There is the often repeated recommendation from Google, that you should only use the included cable and charger for best battery health. This makes sense from Google, to lock people in and maximize their profits. It does not make for GrapheneOS, especially using the meaningless 'advice'. There is a lot vagueness, that I see being enforced, without the technical explanation to back it up
The Google Advice
The official advice from Google is "Use the power adapter that came with your phone" and "Other power adapters and chargers can charge slowly or not at all. They can also damage your phone or battery."
This seems very obvious to someone buying a new unopened Pixel phone but it's unhelpful to everyone else.
There are several scenarios where this presents an issue:
- You buy or receive a used phone, without the charger and/or cable
- You lose or in some way damage your charger and/or cable
- You buy a new Pixel 6, 6 Pro or 6a, which don't come with charger. This will be a likely scenario for future releases too.
When you find yourself in at least on of these scenarios, according to advice from Google "Other power adapters and chargers can charge slowly or not at all. They can also damage your phone or battery.", you shouldn't charge your phone anymore. Only use Google charge with Google cable.
The GrapheneOS Advice
This is then further being propagated by GrapheneOS developers. When people bring up relevant criticism of this argument, not only is not addressed but they are demonized with unrelated comments to the criticism. Another issue is also blaming for using 'cheap' cables and chargers. At no point is this elaborated. Maybe some kind of 10 000$ audiophile USB cables are cheap too, if it does not come from Google. Often this advice is being passed around as the official statement. It often mentions reliance on the provided charger and how the battery monitors itself and manages the charging speed based on temperature. If this is indeed the intended behavior, then its not working on GrapheneOS.
Using the supplied charger and cable from Google, which came with Pixel 4a, it routinely heats up to 40C. The battery never lowers the charging current based on temperature, only after it starts reaching full charge. No matter how many times we see GrapheneOS state that its not 2005 anymore, law of physics are always ignored. Heat is a big issues for batteries, both for charging and discharging. GrapheneOS does not manage heat well. Charging using the Google charger and cable makes the phone heat up. So does regular real world usage, like GSM and VoIP calls, streaming, etc. This becomes an even bigger issue during summer, when phones regularly go over 34C even when idle and not used. Heat management, even outside of charging, is something that GrapheneOS struggles with.
Standards. They exist!
"It's often not spoken of, but Universal Serial Bus is actually an extremely complex protocol, and subsequent generations of it has only increased the amount of complexity it has." USB Power Delivery is a thing. Its a standard implemented on every currently supported Pixel phone. These standards are not only for phones but charges and cables too. They either do support it or don't. There is no in-between, nor is there any Google magic. Follow USB standards and follow USB Power Delivery standards.
But what now?
GrapheneOS developers should know better! If you want to give user an advice, make it useful and meaningful. Repeating the useless Google advice is not helpful. If its USB Power Delivery standard that's important, say so. If you know of a specific charger and cable that are good, say so. In any other case, the advice should be that there is no advice. Current approach is not suitable. It needs to specifically outline what is needed for charger and cable to be suitable. If its USB PD, say so. If something else, say so. If you don't know and you just rely Google magic, say you don't know.
But wait, there is more...
"You need a USB cable for attaching the device to a laptop or desktop. Whenever possible, use the high quality standards compliant USB-C cable packaged with the device. If your computer doesn't have any USB-C ports, you'll need a high quality USB-C to USB-A cable" This repeats the same issue, that the charging advice makes. This needs to be more specific to be useful. If there is a recommended chip used in USB-C <-> USB-A cables, please say so! There is also an issue with the following statement "You should avoid using a USB hub such as the front panel on a desktop computer case. Connect directly to a rear port on a desktop or the ports on a laptop." This is straight up misleading! If you want people to avoid USB hubs, including the onboard one managed by the chipset, says so clearly! If the recommendation (I assume), is that the user should use USB ports wired directly to CPU, then that should be state, following by consulting the manual for user's motherboard/laptop, which ports are wire where. Blanket statements like "avoid using a USB hub such as the front panel on a desktop computer case." are harmful, as there are cases when the individual ports on the front panel are wired directly to CPU (due to the often poor quality of case USB cables, some motherboard vendors now route those directly to CPU and rear ports are routed through the chipset).
Request to the GrapheneOS developers
Please make it clear what's required from the user and how they can make sure, whether its following the proper standards, like USB PD, and when you require them to consult other hardware documentation, like in the case of USB for installation. The reality is that by giving advice like "Use the power adapter [and cable] that came with your phone", will mean that in the case where the user can't follow the "Magic Google charger/cable" advice, they will probably follow some marketing buzz, because no other clarification is made. And please, stop with the 'cheap' factor. I assume that you know too, that there is plenty of expensive garbage. Please, provide better advice and recommendations, such that user can make an informed decision, when buying a Pixel 6 or newer phones, that do not come with charger. They might soon not even come with a cable either.