How best to prolong the life of my Steam Deck's battery?

Question

This question probably applies to most any device with a rechargeable battery, but here goes:

We all know batteries degrade over time. Some types of batteries last longer if you primarily do full discharge cycles, others are better if you keep them topped up continuously. What is best for the Steam Deck's battery? Mostly interested in what to do between playing sessions. If the battery is already fully charged, should I

1. Turn the deck off and unplug
2. Put to sleep and unplug
3. Turn off and leave plugged in
4. Put to sleep and leave plugged in

Obviously (4) is the most convenient, but that causes periodic recharging to happen, which can be observed by the charging light coming on occasionally. Does this activity measurably degrade the battery over time?

Answer 1

The Deck uses a fairly sizable lithium battery, like most modern devices. Unfortunately the games it runs are often built for a full PC rig with no battery drain considerations.

Wired's already written a good article on this: https://www.wired.com/story/how-to-get-better-steam-deck-battery-life/ BUT their article doesn't really address the question you have.

However, given the type of battery it is and the kind of usage, here are some tips:

1. protect it from temperature extremes, which will destroy battery life. That includes playing it close to your lap on a hot day -- I'd recommend putting a book on your lap to ensure its vents aren't blocked by fabric or skin.
2. As described at Battery University https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries, I think your best option is #1, but more importantly, avoid full discharges and full charges unless absolutely necessary. As a rough yardstick, I used the Accubattery app to figure out the best cycle for my cellphone (Galaxy S10e) and it has me charging at 40% and unplugging at 80%. I think that's a good rough guideline for the SD as well.

Answer 2

I came across this post on /r/SteamDeck which is quite relevant to your question.

TL;DR, the deck uses a passthrough circuitry when it's 90% charged so the battery stops getting power while still keeping the deck powered on. This means you can safely put the deck to sleep while leaving it plugged in(4) and you won't have to worry about it degrading the battery.

For reference here's the original /r/SteamDeck thread:

I've done both my own testing as well as a lot of research based on trusted reviewers, so here's a summary of a few important notes about the way the Deck charges:

Passthrough is used when you plug the Deck in at more than ~90% charge. This means the battery is not being used, all power is pulled directly from the USB port. This also means that leaving your Deck plugged in 24/7 will not harm the battery at all.

The Deck can not charge with more than 45W, in practice it tends to not exceed 40W.

The Deck charges at 15 Volts, which is important because it means that 18W PD will not work at all as it maxes out at 9V. Passthrough at 18W might work but I haven't tested that yet.

The Deck's charging controller always tries to pull 38W even with a 30W charger! This will usually cause the charger to shut down and restart, meaning that charging will constantly start and stop (German Source). TLDR: Do not use PD chargers below 38W if you want to make sure the Deck charges correctly! Do note that this can and likely will be fixed with a firmware update in the future. (EDIT: Looks like this update has fixed the issue.)

The Nintendo Switch charger has a 39W PD profile at 15V 2.6A, so it can charge the Deck just fine.

EDIT: The 15V minimum might only count for charging while playing. If the Deck is idle or sleeping or shut down, 9V and 5V charging should work fine albeit slowly.