Fatih

I have just bought a shimano ultegra di2 12 speed groupset but was told I only charge it via a pc! My mechanic told me not to use any adapter (the old ones from iPhone with 5V output) but I am really struggling to understand if Shimano didn’t give any other alternative of ways of charging the Groupset. So basically if anyone has a similar issue I would like to know if you guys as well use only the pc or did you buy something alternative to that. Because when I am travelling I really do not want to take an old HP pc with me which has an usb connection but unfortunately weighs 10kgs (I am exagareting of course) but you know what I mean. Any help more than welcome.

Steve B.

I've never charged off a PC, have always used a generic USB to AC adapter. Shimano says this " This product can be charged by using an AC adapter with a USB port or by connecting it to the USB connector of a PC.

Atlas Shrugged

Welcome to the sport of cycling, where urban myths and unvalidated advice dominate. Luckily we now live in a time where access to factual information is at your fingertips. Charge from any USB adapter and enjoy.

Polaris OBark

Your iPhone adapter is ideal.

(Despite what you were told, a PC USB slot as a charging source can be hit or miss.)

Ryan_M

That seems totally backwards, are you sure he didn't say DON'T charge it from a PC? A PC could be worst case scenario since they can meter and reduce the USB port current draw. Li-ion batteries typically have a minimum charging current, so if your PC is being particularly grumpy that day it may drop the available current from the USB port below that level which could degrade or damage the cell. Likely it would be fine and not drop that low but why risk it? As mentioned the adapter for your iPhone is probably ideal, though I'd see what it's rated for. 2A is probably plenty.

Kontact

This is precisely the opposite of what I was told by Shimano tech services 2 years ago. They didn't want to warranty batteries recharged with a PC, and specifically called for iPhone chargers as being the best.

I think there is now even a warning about that in the battery or Di2 manual.

smd4

Could one lay the bike on top of a wireless charger to charge the batteries?

Iride01 

A type A USB connection from a PC or Mac may only provide .5 amps depending on what version USB is implemented on them. A type C USB probably will provide the needed current.

I once used a old adapter that only put out .5 amps and my battery didn't charge or didn't charge fully by the next morning. So I usually use the higher power chargers for the new phones. Some of which can provide 5 or more amps. There is no maximum for what you can plug it into as it will only draw the current it needs. However if your don't give it power from something that supplies the current it needs, then it might not charge at all.

Shimano's only mention about plugging it into the PC is that they don't want you to plug it into a USB hub and rather have you plug it to a USB directly on the PC. But that is likely because many USB hubs are not powered USB hubs and when too many connected devices get to hogging the limited current provided by the PC, then the data signals sometimes drop and it won't communicate data back and forth.

If your battery charges fast enough with your PC USB then it likely good enough. Make sure the charger or SM-BCR2 isn't getting hot. But consider using a adapter that puts out at least 1.5 amps or better if you just want to charge the battery and the PC doesn't or isn't fast enough.

However you also have to consider any warranty exclusions that might apply and whether the lower amperage might also damage your SM-BCR2 or what ever you have. Usually unlikely but it can be a possibility.

Barry2 

Generally speaking an iPhone adaptor will not charge your Di2. Many have fallen for this issue.

Shimano spec's a USB adaptor capable of more than 1 Amp (1A) and the iPhone adaptor is capable of barely 1A

Most after market adaptors are 5V at 2.4A

Some PC's can meet the 1A requirement, many will not.

Go buy a 2.4A USB adaptor and be happy with your Di2, welcome to bike forums and congrats on the new bike.

Barry



TerryDi2C ,
Come join the party and back me up on this!

Shadco 

Only while sacrificing a chicken and doing a rain dance. Not very effective.

.

Mtracer

USB ports do have varying charge ability. And my own experience is PCs tend to have the least amount of current available for charging. And I'm sure I've had devices that would not charge from a PC. I think there is some sort of smarts in all of this that a device can detect characteristics of the charger and alter charging or perhaps choose to not charge at all.

Here's something right out of the user manual for the Di2 rear derailleur. I believe it is in that manual, because that's where the charge cable is connected.



I think that second part is some butt covering. Simply that if the charger is poorly designed, the Di2 system could try to pull more power out than the charger is rated for and bad things could happen.

I have a multi-output USB power adapter just for charging bike stuff. I keep this in my shop where I service my bikes.

Kontact

It's good to have current information. What I was told about 11 speed Di2 has changed. PCs and chargers are acceptable (again). Center of page 2:

https://si.shimano.com/en/pdfs/um/3G...0A-004-ENG.pdf

Iride01 

Maybe I looked too quick and missed it, but I didn't see any reference to 11 speed Di2 in that. Just the new 12 speed RD.

edit. But maybe I'm misunderstanding and since the OP ask about 12 speed Di2, you are showing that the 12 speed is different.

TerryDi2C

I've always my old Moto G4 "turbo charger" myself

Barry2 

sure, but what’s it rated in Amps ?

TerryDi2C

2.8A, according to Google! A bit more than 1.0A