Dyno Load

I’ve acquired a small dyno to help test the controller firmware I’m developing. I need a way to put a load on the motor opposite the one I’m driving. The first thing that came to mind was a string of lightbulbs wired across the motor phases. That’s not going to fly because my state’s government (California), in their infinite wisdom, has banned the sale of incandescent bulbs, so I can’t buy them locally, and Amazon and other online retailers won’t ship them to my address.

Any other ideas for a quick and dirty solution until I can devise something more permanent?

A rope.

A wet rope will load up a known diameter pulley very easily. A surprising amount of force in tension, can be measured with a rope and a scale, wit increasing weight. You can use a rope slung with a turn or a few turns around a diameter and keep it wet: Measure hundreds, if not thousands, of horsepower accurately and reliable, with the correct rope choice.

Very very easy to calculate tork and power from a Rope dyno. Just put a pulley on the shaft and git to calculating. Honestly you do not even need the scale.. You can calculate the angle of the rope, as it hangs against gravity, being weighted down to the ground, tangential to the pulley, and figure the force load. As it swings under the rotating pulleys load.

Rope dynos, been around since day one of the dyno. My dad once wrote a book on the Dynometer. For his students. It was an important part of his curriculum. It is a good read. Really lays out the math that every engineering student gets wrong.

I love to use hot water heater elements and/or electric clothes dryer heater elements.

You will never go back to light bulbs after.

liveforphysics said:

I love to use hot water heater elements and/or electric clothes dryer heater elements.

You will never go back to light bulbs after.

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I have a ~30kW array of strip heaters from Tempco for this purpose. They fit ( bolt to) a server rack and the rack sits about four feet high. Double sided and laced with 8Ga all around. I can set up upwards of 30 ( 15 per side) high power strip heaters ( 1100w-1700w).

They are less dangerous than a red hot element. Ya know. For long discharge testin. I would rather not watch a red hot element nor could I find one ( 10? in parralel) strong enough in the voltage we see DC ( and congruent RMS rating of the AC they were designed for) ( factories) ( not houses) ( only get so big of a light bulb or water heater element) and the power dissapation needs I have.

I got a ton of these. I also have large 3000w ceramic Nichrome resistors in milliohm ranges.... they can pull some power. About a foot long each.

https://www.tempco.com/Tempco/Products/Electric-Heaters-and-Elements/Strip-Heaters.htm

Here is a pic of the array pulling about 5kW on a 72v battery. These strip heaters can be found on eBay for a reasonable price.

Breville said:

I’ve acquired a small dyno to help test the controller firmware I’m developing. I need a way to put a load on the motor opposite the one I’m driving. The first thing that came to mind was a string of lightbulbs wired across the motor phases. That’s not going to fly because my state’s government (California), in their infinite wisdom, has banned the sale of incandescent bulbs, so I can’t buy them locally, and Amazon and other online retailers won’t ship them to my address.

Any other ideas for a quick and dirty solution until I can devise something more permanent?

Click to expand...

Buy a VESC, or build a second controller and control the regenerative braking back onto the Vbus