Librem 14 and 15 power brick specifications

What are the specifications for the librem 14 an librem 15 A/C power adapters? (I’ve seen the similar posts in the sidebar, but they don’t really answer the question specifically.) Specifically:

  • what size plug do they have to connect to the laptop?

  • How many volts out?

  • How many amps out?

  • Is the polarity positive center or negative center?

Since these are offered as a seperate purchase from the laptop, I want to see if I have any in my giant bin of computer parts that will do the job.

As no customers have the Librem 14 yet (but soon) it may be difficult for a community member to answer that with certainty. You may need to email support@puri.sm

Oh right. Well what about the 15? That’s the one on sale.

Thank you! So my old IdeaPad won’t work (it’s 20V). I was hoping I could save a few dollars.

Librem 14 can also be charged with USB-C.

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Isn’t the power adapter included with the computer at no extra charge?

Yes, but one use case is to have two chargers, one at work and one at home, so you don’t take the charger with you every time.

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… which is one reason to point out that the Librem 14 is different from the Librem 15/13.

Oh? But this is not true for the 15 right? The order page seems clear that you have to pay extra for a power charger.

Yes, for L15, this use case requires to pay for the additional charger.

This should be fine. Your charger won’t force 20V into your laptop.

Bzzzzt! Wrong. Charger will force 20V.

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I thought power was drawn, not pushed?

Voltage (V) is as power brick says.
Current (A) is as the laptop wants.
If voltage is greater than a laptop can handle, the laptop gets damaged.*
If current is greater than the power brick can provide, the power brick gets damaged.*

*In the so-called ideal world. In real world, overvoltage and overcurrent protections may exist.

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Also the ratings on components generally are at some percent of their actual safe range (often +/-10%). So you might get away with 20v on a device that wants 19v nominally. Just like AA batteries give between 1.2 and 1.55v depending on their internal chemistry. Feeding extra voltage to something like a laptop which has internal VRMs is likely to produce extra heat in those VRMs. Likelyhood of damage scales with time and external temperature (which is how you can find people sending 1.8v to their CPU/memory when cooling via liquid N2).

Unless you know what components are downstream of the higher voltage, and read their datasheets, it’s best to go with as close as you can get to their rated specs. Except for maximum amperage on the supply, you can pretty much always benefit from throwing a bigger power supply at it (the supply will run cooler, but after a point will be less efficient).

Oh, also remember that wattage (which causes heat death) scales as the square of the voltage (V2r-1). So a tiny amount over the rated voltage can easily fry components.

Ah, I was never clear on all that. I knew the amperage part, never thought to consider the voltage part. The more you know.

20v vs 19.2v is a complete non-issue. The BJ size (OD, ID), pin, polarity, etc are all more important. I’m not sure I’ve ever seen a lenovo device that uses a standard 55.5/2.5mm BJ plug like the L13/L15/Minis.

The Librem 14 will almost certainly use a smaller BJ connector in addition to having USB-PD charging. If your Ideapad supports USB-PD, then you can use a single charger for both.

Suspected as much, but it is always better to hear from someone who knows, rather than suspects.

I know what you are trying to say but you butchered that. It’s I2R or V2/R.

Yup, that’s a mistake on my part, not sure why I wrote I instead of V.