I’m new to Di2 only having had sram electronic prior to the new bike so I have a question out of curiosity. Will the Di2 battery drain while riding on the trainer in ERG mode? Thanks!
No, the system goes to sleep after a period of inactivity to conserve battery. If you don’t wake it up by clicking a shifter button, battery doesn’t go down… this has been my experience, at least.
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You see, that’s what I thought as well. But I went out to a ride this past weekend and had my batter die on me even though I hadn’t done anything but erg mode trainer rides the 3 weeks prior.
And you are positive that it was actually charged prior to the 3 weeks of ERG?
Yep, 100%.
Can’t say… maybe you got a faulty battery? That hasn’t been my experience when using ERG.
I’m not saying battery life would be indefinite when using ERG, but I go months between charging when primarily using ERG, and I do wake them up for each ride as I like to shift between chain rings for standing efforts.
Edit to add: maybe your system isn’t going to sleep, which will obviously drain the battery over time. You can tell if they are asleep or not by clicking a shifter button. If you click it once and nothing happens, it’s because the system is asleep.
If it IS asleep, you have to click twice for the first shift as the first click wakes up the system.
Do you think there could be something I’m doing to cause it NOT to go to sleep? I fully charged it on Saturday after my ride and I will check it again this Saturday after a few trainer riders.
Nothing to my knowledge, as far as I’m aware, they go to sleep automatically. I don’t recall having to configure anything to make it happen.
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The only other issue I have heard of is: it can get stuck in pairing mode with your head unit. I would think that as soon as your head unit is off then it should go to sleep.
Sort of what you both have said and checked, I suspect you might have a faulty battery, or the system is not going to sleep. Also make sure all the DI2 cables are firmly plugged in. Those can sometimes be the little electrical gremlins causing it it drain the battery.
Yeah, I’m thinking faulty battery as well. I’ve submitted a warranty claim. Now I have to deal with the hassle of getting my bike to a shop and getting a mechanic diagnosis.
The main power drain of an electronic groupset is actually shifting, motors moving the derailleurs with enough force to shift the chain. When they’re not shifting and awake, the power draw is very low. They need to be awake to be able to receive any commands from the shifters. When they go to sleep, they shut off their receivers so as to minimize battery drain and need to awakened in order to shift. On SRAM, the slight motion on a trainer is enough to wake the deraileurs so that you can shift if needed. Of course in ERG mode, you won’t be shifting (much). I believe Di2 is similar.
I had a situation with Di2 where the battery would drain very quickly, even when not in use. Eventually traced it down to a faulty shifter which was causing a battery drain. I believe that Shimano needs a shifter click before awakening from sleep whereas SRAM only needs movement.
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As others have said, seems like a system issue to me too. My Di battery charge is good for longer than three weeks, even when riding 200-300 miles a week outside.
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Interesting about the shifter. Was that the wired shifters or wireless that was causing the battery drain for you?
It was the wired shifters. Shimano R8150 series.
SRAM eTap shifters have a motion sensor that wakes them up/keeps them awake. There is a definite increase in battery drain, basically a coin cell would last 2–3 weeks rather than 6–12 months.
Maybe Shimano Di2 drivetrains have a motion sensor as well?
I did recently go out to ride my bike and found my Di2 battery was completely dead, and I know it was plenty charged when I parked it. Maybe there is a random fault where the unit stays powered on?
It has only happened once so far in 10kish miles.
Given that I hate electronic shifting already, it didn’t put me in a good mood
Have seen this before at the bike shop. Shimano battery drain can be troubleshot but it takes days if the battery drain is slow. Basically you disconnect everything but one component and a time from the battery and see which is the one that makes it drop. Typically if it’s a faulty component you will see a dramatic drop in charge as compared to the rest. Bad batteries exist though, even on “new” bikes as you don’t know how long the component manufacturer and then bike manufacturer sat on those parts before you took possession. Shimano has been decent about warranty in these cases.
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Yeah that’s what I’d to do. Took about a week to confirm the faulty shifter. Got it switched out on warranty without any issue though.