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JohnBee
Not applicable
Posts: 16
Registered: ‎12-13-2015
Location: Germany
Views: 1,827
Message 11 of 26

Re: Yoga 900 Charging cable wiring


@Majestic wrote:

Probably the simplest way would be to visit eBay and purchase a new cable and then spliced that into your old adapter / charger cord so you have the correct end.

 


 

This exactly is what I initially intended to do to produce a 12V DC car charger. But I read so much about people frying their devices. There seems to be some communication between the Yoga and the charger. As I understood it, the Yoga tells the charger either to deliver 5V or 20V on the same wire.

 

Read this before damaging your Yoga:

http://www.mikegyver.com/blog/index.php?id=6253616961827193340

 

 

Majestic
Not applicable
Posts: 4,286
Registered: ‎11-18-2012
Location: US
Views: 1,822
Message 12 of 26

Re: Yoga 900 Charging cable wiring

I was aware that the unit that plugged into the wall had dual DC voltage ability, but I wasn't aware that it extended to the cable that plugged into the laptop.  It sounds like the handshake communication is what defines it and I don't how you would get around that.  Fortunately your extra reading saved you some grief.



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mkitten
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Posts: 24
Registered: ‎03-07-2008
Location: GB
Views: 1,801
Message 13 of 26

Re: Yoga 900 Charging cable wiring

This company in the UK has an alternative AC connector available: http://www.laptopchargerfactory.co.uk/lenovo-yoga-900 (not advertising). They say it is tested. But I doubt it would manage to reproduce the handshake. Do you think it's safe to use? Is there a risk that 20V might be sent to the 5V circuitry of the Yoga 900?

JohnBee
Not applicable
Posts: 16
Registered: ‎12-13-2015
Location: Germany
Views: 1,789
Message 14 of 26

Re: Yoga 900 Charging cable wiring

Read the blog I linked above. They killed 2 Yoga 3 Pro by aplying 20V the incorrect way.

 

I´m afraid, the company you found does not offer chargers with the USB-type connector at all. In their products menu the have only chargers for some older Yogas. Their search function is pulling your leg. You can even order a charger for non existent models like Yoga 740:

http://www.laptopchargerfactory.co.uk/yoga-740

 

mkitten
Not applicable
Posts: 24
Registered: ‎03-07-2008
Location: GB
Views: 1,783
Message 15 of 26

Re: Yoga 900 Charging cable wiring

Wow... Thanks JohnBee!

tintra
Not applicable
Posts: 4
Registered: ‎01-24-2016
Location: California
Views: 1,698
Message 16 of 26

Re: Yoga 900 Charging cable wiring

Was anybody able to modify the cable to get the external battery to charge the Yoga 900?  

I saw the blog and the products from the mikegyver site.  But wondering if there are other simpler solutions?  

 

Would it be possible to make an adapter tip like the ones available for the other Yogas (Yoga 2)?

tintra
Not applicable
Posts: 4
Registered: ‎01-24-2016
Location: California
Views: 1,693
Message 17 of 26

Re: Yoga 900 Charging cable wiring

For external battery, I just got a ChargeTech (27,000 mah) battery pack with an A/C outlet.  

I was able to charge the Yoga 900 with it.  

 

I also have a RAVpower Extreme 23,000 mah and would like to be able to use that to charge the Yoga 900.  But there is no connector available!

garzipan
Not applicable
Posts: 1
Registered: ‎03-03-2016
Location: US
Views: 1,590
Message 18 of 26

Re: Yoga 900 Charging cable wiring

i finally bit the bullet so to speak and cut my cable in half. there is a red V+ and a black V- cable in there, as well as a white cable.  if you connect the white cable to the red V+ cable, it completes the circuit and you can charge your laptop by connecting the black V- to a power supply, and the white and red V- combo to the V+ of a power supply

JohnBee
Not applicable
Posts: 16
Registered: ‎12-13-2015
Location: Germany
Views: 1,577
Message 19 of 26

Re: Yoga 900 Charging cable wiring

Can you confirm that you connected

white wire and red wire to +20V of power supply

and

black wire to ground of power supply?

 

Did you charge your Yoga this way saveral times without causing any damage?

 

Are there any more wires in the charger cable or just this three?

JohnBee
Not applicable
Posts: 16
Registered: ‎12-13-2015
Location: Germany
Views: 1,504
Message 20 of 26

Re: Yoga 900 Charging cable wiring

I finally bought a spare charging cable and removed the insulation for further investigation.

 

There are only three wires in my charging cable: black, white and blue. None of them are connected to each other.

 

With the cable plugged into the charger but the other end unplugged I measure:
5.37V between black and white
4.56V between black and blue

 

With the cable plugged into the Yoga but the other end unplugged I measure:
5.15V between black and white
0V between black and blue
4.29V between white and blue

 

With the cable plugged into both the charger and the Yoga I measure:
20.1V between black and white
3.13V between black and blue

 

I could not find out, how to switch the charger from 5.37V to 20.1V without connecting it to the Yoga. As there is probably no microprocessor in the charger, I do not expect any digital communication between the Yoga and the charger. Just connecting blue to white or black does not do the trick (the charger then stays at 5.37V).


Please Lenovo tell us how the charging process works. We really need to charge our Yogas from DC sources.

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