500w continious.. but PEAKS when IT CAN.

I could ony pull 280A on the 350A controller. Then the tractive effort dropps, back EMC is up, current drops, blah blah blah.. That was it.

....peaks. Off the line. In the first 10 sec. After 30 sec they revert to the lower rating ( that is quite often half the phase amp rating and yes, Kelly does call it the phase amp rating).

Alot matters from the consumer point of view and the rating and how they work is kinda muddled. PersonA ays this: Person B says this.

I will link Kelly Controllers description of the ratings and current applications. How the numbers work. This is how it does it.

Here is one of the million Indian/Pakistani/Middle Eastern/ Far Eastern Engineers describing ( how to fundamentally model and diagram) Tractive Effort. In ye goode ol (broken) British English.
https://www.youtube.com/watch?v=56Ug-gtIqxo

Here is another in good ol American English. By some kid who looks to be a 17 year old enginoor. Lol. Description is great. Lil ol engineering kid with 3.2 million subs. Lol.

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

A REAL Brit.

https://www.youtube.com/watch?v=X7KWtf4wqN4
 
Mine was the original post, and I realized that I read it and didn't respond.
Thanks for the information very helpful. It was good to see that the Kelly can deliver a considerable burst.

My take, you cannot compare amperage rating between a Kelly controller and most other controllers because Kelly reports phase current and other report battery current.
Phase current is much higher than the battery current.
The KEB controllers are the only ones that are listed by Kilowatt power consumption. I had been looking at the KLS controllers(water proof) which are listed by amperage.

I have seen comments that Kelly controllers are weak, but I suspect now it was because people were looking at the phase current and assuming it was battery current.
 
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