Limiting power adapter draw (temporarily)

I usually travel a lot with my laptops, often by train. Now the trains here in Germany often have stickers on their power sockets saying “max. 90W”. I never tried drawing more and I don’t know what actually happens if you draw more but I suspect a fuse will cut supply.

Now I am asking myself if there could be some way to limit my future Framework 16’s power draw so it does not cause problems with those sockets. I don’t want to run on battery on all my travels as that might reduce battery lifetime. I ordered the version with dGPU, so power draw could peak as high as the whole 180W of the adapter if I read correctly.

I’m using Linux, so I was thinking if maybe TLP would provide the necessary settings - but I’d probably have to experiment with settings to find what limits will provide what I need. Any other ideas?

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you should be ok unless u not play games in train , lol and ya fuse will blow up of the socket incase u suck a lot of power . or maybe its just sticker as train have enough power

I believe the only way to do it with the 180W adapter would be to ensure the laptops entire power use is under the limit. Disable the dGPU, set CPU throttle and screen brightness if needed, then set a battery charge limit below the current battery level to ensure your battery doesn’t try to charge.

I don’t believe the control needed to limit wattage directly with the USB PD chip is exposed. Though since the Framework EC is open source, at least the FW13, presuming the FW16 one will be too, one could maybe add the ability.

Usually outlets for passengers share a single fuse of 6ish Ampere per car, or maybe per car side. The fuse won’t blow just because a single person exceeds the limit - outlets wouldn’t work ever if they did.

Just don’t run your electric kettle and it’s going to be fine.

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The fuse won’t blow just because a single person exceeds the limit - outlets wouldn’t work ever if they did.

Good to know - thanks! :slight_smile:

From the reviews I’ve seen, peak draw seems to be ~60W without dGPU

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As a german fellow, i can say you can load your FW16 normally. I tried 170W power adapter and it worked.

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I can confirm your experience. No problems with the Deutsche Bahn
sockets :wink:

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Since the battery is limited to 1C charging and the battery is 85Wh, if you kneecapped the power limit to the cpu and left the dgpu turned off you could pretty reliably keep the draw below 90W.

If the battery is full or otherwise prevented from charging you should pretty comfortably stay below 90W as long as you don’t go ham with the dgpu.

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It would be nice to be able to limit battery charging speeds for health reasons. No need to charge battery at max speed when I plug it in, usually. Fast charging = lots of heat =worse for the battery.

It’s not ideal, but you could purchase a lower wattage charger for use on the train.

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What about a less capable cable?
I know some are limited to 3A, are there any that limit the voltage too?

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>3.25A needs a digitally marked cable and so does >21V so an unmarked cable would limit you to around 65W (I don’t think the fw uses pps so highest mode would be 20V 3.25A).

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This is the answer, a non specified cable will limit the power to 20V 3A