Shimano Di2 Battery Life…..after Death

By Seton
April 25, 2011 on 2:58 pm | In Product Information, Tech Tips | 7 Comments

At TriSports.com, several of us are used as guinea pigs to try new products.  Most of our product testing doesn’t take too long, heck, most products you know if they are going to work or not after just one use.  Others, of course, take some time.  So, let’s rewind the clock to March of 2010 – the day I took delivery of my first Shimano Di2 equipped bike.  I rode the bike for several months and was finally slated to fly out to Las Vegas to do a training ride so I decided before I went on this trip it would probably be a good idea to charge my Di2 battery…..and this is where this review begins.

One of my many adventures during this test, a group ride in Solvang, CAOne of my many adventures during this test, a group ride in Solvang, CA.

This is a review of the actual battery life of Di2 and is not a review of the entire Di2 system – if you want that, please check this out.  The two biggest obstacles for consumers regarding Shimano Di2 are 1) the price and 2) what happens when the battery dies.  Well, I don’t have a lot of control on the cost or MSRP guidelines set by Shimano but what I can answer is the later question.  Little did I know, this little experiment would take me over 9 months to complete.

  • July 9, 2010 – Completely charged my Shimano Di2 Battery. Between July and March 1, 2011 I had ridden an estimated 3200 miles.  I don’t have a computer on my bike in the off season (and this was a year long off season) but 100 miles/week is a good estimate.  Some weeks I rode >200 miles, other weeks I didn’t ride at all.
  • March 1, 2011 – Finally got the Di2 battery life indicator to go from solid Green (all systems good) to solid Red (battery is getting low <25%).  The system still worked fine.   I rode a bit more during this time (from March 1 to March 28) and got in about 600 miles of riding.
  • March 28, 2011 – Front Derailleur shut down.  The Di2 system knows when the battery is getting really low <10% and turns off the use of the front derailleur – once you shift down to the little chain ring it will leave you there (I suppose if you are a manly man and never leave your big ring then you would be left there).  Besides the front derailleur not working, the battery indicator light now blinks Red.  You still have full use of the rear derailleur shifting during this time.  Since the front derailleur no longer functions, neither does the auto trim feature so you do get some rubbing on the front derailleur.  One interesting note is that some of the rubbing of the front derailleur would go away, almost like the derailleur was adjusting itself from the chain rubbing.  I missed almost 10 days of riding in this period (March 28-April 21) but was still able to ride about 250 miles (w/out the use of my big chain ring) before the end of the battery.
  • April 21, 2011 – Full system shut down.  The Di2 battery finally went into its final death throws.  At first the rear shifting completely stopped.  About 10 minutes later I got two more shifts and then it stopped working again.  This continued for about 30 min (for a total of about 10 shifts) until it finally threw in the towel. 

Shimano Di2 BatteryShimano Di2 Battery in my hand.

As you can see, I listed out the miles I rode during this experiment.  I had someone comment that the battery life is a function of shifting rather than miles – yes, that is obvious; but last time I checked I didn’t hear someone say “Hey man, great ride that was a hard 205 shifts there.”  So, the only way for me to convey the longevity of the Di2 battery is by mileage and by time.  I also feel that Tucson (where I did most of my riding) represents a good mix of terrain – flats, wind, hills, mountains, etc.  The most impressive thing to me is that this battery lasted more than 9 months without charging – in the heat, the cold, the rain, etc.  Actually, the most depressing stage of this experiment was the recharge of the battery – it took less than one hour to fully recharge.   Are you kidding me???? I just spent 9+ months trying to kill this dang thing and it was fully charged in less than 60 minutes. 

The feeling I had once I finally killed the Di2 battery was similar to the feeling I had when I finally finished my thesis (for those of you reading this that have done a thesis/dissertation you know what I mean).  I was elated that this experiment, one I thought would take me 2-3 months, was actually over and I could report back with EXACTLY what happens to Shimano Di2 when the battery dies.

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