Di2 gears

[Brainless]

Quick one for guys using it, tried out the 900e today .. wow. I asked merida guy if gears would still work if battery power died, he said yes because the Di2 needs very little power to operate. So out I ride on demo bike, and I thought I would try gears with power switched off and found the gears would not shift ???? , the bike I must say was amazing I tried 8 bikesin total and I’m now back to square one ?

 

[MattyB]

Would they change with the bike switched on and the assistance set to off? That behaviour would seem imply Merida have tapped a feed off the motor battery for the DI2, which I suppose makes sense in that it avoids the cost and complexity of a dedicated battery for the gears.

 

[Kangr]

You need your battery switched on but when the battery runs out of power to give pedal assitance it retains a little to enable the use of the gears.

 

[Brainless]

Would they change with the bike switched on and the assistance set to off? That behaviour would seem imply Merida have tapped a feed off the motor battery for the DI2, which I suppose makes sense in that it avoids the cost and complexity of a dedicated battery for the gears.

Good question I never actually tried that dohh lol

 

[mark.ai]

Yep they do work with assistance off so long as bike is switched on like MattyB suggests. The lowest I've run my battery so far is to 3% but what Kangr says gives me hope they would keep working when it runs out. I will have to try it someday just to find out

 

[MattyB]

Looks like DI2 batteries are a two cell lithium ion of nominal voltage 7.4V...

Shimano BT-DN110 Di2 internal mount battery | BIKE SHIFTERS | Evans Cycles

Based on that price (~£125!) I think it is a very good idea they have tapped this off the main battery! I also agree that the tiny current needed to operate the gears and the fact that the BMS will not allow the battery to be discharged to a level where it could not supply that current means this would be a non-issue in practice; you’d probably have to be peddling multiple hundreds of miles unassisted before shifting would stop.

 

[Kseven4]

I rode my battery til the motor turned itself off and as long as the battery was on I could change gears .

 

[davowood]

Correct. I’ve run out of juice a couple of times now - it holds some charge in the ‘off’ mode to allow gear changes. This is different to when the battery is actually off, bear in mind.