I saw this on Facebook from Calfee:

https://www.facebook.com/pages/Calfee-D ... 5283915144

Basically they have a new simple idea, that instead of taking the seat post/battery out, their new charger requires you to just disconnect the rear der cable, it plugs into that cable and charges the system that way. They did not say how much it costs. I am sure a lot of the smart/motivated people on here could duplicate the idea.

Calfee has also show a system that makes their Di2 seat post battery work for the Ultegra wire harness.

It uses an Ultegra Di2 "module" that they have engineered. Most likely a chip that tells the brain its the battery via CANbus protocol.

I just don't know why they don't have an induction charging system and be done with it. Stick the batteries up the guts of the seatpost (carbon) and have a wrap around module that you can wrap around the carbon seatpost when you want to charge the unit. Different seatpost sizes = different width adaptors. Hold unit in with a star nut kind of design with cables exiting somewhere down near the BB (or even out of a water bottle mount via a hollow water bottle mounting screw).

That's not a pain in the ass at all! I'll buy Di2 when they piss off the cables altogether.

That's not for a few years as they will need to "update" it so we can all buy a new group b/c its not compatible!

I don't think you can use induction charging through carbon. It will attenuate the signal at the very least. Different weaves and thicknesses might also interfere with different frequencies. You really need very little space filled only with inert materials to do inductive charging. Plastics or a little bit of skin in the case of medical devices.

I think the harder problem with induction charging is that you typically need parallel surfaces that are very close in proximity. So a charging mat on the ground 4-6 inches away from the battery is not going to cut it. If you could engineer a sort of dock that would interlock with the downtube, you could probably do it.

How often do you charge your Di2? I think that about the time I was recharging it, I would be thinking of taking the seatpost to clean it...

Calfee has an in line charger, Calfee's Inline Charger for DA Di2, unplug either your front or rear DA Di2 derailleur and plug our charger into the wiring harness. The only issue I have with this charger is its only a charger, and will not balance the cells, and can actually damage the battery, or possibly cause the battery to catch on fire, as is not uncommon with LIPO cells, but it is a clever idea.

Not such a great idea. Connectors are designed to provide a reliable lifespan in terms of number of connections / disconnections. And Shimano's connections weren't designed to be taken apart every 5 minutes; for one thing you need a tool to do so. Better IMHO to use a 4mm allen key to undo the seat post...

But you don't have to charge the battery every 5 minutes. Unplugging the cable a couple of times in a year should not be a problem. When you're worried with wear of the connectors you can also use the front derailleur.

di2diy: aren't you the guy selling a competing system to Calfee's internal battery on Ebay? Nothing wrong with that, but it makes me question your objective criticism. I have talked to Craig Calfee about their system, they are a company with a long history in the business, they have talked directly to Shimano about what they are doing and some key Shimano US people have it on their own bikes.

mrfish, as was pointed out you need to charge the system 3 times a times a year, so the wear and tear is not a major issue. Personally I had my Di2 bike on an airplane 3 times last year and needed to disconnect some cables more for travel than charging. If you use Shimano tool to do it, it is pretty straight forward.

Yes I'm that guy selling on eBay, and no my criticism is not aimed at putting down what Calfee's selling, it's just a fact LIPO and LION batteries can explode if charged with an inexpensive charger like they are using. They should be charged with a balance charger, which requires 3 wires, not just two going to the cell's like they are doing, this can be dangerous, in fact any time you charge these type of batteries, it can be dangerous, including the one I sell with my system with a balance charger. (http://www.rcgroups.com/forums/showthread.php?t=209187) I wouldn't say I'm really competing with Calfee, yes its true I'm selling a similar product, and yes, I also do conversions on non Di2 bikes to place the harness all internal. I do about 4-5 bikes a month for friends, and a few LBS, at a little more than half the cost, I'm doing it because it helps people, not to make money. However I do not have the skill that they have when it comes to painting and touch up, or carbon fiber repair, but thats because I do not cut large holes in the frames like they do, so I don't need the touch up, or repair. I have also talked to Shimano, and to Calfee for that matter. I have also talked to "some key Shimano US people have it on their own bikes" and know that they have had to have frames (SL3) replaced after being done by Calfee, because of the large hole cut in the BB area ruined the frame.... Stuff happens. As I have posted on other forums I think Calfee does a great job, and I think the idea they came up with is clever, but it is less than ideal, in my opinion. What I think is a better way to go if you want to charge the battery without removing it is the way Icarus does it (http://icaruslights.com/batteries/) in fact I like that battery setup more than mine, or Calfee's. Calfee is as you said "a company with a long history in the business" and I seriously doubt that anything that I'm doing, or criticizing will change that. Thanks for your comment.

The charging circuit could be in the battery pack. That picture looks like a standard power supply. I doubt calfee has the technological acumen to reverse engineer the ultegra signaling while not understanding basic properties of lithium batteries. Stranger things have happened but it's odd to assume they're not doing it correctly from what little information is available.

Agreed, but it looks just like lithium battery charger I have bought and tested, with Mini Tamiya Plug, only with a Di2 plug... and its true there could be some circuit in the battery pack. As I said all lithium batteries pose a danger when charged, as I also said its just my opinion.