Dell WD15 dock fast charging not working

[uyjulian]

Charging the system with the Dell WD15 dock does not fast charge. It will give the slow charger warning and slowly charge the system.

The possible issue is that it only has the following USB-PD profiles:
3000 mA / 5V <- The Nintendo Switch (and I presume Steam Deck) selects this
3000 mA / 19V
It does not have 12V or 15V profiles.
(I confirmed this with Hekate on Nintendo Switch)

Possible solution:
1. Program the charging IC to use 19V/20V charging (not sure if this is safe or not)
or
2. Change/add to the "slow charger" notification that fast charging is not supported when there is a higher USB-PD voltage available, but it can't be selected.

#2 would reduce confusion when using certain docks

[Major Gnuisance]

I believe currently the Steam Deck requires 15 V for both fast charging and to run directly off of input power.

The requirement to run at full power and simultaneously fast charge at full speed is 3 A / 15 V

That's 45 W, but some power supplies advertised as "45 W" may not support 3 A / 15 V, so be careful.

If anyone wants to try figuring out if higher input voltages would be possible, iFixit has pictures of the main board and identifies the ICs.

https://www.ifixit.com/Guide/Steam+Deck+Chip+ID/147811

[uyjulian]

Seems like the operating range of the charging IC MAX77961 is between 3.5V - 25.4V
Seems like the input range of the USB-C/USB PD controller IC MAX77958 is between 2.6V - 20V
I also noticed that the peak efficiency of the MAX77961 when charging 3 cell batteries is at 15V.

So the hardware should support above 15V fine.

It seems like the MAX77958 firmware is programmable.
Possibly they programmed it (incorrectly) to where it does not consider voltages above 15V, even if the 15V voltage is not available. Thus, it only considers lower voltages.
So maybe it needs to be programmed so that if 15V is not available, voltages in between 5V-15V are not available, but voltage above 15V is available, it should pick the voltage that is above 15V.

[TinHammer]

One more vote for this. I have a couple of these so would be really helpful if this could be fixed.

[HomelessAvatar]

Same here, would love to have this working.

[uyjulian]

I got a new Steam Deck OLED and tested it there. Same issue.


Apparently the charging circuit may overheat in the Steam Deck LCD may overheat causing the charging chip to pop and fry, causing it to no longer work. In this case, probably limiting the charging voltage to 15V makes more sense to reduce the chances of that happening.

[AwesomenessZ]

Thank you for posting the update that this has not been resolved with the OLED model.

I would think there may be a solution where the Voltage may be higher at 19v, but the advertised amperage would be lower than 15v to prevent overheating. Even if it would end up charging faster at 15v (and thus be preferred if available) it would still (hopefully) charge faster than if you only had a 5v source.