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Powertap Question - does the indicated power drop when batteries are low

Peter GreaggPeter Greagg
in General Training Discussions

Hi Powertap Peeps

I was wondering whether the indicated power falls when the batteries are low?

The reason I ask is that on Saturday I did 2 x 15 mins @ 215 watts which seemed quite doable and was sure I could have done another couple — this was on my Computrainer which I calibrated as usual and was in the TT bars (as usual).

Today, I did my  2 x 20 FTP power test (outside on my usual course) using my Powertap on my TT bike and while I didn't pace it perfectly, there was less than 5 watts difference between the intervals — and it was 215 watts — and it was very hard. I was almost puking at various points and struggled to finish it off. On an RPE basis, it was way harder than the CT set on Saturday. Also, I rested yesterday apart from a 1 hour swim, and felt up for the test.

Now I have been using power for more than 12 months and thought I had a reasonable feel for the watts I am pushing, so this has me a bit confused.

I use the lyc as a head unit and I have noticed that the display is harder to read than it used to be. Also, when I calibrate the hub it is different from when it was new. When new, when I held down the right hand button until the "watts" sign starts to flash, the actual watts display used to be a number (eg 0, or 1, or 2, or -2 etc). Now, the watts display doesn't show a numeral just a confused flashing of the various components of the first digit — then it blinks and then shows a number (which I then wait until it shows "0", then I press the right hand button again).

I have a HIM on Sunday week so I won't be changing anything before then, but was just curious about it?

Hoping someone can help me.

Cheers

Peter

Comments

  • Peter GreaggPeter Greagg
    ps, I haven't changed the batteries since I got the powertap 14 months ago.
  • Keith WickKeith Wick
    change the batteries in the LYC. You'll know if the hub batteries need changing because the little balloon type thing in the top corner will start blinking.
  • tuckermtuckerm
    I'd change those batteries in the PT as well. Won't hurt, plus you don't want to find out a couple miles into the race that the batteries were bad. Happened to me at IMCDA and it isn't fun. Only takes a couple minutes to swap them out.
  • Peter GreaggPeter Greagg
    Thanks Keith and Tucker. My problem is that I have left my only RR until Saturday with the race 8 days later. So I was worrying that changing bateries now might result in an incorrectly paced race as I don't have time for another bike test.

  • John WithrowJohn Withrow
    Peter- low batteries won't change the power that is displayed, but it might make the readout intermittent or spotty or worst case, gone all together. Definitely change your batteries. Change them in your LYC AND in your PT hub. Batteries are cheap! As much time and energy and money you've spent to train with power, you want to actually race with it as well. I change my batteries about 3-4 times per yr because I'm so paranoid about it.
  • Tom GlynnTom Glynn
    I find that with low batteries, you end up with a bunch of dropped data so when you look at the WKO data, there are blocks of zeros. Batteries cost a couple of bucks USD - probably a little more in Australia image. Like John says change them often, if not they will always fail on an important race day!
  • Peter GreaggPeter Greagg
    Thanks John and Tom.
    I realise I just need to suck it up and deal with the fact that my FTP hasn't changed after 14 weeks of the OS — I was hoping that pain and sweat would have pushed my FTP up a bit.
  • kurshingkurshing
    @ Peter - don't lose faith or hope in the system. I have heard, several times in here, that there is a lot of work for some initial gains, and then there is often a 'breakthrough' where things change fairly quickly. I have seen the opposite as well. The variable is your body's process of adaptation.

    If you stick with it, you will grow and you WILL get faster.
  • Keith WickKeith Wick
    Since you still have your RR left to do, I'd make sure to change the batteries prior to the RR.
  • Peter GreaggPeter Greagg
    @ Keith - thanks, I am doing it today.
    @ Stephen - thanks for the encouragement! EN rocks! I am a pretty optimistic kinda guy so while I am disappointed that my FTP hasn't changed over the whole OS, I figure I must be getting benefits from all that work. I have read of others that only reported FTP gains after the OS was over.
    Two that come to mind are that my RPE at 210 watts is way lower than it used to be (FTP of 215 watts), and second, my APB rides that I resarted a few weeks ago are now around 185 watts, compared to last seasons's high 170s — although maybe both are just reflections of the same thing.
    In any case, I enjoy the high intensity approach to training much better than the old-school approach.
    It may be that I have dug myself into major fatigue hole over the OS — I certainly struggled with the VO2 max block and had some symptoms of overtraining.
    After this race, I will rest hard before loading up a short course plan.

    Cheers
    Peter
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