power2max problem - high readings

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wwnick
Posts: 106
Joined: Wed May 10, 2017 8:49 pm

by wwnick

anyone else having or had problems with power2max (my model is S) giving high readings.
i am thinking it could be to do with low battery
the readings are obviously off as I have previous data to compare with.
very annoying when these things cost so damn much then cause problems

UPDATED WITH MORE INFO:
high readings seen in real time and file analysis

battery voltage is 2.91 - new battery tests at 3.3v....
maybe this is cause of all my problems, anyone care to test values of batteries when their p2max goes flat and note if they are having similar problems

problem is not power spikes, it is the whole ride is consistently high, around 20%
(as one post said: I either get a new FTP record or struggle to stay below 200W)

Zero-offset (there is no way for user to calibrate P2M) is done via 3 second pauses whilst riding.
see: https://www.power2max.de/downloads/powe ... al_web.pdf
Your power2max powermeter ensures precise measurement of data using two separate mechanisms: zeroing and temperature compensation. Your power2max powermeter automatically determines the zero value, i.e. the value that is measured when no torque is applied to the powermeter. This compensates for the influence of temperature changes and mechanical factors affecting the zero.
Manual setting of zero through your bike computer is possible but not necessary. Every time the system is unloaded for 2 or more seconds your power2max powermeter sets a new zero value.
In practice this means that every time you are coasting for 2 or more seconds your power2max powermeter sets a new zero.

left/right balance numbers appear OK, the same as they did when I was getting correct figures
Last edited by wwnick on Sat May 13, 2017 9:54 am, edited 3 times in total.

mr4fox
Posts: 258
Joined: Sat May 15, 2010 2:01 pm

by mr4fox

Do you see them in real time or only when analyzing the files afterwards?

I found really high spikes in some files if a grinders when I synced him up to wko4+. I first noticed them because his mFTP was way too high. Didn't notice any abnormal data in training peaks though. Removed the spikes manually in WKO4+.

My friend subsequently sent the s-type back to power2max. They worked some magic and sent it back. Apart from that neither of us have noticed any problems. We have 2 S-Types and a NG between us, all though my two aren't very old yet.


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wwnick
Posts: 106
Joined: Wed May 10, 2017 8:49 pm

by wwnick

i see it in real time and in downloaded file. regards power spikes, this is not what i am referring to, it is the whole ride is consistently high.
i will change out battery tomorrow as I vaguely remember having this problem before and see if that fixes the problem over the next few days.
strange is, that I have not done many miles, but it has been 12 months since last battery change.

would be interesting to hear from other p2m users if you get inaccuracies due to battery.

how long was turn around time for the unit sent back? also which country

stuh
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Joined: Mon Nov 30, 2015 1:30 pm

by stuh

Are the readings in the thousands or just like 25% above what your expecting?

Pugrot
Posts: 62
Joined: Wed May 12, 2010 11:52 am

by Pugrot

Always flat battery in my experience. Happened 3 times now. Usually either get a new FTP record or struggle to stay below 200W, new battery has solved each time. Only takes one ride to notice.

Todaysplan has a feature which tracks the battery voltage over time, so it is definitely reported to and recorded by a Garmin 520, I haven't found a way to display it on the garmin though.

wwnick
Posts: 106
Joined: Wed May 10, 2017 8:49 pm

by wwnick

I was thinking constantly about 20% higher readings. This pretty much is exact problem, "usually either get a new FTP record or struggle to stay below 200W"
Please if anyone else experiences this can you post here as I want to see if this problem affects just a few units or all.

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miltmaster3
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by miltmaster3

some times bad calibration gives bad readings

in watt mode
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wwnick
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by wwnick

the thing with p2max is that, it auto calibrates, all the time

from p2max faqs "Anytime you stop pedaling long enough (approximately 3 seconds or more) power2max updates the zero offset."

now I have a feeling it is not battery as I have just taken a voltage reading of 2.92v, which seems "not low".

putting in new battery has in the past resolved problem but I am thinking it is another problem more serious elsewhere.

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miltmaster3
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by miltmaster3

OK but the correct is to stop release the shoes from Pedals and these push calibration.....then in that base itself calibrate . do it and see the reading

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miltmaster3
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by miltmaster3

the auto calibration is for temperature changes . so if you have bad calibration number is making small adjustments from temperature changes

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wwnick
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by wwnick

hi, thanks for this info, where are you getting it from?

I remember reading in some p2max info not to use head unit to calibrate... can't remember where and now it seems p2max say it is doable but there is really no need

and recently saw a post that p2max was denying responsibility for any problems asnd sayint they user had been been using the head unit to calibrate. (http://www.timetriallingforum.co.uk/ind ... s-problem/)

i appreciate your answers and hope you can send me a link as it makes sense, i would like to try it out if it is p2m that recommend this.

further, i did a dump of some fit files and see that garmin records the p2m unit voltage is down at 2,82v

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miltmaster3
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by miltmaster3

the calibration has to do with your head unit !!!!!! in edge 520 you must stop and un clip shoes

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miltmaster3
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by miltmaster3

https://www.dcrainmaker.com/2015/03/the ... eview.html

"What the Power2Max does support as noted is the zero offset procedure. To trigger this you’ll utilize your head unit and just select ‘calibrate’. This should generally be done while you are off the bike with your bike shoes unclipped, as you don’t want to apply load to the pedals."
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wwnick
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by wwnick

ok, cool, thanks for your replies. just to clear up. The temperature calculation works in the background. you cannot do this manually. the stop pedaling for 2-3 seconds is same as doing headset calibration. this is directly from p2max support post.
so in effect, yes i auto-offset every ride or more.

does anyine have any readings of voltage from battery, mine is as low as 2.82... trying to find out an average so I can rule this out too, thanks

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miltmaster3
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by miltmaster3

do you have left right balance numbers ok ?

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