AeroPod, PowerPod and Newton

Recently, I got "SPD FAIL" on a ride when it seems to me I've replaced the speed sensor battery fairly recently. But I didn't keep track of when I replaced it, so I don't really know how many hours/miles the battery has been in there. But I think my prior battery went for a year before needing to be replaced. It certainly has not been a year, almost definitely not even 6 months, since I replaced the speed sensor battery.

I'm not an electrician, nor do I play one on TV, but I own a multimeter. I applied the multimeter and got a reading of 3.01. I tested a couple of brand new batterys; they showed about 3.25 on the same multimeter. The iBike user guidance is to change the battery when it gets down to 2.75v. Shouldn't my speed sensor be able to operate on 3.0 volts?

I should note that I replaced the battery for today's ride and my iBike worked perfectly in 45 degree weather. And I should note that when it conked out last Thursday, it was rather cold and windy, probably 35 degrees. It was 50 degrees in the garage today when I tested the battery.

And, finally, I should note that the SPD FAIL occurred multiple times; the speed reading kept coming and going throughout the ride. The iBike captured about an hour out of a 1.5 hour ride.

I really hate losing ride data as it affects my TSS. I'm really focused on training for racing this year and want good data.

Does this sound like a sensor issue or a battery issue?

Batteries rely on chemical reactions to create voltage. As the temperature decreases, the reactions are slower, resulting in lower voltage-current generation. You might recall that car batteries are rated at cold cranking (amp-hours, for example) - how much power (current-voltage for some length of time) they can put out at something like freezing or colder.

Your measuring of the battery with a VOM is essentially an open circuit voltage - not what voltage you would measure at some drain current. Do the same measurement on a battery fresh out of the freezer and you will get lower values. You are describing temps in the 30s to 40s where these little 2032 batteries do not have many amp-hours in them.

Every battery is not the same, either. Shelf life comes in to play and it does decrease the useful lifetime of said batteries.

Now, let's also consider how many batteries come in to play here - the sensor, the computer and in a wireless situation that too will be a battery that plays in to the pairing process. So you have several to check - not just the one in the sensor.

Tom

Typically, I start getting the spd fail message when the battery in the wireless mount starts to go.

The batteries in the sensors will last a year or more.

Batteries in the unit go quickest; batteries in the wireless mount seem to last about 40-50 hours of ride time for me.