Hacker News Reader

Comment by cwoolfe | Hacker News Reader

Am I slowly damaging my 2020 M1 MacBook by charging it with a cheap 5V 1A USB-A to USB-C charger at night? What's the actual risk here?

View on HN

If anything, the opposite. Most fast charging devices (any that advertises a 0-50% charge rate) end up throttling charge as it gets closer to 100% because filling up all cells super quickly can actually damage the battery.

That's also why many laptops (such as Macbooks) come with an "intelligent" charging feature that will limit charging to 80%, only charging up that last 20% when it thinks you'll need it

On the other hand, ultra-low-power charging might effectively cause alternating between charging and discharging (e.g. when the Macbook wakes up to do things via "power nap" in the background, which on Apple Silicon devices can't be prevented and which might use more than 5W).

Yeah, slower charging (like 20W) seems good, but I've used phone chargers out of desperation before and seen the alternating charge/discharge. Can't be good for it.

The actual risk is that a cheap charger fails in an unsafe way, and exposes users to unsafe voltages. You need, internally, the right creepage and clearance distances, and you need to use the correct parts in certain places with the correct failure modes (e.g. must fail open or must fail closed). Some cheap chargers are not built to the same safety standards. You won’t notice anything unless they fail in an unsafe way. Unlikely, but possible.

> You won’t notice anything unless they fail in an unsafe way. Unlikely, but possible.

Which, in the worst case, will start a fire that will burn down your house. It's not worth the risk of using cheap chargers; buy from a reputable brand

That's not the only worst-case scenario: You could also die from an electric shock. This actually happens every once in a while with cheap chargers.

Yeah, the reputable chargers aren't even expensive now that we're on USB-C. Knockoffs were a lot more tempting during the MagSafe era.

And from a reliable retailer that doesn’t sell counterfeits or turn a blind eye like Amazon does. If you buy Apple, get it from the Apple Store or B&H.

> You won’t notice anything unless they fail in an unsafe way. Unlikely, but possible.

Cheap chargers skimp on safety. Entirely possible they fail unsafely.

I once bought a cheap no-name Android charger and it literally exploded after a year of use. Hot metal droplet landed on phone screen which was a cute reminder for a while (until later the screen cracked through where the droplet was).

That tingly feeling has been found by me on plenty of different device power supplies. That is high voltage getting passed to the low voltage side - a sign of bad design. The last two devices I remember were (1) a multi-USB charger which tingled but seemed to work okay and (2) cheap speakers for a PC where the voltage hum was causing serious problems with other devices connected to the PC (and hard to diagnose cause).

I'm amazed how many unsafe electrical devices we own: the safety standards are not working in my experience. And I think New Zealand has stronger standards than the US.

> I'm amazed how many unsafe electrical devices we own: the safety standards are not working in my experience.

Safety standards aren't the issue, their enforcement is. In most countries, agencies overseeing the safety of electrical consumer equipment, are perpetually understaffed and/or underfunded.

So they don't have the resources to take a good sampling of what's on the market, and (thoroughly) test those samples.

As a result, it's mostly especially bad gear (discovered by accident, # of incident reports etc) that gets attention. Or becomes subject of a recall.

What's left is relying on paperwork, and manufacturers or importer's integrity. Which (as you note) varies a lot depending on where you look. Especially in this day & age of people buying cheap junk directly from abroad through Ebay, AliExpress & co. Not to mention fakes, or no-name manufacturers that pop up & disappear overnight.

Do a search for “cheap charger bricked phone”

Reply on news.ycombinator.com