how long can I run at peak wattage?

[silentflight]

Bionx has a motor rated at 350W continuous and 700W peak. A thread on the TidalForce forum over the weekend discussed a Bionx motor which normally climbed a hill for three minutes at nearly 700W but seemed to be current limited to "just a few amps" when climbing the same hill, but while the motor was "hot". It was suggested that the Bionx motors in general may heat up quickly as it is advertised as being waterproof and may have less ventilation. "Thermal Protection" is advertised in the Bionx literature as well. Aren't all hub motors watertight, or do some have ventilation holes? Any thoughts???

I am guessing that continuous wattage is set by how much wattage the motor can handle at some standard ambient temperature for an indefinite time without overheating. It follows that peak wattage is higher, and the motor then needs to be monitored when running at peak wattage to prevent overheating. How is this accomplished?

Do most or all Clyte/TF/Bionx motors have a temperature sensor in the motor so that the controller begins to limit current after a certain temperature has been reached? Or do they monitor the amount of current flowing and start an internal timer when it is over the continuous rating?

 

[knightmb]

I would think of continuous as the "normal" running power; the peak as the "burst" power. 700W peak means the motor can handle it for a short time before it overheats I believe. You mentioned they have heat sensors, a wise choice to prevent motor damage. So it's the difference between, for example, running your car engine at 3,000 RPM or 8,000 RPM, sure the engine can do 8,000 RPM, but you wouldn't want to drive around everywhere that way or else major damage would occur along with very short engine life.

From what I've seen, the power controller usually overheats before the motor does, that's where they usually put the temperature overload cutoff in a lot of electric bikes.

As for watertight hubs, they are sealed, so in a way yes they are sorta airtight, even rain resistant, but certainly not water proof that you can go riding through a river in them.

 

[Ypedal]

The BionX has electronics inside the hub ( not 100 % sure.. but i beleive the controller is in there.. it also has electronics inside the battery box.. so that's why i'm not certain what's where.. will know within a few weeks ! )


The Crystalyte motors do not have temp sensors inside the motors.. but the controllers will shut down at a certain temp. The motors are a tad overbuilt like that so if the controller can handle it.. the motor is just fine.

Tidal Force.. well.. that's just a whole different beast of a machine.. sadly.. no longer in production.

 

[knoxie]

Matra are bringing the Tidalforce back this year, they will be in the shops in the summer here in the UK and across europe. Mark at Team Hybrid will be getting some in


Cheers

Knoxie

 

[fechter]

Some motors have temperature sensors built in. Most are just thermostats that totally kill the power when overtemp is reached. A fancy one might slowly reduce the current limit at the temp increases.

Any motor can take much more power in a short burst than it's continuous rating. More cooling will increase the continuous rating.

 

[silentflight]

Thank you everyone.

I should mention that I am new here and have been enjoying e-s for about three months.

The Bionx is probably the right system for me, but I am still learning. The thread on the TF forum was the first I had read about a motor limiting it's power to a very low level. It got me thinking about peak vs. continuous wattage (even though I know next to nothing about it) and most importantly, whether I was likely to be riding along some summer day with a hill in front of me and a motor that had unexpectedly decided to call it a day due to high internal temperatures. You guys tell alot of great stories here, but "oops, I overheated my motor" doesn't seem to come up very often, so it sounds like I may be in the clear unless Bionx is especially sensitive.

I brought up Matra on the TF forum as well and Rich replied that alot was happening behind the scenes, but he could not discuss specifics.

Ypedal, I don't understand what you meant by "within a few weeks..."? Do you have a package coming your way?

Any more thoughts about ventilation? Do your crystalyte motors have ventilation which Bionx is lacking?

Best to all!