The Inside of a PowerTap

I replaced the batteries on my PowerTap yesterday and decided to take a picture of the guts.  Pretty interesting stuff going on in there -

• Lots of empty space.  I guess this is a function of the torque meter needing as wide a diameter as possible to better measure values.
• You can see two small watch batteries on either side of the blue wire.
• There was a little circuit board between the two batteries.
• A black transmitter on the top left labled "FCC something something"

I had to pull out a module that held the circuitboard and batteries as one.  All of this was easy, but it was the reassembly that had me a little worried.  There's O rings to seal it against water and if they get grimey, they can leak.  I pulled out the big one, cleaned it, and regreased both.  I'm positive it has a good seal, but you can never be too careful when washing the bike.  Never ever point water spray directly at it.

I'm coaching somebody who has a power meter and I suppose checking out all her power graphs motivated me to take the dang thing apart and fix it.  I was going to do it eventually, put looking at somebody else's watts makes me want to chart my own!