KNW-127 Battery Selection & Safety

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KNW-127
Battery Selection and Battery Safety

By Earl Pack – AE5PA
(Written 12/16/2013; Updated 1 Jan 2020)
updated 04 Aug 2025 by Paul Smith (K5PRS)


BATTERY SELECTION AND BATTERY SAFETY
Amateur radio operators work with many types of batteries. Each battery type has specific charging and safe use requirements. Charging requirements will be covered in a separate lesson. Because of their high capacity and relatively low price, the lead acid battery is most commonly used in amateur radio emergency communication service for long term comms. They are also a good choice to have in your home as a source of backup power for your radio and some DC lighting. That is changing, however, as new battery chemistries are developed. Let’s look at the different types, explore why you would use one type vs. another and review safety procedures that should be followed when you use them.

The most common types of Batteries are:

  • Alkaline
  • Nickel based: Nickel-cadmium (NiCad), Nickel-metal-hydride
  • Lead acid
  • Lithium and Lithium Iron Phosphate (LIPo4)

Which Battery to Use

  • AA size, non-rechargeable Alkaline and rechargeable Nickel based batteries are the most commonly used batteries in HT’s. They are also available in AAA, C, D and 9 volt sizes and are a good source of emergency power that can be purchased almost anywhere and have good shelf life.
  • While more expensive, the nickel based batteries like NiCad can deliver several hundred charge/discharge cycles making them significantly cheaper per Watt-hour in the long run than alkaline and they are better for field use if power to recharge them like solar panels are available.
  • Plain lead acid batteries deliver large amounts of instant energy and are used most commonly in automobiles. They are also common, but are not ideal for, field deployment mainly because of their weight. Deep discharging plain lead acid batteries will quickly damage them so it’s important to have a generator of some sort available for extended usage.
  • Lithium batteries are smaller, lighter and provide the largest power capacity for their size. They are used in HT’s, GPS units, cell phones, etc. The lithium battery has the longest idle life span of any battery construction to date.
  • Deep cycle lead acid batteries, often called marine batteries because they’re designed to drive electric trolling motors, deliver a longer-term energy supply before voltage drop begins and are designed for hundreds of discharge cycles if properly maintained.
  • Wet cell (flooded), Gel cell and Absorbed Glass Mat (AGM) are variations of the lead acid battery. The Gel cell and AGM cost significantly more than the lead-acid cell but are not as prone to degradation and are much lighter for equivalent capacity. They are the safest to use because less explosive hydrogen gas is produced and they can’t spill so exposure to sulfuric acid is unlikely. These batteries require special charging equipment. The AGM battery is the most versatile and should be given strong consideration for stand by power use. They hold a charge better; have greater life span, and can be charged many times. Deep cycle AGM batteries that are not discharged more than 60% will last hundreds of charge cycles.
  • Since LiFePO4 Batteries are new and have excellent characteristics, they may be worth the higher price point to replace heavy lead-acid batteries. Here are the major reasons you might want to consider them:
    • Longer Lifespan: LiFePO4 batteries typically last 2,000 to 5,000 charge cycles,
    • Higher Efficiency: With a round-trip efficiency of 90-95%, you get more usable power from a LiFePO4 battery than from a comparable lead-acid battery.
    • Safety: LiFePO4 chemistry is inherently more stable and are less prone to thermal runaway than other Lithium compositions.
    • Lightweight: LiFePO4 batteries are significantly lighter than lead-acid batteries for the same energy capacity
    • High Power Density: They can deliver high power output without significant voltage drop
    • Faster Charging: LiFePO4 batteries typically charge faster than lead-acid batteries, which is great for field work.
    • Wide Operating Temperature Range: temperature range (typically from -20°C to 60°C), which makes them more versatile in various environments. Note, however, that they do not charge well below freezing.

There are disadvantages as well such as the need for a Battery Management System (BMS) which adds to the higher battery cost but I don’t think they outweigh the advantages noted above.

As you know, battery chemistries are evolving so watch for:

  • LMFP (Lithium Manganese Iron Phosphate) is a likely near-term successor to LiFePO₄: similar cost and safety but with improved energy density.
  • Sodium-ion is not better in energy terms but is cheaper and very promising for stationary storage and low-cost EVs.
  • Solid-state lithium and lithium-sulfur could leapfrog LFPO eventually — but need breakthroughs in durability and cost.
  • Silicon-anode and high-nickel chemistries push energy density boundaries but have trade-offs in thermal stability and cycle life.

Buy the battery with the greatest reserve capacity or amp hour (AH) rating possible given financial and battery weight/size considerations. Nickel based battery and lithium battery packs along with deep cycle batteries usually list an (AH) power rating. A battery rated for 50 AH should deliver 5 amps for 10 hours or 10 amps for 5 hours. If your radio is rated at 50 watts, current draw would be 50 watts divided by 12 volts equals 4.167 amps. 50 amp hours divided by 4.167 amps should provide about 12 hours of operation at 100% duty cycle. However, keep in mind that lead-acid batteries are not 100% efficient, and their performance degrades with age, temperature, and discharge depth. Typically, you wouldn’t want to discharge a lead-acid battery fully, so the actual usage could be shorter depending on these factors.

Hints:

  • Extending Battery Life: The longer a battery sits without being re-charged, the greater the damage. In extreme temperatures (hot or cold) a 24 hour wait might be too long so take care in how your battery is stored. Hint: Auto batteries experience both extremes so make sure you run your vehicles to keep those batteries topped off and healthy.
  • Follow the charge/recharge recommendation for nickel based and lithium batteries carefully.
  • Recharge batteries immediately after discharge and keep them topped off with managed trickle chargers for optimal life.
  • Don’t use plain lead acid batteries for deep discharge applications. Totally discharging or repeated deep discharges will shorten their lives.
  • If you are running your radio off your automobile battery for a long period, set a timer and start your vehicle to charge the battery periodically so that you do not become stranded when your assignment is finished. Use a separate, deep cycle battery for long term, stationary assignment use so that you do not have to worry about the vehicle battery having sufficient charge to start your vehicle. If you don’t have a solar, etc. charger, jump the battery to the vehicle periodically and keep both batteries topped off for long deployments.
  • Undercharging allows sulfation to occur and will damage the battery.
  • Avoid operating with batteries exposed to temperatures greater than 100F or less than 32F.
  • Use the right charger for your battery. Gel cell and LiPO4 batteries require a charger designed and adjusted for these types of battery.
  • Be aware of any constant power drains which discharge the battery. Many of the HT’s and GPS devices have a small but constant power drain even when turned off so store batteries separately from devices.
  • REPEAT: Fully discharged alkaline batteries leak battery acid. Never store gear with these batteries installed.

Safety Tips

  • Don’t store batteries in a bag or pocket with other metal objects where they can possibly short and cause a fire. This is especially true of 9 volt batteries that have close, exposed contacts.
  • Never put batteries in a fire as most will explode.
  • Do not over charge lithium batteries, they can catch fire. Use the proper controlled charger.
  • Install fuses as close to the battery as possible to protect wiring that may get frayed and short.

Specific Safety Tips for Lead Acid Batteries

  • Lead-acid batteries can deliver up to 800amps of instant and continuous current which can cause severe burns or death. Remove all jewelry when working around lead acid batteries. Shorting one post to the other can blow the post completely off the battery or short the battery internally. A blown terminal post can be equivalent to a 45 caliber bullet.
  • Wear safety goggles. If acid enters the eyes, flush eyes with water for 30 minutes and see a doctor. Even a short delay in flushing can cause corneal damage, vision loss, or perforation.
  • Wash acid off skin promptly.
  • Battery fumes are explosive so keep sparks and flames away from the battery.
  • When working on vehicles, connect the positive lead first making sure that connectors don’t short and then attach the ground lead directly to the vehicle chassis. Disconnect the ground cable first to prevent sparking at the battery.
  • Don’t make live connections to a battery; ensure the load is turned off.
  • Keep children away.
  • Properly ventilate the area when charging to vent battery fumes.
  • Store batteries in a cool, dry place to prevent moisture accumulation that can result in trickle discharge and the extreme temperature issue mentioned earlier.
  • Lead acid batteries are heavy so protect your back by using proper lifting techniques.
  • Do not use metallic tools like screwdrivers and pliers long enough to reach between battery terminals.
  • Protect the top of the battery so equipment can’t fall onto the terminals.

A properly selected, used, maintained, and charged battery can be a great source of home emergency or field power for your comms. Every ARES member should have at least one plus the cables, jumpers, chargers, etc. needed to use and maintain it in their radio go-kit.

That is the end of tonight’s training. Are there any comments, questions or suggested additions?

Thanks, this is (callsign) clear to net control.