Di2 battery problem - now solved!

[Jeffr]

That sounds likely.

I haven't looked for retail battery supplies much so I can't make a lot of recommendations but if you find something and want me to look at it you can paste a link in here.

[pritchet74]

I would be somewhat concerned about identifying the source of the problem before just replacing the battery. Although at $10-$20 a piece I guess you can afford to experiment. The battery itself should not be particularly expensive. The shimano battery is only 800mAh

As far as a source of batteries goes, sparkfun has some polymer lion batteries that weigh only 3g and store more energy than the shimano ones. You'd need two and a special charger that can handle two. They are only $7 each.

http://www.sparkfun.com/products/731

Those batteries are 3.7V and 110mAh, so I would need 2 in series to get the 7.4V required, but at least 2 on parallel (for 4 total) to get 220mAh, right? That would give me ~1/4 the time between charges that I (had) with the Shimano battery.

Of course, I just found this and I would only need 2 of 'em. http://www.all-battery.com/polymerli-io ... 540-1.aspx

[pritchet74]

So I got out for my 2nd ride since I last charged the battery (not fully, but more than 50%) and after 30 minutes the front derailleur stopped working. So that should have left me with about 100 miles until the battery died, but no, it was about 5 shifts. Luckily I was in a pretty central gear and I was able to finish the ride at a normal cadence.

So....

I have ordered my new batteries.

[coloclimber]

Sounds like the battery fried when it was re-wired and still plugged in.
Batteries are much cheaper than cables and fast to replace too since there is no need to adjust the gears, stretch cables, housing etc.
Yet another cool benefit of Di2.

[pritchet74]

Batteries and charger arrived this morning. They sent the wrong batteries though - the ones sent are 300 mAh each instead of 220 mAh. So that's just awesome. I took pics, but they are on my Blackberry and I don't have time to try and upload them right now.

I used 4 batteries, 2 in series and 2 in parallel, so the "battery" is 7.4V and 600 mAh. The Di2 battery is only 530 mAh - so I should get an extra 10% of charge time over the Di2. This should give me 4 months between charges.

The weight of a new Di2 battery and the harness is about 125g (if I remember correctly). My new setup with the plug attached (to plug it into the main wiring harness) is only 25g. So 100g lighter than "stock" and it will last longer.

Also, a Di2 battery and the charger is about $200. These batteries and the charger were shipped to my door for $55.

[Boonen]

Sounds good! So did replacing the battery fix things?

[pritchet74]

I rode with it and it works great. Everything should be good as new.

I rode yesterday and after 78 minutes my old Di2 battery died.- and that was after giving it multiple charges for 2 days straight. The battery was definitely the problem.

[dunlinii]

"The battery was deffinitely the problem"

I bet your glad

[pritchet74]

Hell ya I am.

This was such a fun project that I am finally going to wire up connectors for my shift buttons to the front harness and also get 4 sets of buttons onto my TT bars. I finally decided how I want to wire 'em up.

[pritchet74]

Pics here:
viewtopic.php?f=6&t=7580&p=96430#p96430

[dunlinii]

Sweet.

[chops]

Can anyone help? I've done the internal battery mod for my ride but wired the battery directly into the wiring loom. Will I be ok to charge it (circuit protection is still attached) if I disconnect both derailers and the shifters?

[Oilman]

Yeah off course. Even when you wouldn't disconnect the shifters and derailleurs you should be fine.

[chops]

Reason I ask is I saw a post on Weight Weenies about a replacement di2 battery which was available with an optional de-coupler so you could charge it without disconnecting it. This made me think that charging it without disconnecting it could lead to problems.

[Oilman]

The charging voltage is exactly the same as the voltage from the battery after is is charged.