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Dell Laptop PSUs has this for at least 15 years. Internally it use a DS2501 to store the manufacturer, wattage, output voltage, output current, Dell SN and check sum. It is more like EDID for power supplies, it is definitely not DRM. It helps the laptop to understand how much wattage it can get from the PSU to avoid over heating, and use the output voltage to determine whether it is safe to use it to charge the battery.

The content is something like `DELL 01 AC 065 195 033 {23bytes} 01`, where 01 matches the revision number on the label of the PSU, 065 means it is a 65 watts adapter, 195 means the output voltage is 19.5V, 033 means the output current is maxed at 3.3A. The {23bytes} contains the country where it is produced, the Dell part number and date codes which I don't have enough data to understand how that is coded.

There was a github project which provided tools to copy and reprogram the chip, HP follows a similar protocol for its high end laptops, it is possible for a Dell laptop to use a HP PSU, if the BIOS is not implemented correctly.




Which I guess is among the things usb-c power delivery covers as well.

Usn-c for charging, despite its warts, are quite the game-changer. Especially in these absurd times where batteries are non-replacable being able yo juice-up from a power bank is fantastic. (yes you could do that before but it was very niche and/or expensive and with less utility).


Side note: integrated batteries are still replaceable if you're handy. (Though not quickly swappable like you're suggesting for more energy capacity over a single day!)

On the MacBook Pro I'm typing on right now, I replaced my the battery myself a few months ago. It took about an hour including a thorough cleaning of the laptop internals and I documented it here https://www.youtube.com/watch?v=CAYFDDxUxHA . That's still 59.9 minutes longer than it would have taken if had a modular battery, but about the same price in dollars. And a fun little weekend project.


Where did you get your replacement battery from? I was looking into replacing my battery, and my options for sourcing the part appear to be Amazon or iFixIt. The former’s reviews are show a number of people complaining that the part they received was of poor quality and barely held a charge (although this might be a vocal minority? Hard to tell). The latter is almost the price of just getting Apple to do it in the country I reside. What route did you take?



I've replaced my 2012 MBA battery a couple times now. Totally worth the ~$50 and 10 minutes it takes. Damn thing is a personal workhorse 8 years later.


Something I discovered the other day, while looking for a high-wattage Dell USB C adapter to use with my older XPS 15 (which came with just a old-school charger, so it doesn't get full juice out of most other USB C ones) is that the new 130W Dell USB-C charger only shows up as 90W on an older one like mine.

Looking around, stuff like this isn't uncommon. Apparently a lot of HP's won't work with non-HP USB C chargers at all, for instance.


That's probably because USB c only goes up to 100w for power delivery. Anything higher must be manufacturer specific, so I guess dell hasn't provided any updates for thee older xps to understand the new charger's protocol thing. Not great, but probably not malicious.

I had a xps 15 with 130w charger, and used it with the dell usb-c/thunderbolt docks (wd15/tb16). The wd15 had a 130/180 watt power supply option, after subtracting for the dock's power usage they were specified to provide 90/130w to the laptop. I had the 130 watt wd15 and it still worked perfectly with the laptop. The laptop never discharged while connected (maybe if you spend hours compiling a big project on 8 cores while playing games with the nvidia card?). But I assume it would charge slower/not at all if under heavy load. And the bios warning for a lower power adapter can be disabled.

It should be capable of taking 130w over the USB c port; dell explicitly specifies that it should be used with the 180/240w wd15/tb16 docks which provide 130w to the laptop. XPS 15 9560 iirc.


I guess it's possible to build something similar to this, but for Dell: https://www.tindie.com/products/mikepdiy/lenovo-charging-por...


Yep, I've worked from coffee shops and in trans-European trains where I couldn't get a power lead. No matter, a 25,000 mAh battery is sure to get you through the day. USB-C charging is absolutely fantastic.


Or do something like charge one phone from another.



Yeah, that sounds about right. I was working for a call centre providing support for Dell at the time, and the year before this was introduced we had a LOT of customers who got their laptops fried by dodgy chargers.

I'm not qualified to answer whether the ID pin constitutes DRM, and whether it is legal or not, but Dell's customers definitely were having issues with dodgy chargers before this was implemented. The implementation sucks though, as the design means it's easy to short the ID pin, rendering the charger useless.


Oh man, I had the chart which could decode dell part numbers and date codes, you explained it perfectly.

Let me see if I could dig it up...


Got a link to the github project?


>t is definitely not DRM.

It is definitely functionally DRM since it prevent using other suitable chargers for no reason.


Not only DRM.


Doesn't DRM means they tried hard to stop you from clone it? Any hobbyist can get a sample chip from Maxim, clone the data from the original PSU and write it to the new chip.

I agree it should be an open standard, but the implementation is really similar to EDID. As we are moving forward with USB-C power supplies, this is probably going to be irrelevant very soon.


“Any hobbyist can circumvent it” is a poor test to determine if something is a DRM though, most DRMs pass this test too, since most of them are vulnerable to the “analog loophole”.


> The content is something like `DELL 01 AC 065 195 033 {23bytes} 01`

Are they doing that trademark hack thing where they threaten 3rd party manufacturers who put that "DELL" string in their product without a license?


That's ridiculous. What the hell kinda court would accept that claim? The packet is clearly 0x44 0x45 0x4c 0x4c 0x01 0x41 0x43 0x65 0xc3 0x21 <23 bytes> 0x01!


Are you being sarcastic? I unfortunately can't find a source as the exact case is escaping my memory at the moment, but this was successfully argued in court that a third party using "TRADEMARK" in a chip (which is checked by the DRM system) was a violation of their trademark.


https://segaretro.org/TradeMark_Security_System

https://en.wikipedia.org/wiki/Sega_v._Accolade

I read it like Sega was on their way to losing the appeal, so they settled it out of court.


Even if it doesn't hold up in court, it may still be a deterrent to any company looking to produce compatible parts. Shipments of their product could very plausibly be stopped at customs then held up for years until the court case is won.


That's exactly what Apple does to prevent other companies to sell computers with MacOS on them![1]

[1]: https://en.m.wikipedia.org/wiki/Psystar_Corporation#Legal_is...


It as DRM as Printer cartridges or Keurig 2.0 K-Cup[1]

[1]https://news.ycombinator.com/item?id=8726707


Yes, I'm sure it has nothing at all to do with forcing customers to buy OEM chargers for $119 a piece plus tax and shipping instead of buying a generic one for $30.


If a company is making a "Generic" charger using a proprietary connector(only used by Dell in this case), it is their responsibility to make sure it works. Otherwise, it is a bad quality knock-off.


If someone is making a dell-specific charger, I can see that. But generic chargers usually have interchangeable tips, and they should not need to embed a different chip inside each one of them.


I don't like the proprietary protocol, but actually there is a good reason for this communication between the charger and the laptop.

There are multiple charges with the same barrel jack, but different wattage. You plug a low wattage power adapter to a high powered laptop. Without the chip: The laptop can draw to much power and in the best case scenario it damages your power adapter, in worts case damage your laptop or burns down your house. With the chip: the laptop can throttle, so it draws less power.

USB Power Delivery does the same thing, just without the properitary protocol.


> in the best case scenario it damages your power adapter

The best case scenario is that your charger is not a garbage fire hazard, and so it slowly drops the voltage when the laptop tries to draw too much.


A barrel connector is hardly proprietary.




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