power

The PoE+ HAT powers a Raspberry Pi 3 B+ or 4 model B over a single Ethernet cable, allowing you to skip the USB-C power adapter, assuming you have a PoE capable switch or injector.

Unfortunately, I would recommend the original PoE HAT over the newer PoE+ HAT for most users—though Raspberry Pi have redesigned the HAT slightly and it's more on par with the original, though hard to distinguish which model you're getting. (Updated mid-2023)

For more background on PoE in general, and a bit more detail about the board itself and my tests, please watch my video on the PoE+ HAT—otherwise scroll past it and read on for all the testing results:

I recently wrote about using a Raspberry Pi to remotely monitor an Internet connection, and in my case, to monitor Starlink (SpaceX's satellite Internet service).

One other important thing I wanted to monitor was how much power Starlink used over time, and I was considering just manually taking a reading off my Kill-A-Watt every morning, but that's boring. And not very accurate since it's one point in time per day.

tl;dr: The Innergie PowerJoy USB-C charger is a solid power adapter for charging via USB-C and USB-A simultaneously. If you have a high-power-draw device like a MacBook Pro, then the adapter may have a little less utility, but if you use a smaller USB-C device and need to charge both it and a USB-A device, then this is one of the most compact and well-built adapters I've used.

A month ago, I received an email from Innergie asking me if I'd like to review their new USB-C charger they were releasing. I had just returned from a business trip and was slightly regretting only having my MacBook Pro's included USB-C charger, which has one USB-C port. Charging my phone meant plugging my laptop into the AC adapter, then plugging a Lightning cable into my MacBook Pro.

I didn't want to have to bring along a separate USB-A power adapter, but it would've been more convenient, since I could charge the phone separate from the laptop.

Jeff's Rating: 3/5

tl;dr: Slightly pricey, could use a better interface for charge status, and holds 20% less than the advertised capacity, but the still-plentiful amount of stored energy and the ability to charge via USB-C or USB-A makes this a versatile and potent power pack for the price.

Ever since the mid 90s, when I was able to lug around 'power bricks' with my then-amazing PowerBook 190 and 180c (hand-me-downs from relatives), I've been hoping for a reasonably-priced power brick that would double my laptop's battery life, affording me the ability to work all day even when I'm doing a ton of crazy things, like building a ton of VMs and Docker images.

tl;dr: It's a power meter, not a protection circuit. It works well and is worth the money if you need to monitor power consumption, but it's made of plastic and doesn't feel like it can take a beating, so handle with care.

For some time, I've used a PowerJive USB Power Meter to measure the charging rate of various USB power adapters, and even things like how much power a Rasbperry Pi uses under load.

Update 2015-12-01: I bought a PowerJive USB power meter and re-tested everything, and came up with ~80 mA instead of the ~30 mA reported by the Charger Doctor that I was using prior. This seems to be more in line with the results others were measuring with much more expensive/accurate meters in the Raspberry Pi forums: Raspberry Pi Zero power consumption. I've updated the numbers in the post below to reflect this change. Seems the Pi Zero is only incrementally better than the A+—still excellent news, but not nearly as amazing as I originally thought :(

Update 2021-10-28: With the new Pi Zero 2 W, you can also disable some of the CPU cores to reduce power consumption for a heavily-utilized Pi if it doesn't need all the CPU cores running.

tl;dr: The Raspberry Pi Zero uses about the same amount of power as the A+, and at least 50% less power than any other Pi (B+, 2 B, 3 B).

On November 26, the Raspberry Pi foundation announced the Raspberry Pi Zero, a $5 USD computer that shares the same architecture as the original Raspberry Pi and A+/B+ models, with a slightly faster processor clock (1 Ghz), 512 MB of RAM, and sans many of the essential ports and connectors required for using the Pi as an out-of-the-box computer.

The Raspberry Pi Zero - quite a small Linux computer!

I run dozens of websites, and help build and maintain many others. Almost every one of these sites is served on a server in one of the giant regional data centers in New York, Atlanta, Seattle, LA, Dallas, Chicago, and other major cities in the US and around the world.

These data centers all share some very important traits that are key to hosting high-performing, highly-available websites:

• Power redundancy (multiple power feeds, multiple backup power sources)
• 1 Gbps+ upload/download bandwidth (usually with many redundant connections)
• 24x7 physical security, environmental controls, hardware monitoring etc.

When I choose to host the Raspberry Pi Dramble website in my basement, I get almost none of these things. Instead:

All Raspberry Pi models have a few built-in LEDs; the earlier models had PWR, ACT, and networking status LEDs all lined up on the board itself; for the B+ and model 2 B, the networking LEDs moved onto the network jack itself, leaving just two LEDs; PWR (a red LED) and ACT (a green LED).

Normally, whenever the Pi is powered on—except if the power supply dips below something like 4.5VDC—the red PWR LED remains lit no matter what. If you wanted to 'disable' the LED, you'd have to put a piece of tape or something else over the LED, or get out a soldering iron and modify the hardware a bit.

Raspberry Pi model 2 B, B+ and A+ (and beyond)

Luckily, with the Pi 2 model B, B+, A+, and Zero, you can control the LEDs in software, in a few different ways. The simplest way to change the way these LEDs work is to modify the trigger for each LED by setting it in /sys/class/leds/led[LED_ID]/trigger, where you replace [LED_ID] with 0 for the green ACT LED, and 1 for the red PWR LED.

For example: