Erratic (mostly zero) and Cal Check

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mo_mo
Posts: 7
Joined: Mon Sep 21, 2020 10:16 pm

Erratic (mostly zero) and Cal Check

Post by mo_mo »

Yesterday my powerpod started outputing really low power values (like zero for extended durations). This was confirmed in Isaac and not just on my head unit. It would only show brief power spikes during moderate to high efforts. Uphill and downhill wasn't a big contributor, so I went over to a local hill that I would typically push over 200 watts minimum, and I could barely break 100 while trying. See attached ride file Velocomp_04_19_2021_1722_7_Miles.ibr

Prior to that, I thought I had a reasonable calibration. Velocomp_04_10_2021_0928_47_Miles.ibr

Changes to the bike:
thorough cleaning
new cassette (10 speed 11-28 replaced 11-25)
new chain
trued wheels
new tires (700x25s replacing 700x23s)
Dropped handlebars ~5mm on steer tube (did not adjust stem or velcomp mount [bolts were never touched]).

Pitot tube is not obstructed.

After 7 mile problem ride, I put the bike on a dumb trainer (speed = power) and it automatically switched to profile 2 (which is in trainer mode), and worked flawlessly for an hour.

I've since charged the powerpod overnight to make sure that wasn't the issue, but it is still present. I've played around in Isaac, and it isn't helping. I've also reset and recalibrated and the problem persists.

What do I need to do to resolve the issue with the 7 mile ride?

Once that is fixed, are there any changes I should make to my 47 mile ride calibration other than the new tire size?
Attachments
Velocomp_04_19_2021_1722_7_Miles.ibr
7 mile problem ride
(99.23 KiB) Downloaded 105 times
Velocomp_04_10_2021_0928_47_Miles.ibr
47 mile good ride
(909.97 KiB) Downloaded 115 times
mo_mo
Posts: 7
Joined: Mon Sep 21, 2020 10:16 pm

Re: Erratic (mostly zero) and Cal Check

Post by mo_mo »

Fixed!

Somehow my Crr became a relatively large negative number (~-.034 compared to +.0054). This was giving me a 'motorized boost' of ~300 watts that I had to overcome for the PP to give me a number above zero. Otherwise the PP just reported zero.

For some reason this was not simple to correct. When I would push a profile to the PP, it would not accept the updated Crr value. I reset the PP and it still wouldn't take the correct Crr value. I then tried a cal ride and still no dice. I then adjusted the Cal Weight along with the Crr and the PP then accepted the new values! Back in business!

Why PP would allow a negative value for Crr and then not accept a corrected value is beyond me.

Another anomaly is that Isaac doesn't seem to update the power graph properly for values that are originally zero. The graph will show zero over a manually highlighted section with an updated profile/Crr, but the Selection Stats table averages will read:
Power - 0.0
Aero - 81.4
Rolling - 46.7
Gravity - 30.3

Shouldn't Power over that same segment average approximately ~158.4?

Glad it is solved, and I hope not to come across this gremlin again :)
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