Here’s another topic you hear battery nerds talk about a lot (and electrical engineers in general): Series and parallel connections. In the context of battery building, you don’t just buy one cell of the desired voltage and capacity and attach powerpoles to it. (Wouldn’t that be nice?) Cells and capacities need to be combined and calculated to total 12-ish volts and have enough runtime to power your ham radios and 12V devices. You can use a variety of battery chemistries to try to arrive at your desired voltage and capacity, but in the end it will almost always involve putting the smaller cells into series connections, and optionally into parallel connections. To describe this combination of series and parallel connections, we use abbreviations like “4S3P”.

The tl;dr

Lithium Iron Phosphate (LiFePO4) batteries are the cheapest, safest lithium chemistry with lighter battery packs, have a longer life with thousands of recharges, match traditional 12-volt specifications better than other chemistries, and have the most output: a 90% usable capacity. Hams love them!

I Need Power

Ham radio is a hobby that starts simply enough, normally through the purchase of a VHF/UHF handheld transceiver with its own battery pack and charger. Once an amateur radio operator decides that they want to go to more advanced HF and get their General class license (or move to mobile VHF/UHF rigs), that’s where the gear starts getting a little more complicated. One of the things a new General class ham will find about new HF radios is there’s very little in the way of explaining how to power the more advanced rig. All you get is a funky Molex connector and a pair of bare wires with fuses on them. When I got my first HF rig, a Yaesu FT-857D, I was perplexed that I couldn’t just plug it in to the wall AC outlet. Many manufacturers do this because they do not know how you will install your new radio. Mobile ones like the 857D I had are intended to be wired to the 12V electrical system of a vehicle. Larger desktop HF radios also use 12V, but the manufacturer does not assume how you’re supplying that 12V or what type of power connector you’ll be using, so they just give you a long pair of black and red wires. Naturally, a new ham will want to either buy a 12V battery, or a 12V power supply. And not knowing any better, what are the 12V batteries we find everywhere? Car batteries. Sealed lead-acid (SLA) heavy batteries that power everything from motorcycles to boats.

What tools and supplies does it take to build your own Lithium Iron Phosphate (LiFePO4) battery for ham radio? This is the start of a small series I plan to write for the DIY battery and offgrid community. Here I will try to list some tools that I find essential, and later, nice to have, for a person who wants to work on small pack and large battery making. Here’s the list (links below may contain affiliate links that pay me a small commission at no additional cost to you):

I’ve been sharing each of my LiFePO4 DIY battery builds on Twitter, and inevitably people want to know what parts they need. They’re too many to list in a tweet, so I thought I’d keep a running page here to refer people to. These things have been acquired over many months, and are not all inclusive. The reason I keep making them is to try out new things. Typical 6.5Ah to 7Ah 32700 build:

I know I am getting tired watching myself talk about batteries. But it’s just fascinating to me to refine the build and power management process of readily available LiFePO4 cells. There are so many kinds! And they keep improving. I guess I have China to thank for that, so much of Maker / electrical components can be found from inexpensive Chinese distributors, making it easier and easier to have your own DIY projects. Anyway, here’s the latest in my series of portable battery builds. I found some really cheap 7Ah cells on Aliexpress, and had to try them out. I don’t want to become “the Battery Guy” since there are tons of people already doing that– and much much better than me. However, I want to share in the collective knowledge. Here’s the latest test of the promising specifications of LiitoKala 32700 batteries.   https://youtu.be/IJ7DjxWB0Pg

As many on Twitter have seen (and are probably already tired of seeing), I got myself a budget 3D Printer. Several of my coworkers would come to work with their “latest print” and it would range from utilitarian to really cool movie prop reproductions. In my mind, this hobby was prohibitively expensive. Last I heard about 3D printers, the entry-level ones ranged in the $1500+ range. And all I was seeing from those early adopters (circa 2013) was plastic bow ties and other such useless figurines; not enough of a motivator to dish out that kind of cash. I carried this mindset even to just this month, where one coworker said I could obtain a 3D printer for less than $200. He recommended the Anet A8, perhaps the cheapest consumer printer on the market. However, I went with a Creality Ender 3 since my other coworker had extensive experience with this model, and I thought it might be easier to diagnose problems if someone else I knew had the same machine. Since then I’ve started to apply this “toy” toward actual practical uses. And in the latest step, last night I designed a 3-hole guy ring for a portable mast completely from imagination, and printed it. It happens all the time with engineers and artists, but the thought really hit home with this print that something completely in my mind became a real physical object through this process. Here’s another video of something I made from a design I found on Thingiverse. https://youtu.be/NzcrkViZPd8 Build projects will only increase now that it is possible to daydream designs and fabricate my own actual plastic parts.