eTap Front Derailleur Battery Draining Faster than Rear

[odonnebj]

Title says it all... has anyone experienced their eTap FD draining faster than their RD? I have two bikes with eTap on it, and the FD on one bike drains much faster than the other. I've swapped batteries around, re-paired the devices, etc. I live in Houston too so there's not much shifting to be done on the FD... mainly RD shifting only. I still get a few weeks out of it, but on the other bike I can get close to 2 months. And yes, I ride both bikes equally.

[bikinchris]

Sounds like a bad front derailleur to me.

[ahumblecycler]

Originally Posted by bikinchris

Sounds like a bad front derailleur to me.

Having ridden eTap for the last 5 months, I agree with the above (my imagination fails to generate a better idea). Unfortunately, I have no clue how to test for it. Have you tried updating the firmware? If not, I would that first.

[Unpredictable]

Kinda makes sense to me that the front goes quicker. The motor moving the front does much more work than the rear. The distance the and amount of movement is more.
The exact thing happens with all Di2. When you battery is low with Di2, the front stops working first.

[BSBD]

Originally Posted by odonnebj

Title says it all... has anyone experienced their eTap FD draining faster than their RD? I have two bikes with eTap on it, and the FD on one bike drains much faster than the other. I've swapped batteries around, re-paired the devices, etc. I live in Houston too so there's not much shifting to be done on the FD... mainly RD shifting only. I still get a few weeks out of it, but on the other bike I can get close to 2 months. And yes, I ride both bikes equally.

How old are the batteries?

[SoCalSteve]

Originally Posted by odonnebj

Title says it all... has anyone experienced their eTap FD draining faster than their RD? I have two bikes with eTap on it, and the FD on one bike drains much faster than the other. I've swapped batteries around, re-paired the devices, etc. I live in Houston too so there's not much shifting to be done on the FD... mainly RD shifting only. I still get a few weeks out of it, but on the other bike I can get close to 2 months. And yes, I ride both bikes equally.

Do you ride with a Garmin paired to the ETap? I think the wireless transmission to gps units comes from the front derailleur. Hence it draining faster. Just a working theory, I have no proof of this.

[bcroslin]

Seems like a FD issue. I always cycle my FD derailleur battery to the rear when the rear battery dies. I then usually get at least a few weeks out of the battery.

Here's a question: do you transport your bike via car to your rides? I was told to remove the batteries from etap when transporting by car because any movement sets off the gyros in the derailleur and saps the battery. Just an idea.

[odonnebj]

Some answers to all the good questions. Thank you everyone!

1) Batteries are new. I even have a couple spare batteries that were also new.

2) Batteries are removed whenever I put the bike in my car.

3) I don't pair the Garmin with eTap to get the battery status.

4) Firmware has not been updated only because SRAM hasn't issued any updates yet.

Per my original post, I have eTap on another bike as well and it lasts a lot longer. In fact, the rear always drains first and then I swap the front/rear batteries to get more juice in the rear if it comes at an inopportune point in the ride. As I mentioned too, I live in one of the flattest places on earth so not much shifting to be done in the front.

[dddd]

Stay in the big ring!

[Mark McM]

Originally Posted by bcroslin

Here's a question: do you transport your bike via car to your rides? I was told to remove the batteries from etap when transporting by car because any movement sets off the gyros in the derailleur and saps the battery. Just an idea.

Why would a derailleur need gyros?

[FlashUNC]

Originally Posted by Mark McM

Why would a derailleur need gyros?

To auto start/stop to preserve battery life. There's no on/off on the system, and to extend battery life, SRAM puts the derailleurs to sleep when the bike hasn't moved for a set amount of time.

[Mark McM]

Originally Posted by FlashUNC

To auto start/stop to preserve battery life. There's no on/off on the system, and to extend battery life, SRAM puts the derailleurs to sleep when the bike hasn't moved for a set amount of time.

Putting the derailleur to sleep to save power makes sense. But using a Gyro to wake it up doesn't. Gyros require electric power to operate. Why not use a passive motion sensor, which requires no energy (and are probably cheaper, too)?

[FlashUNC]

Originally Posted by Mark McM

That makes no sense. Gyros require electric power to operate. Why not use a passive motion sensor, which requires no energy (and are probably cheaper, too)?

From what I've read, they're accelerometers actually.

[SoCalSteve]

Originally Posted by odonnebj

Some answers to all the good questions. Thank you everyone!

1) Batteries are new. I even have a couple spare batteries that were also new.

2) Batteries are removed whenever I put the bike in my car.

3) I don't pair the Garmin with eTap to get the battery status.

4) Firmware has not been updated only because SRAM hasn't issued any updates yet.

Per my original post, I have eTap on another bike as well and it lasts a lot longer. In fact, the rear always drains first and then I swap the front/rear batteries to get more juice in the rear if it comes at an inopportune point in the ride. As I mentioned too, I live in one of the flattest places on earth so not much shifting to be done in the front.

You may want to give SRAM technical a call. They were super helpful when I was installing my first ETap group. Fun, knowledgeable, helpful, generous and enthusiastic.

If you figure it out, please update us. Enquiring minds wanna know!

[Mark McM]

Originally Posted by FlashUNC

From what I've read, they're accelerometers actually.

Yes. Piezoelectric accelerometer/vibration sensors are passive, in the sense that they need little to no external power to sense motion.