Conflicting info Di2 Battery Light / Levels. Please clarify
 

In my Googling around to understand what the battery level indicator lights are telling me on my Di2 system, one website is telling me this:

• 100% remaining: Illuminates green (for 2 seconds)
• 50% remaining: Flashes green (5 times)
• 25% remaining: Illuminates red (for 2 seconds)
• 0% remaining: Flashes red (5 times)

Another website is telling me this:

• Red, flashing 5 times: less than 25%
• Red for 2 seconds: 25% – 50%
• Green, flashing 5 times: 50% – 75%
• Green for two seconds: more than 75%

Anyone have any idea which one is correct? For example does the flashing red indicate 0% percent batter life remaining, or less than 25%?

Thanks.

Both are just approximations, but you know of course that flashing red cannot mean 0%. If it were 0%, the light would not illuminate at all.

I've been using Di2 for ten years. Here's how my experience tells me to take them . . .

Solid green - 75%+
Flashing green - 50% to 75%
Solid red - 15% to 50%
Flashing red - Less than that.

As a practical matter, I recharge when the green starts flashing. Even though I put about 8,000 miles per year on the bike, I still only have to charge the battery three or four times a year. Charging on flashing green means I never have to worry about it.

I get about 600 to 700 miles to a charge.

I use my Garmin to get the approximate battery %.

The lights represent a range.

Solid green is above 75% to 100% charged.
Flashing green is above 50% to 75% charged.
Solid red is above 25% to 50% charged.
Flashing red is above 0% to 25% charged.

The system cannot indicate 0% charge because at that point the battery is dead and unable to power anything.


-Tim-

Like others have said, I wouldn't even really worry about it, because I'd never let it drop below the solid red level. That's when I recharge mine. Of course, if I was doing some huge ride, I might charge it up anyway, regardless of the level, just to be safe, but normally I run it to solid red, then recharge. I'm not sure if these batteries have a "memory" and need to be discharged as much as possible before recharging, but I figure the solid red indicator is close enough for me. Not worth having it die on the road.

I've always been curious as to what happens if you run out of battery so I did that earlier this year. On a ride this spring my Wahoo Bolt warned me that my Di2 batter was low, but I ignored it and went on a ride anyway. When the battery got to a certain point the front derailleur stopped working but the rear kept going. I was able to do another 15 miles home in that condition. I figured I pressed my luck as far as I wanted and charged the system from there. Haven't charged it since.

Front derailer uses more power that's why it cuts out leaving u some power to use the back and if your not to far from home. Can more usally get home fine. Also if I'm not mistaking the one time I did run low on power the front will give a few shifts but really slow so if u pay attention u will know what front ring to leave it in. Depending how hilly your ride is

At low charge, the front derailleur automatically shifts to the small ring and stops functioning. At that point, you have approximately 50 miles of shifting available on the rear derailleur.

Di2 MTB display is great.
 

Being red/green color challenged I always had problems with the Di2 battery status lights. I also had problems with the newer Shimano inline wireless unit leaving Bluetooth active and running the battery down. That is all in the past now. I have replaced my 3 port junction box with the Shimano SC-MT800 XT Di2 Digital Display Unit. It works perfectly and my Di2 battery lasts longer. The display comes on when you shift and you can configure how long it stays on. Universal Cycles has them for $89.99. There appears to be no difference between the XT version and the more expensive XTR display version other than the case.
https://cimg6.ibsrv.net/gimg/bikefor...d111846d56.jpg

@jmess wait. So the cables that were running in to the junction box now run in to the SC-MT800? Or does this gadget need the Bluetooth connectivity?

Right the SC-MT800 has 3 Di2 ports and can replace the junction box or be plugged into the Di2 network like a D-Fly is wired. The unit doesn’t connect to a bike computer. It does support Bluetooth for firmware updates.

Wow. Good to know. Thank you!

The opposite - according to the Shimano e-tube compatibility charts this (or the SC-M9051) does not work when you use it together with the Wireless Unit ;-).

I removed the wireless unit when I installed the display. My point was I don’t think you have to use the display as a junction box and could wire it inline like you connect the wireless unit.

aha, I see!
I'm not sure, but I would like to find out ;-)

The compatibility charts state:
It doesn't say "max 1", so you could be right!

@TerryDi2C if you do find out, could you share your findings (with photos?) here? Also, your website is very informative. I took at look at the Di2 for dummies page. Well done :thumb:

@jmess I like the idea of replacing the junction box with the SC-MT800. I'm just not sure how I would make it work on my bike. As I look at where the junction box is - under the steam - I don't know if I'd be able to switch it around.

How I did it
 

My left Di2 shifter wire was too short to reach the display junction plugs without redoing my bartape. Since the bartape was fairly new I purchased a Di2 junction (female/female). I already had a short Di2 wire that I had used for the D-Fly unit. So with the extension I could replace the 3-port junction box.

https://cimg1.ibsrv.net/gimg/bikefor...76ebbc605a.jpg


Left Di2 shifter wire extension

https://cimg2.ibsrv.net/gimg/bikefor...0a57fb16ef.jpg


Display mounted on bars

I think the giveaway is that you'd never have 100% more than for eg. an hour, or otherwise that solid green notification is kinda worthless.. the first website is wrong. What would you get if you had 85% remaining?

Thanks for the photos @jmess.

Didn't know about the display unit, that's pretty cool. FWIW, I have no issues with my EWU1111 wireless Bluetooth unit sending all the same information to my Garmin and Etube app. A lot easier than remembering the meaning of the lights on the junction box.

@jmess when adding the SC-MT800 and swapping out the junction box, it just a matter of pulling the cables out of the box and putting them in the SC-MT800? Or does something need to be done?

Nothing special, just move the cables from junction box to the display. You might want to do a firmware update at some point. The firmware update for the display hung the first time I did it using the E-Tube phone app. I had to disconnect and reconnect my internal seatpost battery from the system to clear it up. The Di2 controller resides in the battery module so disconnecting it is like a reboot. I would use the PC app connected via the battery charge wire for the initial firmware update if you have it. This should eliminate any Bluetooth version issues/bugs between what the SC display shipped with (year old?) and your phone.

@jmess does the unit stay 'on' all the time? Or does the display only activate when the bike is in use?

Mine stays on green when it's full. It flashes green when it's above 50%. Rely on your owner's manual or Shimano's website information.

The display comes on when you shift. The time it remains on is configurable with the E-Tube project software. I don’t recall what the max time is, I have mine set for 1 minute. Here is the manual but it doesn’t mention the display time adjustment.

SC-MT800 manual