Di2 dead and won't charge after long period of storage
 

Due to work commitments taking me away and Covid problems preventing me getting back, my Di2 bike was left leaning in my apartment unused for over a year. Previously the Di2 worked flawlessly, battery life was strong, no problems. Today I finally had the chance to blow off the dust and get it ready to ride. Di2 showed zero signs of life. No response when shifters pushed, no lights at all when A junction button pressed. Dead. So I plugged in the SM-BCR2 charger into a USB wall socket, and got no lights on the charger at all. I have tried various USB wall sockets up to a 2.1A unit, and nothing.
The bike has been moved around by my wife a few times, maybe it was knocked over, but it looks ok. Maybe it was leaned against something that pushed and held a shifter button, I'm not sure. The coldest it got inside while away was 16 degrees. I have checked and reseated the A junction cables, seem ok. After some searching it seems others have had a similar problem when shipping bikes when a button was pushed completely draining the battery to zero, with one poster resolving it with a higher AMP USB charger (3.5A he says, but I can't see any that exist).
Shimano says 1A minimum so 2.1A should be fine. It's been plugged in a few hours and still no lights on the BCR2 box or the A junction, but the BCR2 box is warm to the touch. I'm just not sure what else to try before I look into replacing the battery, ouch. I'm not convinced that necessarily will solve it. Any clues appreciated.

My road Di2 system went from 50% charge to 25% while sitting unused for 6 weeks, hanging on a beam hook so no buttons getting pressed. So yes the battery can discharge while not used. I suspect your battery is dead and buried having gone to zero and stayed there too long, maybe call Shimano tech support on Monday. I suspect you'll be buying a new battery though, sorry.

Unless there is a way to completely power down the battery should be removed for storage. More than likely Bluetooth is still pulling power.

Definitely sounds like a dead battery from sitting at zero charge for too long. In storage it's always worth charging periodically up to around 70% to keep the battery healthy. Cold storage is not a problem, in fact it actually extends battery life.

I thought the BT unit went to sleep, would not awaken and connect unless you activate the system by pressing a shift button.

You might just pull the battery out and check it with a volt meter to be sure it's dead. Then connect it directly to the junction box or what ever you plug your charging cable into and try to charge it that way.

Maybe there is a bad connection elsewhere along the line. Everything in Di2 is essentially connected one to another. So any one of many connections might be bad preventing the battery from charging.

Ok I've pulled the battery and it is reading very low. As for connecting the battery directly to the junction box, they both have the same kind of male coax, so it looks like I'd need to find a spare cable with a female coupling on each end to do that without disassembling the bike. I've never really had a close look at it before. Thanks for the feedback so far.

Sounds like a dead battery to me. My bike equipped with DI2 is stored for 4-5 months in a row during winter and when I pull it out for my first ride in spring, the battery SoC has barely decreased.

Yes, you are going to have to find a cable to connect them together with. If you can't find one cable length on the bike you can pull and use then just connect it up somewhere that it wasn't before. But you have to know that cable is between the battery and the charger.

Or if you have a buddy at the LBS, I'm sure they will throw a spare cable at you and tell you to keep it. One did that for the shimano tool you use to connect and disconnect the cables, and they aren't even the bike shop I use the most.

Sometimes batteries get better when you charge and discharge them several times. But I don't remember what type the Di2 are.

No lights on the charger generally means it cannot find a battery to charge, or that the charger/cable is dead :)

If you have access to a Windows computer, try connecting the bike to that and running E-Tube Project 3.4.5 or 4.0.4 - then look at the components it detects. It'll tell you if it thinks the battery is missing.
(and if it doesn't connect at all, that'll tell you something about the state of the BCR2)

Thanks. When you say "cannot find a battery to charge" do you mean that even if the battery was dead, I would get some lights on the BCR2? As both the Battery and BCR2 were working fine a year ago, I believe it's more likely the battery is dead than the BCR2, but I'd still like to know if the BCR2 would show something if the battery is dead. If there should be lights on the BCR2 no matter what, then that means I have a double fault of a dead/disconnected battery AND a dead BCR2, which seems unlikely to me. The BCR2 chargers are shockingly expensive for what they are. Unfortunately I am a mac user but will try to sort something out to get e-Tube hooked up to a windows device. Thanks for your advice.

Well! If the battery is there then the SM-BCR2 should always display a light, as far as I know. Either the error led (red / flashing), or the orange charge led.

I don't think both your battery and BCR2 are dead, but just one of them (or something is disconnected).

It's just that I've not connected a BCR2 to a known-dead battery myself before, so I'm not sure what it'd do :)

As mentioned above I have pulled the battery and the multi meter is reading .2 volts (i.e dead). I was hoping that the BCR2 would bring it back to life but having done some reading it seems there is a threshold below which the charging circuit in the battery pack itself won't pass on the BCR2 juice....but.....there is a way of reviving and in fact restoring [some] Lithium Ion cells (generally) so I am looking into that. It has opened up a whole other field of discussion now that I discovered the pack contains 2 standard 14430 cells in series. It seems it is possible, and easy, to replace these cells for a fraction of the cost of a new Shimano pack. I'll let you know progress.

Poor design as with most lithium batteries the internal circuitry shuts it down for discharging when it gets to 10% SOC. At 0% SOC many lithium batteries cannot be charged again. There are times when going digital provides one more point of failure and I decided against an electronic derailleur. Bad enough to be keeping my smartphone charged and my Wahoo and my e-bikes without having to also monitor bike derailleurs.

I saw that later where others report the battery will drain if something rests against one of the buttons. But I bet in sleep mode there I still a small drain on the battery. Just waiting for the make contact.

Also most Li ion batteries I have recommended to top off every 3 months.

Yeah, that makes sense.

I charge my road bike maybe 3 times per year. My Mt. Bike maybe once per year. That's not particular onerous.

Don't you hate it when people never come back with the outcome to a problem? I do, so here it is, and there is some good stuff in here.

Firstly, contrary to the discussion above, I did have a double fault - a dead battery AND a dead charger. But I managed to recover the battery by taking it apart.

1. The SM-BCR2 Charger - Shimano have dropped the ball on this because the give no indication lights on the charger when it is plugged in and ready to supply power to the bike. I could feel it was warm so I knew the wall USB charger was delivering juice to the BCR2, but nothing else was happening. As it turns out, a perfectly functioning or dead charger both look identical if you have a 'dead' battery on the bike per the instructions and info online, although a misbehaving battery can also make the red battery indicator flash, if the charger is working.

2. The SM-BTR2 Battery - I carried out a bunch of experiments on this battery. It is easy to open it up and find 2x 14430 cells inside, along with a control board. The control board is important because it is this that determines if the battery is usable or not, not the state of the batteries. I desoldered the batteries and put them individually in a smart charger, one was slightly down and the other was very low. The smart charger recovered them both and both tested as healthy batteries, but when put back into the pack the board would not pass on the full volts to the bike. When I put a multi meter on the battery pack coax, it was still showing a fraction of a volt, and the bike was dead. My assumption is there is circuitry that kills the pack once an imbalance is detected between the cells. So I ordered a new battery. When I plugged in the new battery it lit up the stem controller shifting worked, but showed it needed a charge. This was when I discovered I had a dead charger because nothing was happening now with the good battery. I borrowed another charger and charged the new battery, but when it was done I thought I would see what it did with the old battery....well it showed a flashing red "malfunctioning battery", and still the old battery was not powering up the bike. However, I discovered that a good SM-BCR2 charger seems to remember it's last status because even even unplugged from the bike it continued to flash red. So I tried unplugging from the USB and then a few different sequences of plugging in the bike first, then the wall, wall first then bike and voila the old battery no longer registered a fault, and charged perfectly.

3. There are tons of variables in this story so make of it what you will. I do believe that without desoldering the 14430 cells from the pack and renovating them on the charger that the pack would never have recovered even with a good SM-BCR2 charger, but I will never know. I did discover you can effectively remove the cells (worth about 3.50 eur each, check out youtube "What is inside of a Shimano di2 Internal Battery" Sorry I can't post the link) and charge them with a suitable Lithium Ion smart charger, but I believe the battery pack controller circuitry is designed to kill a pack and force a replacement. Maybe I managed to fool that circuitry into reseting by trying different sequences with the SM-BCR2 charger. Anyway, now I have 2 well functioning battery packs. It says to me that you can replace the cells in a Di2 battery pack when it's dead, and the soldering isn't complicated. Photos below....oh no they are not because I haven't posted enough yet.

None of this is true of my Di2 system. None.

I was a software engineer for years. I will never purchase a bicycle that runs software.

Nope.

Never.

Do you own a car?

Heck, even my coffee cup is bluetooth connected. I was skeptical when I was gifted it, but I've grown accustomed to it's quirks.

Tell us more about this coffee cup! :)

https://cdn.shopify.com/s/files/1/10...g?v=1600320908
https://ember.com/

https://ember.com/products/ember-mug...30843977826389

It does keep my coffee or tea at my ideal temp. Battery alone doesn't last long, but when it on it's charging plate I've come back after going to the store and had it still at temp. Though the software has been flaky. Sometimes it does and sometimes it doesn't.

I could do the same with a hot plate and mug, but then I wouldn't have the pretty user interface on my phone to play with the temps. It even sends a notification to my phone when my coffee has reached my ideal temp if it was poured too hot or cold.

Yes, I own a car. If you think that fact points out some logical inconsistency with my position, you are being silly.

If your coffee cup runs Bluetooth, you have my sympathy. You were given it, not gifted it. Gifted is an adjective roughly meaning 'blessed with talent'.

YWIA

Of course I'm being silly. Just making sure you weren't espousing this as a credo for everyone else.
Well others might disagree. It's a proper past tense of gift.