Di2 battery life?
 

I got my 19 Roubaix Comp in December of 2020 and it probably has about 4000 miles on it. I generally ride it on the weekends and have another bike that gets ridden during the week. I would usually put the charger on it every month or so even though it was not showing low. On a ride yesterday after 11 miles it went into low battery mode where it goes to the small ring in front and the rear continuous to work. I rode another 30 miles and put it on the charger when I got home. As of this morning it is still not showing a full charge so thinking the battery is shot. Doesn't seem right that the battery wouldn't last at least 2 years.

Is there something else that would cause this problem that I should be looking at?

How many mA is your chargers output? If you are charging through the PC usb port, then you might be quite a while if at all.

I don't charge mine until it fails to shift the front. Unless maybe I have a really important to me ride the next day and it's been a while.

I generally use the same 2.4 mA output adapter I use to charge my phone.

Either the battery is shot, your charger is shot or there's a loose/dirty connection somewhere. Firstly, try a different USB charging pack if you can and plug into the wall not a computer or power bank.

I've got roughly 25,000km on my original Di2 battery and get an easy 2000km from a charge (I never let it go as low as limp-home mode).

The charger light goes out when it's done charging. I don't watch mine, but it seems to take just a couple of hours at the most with an old 1.3A wall charger.

There's been a few comments on BF of failed Di2 batteries this summer.

My original battery lasted more than 5 years, and was still working, but I had to recharge it quite often during the final year. The replacement battery has been fine for a few years now. I have about 30,000 miles on the bike now, and everything still works like new.

I had a few minutes to look at the bike this morning. I noticed that one of the two pins in the charging port (bar end type) is more recessed than the other and perhaps the connection is intermittent.

Can anyone confirm that the two pins are recessed the same or different? I saw last night the batter is $160.00 and I certainly don't want to buy one if not necessary.

Nope. Each pin same length on mine.

You are using the SM-BCR2 aren't you? What are you connecting it to for power?

Planned obsolescence

I've been charging 4 years or so, never had issues with the charging cable. The charger does want X amount of power, a good quality wall wart and right to a real outlet is recommended.

If it is the battery you might want to look at a warranty claim. The battery is warranted for two years.

Well. I got the battery charged now. I think the recessed pin was causing an intermittent connection and that causes the charger to stop charging until it gets unplugged and plugged back in. I may look at a warranty claim for the bar end junction box since it is a hundred bucks. But for now, I know what I need to do when charging.

Thanks for all the advice.

I wrap a turn or two of the charge cable around my handlebar before I plug it into the bike -- that takes all the strain off the cable plug. Perhaps your cable is getting pulled loose enough to stop charging.

My charger port on the junction box (made in 2014) under my stem has the right hand pin recessed more than the left one. It still works fine. The charge plug clicks in easily, there's no tricks to getting it seated fully. Maybe the short pin is designed on purpose? Check a different bike with Di2 and see if it's pins are similar.

I see that the charging light on my SM-BCR2 won't come on until it's connected to the bike--good. I used a silver sharpie on the box to note "LED ON=charging", when I first got it, and colored the top side of the charge plug in silver--it's not obvious which way is "up", and the plug is keyed so it can't insert upside down. I've never seen the other "Error" light on the charge box lit up--good!

Lithium batteries don't need to be drained toward empty. I only check my battery charge occasionally, and charge it soon after it goes from solid green to blinking green. That's at the 50% charge level. I've only twice forgotten to check often enough to get where the front quits shifting. (I usually think to check while I'm riding--that works easily, it's just holding down the front shift button for 5 seconds.)

An old 1.3A phone wall charger works fine. I just keep it connected to the Di2 charge cable--very convenient.

I didn't know I could drain a battery toward full. <grin>

Well. I thought the battery issue was solved but no joy. I was showing a full charge on the indicator after charging but yesterday I started out on a ride of about 82 miles. 30 miles out, the battery was dead. Another limp home in the small ring. The bike is not two years old yet so will contact the LBS about possible warranty. Either the battery won't hold the charge or something is draining it.