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USB-c charging, what wattage/voltage is needed?

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Olangu
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USB-c charging, what wattage/voltage is needed?

#1 Post by Olangu » Thu Oct 12, 2017 5:55 am

Hi all!

Do anyone have any information on how much wattage or voltage a USB-c charger needs to produce for the TP25 to start charging on it.
I don't care how slow it charges or if it have to be off to charge. Looking to have the smallest possible charger for my phone and laptop while on the road.

My phone charger at 18W (9V, 2A) is not enough from my tries.

Might it be that the voltage must exceed the battery voltage?
That a 27W (15V, 1.8A) will work but a 27W (9V, 3A) will not?
https://en.wikipedia.org/wiki/USB#Power ... y_.28PD.29

The USB-c standard is a complete mess. One port that have so many different profiles...

Thankful for any help!

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Re: USB-c charging, what wattage/voltage is needed?

#2 Post by Thinkpad4by3 » Thu Oct 12, 2017 2:23 pm

Now about instead of blowing up your T25, why not use this: https://www.amazon.com/Lizone-40000mAh- ... B015TMJAW2
Thinkpad4by3's Law of the Universe.

The efficiency of two screens equally sized with equal numbers if pixels are equal. The time spent by a 4:3 user complaining about 16:9 is proportional to the inefficiency working with a 16:9 display, therefore the amount of useful work extracted is equal.

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Re: USB-c charging, what wattage/voltage is needed?

#3 Post by Olangu » Thu Oct 12, 2017 2:58 pm

I'm not looking for a power bank.
I want to know what USB-c spec is needed to charge the TP25 over the USB-c port.

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Re: USB-c charging, what wattage/voltage is needed?

#4 Post by theterminator93 » Thu Oct 12, 2017 3:02 pm

Lenovo's own USB-C charger for the T470 is 20V at 2.25A.
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Re: USB-c charging, what wattage/voltage is needed?

#5 Post by NonesensE » Thu Oct 12, 2017 3:57 pm

The battery connector on the T470 is the same as on all other thinkpads since 200x and supports 3 and 4 cells in series, so although all available batteries for the T470 are 10.8V, it supports 14.4V batteries as well. And the charging circuit behind the connector does this, too. Now those voltages are nominal voltages, the nominal voltage of a lithium ion battery is 3.7V. The full charge voltage however is approx. 4.2V, so when fully charged, the thinkpad batteries reach 12.6V and 16.8V, respectively. This means, as long as they don't incoprorate a boost converter, the thinkpad needs 20V to feed the power circuit. This is the same voltage the classic chargers deliver and thus the easiest to integrate.
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Re: USB-c charging, what wattage/voltage is needed?

#6 Post by w0qj » Fri Oct 13, 2017 1:48 am

Wow, congrads on your TP25 ;)

Think of the TP25 as a T470 (which it was based upon), and read up on T470 hands on review especially regarding charging your laptop.

For example:
www.notebookcheck.net/Lenovo-ThinkPad-T ... 130.0.html

~USB-C chargers for T470 (presumably same for TP25) comes in 65W and 45W varities.
~Strongly recommend get that 65W USB-C charger as it also supports Rapid Charge technology (Power Deliver 2.0).
(Caveat: USB-C chargers are slightly slower that the traditional rectangular-tipped 65W chargers, but only if you use a timer to time the difference).
Last edited by w0qj on Fri Oct 13, 2017 7:01 am, edited 1 time in total.
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Olangu
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Re: USB-c charging, what wattage/voltage is needed?

#7 Post by Olangu » Fri Oct 13, 2017 3:10 am

NonesensE wrote:
Thu Oct 12, 2017 3:57 pm
The battery connector on the T470 is the same as on all other thinkpads since 200x and supports 3 and 4 cells in series, so although all available batteries for the T470 are 10.8V, it supports 14.4V batteries as well. And the charging circuit behind the connector does this, too. Now those voltages are nominal voltages, the nominal voltage of a lithium ion battery is 3.7V. The full charge voltage however is approx. 4.2V, so when fully charged, the thinkpad batteries reach 12.6V and 16.8V, respectively. This means, as long as they don't incoprorate a boost converter, the thinkpad needs 20V to feed the power circuit. This is the same voltage the classic chargers deliver and thus the easiest to integrate.
What you are saying is that with the 10.8V batteries a 15V charges might still be able to charge it at full speed (unless there's a limit on the current).
w0qj wrote:
Fri Oct 13, 2017 1:48 am
Wow, congrads on your TP25 ;)

Think of the TP25 as a T470 (which it was based upon), and read up on T470 hands on review especially regarding charging your laptop.

For example:
www.notebookcheck.net/Lenovo-ThinkPad-T ... 130.0.html

~USB-C chargers for T470 (presumably same for TP25) comes in 65W and 45W varities.
~Strongly recommend get that 65W USB-C charger as it also supports Rapid Charge technology (Power Deliver 2.0).
(Caveat: USB-C chargers are slightly slower that the traditional rectangular 65W chargers, but only if you use a timer to time the difference).
Thank you!
I'm actually liking it more and more.

I read up on the T470-45W charger, it is specced at:
Power output ranges:
20V 2.25A
15V 3A
9V 2A
5V 2A

Now I really feel the urge to try out charging with a 15V charger. Going to call my friends with fruit computers, see if anyone is sitting on the 29W charger (14.5V, 2A).

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Re: USB-c charging, what wattage/voltage is needed?

#8 Post by NonesensE » Fri Oct 13, 2017 3:50 am

Olangu wrote:
Fri Oct 13, 2017 3:10 am
What you are saying is that with the 10.8V batteries a 15V charges might still be able to charge it at full speed (unless there's a limit on the current).
In theory, yes, but probably not with the thinkpad charging circuit, that's what I'm saying. However, until someone tries, we won't know for sure.
Now I really feel the urge to try out charging with a 15V charger. Going to call my friends with fruit computers, see if anyone is sitting on the 29W charger (14.5V, 2A).
Good luck!
Sometimes coming over from the German forum...
X62s 3rd batch, [s]T61[/s] T70 14" 4:3 1st batch

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Re: USB-c charging, what wattage/voltage is needed?

#9 Post by marsman2020 » Sun Oct 15, 2017 8:39 pm

You'll need a charger that supports USB Power Delivery and can negotiate up to at least the 15V voltage and preferrably the 20V voltage. Something in 45W-65W range - 45W might not charge while running in all circumstances, the TP25 ships with a 65W adapter.

I'd be very careful with this. As you may have already seen, USB-C is kind of a cluster@$@$ right now and there are cables and chargers out there that can literally fry your devices.

There is a table of devices that have been independently tested at - https://docs.google.com/spreadsheets/d/ ... X8/pubhtml#

I might try this - https://www.anker.com/products/variant/ ... -/A2053111 - which is 45W.
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Olangu
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Re: USB-c charging, what wattage/voltage is needed?

#10 Post by Olangu » Tue Oct 17, 2017 3:50 am

NonesensE wrote:
Fri Oct 13, 2017 3:50 am
Olangu wrote:
Fri Oct 13, 2017 3:10 am
What you are saying is that with the 10.8V batteries a 15V charges might still be able to charge it at full speed (unless there's a limit on the current).
In theory, yes, but probably not with the thinkpad charging circuit, that's what I'm saying. However, until someone tries, we won't know for sure.
Now I really feel the urge to try out charging with a 15V charger. Going to call my friends with fruit computers, see if anyone is sitting on the 29W charger (14.5V, 2A).
Good luck!
I was in a store yesterday and was able to try the apple chargers. The 29W one did not work, but the higher power ones did. My conclusion is that the TP25 probably needs 20V to be able to charge.

Olangu
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Re: USB-c charging, what wattage/voltage is needed?

#11 Post by Olangu » Tue Oct 17, 2017 3:54 am

marsman2020 wrote:
Sun Oct 15, 2017 8:39 pm
You'll need a charger that supports USB Power Delivery and can negotiate up to at least the 15V voltage and preferrably the 20V voltage. Something in 45W-65W range - 45W might not charge while running in all circumstances, the TP25 ships with a 65W adapter.

I'd be very careful with this. As you may have already seen, USB-C is kind of a cluster@$@$ right now and there are cables and chargers out there that can literally fry your devices.

There is a table of devices that have been independently tested at - https://docs.google.com/spreadsheets/d/ ... X8/pubhtml#

I might try this - https://www.anker.com/products/variant/ ... -/A2053111 - which is 45W.
I'm currently eyeing this charger:
http://www.ebay.com/itm/87W-USB-C-Type- ... 1438.l2649

Nice selection of ports, good price and a lovely form factor.

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Re: USB-c charging, what wattage/voltage is needed?

#12 Post by marsman2020 » Tue Oct 17, 2017 10:19 am

Olangu wrote:
Tue Oct 17, 2017 3:54 am
marsman2020 wrote:
Sun Oct 15, 2017 8:39 pm
You'll need a charger that supports USB Power Delivery and can negotiate up to at least the 15V voltage and preferrably the 20V voltage. Something in 45W-65W range - 45W might not charge while running in all circumstances, the TP25 ships with a 65W adapter.

I'd be very careful with this. As you may have already seen, USB-C is kind of a cluster@$@$ right now and there are cables and chargers out there that can literally fry your devices.

There is a table of devices that have been independently tested at - https://docs.google.com/spreadsheets/d/ ... X8/pubhtml#

I might try this - https://www.anker.com/products/variant/ ... -/A2053111 - which is 45W.
I'm currently eyeing this charger:
http://www.ebay.com/itm/87W-USB-C-Type- ... 1438.l2649

Nice selection of ports, good price and a lovely form factor.
Nope, no way I'd plug that into my machine. That's a knockoff of the Apple 87W charger.

A USB-C Power Delivery charger is a 'smart' device with much more complexity than a simple 5V charger or even a single-voltage laptop charger. It has to be able to negotiate pairs of voltage and currents - 5V, 9V, 15V, 20V - before it delivers any power. If something goes wrong it needs to be able to turn itself off before it delivers too much voltage and/or current and damages the device it plugs into.

Here's some fun videos:
https://www.youtube.com/watch?v=SjeZB12985c
https://www.youtube.com/watch?v=9FZltqOaiOA
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Re: USB-c charging, what wattage/voltage is needed?

#13 Post by chx1975 » Sat Nov 11, 2017 1:40 pm

It has to be able to negotiate pairs of voltage and currents - 5V, 9V, 15V, 20V
Has to? Nope. Look at the Nintendo Switch forums, tons of chargers are not compatible because they do not deliver 15V. Power Delivery is a very flexible standard and the charger tells the system what it does and what it doesn't support.

To charge the T25 you need 20V, period. Any amperage will charge the laptop switched off. The only question I would have is whether a 29W charger is enough to keep the laptop ticking. Someone reported using a 45W to charge while using the laptop with the caveat of not testing the dGPU at all so just 29W might be enough to keep the lights on even if the battery doesn't charge.

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Re: USB-c charging, what wattage/voltage is needed?

#14 Post by w0qj » Mon Nov 13, 2017 7:57 am

If one uses a non-ThinkPad USB-C charger and it wrecks your (expensive) ThinkPad, think this voids your warranty.
Therefore only use ThinkPad USB-C chargers if you really have to, for the sake of your warranty.
(You still can use the traditional ThinkPad rectangular charging pin ones on all ThinkPads).

Until USB-C chargers of any maker can be used to charge your ThinkPad, then I'll avoid it with a 10-foot pole.
The USB-C charging "standard" is just not mature yet.
You are the white lab rat.

Personally, I suspect that by the time this USB-C charging situation becomes universal (ie: USB-C chargers of any maker can be used to charge your ThinkPad),
by that time I would suspect that something a USB-D charging port of different shape would be introduced.
(So as to steer clear of incompatible USB-C chargers that may ruin your ThinkPad). ymmv
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Re: USB-c charging, what wattage/voltage is needed?

#15 Post by marsman2020 » Thu Nov 30, 2017 1:37 am

There are certainly reputable USB-PD chargers that follow the spec properly and autonegoatiate the way they are supposed to out there. I just don't think that a random Chinese knockoff is one of them, and I'd want to see some testing by one of the savvy USB-C early adopters before I used a 3rd party charger on my new TP25.

I ordered the official Lenovo 65W USB-C charger for $37 on sale with Black Friday pricing. So I'll use that for an USB-C charging needs in the future.
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Re: USB-c charging, what wattage/voltage is needed?

#16 Post by daten » Sun Aug 26, 2018 11:26 am

I'd just like to state that - to my surprise - my Nintendo Switch charger, which does 15V @ 2.6A (no 20V according label), charges my ThinkPad T480s, so 15V seems to be enough to keep the charging circuit happy.

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Re: USB-c charging, what wattage/voltage is needed?

#17 Post by w0qj » Mon Aug 27, 2018 7:52 am

Personally, I'll stick with Lenovo/ThinkPad USB-C chargers, to the point of suggesting to buy a few more (expensive) chargers.
ie: one at home, one at office, one for carrying around in my backpack, etc.

Not too long ago, USB-C chargers of different manufacturers are a hit-and-miss;
meaning that incompatible USB-C chargers may fry your notebook computer and void your warranty!
(And this is from manufacturers using USB-C chargers made in many different countries of origin).

Carefully compare the cost of the USB-C chargers vs your computer, is it really worth the risk to use non-ThinkPad USB-C chargers?
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Re: USB-c charging, what wattage/voltage is needed?

#18 Post by tdot » Sun Sep 30, 2018 3:36 pm

marsman2020 wrote:
Tue Oct 17, 2017 10:19 am
Nope, no way I'd plug that into my machine. That's a knockoff of the Apple 87W charger.

A USB-C Power Delivery charger is a 'smart' device with much more complexity than a simple 5V charger or even a single-voltage laptop charger. It has to be able to negotiate pairs of voltage and currents - 5V, 9V, 15V, 20V - before it delivers any power. If something goes wrong it needs to be able to turn itself off before it delivers too much voltage and/or current and damages the device it plugs into.
I'm going to second this. It's just not worth it getting a knockoff charger ...

If you YouTube "dangerous cheap USB chargers" you can find some designed with the 120V rails right next to the 5V rails ... with disgusting soldering. One little mistake and your phone will go up in smoke. Definitely wouldn't trust them with a laptop.

However, I *can* say that I was curious, and plugged the USB-C charger for a MacBook Pro (my work machine) into my T25 - it's listed as 87W - 20.2V/4.3A - 9V/3A - 5.2V/2.4A. I figured it's a real Apple charger so I didn't think it could be dangerous. It did work fine, and charged as expected.


Though, it's probably a pointless observation, as I have a feeling an Apple charger is probably twice the price of a Lenovo one :lol:

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