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[kcoplan]

I have a '12 S, my wife bought a '13 XU last Fall.  Most of us are familiar with the way the motors on the Zeros "growl" a little when you push the bike forward or backwards with the power on.  I have noticed that my wife's XU makes this "growl" (and you feel the resistance to pushing the bike) even when the key is turned off.  My S does not do this -- key off, no growl, no motor resistance to pushing the bike.

Is this normal for the '13 XU?  Trying to decide whether I need to drag both bikes in to the dealer (need my recall service done on the S anyway, but I dont have a truck or van to take the bikes in).

--Karl

[BSDThw]

My FX 2013 has also more resistance when pushing as the 2012DS (better magnets?) if you have your 2013 bike in charging mode it will have the same Growling as the key is ON and if disconnected it will still do it some time till the sevcon capacity will become empty.

I don't know for sure but my experience with the 2012DS and my manual power on the sevcon while the bike is off (to use the battery relay for high current charging ) is doing the same

There for I guess the 2013's are powering on the sevcon while charging! 

[LiveandLetDrive]

For me, '13 FX, growls when pushed when on, when off and charging, but never when off and unplugged, though there's some resistance and cogging.

[kcoplan]

For me, '13 FX, growls when pushed when on, when off and charging, but never when off and unplugged, though there's some resistance and cogging.

Pretty sure it was happening even when unplugged -- but I will check again tonight.  Maybe it needs to be unplugged for a few minutes before the charger turns off the Sevcon?

--Karl

[LiveandLetDrive]

Should be a matter of seconds at most, you'll hear the contactor click and the charging LED will turn off.

[trikester]

My '12 DS & my '13 FX do not growl when pushed with the key off and not plugged in. However, the motor's magnetic gogging will add some resistance to pushing. That's why I carry a chain-break tool in case I ever had to push it a long distance (I have chain drive on both bikes).

Trikester

[kcoplan]

Thanks for all the replies and information.  The growling does go away after a few minutes of being unplugged and turned off -- but there is still much more resistance to pushing than with my '12 S.

Looks like I have to take the '13 XU back to the dealer for service anyway -- the bike boots up, but doesn't run -- throttle doesnt do anything.  This problem was intermittent before, and nobody has tried to ride the bike since December anyway given the less-than-conducive weather in NY this winter  . . .

--Karl

[BrianTRice@gmail.com]

However, the motor's magnetic gogging will add some resistance to pushing. That's why I carry a chain-break tool in case I ever had to push it a long distance (I have chain drive on both bikes).

What's this effect you're calling "gogging"? Is there a good explanation online of this or of the Z-Force physics? Naturally, it makes sense that motor rotation is going to induce some current in the stator, but I haven't investigated how the Z-Force motor works so I am making rough analogies.

[NoiseBoy]

It's Cogging. Probably a typo. It's just a roughness or stepping caused by the motor jumping from one magnet pole to the next.

[trikester]

Yes, my typo - it's cogging not gogging. The poles of the rotor line up with the magnets and jump to the next set of magnets when the rotor is turned. Because of the high strength of the rare earth magnets used in modern motors it is much more pronounced than in older alnico or ferrite (much weaker) permanent  magnet motors.

Tech tidbit:
The stronger the magnets the fewer turns of wire it takes to rotate at a given RPM for a given DC voltage. Fewer turns means less copper loss = higher efficiency. As more motor designs go to the greater magnetic strength of the rare earth materials, to reduce motor size and increase efficiency, the material prices keep coming down thus encouraging more use in motor designs. I fly electric R/C model airplanes and these magnet materials have made a huge difference in power to weight ratio of our motors. It used to be a challenge just to get the model to have a reasonable climb. Now many of them can go straight up like a rocket. The lithium batteries we use now also help in that regard.

Trikester

[kensiko]

Isn't that bothering that we use rare earth magnets for our electric vehicles? How much motor can we build with the existing magnets in the earth?

[LiveandLetDrive]

"The term "rare earth" can be misleading as these metals are not particularly rare or precious;[1][2] they are about as abundant as tin or lead."

http://en.wikipedia.org/wiki/Rare-earth_magnet


You can replace them with an electromagnet as well as in the Tesla Model S induction motor.  I imagine that is at some cost to efficiency (resistive losses), or at least some complication.

[peter]

Karl, the dud throttle is one of the problems we've experienced with my wife's 2012 XU. It's most likely just a bad throttle assembly. Ours was, with similar symptoms to what you've described. Quick & simple fix for the dealer - as long as you have a dealer close by.

Peter

[BSDThw]

Peter,

I had a defect throttle at my 2012DS too. (other issue)

But I don't see a change how the throttle at a 2012 Model can produce a growling when the key is turned off!

[trikester]

Yes, the term "rare earth materials" is misleading. They are not rare in the usual sense of the term. However, they were very expensive until the use of the magnetic material exploded with the advent of computer hard drives. All hard drives have those magnetic materials in them. The massive increase in computer use caused a huge increase in demand so mining the materials increased greatly, thus bringing the prices down considerably and still dropping.

One of the largest rare earth mining operations is located in the Eastern California Mohave Desert, very close to Las Vegas NV. China has bought up rights to other deposits around the world. They tried to buy the CA deposit but it was not for sale.

Trikester