Most new hams start with an HT (handie-talkie) radio. They’re very affordable, portable, and will get you on the air quickly. No one has to think about batteries and chargers—they’re almost always included. The only real decision is whether you want to buy a spare battery.
Going mobile doesn’t take a lot of thought either. You find a place for the radio and remote head, then follow your car manufacturer’s recommendation for power connections. Technically the battery isn’t free, but you already have it.
However, when it comes to field operations like POTA, SOTA, and all the other OTAs, you should consider several factors before investing in a portable battery system. Things like weight, size, durability, and capacity become important considerations.
Understanding LiFePO4 & Other Portable Battery Types
Power for portable operations can come from various sources, like generators, solar, wind, and batteries (the primary choice of portable operators). Lithium-ion (Li-Ion), sealed lead acid (SLA), gel cell, and absorbent glass mat (AGM) are among those available.
However, the most efficient battery choice is a member of the lithium-ion family, LiFePO4 (lithium iron phosphate).
LiFePO4 is superior to other lithium-ion batteries for a couple of reasons. Number one is safety. The LiFePO4 chemistry has better thermal stability than lithium-ion. It will remain cool at room temperature while charging, while Li-Ion heats up faster and may potentially suffer from thermal runaway. LiFePo4 battery systems also contain built-in battery protection modules to address concerns like overvoltage and balancing. You probably remember stories about hoverboards whose lithium-ion battery packs began overheating, which led to sparking, catching fire, or melting.
The voltage supplied by a LiFePO4 is a good match for today’s radios.
Each fully charged cell produces 3.6V. With four cells in series (4S), a typical LiFePO4 battery pack comes in at 14.4V. The nominal voltage is 3.3V per cell, making the working voltage about 13.2V—an excellent choice for a typical 100W transceiver.
Li-Ion/LiFePO4 batteries maintain a flat voltage curve compared to sealed lead acid or absorbent glass mat batteries, which start dropping voltage right from the beginning. SLA or AGM runtimes will be considerably shorter than a comparable Li-Ion or LiFePO4 battery.
Though people still buy lead-acid batteries because of their low prices, LiFePO4 is a better bargain in the long run. When you consider the lifespan of each type of battery, the LiFePO4 will last more than 12X longer, yet only costs 3-4 times the price. Lithium batteries will also hold a resting charge much longer—LiFePO4 is typically rated at 5% discharge per month.
Each one of these battery types has its pros and cons, and you can find in-depth discussions online about the nuances of each battery chemistry. However, what matters is which best suits your particular application and provides your gear with the appropriate voltage and operating time. If you’re looking for a simple and effective portable battery solution almost custom-designed to power radio gear, invest in a LiFePo4 battery and charger.
Which Battery Works Best for Ham Radio?
Everyone is looking for maximum operation time in the smallest package. SLA, gel cell, and AGM batteries will do the job but have drawbacks for portable operation, especially with weight and available power.
I suggest that those new to these battery packs look for something that is safe, hassle-free, and performs well. The battery management system built into the lithium batteries avoids the “oops” factor—it won’t let you draw more than their rated capacity.
For that reason, the lithium-ion battery—specifically a LiFePO4—is a no-brainer, especially the Bioenno Power line.
For example, Bioenno Power’s BLF-1220A LiFePO4 Battery is ideal for stationary applications requiring a higher capacity and greater power output.
The integrated PCM (Protection Circuit Module) provides complete internal cell balancing and management, protection from overcurrent, undervoltage (over-discharge), overvoltage, and short-circuiting, as well as integrated charging circuitry. As shown above, the BLF-1220A can also be purchased as a combo with a 14.6 VDC charger.
It’s easy to find various lithium-ion batteries online with a casual search. The problem is that you can quickly become overwhelmed by all the choices. I consulted with several hams who have experience with portable operation and got some excellent advice.
- QRP operation (10W or less, CW/SSB): A good starting point is a 6 Ah LiFePO4. It’s relatively small and will keep you going most of the day. If you intend to add digital, consider 10-12Ah instead.
- 100W operation: Sometimes you need an extra boost, especially in crowded bands or with marginal propagation. About a year ago, a friend suggested I purchase a 20 Ah LiFePO4 and use it during the Ohio State Parks on the Air event. It was used for at least five hours on sideband, with power to spare. I prefer a battery capacity that meets my needs so I don’t have to worry about recharging in the field.
When you buy, be sure you have the proper charger for LiFePO4 batteries. Some come in battery/charger combos like the above example. SLA chargers are NOT compatible and may damage a LiFePO4 battery. Whatever you do, don’t compromise on your battery and charging system.
Useful Info
The following will help you get a better understanding of your battery needs and help you narrow the options.
How Much Power Am I Really Using? Weighted Average Calculation
Your radio doesn’t demand a consistent amount of power; rather, it varies according to the transmit time, receive, and transmit modes used. According to the Yaesu FT-891 mobile transceiver manual, the receive takes about 2W while the transmit may take as much as 23W. Sideband will draw less power than a continuous mode like FT-8 or RTTY.
Weighted averages will give you a better picture of power consumption.
Weighted Average Formula:
(x) * (power 1) + (1-x) (power 2)
Example
20% of time transmit at 100W
80% of time receive at 2W
0.20*100 + 0.82*2= 21.6
11 hours of run time on 20 Ah LiFeP04 ([12v x 20 Ah]/21.6)
Don’t forget to account for accessories such as portable tuners.
Live Testing
Inline DC Power Analyzers and wattmeters allow you to measure and monitor the DC power consumption of your portable equipment. These DC power meters read voltage, current, watts, amp/hours, and watt/hours. They’re connected between the power supply and radio to help you monitor power consumption.
You can also utilize these as part of your portable OTA gear, which gives you real-time information about your battery’s state while operating.
E-Z Match
Bioenno mobile transceiver compatibility guides cover the most popular radios. They are available on the DX Engineering website at the links below.
In addition, Bioenno provides battery runtime charts for all their models
- Bioenno duty cycle guide 20/80 – normal
- Bioenno duty cycle guide 50/50 – contesting/Field Day
