Bought a second hand Di2 system with the old style Junction A box and an external battery. I want to upgrade to an internal battery and know that normally you would also buy the dedicated charger and new 3 port junction A box with the charging port. However just wondering if I can get away with keeping my old junction A box, see picture below and then is there a way to charge the battery by taking it out of the bike when needed or just connecting a charger to one of the ports.

Grinds me that Shimano DI2 tuffs so expensive. £60 for a charger, £75 for battery and £17 for one bit of wire. Getting on for Apple prices.

I have a feeling the internal Di2 battery is only compatible with E-Tube, which is the newer system. So I don’t think that’s possible.

That junction is also etube.

I think you could stick in an internal battery and keep that junction box. You’d still need a new junction box to charge as that’s got the socket for the charging cable. You could probably just unplug the rear mech, plug the cable into a junction box and charge via that. Or you could just take the battery out and plug it into an a junction and charge that way. Either way you still need at least a new A junction, charger and battery.

mrblobby is correct – internal battery works fine with that junction box, however you need something with a port for charging. Doesn’t matter where in the system you add it, so unplugging any component in favour of the junction with a charging port would work.

Cheers, Rich

Which Di2 isn’t e tube then? When did it change?

The first Dura Ace wasn’t e tube. Everything else is.

Hi all thanks for the info. I thought as much. They certainly don’t make things easy to upgrade without spending a ton. Surprised there are no 3rd party alternatives yet as £17 for a cable and £60 far a charger really is taking the p*ss.

If you are handy with a soldering iron you can save a bit of cash. For all bar my first Di2 build, where I didn’t really know how the system worked, I only bought half the number of cables and didn’t buy a central junction box. I cut all my cables in half and spliced R/C car extension cables onto the cut ends. The central junction simply joins all the +ve and -ve wires together, so I soldered a female set of R/C cables together and glued them together.

You still need to buy the bits which contain any logic, but does save a bit on a boggo stuff.

Cheers, Rich

Wow… the lengths people will go to to save £16 on a junction box on what must be a £3k+ bike build!! Now if you managed to work out how to make a stem -mounted junction box or a charger for less than £60 a bit I’d be interested!

I bought all my e cables on ebay at half price, internal battery and charger on here, half price too.
The only thing i am missing is the stem junction box, struggling to get a bargain on one.
Just need to be patient and lucky.

What I think a bit crap is that despite all the technology you have to attach the stem junction box with a rubber band….

Wow… the lengths people will go to to save £16 on a junction box on what must be a £3k+ bike build!!

It’s a time trial bike… I have 5 b-junction boxes in mine and probably about 12 eTube cables. That’s about 250 quids worth of wiring without any of the fancy electronic bits 😕