What you can expect from a battery:
After doing some calibration etc I have the following to share
A Full charge lasted 10 days and ~360miles with the longest ride ~55 miles in a day.
Meaning that a full charge will give 3,500 to 4,000 activations (single steps)
The unit was used until it failed i.e. battery depleted which was at the final stage of a 20-mile ride.
The voltage of the battery before the ride was 10.30v
Note: The battery indicator in the App (Android) is not worth using as it is just wrong i.e. not proportional to use and indicated “?” or empty for several days before it failed.
It appears the battery will fail at around 9.8v. However, if it is about 10.30v then you have ~20 miles remaining or should be charged.
When the battery fails there is no warning or noticeable problem. It will change and then it will not. You are then in that gear.
I had a portable USB charger (for this very test) with me so I connected it and then rode home all okay. Being able to change gear whilst it was charging.
The unit had a good 10 minute charge and use (gear changes). I then set the bike up on a static trainer and used the shifter until the 10 minutes charge was depleted.
That took about 450 single step activations. Easily enough for a 60 mile ride
I have now full charged the unit once more and will see if similar results are obtained
When fully charged the battery is indicating 12.63v via a voltmeter.
The ability to charge the unit without a dedicated charger means just carrying a cable should get you out of most problems as a few minute charge from an “available” USB port would get you home.
Even some new phones allow for their battery to be used other devices so that is an option as a portable backup battery. However, almost everyone/everywhere will have a USB port to power a battery for a few minutes.