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Ask a Mechanic: All about SRAM eTap

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The battery life on the rear derailleur sounds total unacceptable to me. The other batteries last longer.
No, it's better than that. Overall battery life on the rear is between 30 and 60 hours. A full charge should get you about 55-60 hours.

Breakdown:

Green light: Between 60 and 15 hours left
Red light: Between 15 and 5 hours left
Blinking red light: Less than 5 hours left
 

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Plus one can easily:

a. carry a charged spare

or

b. swap front to rear.
 

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I agree, unacceptable. Replacing the shifter battery every 6 months is something I could do with out also. Just did a quick google and couldn't find a place selling them by the way. Wonder what those cost.

Looking at it as if worse case scenario applies is probably wise for those of us who live in hilly areas or for whatever reason do a ton of shifting.
 

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I agree, unacceptable. Replacing the shifter battery every 6 months is something I could do with out also.
I could handle that, like the second generation PowerTap batteries (357) which last 3 months for me.

Looking at it as if worse case scenario applies is probably wise for those of us who live in hilly areas or for whatever reason do a ton of shifting.
Absolutely, although I would not accept the manufacturer's estimate which may be overly optimistic.

Although Campagnolo states Ultrashift levers require cable replacement annually or every 9000 miles with competitive use, with my ADHD shifting I break rear cables around 2500 miles and am on a 2000 mile replacement schedule every 8-10 weeks.
 

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Discussion Starter · #7 ·
y
I could handle that, like the second generation PowerTap batteries (357) which last 3 months for me.



Absolutely, although I would not accept the manufacturer's estimate which may be overly optimistic.

Although Campagnolo states Ultrashift levers require cable replacement annually or every 9000 miles with competitive use, with my ADHD shifting I break rear cables around 2500 miles and am on a 2000 mile replacement schedule every 8-10 weeks.
ya think? i'm immediately thinking of those mpg numbers on cars..
 

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I was told by a bike shop employee that the batteries (not sure whether he was referring to the shifters, derailleurs, or both) are activated by an accelerometer.

The implication is, the batteries save energy by being in some sort of sleep mode when the bike is not moving.

What the employee went on to say is, the batteries go active when the bike is on a car rack because the vehicle is moving. This leads to an unexpected decrease in battery life. The workaround is to remove the derailleur batteries when the bike is mounted on a roof rack. Not sure if this also applies to the shifter batteries.

Can anyone substantiate these statements?
 

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Discussion Starter · #9 ·
I think the issue of battery life is something once the product gets used we'll hear a lot about. Its either a non -issue or a very real issue. And like all electronic products I pretty much expect in a year we'll see version 2.0 that promises longer battery life if not other improvements.
 

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I agree, unacceptable. Replacing the shifter battery every 6 months is something I could do with out also. Just did a quick google and couldn't find a place selling them by the way. Wonder what those cost.

Looking at it as if worse case scenario applies is probably wise for those of us who live in hilly areas or for whatever reason do a ton of shifting.
I thought the shifter batteries were basic 2032. get them up at any Wal-Mart, battery store, 7-11, or even my bike shop.
 

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I was told by a bike shop employee that the batteries (not sure whether he was referring to the shifters, derailleurs, or both) are activated by an accelerometer.

The implication is, the batteries save energy by being in some sort of sleep mode when the bike is not moving.

What the employee went on to say is, the batteries go active when the bike is on a car rack because the vehicle is moving. This leads to an unexpected decrease in battery life. The workaround is to remove the derailleur batteries when the bike is mounted on a roof rack. Not sure if this also applies to the shifter batteries.

Can anyone substantiate these statements?
I have heard similar. Only an issue with the rechargeable derailleur batteries, not the shifter batteries. At least, that's my understanding. Probably not a big deal if you've only got a 10 minute drive to the group ride, but of traveling longer, probably good idea to just pop the batteries off and put then back on at your destination.
 

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There's some details in this Bike Radar article.

The accelerometer is used to turn off the radio transmissions when the bike isn't in use. But even if it's moving on a car, it's not powering the shifter motors, so it shouldn't affect the battery life too much.

Heh, they mention "1000 km or 60 hours". That's around 17 kph, or a little over 10 mph average speed... I don't think that's too likely.

I've burned through almost a full charge in 400 miles on my Di2, after a week of rolling hill riding. I was doing big ring--small ring and half the rear cassette on every roller. It was great.

My normal recharge interval is around 800 miles, and other riders can get 1200+ miles. So it'll be interesting to see how the Sram works in real life.
 

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I thought the shifter batteries were basic 2032. get them up at any Wal-Mart, battery store, 7-11, or even my bike shop.
I assumed it was proprietary but you very well could be right. I don't know what they take. Did't see anything on line but didn't look all that hard.
 
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