Ode to the 12V Power Bank

I got my new favorite thing yesterday: a 12V power bank made by TalentCell.

Most power banks are 5-volt USB and designed to recharge phones and other smaller devices. Many of the newer ones are packed with lithium ion batteries that usually come in a flat, rectangular shape. This allows the banks to be lighter and easier to carry.

This power bank is packed with 18650 batteries, the AA sized lithium ion cells that are the core of most larger rechargeable projects. Tesla uses banks of these batteries. It’s amazing to me that a Tesla is ultimately run by thousands of these batteries, and if you want to, you can build your own power wall using the same bits. These batteries are also found in most recent laptop batteries, and can be harvested and re-used for projects (often only a single cell in a laptop battery goes bad, making the charging circuit stop working.

These cells can also be wired for different voltages. In parallel, they can be made to share the same voltage across the whole bank, offering longer charge times by boosting the amperage. In series, they combine their voltage, so a handful of 4v batteries can become a 12v bank that can run larger devices.

As I get more interested in limiting ewaste, re-using gadgets for different purposes, and just playing with old tech in general, it becomes obvious that one of the main limiting factors of devices from the last twenty years is that the batteries just don’t hold up, and it isn’t in manufacturers interest to keep producing batteries that work. There is no universal laptop battery (although there really should be.) In the wild west of cell phone days, having different chargers was part of the profit margin that companies used to make their devices cheaper. The practice is still alive and well with Apple’s stubborn use of the lightning cable, forcing a suit from the EU to get them to standardize to USB-C. What’s even more ridiculous is that many of the weird barrel connectors that were used by manufacturers could easily have been standardized, and it’s easy today to buy adapters. They were selling convenience based on forced inconvenience, creating more plastic waste.

Old devices are cool and I enjoy using them, especially when they do a basic thing like text wrangling faster and with fewer distractions than even a basic Linux machine.

While 12V AC adapters are no more standardized than batteries, I’ve discovered that you can easily buy barrel adapters, and 12V power banks are cheaper than buying the individual cells and building them yourself. Portable power sources like this make it possible to re-use old tech like my Vadem Clio-1050, mostly how it was intended to be used, without needing to rebuild its original battery.

In the case of the HP Jornada 820, probably the nicest netbook I’ve ever typed on, if its battery loses power for long enough, a relay in the charging circuit dies and there’s no way to rebuild the battery with new cells. I’m still experimenting on how to do that. With a 12V powerbank, however, a device like the 820 can sit in a coffee shop again.

A powerbank is going to make it hard to have the device sitting on your lap, but you probably weren’t going to do that anyway.

Many newer laptops require 19V, so they aren’t going to be great candidates for this kind of hack unless you want to pack around a Jackery or other “battery generator.” But it’s possible, and the circuits to build your own batteries are getting easier and easier to find.

You can get smart on this side of gadgets by paying more attention to the charging information required to be listed on the bottom of every laptop or other device you buy. You can see the input voltage for the AC adapter, and then the same info on the battery. This info should match what you’ll find on the AC adapter itself. Voltage (12V, 9V, 5V etc) must always match. Some devices can handle different input voltages but never assume it. A higher voltage can fry your device. The amperage (1A, 2A, 3A, etc) is the minimum threshold of electricity the device needs to operate. You can use an AC adapter with a higher amperage as long as the voltage matches. An adapter with a lower amperage my start the device but won’t charge its battery.

If you have a ton of old adapters like I do, it’s relatively easy to find one with the correct voltage/amperage, and another with the correct barrel adapter. It’s pretty easy to cut the cables and solder (or just twist wires and tape) the two together to make an adapter that will work. I’m actually working on making quick connectors for my various barrel plugs so they can be easily swapped among AC adapters. This is a hobby that’s lower on the priority list than working on the yard, writing, and other household chores but it’s happening with time.

The downside of using a 12V powerbank is that devices aren’t designed to monitor the remaining battery life of that sort of input. It helps if your powerbank has some kind of display so you can see if you’re about to run out of juice. Older devices don’t use autosave, so I get in the habit of hitting CTL-S, and it helps me stay focused on the task at hand. Still, my current 12V/6000mah power bank is providing hours of use on the Clio.

Pretty sweet.