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<p>Hi, Have my bike since Mar 2015, and in that time the battery has been very good. I have had it on the road and done around 300kms&nbsp;with even&nbsp; the red indicator flashing red. The last time I charged the bike, I only charged it for a short while and it was flashing green, yesterday morning, it was still flashing green ( charged on Feb 28, 3 rides and around 300kms since). Had a tea stop at 35km. Took off afterwards on the small ring, changed up out the road, and after 10kms it changed down its self to the small ring, I could do no more with the front derailleur, rear was ok, but no trimming in the front. Checked the battery indicator and it was now solid red. When I got home charged for 10 minutes and front all working ok. Put it back out in the garge and left the charger on for three hours , all ok now. This is the second time this has happened this year. ...... Is my battery failing(first day battery) or do I have a higher than normal energy consumption at the moment with one of my derailleurs ? Thanks in advance.</p>

14 comments

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Pilot Pete [62 posts] 5 months ago
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Er, not sure how we are able to offer an opinion as you said you didn’t fully charge it the first time, charged it for 3hrs the second time and now ‘all seems ok’. How can anyone pass judgement based on this?

PP

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kil0ran [987 posts] 5 months ago
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Possibly the front derailleur is on the way out. Which Di2 group are you running? If when its working can you hear it auto-trim if you cross-chain?

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CXR94Di2 [2157 posts] 5 months ago
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Di2 disables the front derailleur when tbe is battery getting low. I find if I charge my bike on a low current usb charger it doesn't do a proper charge. I now use a 2A usb charger and all is well. leave it for a couple of hours to ensure full charge

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Kevin Sexton [7 posts] 5 months ago
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Hi Pete,

What I gave was a rough back ground of the history, the main question is that if you are going out with a flashing green indicator,  you should have a couple of rides left, my one on Sunday went from flashing green to red and no front derailleur within 45kms.

Pilot Pete wrote:

Er, not sure how we are able to offer an opinion as you said you didn’t fully charge it the first time, charged it for 3hrs the second time and now ‘all seems ok’. How can anyone pass judgement based on this?

PP

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MrMajic [36 posts] 5 months ago
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I had similar erratic charge/behaviour with a di2 battery. It was less than 2 years old so I returned it under warranty. That fixed it.

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Kevin Sexton [7 posts] 5 months ago
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My one is three years old, I will watch the performanace over the next few weeks and if I think the battery is at fault, I might buy the newer BT-DN110 battery. 

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simon59 [11 posts] 5 months ago
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It isn't helped by the mis-understanding of Lithium ion batteries. With old NiCd batteries you did have to let them run flat before re-charging them otherwise they developed a memory. With Li batteries its diffierent. You should not store a Li battery flat or low on charge for any time as they degrade. It is better to keep them topped up and always store them fully charged. They do degrade when they are charged but this happens whether you charge them with a few big charges or lots of little ones. So its better to keep them charged up whenever you can. The battery should still be able to hol 50% charge after about 700-800 full charges, so about 700,000 miles for a Di2 battery.

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Kevin Sexton [7 posts] 5 months ago
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UI have left mine go down to the red indicator most of the time before recharging.

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Kevin Sexton [7 posts] 5 months ago
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Auto trim is working OK . The groupset is 6870.

kil0ran wrote:

Possibly the front derailleur is on the way out. Which Di2 group are you running? If when its working can you hear it auto-trim if you cross-chain?

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Kevin Sexton [7 posts] 5 months ago
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I will keep an eye on it. I have checked the current draw on both derailleurs. All look ok and both do not draw load once the movement has been made. If you push any switch beyond the derailleur, range and keep it pressed, both derailleurs draw about 9.00mA each. 

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Johnny5 [10 posts] 5 months ago
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I would check to make sure the rear derailleur low limit is set correctly. Aside from A & B junction failures (which would end up disabling the whole system) the battery drain issues I've had to debug at the shop using Shimano's ETube Project tools and tech support, were battery draining issues that resulted from the rear derailleur limits being off just enough that the rear D was draining the battery in the granny gear due to it drawing a load as if it were auto-trimming, but you wouldn't see it moving, it would just draw a load. 

 

If that isn't the issue, fully charge the battery, then unplug the rear d over night, then check to see battery level in the morning. If it is still full charge. Repeat, but unplug the Front D over night.  Then check levels. That is how Shimano Tech Support will have you test the components to see if any one in particular is drawing undue load on the battery. 

 

Having said that, it could be the battery starting to go, but at least the steps above can help debug the issue in the case that the battery is fine. 

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Kevin Sexton [7 posts] 5 months ago
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Thanks for that.  I will mointor it over the next few months, the main question was, that after only 45km, it went from flashing green to not enough power to work the front derailleur. ....... Looking back on my notes, on 7th November last year I changed the rear derailleur from normal to fast changes. I will leave all alone for the moment, but I will change this back the next time I will connect up to the e-tube.

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Johnny5 [10 posts] 5 months ago
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Another thought just to watch for, sometimes when leaning a bike at a stop, the shifter can become partially engaged and run a load on the battery. That has happened twice in my experience, someone leans their bike against one with Di2 and the lever gets engaged. Could explain a stand alone green to red battery drain. Food for thought.

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Kevin Sexton [7 posts] 4 months ago
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Measured the voltage on a daily basis and before and after each ride. for a week. Removed the seat post and checked the battery on its own for another week, the results indicated that the battery is at fault. The voltage drop per day is the same when it is connected to the system or on its own. One ride I had was 130km with a nice bit of shifting, the voltage drop for that ride  was the same as for 8 hours at standby.  this would indicate how low the power consumption is in the system.