How can I determine how many amps I need to power/charge my Chromebook

Question

The power supply that came with my Chromebook died recently and I've had a hella time just to find a charger that's just right for it. When studying different recommendations from different sources it wipes me out. I serviced consumer electronics for many moons but, this USB C standard has got me bumfuzzeled. What can I pick that's "Safe" but, maybe a little extra under the Hood for a little zoom? Samsung supplied a small Wall unit that had a USB "C" jack on it with a good size cable, (but Way to stiff),that went 1st. I purchased a "cheapy" to try to get by but it's not any better than a smartphone variety kind. Could you please steer me in the right direction?

Answer 1

this USB C standard has got me bumfuzzeled. What can I pick that's "Safe" but, maybe a little extra under the Hood for a little zoom?

The Chromebooks I looked at require about 30 watts minimum, so use that as one alternative.

Look on the bottom of the Chromebook or its docs and this will tell you what power to use.

Adding much more power will NOT supply more "zoom" to the computer. Computers (and all like DC devices) draw current. Current (power) is NOT pushed. A larger power adapter may provide faster charging and that will be useful. 50 to 65 watts are common.

So just get the best charger / adapter that fits your machine.

Answer 2

With something like a chromebook with USB C - chances are its USB power delivery, and something with 65W would be a safe bet (45W might be enough), with a matching cable if seperated (they're rated as well - I standardised on 100w capable cables). The charger and the system will negotiate the right voltage and safely and efficiently charge it. Essentially any usb power delivery capable charger with the above specs ought to work.

This is true of nearly all 'modern' laptops that run USB C - just a matter of how 'big' the charger would need to be.

Answer 3

When USB-C first came out it was quite common to see USB-C power bricks, and the devices that would charge up from them, violate the specifications in ways that could, and did, break things and start fires. Those days are long gone so if you've bought gear that is has been built recent enough (in "internet years") to not be considered ancient, and wasn't built by some fly-by-night outfit, then it will be safe.

The USB Power Delivery specification requires anything with USB-C to be safe when connected to each other, even if connected in nonsensical and nonfunctional configurations. For example plugging two power bricks together by a USB-C cable won't short anything out because neither power brick will put voltage on the power pins until there's something connected that asks nicely for power. There are pins that provide low voltage at low power so a phone that has run the battery completely dead will have enough power from the brick to "wake up" and do what's necessary to ask nicely for power to charge up. It would take damaged hardware to make this unsafe.

But then you had "safe" in quotes so I suspect this is more than about not causing damage but being of sufficient power capacity to meet the power requirements to charge in a reasonable amount of time. If you still have the old power brick then you should be able to find the rated power written somewhere on it, perhaps in faded ink and small print so it could take looking very closely. Getting a power brick of the same or larger power rating will be "safe". A more powerful brick won't hurt, and a power brick that is slightly less powerful won't start any fires and so should be "safe" as well.

Apple is somewhat (in)famous for including power bricks with their products that are less powerful than the device can take on in power. I doubt Apple is alone in this tactic for up-selling. I use Apple as an example because that is what I am most familiar with, not to endorse them. Using Apple products as a guide I suspect a Chromebook, or any notebook, on the "small" end of the spectrum will work fine with a 20 or 30 watt USB-C power brick but will be able to charge more quickly with a 40 to 60 watt brick. Until about a year ago the USB-C spec was limited to 100 watts so that was the limit for any notebook computer, Apple or not, which means many devices on the market are still built to this 100 watt limit. This means a lot of "medium" notebooks in the 40 to 60 watt range, and "large" notebooks in the 75 to 90 watt range. As of a year or so ago USB-C will allow up to 240 watts so we find "extra large" notebooks will be happiest with a power brick in the 150 watt range. If history is a guide then power requirements will creep up to fit this new 240 watt limit for "small", "medium", and "large", but perhaps I digress.

The price differential between USB-C power bricks of different power levels is usually quite small, so it may be "safest" to buy the largest power brick that you feel offers the best value. For example a 30 watt power brick might be $60, a 45 watt brick $65, a 60 watt brick $70, and an 90 watt brick $75. For 125% in dollars you get 300% in power. A 90 watt brick is going to charge most anything with USB-C, from a Bluetooth headphone set to the most powerful notebook computer available today. It's quite "future proof", but also an extra $20 or so.

So, perhaps the best option is find the power rating of the old brick and buy a new one with the same power rating. Don't sweat a few watts plus or minus but if there is any doubt then pick something slightly more powerful. If you don't know for certain then take an educated guess by buying something that matches the power on similar products, and again if in doubt go with a few extra watts to be "safe". If all else fails then just go big, the higher power rating won't hurt anything. The higher power rating might not help either but it won't break any hardware, and that's cheap "insurance" for $20 or so.

If the question is which brand of power supply is "safe" then that can get in the realm of opinion, and this is not the forum for opinion. If looking for the closest thing to objective data on this then some research on customer satisfaction and reported failures can shed light on that. What is likely "safe" are brands that have been in the business for a while. Again, I used Apple as an example because that's where I have most experience, not as any endorsement. I can think up many brands I'd trust, all likely to give as much value for the dollar as Apple. Stick with established brands and you are not likely to get burned, and that burn may be more than figurative.