"Projected charging time" displays incorrectly when using a weak charger.

[squeakyneb]

Your system information

• Steam client version: 1748914100
• SteamOS version: 3.7.8
• Opted into Steam client beta?: [Yes/No] No
• Opted into SteamOS beta?: [Yes/No] No
• Have you checked for updates in Settings > System?: [Yes/No] Yes

Please describe your issue in as much detail as possible:

When running the Deck with an under-powered charger (that supplies less power than is being used) the performance menu shows a "projected charging time" which is not at all accurate. I think what's happening is that the timer is calculating how long until the battery is either full or empty, but the text indicates that it's a "projected charging time" just because the charger is plugged in. So with an under-powered charger, what I'm seeing is a "projected charging time" which is actually the projected time until empty.

I would expect that in this scenario the display would indicate that it's plugged in but still discharging*. Perhaps a watts in vs watts used display would be cool too.

* yes, I know the charging LED indicates an underpowered charger, but it doesn't indicate how underpowered or whether the battery is actually charging or discharging during use.

Steps for reproducing this issue:

1. Plug in a low wattage charger (e.g. a dumb old 5V USB-A charger)
2. Do something that consumes a decent amount of power
3. Observe that the performance menu shows a "Projected charging time" that goes down despite the battery charge percentage also going down.