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Author Topic: Motor output degradation  (Read 424 times)

rayivers

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Motor output degradation
« on: April 01, 2017, 07:44:13 AM »

Yesterday I was riding both my bikes on the street, and was amazed at the power difference between them (relative to late December 2014, when there was almost none at all).  Then I remembered this was at least the 3rd time I'd noticed a power drop, so I thought I'd post about it.

The first time was in my street FX, in the summer of 2014.  I'd been riding the (new) bike all spring and really loved the initial trip out my driveway, which I'd always do WOT with a slight front wheel lift and panic braking before the street - my "yee HAA!" moment of the day. I'd read at EMF about thermal limiting / power reduction (which I'd never experienced), so this day I decided to check to make sure my limiter circuit was functioning correctly.  I took the bike up a long hill until the red indicator blinked (I think the indicated temp might've been 210F?), then backed it down and let it cool; power was never reduced.  In retrospect, this was probably the worst thing I ever did to that bike, though I didn't know it at the time.

The ride out the driveway the next day was quite different.  Unlike every previous one, there was no wheel lift or need to panic brake.  I ended up riding up & down the driveway several more times to make sure I wasn't imagining it, but no - the yee-ha era was over. :(

The next time was when I bought my used 'MX' dirt FX, in August '14.  This 5.7 was slower in Sport mode (below 40mph) than my 2.8 in Eco.  At the time I just chalked this up to 'used bike syndrome', but later I found out the motor had been torture-tested by the dealer (remember the magnet-adhesive recall?).  Once firmware issues were corrected and the motor was replaced under warranty in December of that year, the bike felt nearly identical to the street bike.

Yesterday was probably the worst.  Despite the new 10/65 sprockets - which I really had high hopes for - the 'MX' (with 10X the mileage of the other bike, and one unintentional thermal-limit with the replaced motor) accelerated much slower than the FX street bike, except maybe below 10 mph.

Zero had a huge presence at the 2015 AIMExpo show in Orlando, and I remember relating much of the above to a Zero tech there and asking if it's possible my motors could've lost power due to overheating or hours of use.  I'll never forget his answer: "There could well be something to that".  When I heard this, I finally stopped second-guessing myself and now firmly believe both my bikes were actually faster when their motors - especially the magnets, which hate being overheated or vibrated - were new.

I've had a number of ICE ignition rotors remagnetized with good results - maybe I'll look into doing that with the Zero motor.

Ray
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'14 Zero FX 5.7 (now 2.8, MX), '14 Zero FX 2.8 (street), '08 YZ250F, '82 RM250Z, '75 MR175, '74 CR125M (175cc)

odedmaz

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Re: Motor output degradation
« Reply #1 on: April 01, 2017, 09:47:45 AM »

Hi Ray,
I would look into 2 things:
1. Battery condition - check the logs to see voltage sag and cells balance. Perhaps one of the battery packs is responsible for that behaviour.
2. There is a thing in brushless motors called "timing". These motors need to have there timing checked from time to time by a dealer, by connecting the bike to a diagnostics computer. The fix is simple and takes few minutes. I would start there.

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Kocho

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Re: Motor output degradation
« Reply #2 on: April 01, 2017, 06:33:44 PM »

I've gotten the red blinking warning for *approaching* high temp on my '15 SR once so far, at fast highway speeds. And the *limiting* of power I experienced only once. After I backed down on the throttle a bit, in both cases the temp went back to "normal". I did not observe loss of power subsequently.

The way you describe your situation, there is a drastic loss of power from just one time overheating (and actually not truly overheating, but *approaching* the limit (your power was not reduced then). If this was due to motor demagnetizing or whatever due to temp, we'd have more reports like that - many people routinely overheat theirs, and I don't remember anyone having reported a permanent loss of power like in your case...

Check the logs first as mentioned. Check cell balance and SoC. May have the dealer check your batteries and check/adjust the motor/controller timing ("commissioning").
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rayivers

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Re: Motor output degradation
« Reply #3 on: April 01, 2017, 07:23:45 PM »

Quote
Battery condition

I tried both my batteries, Oded - the results were the same.  I don't have a smartphone now so I haven't checked them lately, but the 2nd battery (in the bike now) was in great shape before being stored.  In my first example (driveway ride) the battery was still nearly new and the condition wouldn't have changed significantly in 24 hours in any case, and the batteries were barely used in my 2nd example (bike had < 250 mi. on it).

Quote
These motors need to have there timing checked from time to time

The MX bike has had this adjusted twice; once during the first dealer visit after purchase (it made a slight difference), and then again at the new-motor install (big difference, mostly from the new motor obviously).  Taking the bike to the nearest dealer I trust involves a van rental etc., so I've been putting it off as long as possible. :)

Quote
drastic loss of power

No, not drastic - but quite noticeable.  If I hadn't been doing the exact same thing every day at WOT, I wouldn't have noticed it.

On that note... if you don't ride your bike often at WOT in similar circumstances you probably won't notice a reduction in max power, any more than you'd notice a reduction in max battery range if all your rides are short & start from full SOC.

Here's a recent quote from laramie lc4 that kind of planted the seed for my post:

"my bike (2016 FXS) has been a little off since i took it to the track last time and completely pushed it to it's limits."

IMO track-day situations are pretty much ideal for assessing loss of motor power, for both EV and ICE machines.  Every dirt ride is basically a 'track day' for me, so I tend to notice right away if something's off and/or trending downward.

Ray

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'14 Zero FX 5.7 (now 2.8, MX), '14 Zero FX 2.8 (street), '08 YZ250F, '82 RM250Z, '75 MR175, '74 CR125M (175cc)

clay.leihy

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Re: Motor output degradation
« Reply #4 on: April 02, 2017, 04:59:03 AM »



2. There is a thing in brushless motors called "timing". These motors need to have there timing checked from time to time by a dealer, by connecting the bike to a diagnostics computer. The fix is simple and takes few minutes. I would start there.

Is that the motor commissioning that the IPM motors need regularly? There's nothing in the manual about that for my 2015 FX.

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Clay
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