Hams use mobile radios to communicate with each other. All of these mobile devices use batteries to provide the power to operate. This page lists a number of resources that talk about batteries, and their use in Amateur Radio.
18650 Battery Packs
18650 battery cells are becoming very common for radio control cars, boats, and airplanes. Other common uses are for flashlights. Hams have started to use these for amateur radio ‘go-boxes’ to power their radios on the run. These lithium-ion batteries are lighter, charge faster, and discharge faster than any previous chemistry.
These cells provide some great DIY opportunities. You can series connect 3 or 4 of these cells to power a radio. You can also parallel some cells to increase their power capacity.
There are a number of factors that you need to pay attention to when working with these cells. The first is the battery style. They can be constructed as flat-top or button top devices. The button top cells have a positive post stick out and work best when mounting them end to end in a removable case. The flat-top batteries allow you to weld some tabs to the top of the batteries to make permanent connections.
Capacity is a big variable when buying these cells. They are typically measured in milliamp-hours (mAh). Make sure that you know if the ads are providing the mAh capacity for each cell or a cell-pack. Sometimes a manufacturer lists these in a confusing manner. The continuous discharge rating and lists the maximum current that can be drawn continuously without damaging the pack. The pulse discharge rating is the maximum current that you can draw for a short period of time without damaging the battery.
One more thing to consider is that these cells typically run at 3.7 volts DC. However, the fresh cells, right off of a charge run at 4 volts DC. Running 3 cells will typically give you 11.1 volts, with a peak of 12 volts. This is a bit too low to operate most amateur radio gear. For example, Icom gear tends to operate poorly in these conditions. However, 4 cells typically provide 14.8 volts DC, but they peak at 16 volts DC. This is a bit too high for most amateur radio gear. For example, the KX3 has a do-not-exceed voltage of 15 volts DC, or their warranty is void, and the finals are prone to fail. One typical way that hams are solving this high voltage problem is to insert a high current diode or full-wave bridge, or 2, in line with the output line to drop the voltage .7 volts DC for each diode. Once the battery voltage lowers, the diodes can be switched out of the circuit.
Protected cells contain small integrated circuits in the battery pack. These circuits provide overcharge, over-discharge, short circuit, temperature limits, and short circuit/overcurrent protection. These cells are typically physically larger than other cells due to these additional circuits.
These links should get you started down the 18650 trail.
KI5AIF Lithium Battery Presentation
Dr. Thomas Hays KI5AIF gave a great presentation to the SCARS members on November 9th, 2019. There will be a video for this presentation on the SCARS YouTube channel soon. A copy of his PowerPoint slide deck is available by clicking this link. A PDF copy of this presentation is available by clicking this link.
Interstate Battery Li-Ion Presentation
Our good friends at Interstate Battery have created a great presentation on the chemistry of Lithium Iron batteries and they have allowed us to share it by clicking this link.
Lithium Iron Phosphate vs. Sealed Lead Acid Batteries
KF7IJZ provides a great video comparison of an AGM sealed lead acid battery vs. a couple of Lithium Iron Phosphate batteries. These two batteries are A123, and Bioenno, respectively. Use this to compare these two technologies. After watching this video, it’s hard to justify a sealed lead acid battery system.
Flint Hills Radio
Once you start working with battery power, you quickly learn that you need some switching gear to select the proper power path. Flint Hills Radio has a couple of power gate and solar control devices that work well for amateur radio systems.
West Mountain Radio
If you’re looking for the mother lode of battery power connection devices, West Mountain Radio has them all. Power switchers, solar power controllers, and low-voltage cutouts are just the start of their line. And, they even exhibit at HamHoliday in Oklahoma City, and Ham-Com, in Dallas!