rMB 12 Rechargeable on any USB 2.4a outlet?

[bibyfok]

Is there any things that would prevent the rMB 12 to be recharged on any 5V 2.4a USB port? Does anyone know the tension that will deliver the 29W adapter?
I would love to see this computer be able to be recharged with external batteries or with something like this!

 

[Theophil1971]

Is there any things that would prevent the rMB 12 to be recharged on any 5V 2.4a USB port? Does anyone know the tension that will deliver the 29W adapter?
I would love to see this computer be able to be recharged with external batteries or with something like this!

5V @ 2.4amps is only 12 watts... So, nope. Any charger will need to be a full 29 watts (5.8amps)

 

[bibyfok]

5V @ 2.4amps is only 12 watts... So, nope. Any charger will need to be a full 29 watts (5.8amps)

I can recharge my 85W rMBP on a 45W charger without any issue except longer recharge time.

 

[MyopicPaideia]

5V @ 2.4amps is only 12 watts... So, nope. Any charger will need to be a full 29 watts (5.8amps)

Can this be true, physically? Because I've been told that apparently USB 3.1 only can handle 3.0amps? The speculation is that Apple's charger is running higher voltage, and thus standard USB as well as iPhone and iPad chargers may not be able to charge the MB because of too low voltage rather than too low amps. The battery interface circuitry on the MB may not activate at 5V, it may be something like 9-10V instead.

Nothing to stop you charging all your iDevices with the MB charger though, assuming a USB-C/Lightning cable is released by Apple.

 

[PBG4 Dude]

USB Power Delivery allows for 20V @ 5.0A.
See https://en.m.wikipedia.org/wiki/USB#USB_Power_Delivery

 

[newellj]

Can this be true, physically? Because I've been told that apparently USB 3.1 only can handle 3.0amps? The speculation is that Apple's charger is running higher voltage, and thus standard USB as well as iPhone and iPad chargers may not be able to charge the MB because of too low voltage rather than too low amps. The battery interface circuitry on the MB may not activate at 5V, it may be something like 9-10V instead.

Nothing to stop you charging all your iDevices with the MB charger though, assuming a USB-C/Lightning cable is released by Apple.

Assuming that something is smart enough to step down the voltage from the rMB adapter (assuming it's more than 5v nominal). I don't know if the adapter is smart enough to do that. I'm doubtful that iPhones and iPads are able to do that. I could be wrong...

 

[MyopicPaideia]

Assuming that something is smart enough to step down the voltage from the rMB adapter (assuming it's more than 5v nominal). I don't know if the adapter is smart enough to do that. I'm doubtful that iPhones and iPads are able to do that. I could be wrong...

Apparently USB 3.0 and up has a mandatory 5V compatibility requirement, but that is according to forum member Rigby, I haven't verified that. So if he/she is right, the iPhone and iPad don't have to do it, the cable will "know" to deliver 5V when connected...apparently.

 

[Rigby]

Apparently USB 3.0 and up has a mandatory 5V compatibility requirement, but that is according to forum member Rigby, I haven't verified that. So if he/she is right, the iPhone and iPad don't have to do it, the cable will "know" to deliver 5V when connected...apparently.

The way it works is that a USB power supply must default to 5V so legacy USB devices cannot be damaged. Higher voltages and currents are only enabled after a negotiation between the device and the power supply.

You can download the specs if you are interested in the technical details:

http://www.usb.org/developers/docs/usb_31_040315.zip

 

[newellj]

The way it works is that a USB power supply must default to 5V so legacy USB devices cannot be damaged. Higher voltages and currents are only enabled after a negotiation between the device and the power supply.

You can download the specs if you are interested in the technical details:

http://www.usb.org/developers/docs/usb_31_040315.zip

Thank you - so plugging an iPhone into the rMB adapter (assuming correct cables/adapters) shouldn't hurt the iPhone? I think that's the bottom line, please correct if not.

 

[MyopicPaideia]

The way it works is that a USB power supply must default to 5V so legacy USB devices cannot be damaged. Higher voltages and currents are only enabled after a negotiation between the device and the power supply.

You can download the specs if you are interested in the technical details:

http://www.usb.org/developers/docs/usb_31_040315.zip

Excellent, thanks for this, and sorry for quoting you without quoting you, appreciate the follow up!

 

[Lucifer666]

We shall see.

I'm liking this spec though. Should be fun