di2 dead - but not buried

leeefm

It's probably me being stupid and not having charged the battery recently , but I'm not 100% sure.

I'm not at home for the week, and I was just getting ready to go out on my boxing day "burn it off" ride, and noticed the gears were dead. Not even any lights on the junction box. Was fine last week, and the front mech hadn't locked (that I recall). I've checked the connections as I have my wire connection tool with me, but I can't check or charge the battery.

Miffed - with myself mainly if it is because I haven't charged the battery.

(waiting for the slaps for not using a mechanical gruppo )

meanredspider

Can you pop to an LBS and have them charge the battery? 15-20mins will be plenty

It's only like having a mechanical cable snap

leeefm

Yeah, I'll give that a go tomorrow, there's one not too far away that's pretty good. Hope this snow doesn't settle tonight though..

leeefm

LBS only has the external battery charger... have to wait until I return home

meanredspider

leeefm wrote:

LBS only has the external battery charger... have to wait until I return home

Ah, OK - makes it seem even more likely that you just let it run flat.

menthel

Hope you get it sorted. The gentle snick as you changed gears on your Shand was a particular memory of those rides we managed! Better than when you had that flat!

leeefm

Cheers. I'm pretty sure I've been a dumba*se and let the battery run flat - hopefully anyway. :oops:

Got different tyres now though after that flat... Those open paves were impossible on the pacenti rims

leeefm

Ok, possibly some more trouble...

Charged it fully on the 28th, been riding to work since the 2nd. Only about 12 miles a day and it's pretty flat terrain, so I'm not constantly shifting. Got very drenched coming in to work yesterday, was fine on the way in. Start riding on my way home, come to shift and dead again.

It could be a problem, or just coincidence that something else happened. Anyway, I've charged it again and will keep an eye on it. Hope this isn't the start of something unsavoury.

il_principe

Sorry to hijack! I'm new to Di2 but have EPS as well. EPS comes with a magnet which you use to shut the system down when not in use. This prevents exactly this sort of issue. Am I right in thinking that there's no way of shutting down Di2? So if you leave Di2 unused all winter you still need to charge it sporadically?

leeefm

As far as I know, there is no explicit shut down or sleep functionality. I think it is supposed to sleep when not in use anyway. If I recall correctly, Shimano say that you should store the battery separately if you are not going to use the bike for a long period of time, but I'd have to check that (I'm using the internal seat-post battery).

I've been riding it for nearly a year now, and it has been fine. The first dead battery I'm pretty sure was my own fault for not charging it in literally months - although I can't be sure. The second one is a bit more troublesome, as I've gone from months to a week in the time it takes to discharge.

Just to be clear, the bike hasn't been left without use; it has been used frequently.

imposter2.0

There's something distinctly unusual about not being able to ride a bicycle because of a flat battery...

rafletcher

sounds more like a cell failure in the battery.

leeefm

I'll have to keep an eye on it. Water could have gotten in somewhere potentially causing a short, but that would be a bit extreme as I've ridden in much worse conditions in the past without issue.

Do shimano do warranty exchanges, or would it be a case of returning to seller (internet seller)?

Ouija

Should go and have a look at the big lights thread if you want to hear discussions on the common failings of lithium ion (Li-Ion) batteries. Unlike traditional metal batteries used for AA/AAA type cells, Li-Ion batteries should never be drained below 30/40% capacity or they fail or just refuse to hold a charge for very long. If they remain connected to anything that leeches a small amount of current then not charging for a year can cause them to drain below the aforementioned 30/40% (even some protection circuits can cause a small but constant drain on the cells). With Li-Ion it's better to keep them topped up, unlike traditional metal batteries where it's best to drain completely before recharge.

As mentioned above, it sounds like you killed one or more of the cells in the pack.

leeefm

I really hope not. I'd charged it a few time over the year I've had it, and this is the longest I left it.

One thing that I forgot to mention; when I charged it last night, after a few minutes the front mech moved by itself. I've never had that in the past, and was wondering if anyone else has had this during a charge?

Bar Shaker

Has anyone showed you how to check your battery by pressing and holding a shift button?

You should do this after every ride, if you aren't using a Garmin 1000.

Di2 goes into a sleep mode after a period of inaction. Not sure how long that is.

leeefm

Yeah I do know how to check it, but I got lazy. Like I said, if I have destroyed the cells, I've only got myself to blame really.

I've had it running after a charge for a few days now, and the charge indicator says it is still at 100%. Not long rides though. I'm still waiting for it to drain...

Ouija

A dead cell wont affect voltage, just capacity. In a four cell pack (2s/2p) if one cell dies it takes out the next cell wired in series with it. But the remaining two working cells wired in series will still put out full voltage so the charge indicator says everything is hunky dory. It's simply that the capacity is compromised so the runtimes are much shorter.

If it's a smaller 2s/1p setup then any cell failure would take down the whole battery pack.

leeefm

True, but you'd expect it to show up on the indicator that it is draining faster, right (as you've effectively halved capacity)?

Bar Shaker

If you have run it low but not fatally so, it may fully recover after a few recharges.

Ouija

leeefm wrote:

True, but you'd expect it to show up on the indicator that it is draining faster, right (as you've effectively halved capacity)?

True, if you keep checking the indicator and keep a mental note of how fast it drains in comparison to a fully working 2s/2p pack. But there is no way the indicator can ascertain the capacity of a pack, just it's voltage state which doesn't change weather you've got a 2, 4, 6, 8 or 12 cell pack. Larger packs with faulty cells still put out the same voltage, just not for as long. For Di2, we're talking around 8.4v fully charged draining down to less than 7v when depleted. The speed this happens depends on how many working cells you have in the pack. Most Di2 packs look like they come in either 2 or 4 cell varieties. The 4 cell ones being better as the pack will still work if one of the cells dies where as a 2 cell pack will either work perfectly or suffer a complete failure (no redundancy).

leeefm

Ok, that all makes sense. I've got the internal seat post battery (BTR2). I'm not sure how many cells it contains, or in what configuration.

Ouija

It'll have at least 2 cells has a minimum of 2 are required in series to produce the 8.4v voltage (each cell is typically 4.2v fully charged). Taking another 2 cells wired in series and joining it to the first two in parallel doubles runtimes but not voltage (2s/2p). A lot of the external ones look chunky enough to be 4 cells. Couldn't say about the seatpost ones. Unless they are very long i'd imagine they could be just 2 cell packs (in which case it would either work or fail completely, as mentioned above). But there is nothing to say they couldn't be using a 4 cell battery made up of half height cells. Who knows?

leeefm

I have no idea, but they are particularly small. When I ordered it, I was surprised at the size of it. I can't find anyone on the web who has disassembled one either.

Ouija

Have you also considered the possiblity that the derailleur's might be constantly draining the battery due to poorly set limiter screws? It may be an urban myth but they say that if your derailleur tries to push up against a limiter screw that's been set badly then the motor remains on trying to push past the limit point to the correct position, draining the battery. This would obviously affect the front deraileur when on the big ring and the back derailleur when on the largest (or possibly smallest?) cassette ring.

Not sure of the validity of that one but who knows?

leeefm

I had read about that too, but I had dismissed it on the grounds that I'd been riding it for a year that way with no problems after I initially set them up. I suppose they might slip over time, but I've never had that in the past. Is it possible for that to happen (I'll check the limit screws anyway)?