Homebrew Question Switch Lite charges slowly under "stress" conditions

[MrSandstorm]

Well if you have two chargers at 15V and one at 1A and the other at 2.6A obviously the 2.6 one would charge the switch battery faster, same concept goes for laptop charger, charger with the same required voltage with higher amp would always charge faster, as it supplies more amp, similar concept would be 5V/4A phone charger charge faster than a 5V/1A charger. On the back of the switch, it stated 15V/2.6A.

Normally I have the unit fully charged then I play, it does get a little bit hotter than usual when you play and charge at the same time. If your thermal paste isn't dry up then you shouldn't worry too much about the temperature too much, not like it would shut off on it own. Heavy CPU clock usage obviously would make the unit hotter, and the battery drains faster.

Yes, I'm aware. There are some things to consider, however.

First is that the charger is simply a power source, and how much power is drawn from it is determined by the power management circuit in the device it's connected to, up to the charger's limit, of course.

The Lite has, AFAIK, two profiles: one for USB-A chargers and one for the official and PD chargers. The first works at 5V and draws up to 2A, and the second works at 9V, 12V or 15V depending on what the charger offers, and will draw up to 13.5W (the current will depend on the PD voltage).

The Lite will never draw anywhere near as much power as the official charger can supply at 15V. The charger is capable of that because it's probably cheaper for Nintendo to manufacture only one design, and it has to be able to handle a docked normal Switch at full load with a bunch of stuff plugged into the dock's usb ports.

The system is also able to tell apart a PD charger from the official charger, and will only reach it's highest possible clocks with the latter, regardless of overclock.

The way I'm testing this is having the device fully charged and at room temperature before I start playing, and monitoring temps and rate of discharge.

 

[FAST6191]

Apologies if it was already covered but I will mention it anyway.

Batteries depending upon their chemistry (and physical nature in some instances) are not just charged at a fixed rate. As they near completion the charge rate (or even nature -- see constant voltage vs constant current) might have to be changed for something else, usually a lower current top up phase compared to bulk charging that you see when going from lower percentages.
One of the crude, but still reliable enough (the better methods being expensive and often a bit more bulky), measurements of this state change is the battery/batteries will rise in temperate by a few degrees, or perhaps above an absolute value. If the high ambient temperature combines with the less than stellar thermal management it might well trip this sensor (usually a crude thermistor) into thinking it is at that stage when it is not and thus you end up with more of a trickle charge.

This is all independent of whatever fun you are all having with Kirchhoff's current laws and internal resistances (though in a crude/simplistic sense I suppose it is one) as it pertains to junctions.

Edit.
Have a video if you want to learn more. It is a bit old (you will be reasonably hard pressed to get the old type today) but still very good.

 

[MrSandstorm]

Apologies if it was already covered but I will mention it anyway.

Batteries depending upon their chemistry (and physical nature in some instances) are not just charged at a fixed rate. As they near completion the charge rate (or even nature -- see constant voltage vs constant current) might have to be changed for something else, usually a lower current top up phase compared to bulk charging that you see when going from lower percentages.
One of the crude, but still reliable enough (the better methods being expensive and often a bit more bulky), measurements of this state change is the battery/batteries will rise in temperate by a few degrees, or perhaps above an absolute value. If the high ambient temperature combines with the less than stellar thermal management it might well trip this sensor (usually a crude thermistor) into thinking it is at that stage when it is not and thus you end up with more of a trickle charge.

This is all independent of whatever fun you are all having with Kirchhoff's current laws and internal resistances (though in a crude/simplistic sense I suppose it is one) as it pertains to junctions.

Edit.
Have a video if you want to learn more. It is a bit old (you will be reasonably hard pressed to get the old type today) but still very good.

This is some great information, and I confess I forgot to consider the battery's charge curve. The thing is, the system will drain the battery way too fast even when it's completely charged, like it was drawing more power from it than from the charger.

More specifically, what you mentioned about the battery's thermal protection might explain what I've been seeing:

-> Power draw goes momentarily above what the charger can supply causing some battery drain and generating more heat than usual;
-> the extra heat combined with high ambient temps raises the battery temperature enough to trigger it's thermal protection;
-> the battery management circuit reduces charge current significantly and now the battery can't charge fast enough (or at all) before the next high demand "event";
-> this keeps repeating every few minutes resulting in the battery being drained rather quickly.

It's just a theory, but I think it makes more sense than my initial idea of the system applying some sort of current limit or thermal protection too soon, and that by itself causing the excessive drain, and better explains the situation than simply saying that "the charger isn't enough so what you're seeing is normal". It even explains why the thermal protection is kicking in at around 45C, as Lithium batteries are far more vulnerable to heat-related damage than an SoC.

What do you think? And thanks for the help!