advice on choosing the right motor controller

[dexdrako]

hey everyone i need help

I have two 72 vote 4000 watt motors that i need controllers for and I've been eyeing kelly controllers. the KLS-N to be exact but i don't know if I should choose the 140\50 amp version or the 200\60 amp. I believe the 140\50 should be the one i choose because my motor falls in the middle of its range (volts x amps) 3,00 to 6,480 watts. but the 200\60 range would be 4,320 to 7,920 watts so it wouldn't be worked as hard.

hopefully I'm somewhere in the ball park with these numbers but i'm not sure so any help would be welcome

 

[amberwolf]

To find the right controller, you need to know the job the system has to do for you, to find out how much power the system must produce to do the job. The motor simulator at ebikes.ca can help you do that, if you know the riding conditions, terrain, weight, etc. (you don't need to use the exact parts you have to find the power, just follow the instructions on the page and experiment).

Once you know the power required, then if you already have a system voltage picked out, you divide that power by that voltage, to get a guesstimate of amps required. That lets you find a controller that supports that much *battery* amps, and that battery voltage. Some controllers are rated in phase amps instead, so you then need to check with the controller manufacturer on how they rate them so you can get one that will support the battery amps / total power you need.

Once you have the controller, if it's capable of more than the power you need and more than the battery or motor can handle, then assuming it's user-programmable, you would set the current limit in it to whatever those parts are capable of, or less.

While you're looking at controllers, you can decide what features you need it to have to support your riding style and usage (such as programmability (and what level of user-changeability you want, meaning what things you will want the ability to change), display support, FOC, multi-speed switches, variable regen braking, etc).


Then you can look for a battery that can supply *at least* that many amps (preferably at least 25-50% more, so you are not stressing it), at the voltage your system needs.

If your motor already supports that much power, then you can use it, otherwise you may need to look for a new motor that will do the job required.