Speed controller current

**gizz** · 21st November 2010, 16:13

Hi.

Im curious how much current a speed controller for a heavyweight should be able to give continiously when running with
Wheelchair motors, Bosch 750's and the mag/ampflow motors, roughly?
I'm a bit confused since there are so many different controllers on robotmarketplace with roughly the same price.
Should i use something with handles a range of 60 amps continiously or higher / lower?

I know gearing and wheelsize / numbers of wheel driving etc counts in but a rough estimate.

**typhoon_driver** · 21st November 2010, 16:47

how long is a piece of string?

In all seriousness, you need to have some restrictions on your system before you can work out rough current draw values, even things as simple as whether you are going to run the motor at it's rated voltage, or go higher or lower vastly affects the numbers.

I believe there is a calculator kicking around on the net somewhere that allows you to play about with the values but I can't for the life of me remember where. I'm sure someone else will be able to post a link.

**gizz** · 21st November 2010, 16:52

Yeah ofc there are tons of things which affect the deal but it would be interesting to see what motors
and controllers you heavyweight drivers use on your robots and if u run at the correct voltage or higher.
It could at least narrow it down a bit for me.

**woody** · 21st November 2010, 17:35

http://architeuthis-dux.org/torquecalc.asp

**gizz** · 21st November 2010, 17:58

That was very handy woody, thanks.
Tried a bosch 750gpa with an 8 inch wheel with an 8:1 reduction. It says 49,7 amps to spin a wheel and 99.3amps peak.
So a speed controller for 60A continous with a peak capacity with say 120 would be almnost perfect then?
I suppose the amps to keep the wheel spinning once started will lower but just to be sure.

Couldn't really find motors in the list named wheelchair ones, does anyone know roughly what currents they draw?

**widow_twanky** · 21st November 2010, 18:33

Originally Posted by gizz

That was very handy woody, thanks.
Tried a bosch 750gpa with an 8 inch wheel with an 8:1 reduction. It says 49,7 amps to spin a wheel and 99.3amps peak.
So a speed controller for 60A continous with a peak capacity with say 120 would be almnost perfect then?
I suppose the amps to keep the wheel spinning once started will lower but just to be sure.

Couldn't really find motors in the list named wheelchair ones, does anyone know roughly what currents they draw?

Theory's always fantastic. I found the NCC70's (70A) would blow reasonably regularly on a bosch 750 at 36V. For Bosch's I'd go for either a roboteq which has a 120A continuous current

Andy