Current Limits

[Dryer]

New here.  Wow, what a forum!  I've been messing with electric scooters/bikes for a couple of years before moving up to something programmable, which has opened up a whole new world.   My question is about current limits if anyone can share some insight. 

I'm running a:
1500 watt motor, chain drive
Controller is an external BLDC (bac-0501) 48vdc / 2000 watt controller (Magic Pie)
48vdc lithium battery

When I first connected to the controller with software, I was astounded to learn the default settings were left in place....24 volts, 90 amps average, 180 amps max!  The scooter was so frisky it was almost unrideable.  I set the voltage to 48, first thing. 
Ohms Law tells me a 1500 watt motor at 48v wants to see 31.5 amps.  I changed the average current to 30 and the scooter ran well, but sluggishly.  Dialed it up to 50 average with 80 max, pulled the acceleration back to 75%, and now everything is perfect.   No heat build up in the motor or controller, but then there was none at the higher settings either....which is puzzling.   
I'm trying to understand current settings, and surprised the original settings didn't fry something. 
What are some amperage guidelines here? 

Paul, Texas

[Bikemad]

Hi Paul andto the forum.

I don't have any practical experience with the BAC-0501 controller, but the description states 50A continuous and 100A max.

I can only assume that the original "90 amps average, 180 amps max" setting relate to the Phase current instead of the Battery current.
Do you have a Cycle Analyst or wattmeter to check how many Amps are actually being drawn from your battery?

If your battery has a BMS, the maximum current it will deliver is unlikely to be anywhere near as high as 90A never mind 180A. 

If your scooter has very small wheels, you are unlikely to place sufficient load on the motor to draw high current for long periods, therefore the motor is unlikely to overheat.

Higher gearing, combined with a heavier payload and steeper gradients would be more likely to overheat the motor, but if your motor and controller are not getting hot, you are obviously not overloading either of them with your current setting and usage.

My personal preference is to have the current set as high as possible, as this produces the maximum useable torque/power, but I also check that the motor and controller do not get excessively hot during sustained use.

If any of the components are getting quite hot (switches, fuses, wiring, battery, controller or motor) you will need to decrease the current to prevent overheating.

Alan
 

[Dryer]

Thanks Alan!
Yes, I have loads of test equipment (ham radio operator) and can put an in-line amp meter in place.  That's the next step. The battery is supposed to be able to deliver 60 amps....and has an inline 100amp fuse. 

The odd part is that the controllers defaults to 24volts when reset to factory spec.  That's how the scooter came.  Didn't seem to matter but I changed it to 48v.  No performance change.  I suspect the controller senses voltage and deals with it. 

As I understand it, yes, the continous and max amperage have to do with motor phase current, not battery.  The settings are very effective and I think I have it dialed in nicely, after a few tries.  That's what makes these controllers so much fun...you can change things!   

The biggest issue I had with this scooter is the raw off-the-line power. It's geared to climb hills, which makes it even worse (12" tires).  It would actually unseat the rear tire and lift the front end at every start.  I dialed back the acceleration which helped.  Now that the amperage is pulled back. It's a quite enjoyable ride and easily loafs up hills, while still maintaining a very respectable cruise speed.  Just want to make sure I haven't set a trap for myself.  Cycle Analyst sounds interesting!