The Di battery has been failing after 100k’s

[Stevesoutside]

I have a Giant TCR Advanced. The Di battery has been failing after 100k’s. My local bike store told me to buy a new battery which I did. I had the battery charged at the bike shop and the battery failed after one ride! The shimano rep ran a diagnostic on the bike in the store and has come up with nothing. Has anyone had this experience?

[AlanAtom]

I wonder if there is a short/ fault in your bike's wiring that's causing the battery to drain abnormally till it's empty. With the Di battery being a LiPo chemistry one, draining LiPo batteries to completely empty can cause them to fail to recharge. If the battery fails during your ride, try changing to your spare battery mid-ride. If the one battery sustains your whole ride, then remove the battery immediately after your ride and stick it on the charger.

[Duck!]

Has it done it since new or is it a recent development?

If it's always been the case then it's possibly incorrectly set limits on the rear derailleur. If it was good & the battery drain is only recent, it's probably a component not going into "sleep" mode & continually drawing power. I've had a bike in with just this problem this week; the E-Tube diagnostics came up clear, but there is clearly still a problem. There's a staged process for testing components, but you need two batteries and about four days to do it!

[bianchi928]

Hi Steve,

Yes, I had the same experience. Changed battery, diagnostics etc, same thing. Turned out to be the Di2 junction box. Changed that and all is sweet.

Cheers

[Duck!]

Has it done it since new or is it a recent development?

If it's always been the case then it's possibly incorrectly set limits on the rear derailleur. If it was good & the battery drain is only recent, it's probably a component not going into "sleep" mode & continually drawing power. I've had a bike in with just this problem this week; the E-Tube diagnostics came up clear, but there is clearly still a problem. There's a staged process for testing components, but you need two batteries and about four days to do it!

UPDATE: The one I have been working through appears to have a malfunction in the front derailleur causing continual power drain. I first tested with a different battery, which like the first drained overnight. Recharged, disconnected the cable from the upper junction (isolating that + shifters from the lower system) and again left overnight. Same deal, depleted battery charge with the top system reconnected, so clearly the problem is in the lower components. Again fitted a full battery, disconnected the front derailleur, but left all other parts hooked up. Next morning, battery still fully charged. That points to a dodgy front derailleur, which strangely showed up as normal on the E-tube diagnostics.

[im_no_pro]

There's a staged process for testing components, but you need two batteries and about four days to do it!

Im curious to hear about this, I have a mate with an intermittent issue with batteries losing charge, components have been isolated, battery replaces, system tested etc etc etc and each time it comes up with nada.

[Duck!]

Here's the check process I got from Shimano to find where a battery drain may be coming from.
1: Try a different fully-charged battery. Leave overnight & check battery level the next day.
If the indicator is still solid green, the original battery is a dud & needs replacing. If the charge indicator is anything other than solid green, go to.....

2: With battery recharged (recharge between each step), disconnect the cable from upper junction box & leave overnight. Check power level....

3a: If power indication is good, the problem is in the upper system (junction/shifters). Go to step 4a.

3b: If power is depleted, the problem is in the lower system (derailleurs & battery mount). Go to step 4b.

4a: Disconnect derailleur & one shifter cables, so only battery mount, junction & the other shifter are connected. Leave overnight, then check. If power is good, your disconnected shifter is bodgy.
4a (2): If power is down, plug the disconnected shifter in & unplug the other. Repeat step 4a. If power is good, the problem is in the second shifter. If power has dropped, the problem is in the junction box.

4b: Disconnect front derailleur & leave overnight. If power next day is good, the FD is dodgy.
4b (2): If power has dropped, plug FD back in & unplug RD. Repeat 4b. If power is good, RD is the problem. If power has still dropped, battery mount is the problem.