Communications Preparedness
Powering your radios when the grid is not.
A radio with a dead battery is a paperweight with an antenna. This guide does the arithmetic on how long each kind of radio actually runs, which batteries to stock, how to build a 12-volt supply for a base or mobile, and how to recharge everything without a house fire or a carbon monoxide call.
Receive is the load
How long a radio actually runs.
Every radio spec sheet quotes a battery life, and every one of them assumes the same thing: a duty cycle of 5 percent transmitting, 5 percent receiving with the speaker on, and 90 percent sitting quietly in standby, or a slightly heavier 10-10-80 version of the same idea. That is roughly how a radio gets used on a normal afternoon. It is not how a radio gets used during a storm, when people leave the volume up for hours and key the microphone every few minutes.
Here is what the numbers look like on real equipment. Yaesu's FT-65R handheld ships with a 7.4 volt, 1,950 mAh lithium-ion pack, which is about 14 watt-hours of energy, and the company rates it for over 9 hours of operation on a 6-second transmit, 6-second receive, 48-second standby cycle.1 Yaesu's FTM-300 mobile radio draws about 0.5 amps receiving and about 11 amps transmitting at 50 watts.2 Those two data points are enough to size everything else on this page.
Take the mobile radio first, because the lesson is clearest there. Transmitting pulls 22 times the current of receiving, but you transmit for a few seconds at a time. Receiving pulls a tenth of an amp here and there, but it runs all day. At a 10 percent talk share, the average draw is about 1.5 amps: 90 percent of 0.5 plus 10 percent of 11. Over 24 hours that is roughly 37 amp-hours, and two thirds of it went to listening. The way to stretch a battery is not to talk less. It is to control how the radio listens.
| Device | Energy per day, realistic outage use | What that means |
|---|---|---|
| Weather radio on AA cells | A few watt-hours | Days on one set of alkalines; weeks in alert-standby mode |
| 5 W handheld, monitoring plus check-ins | 15 to 30 Wh | One to two battery packs per day, or one pack plus a battery saver and low power |
| Smartphone, one full charge | 12 to 20 Wh | Cheap to keep alive from any USB power bank |
| Meshtastic node or satellite messenger | 2 to 10 Wh | Runs for days on a small power bank |
| 50 W mobile as a base, 24-hour monitoring, 10% talking | About 37 Ah at 12 V, roughly 450 Wh | A 50 Ah LiFePO4 battery covers one day; 100 Ah covers two with margin |
Handheld and small-device figures are ranges from typical published specs and battery capacities; the mobile figure is calculated from the FTM-300 current draw above. Your radios will differ, but not by enough to change the plan.
Five habits that double battery life
- Turn on the battery saver. Nearly every handheld has one buried in the menu. It pulses the receiver instead of running it continuously and costs you nothing but a fraction of a second at the start of each incoming call.
- Transmit on low power when the other station is close. Across the street, 0.5 watts works as well as 5 and draws a fraction of the current. Save high power for the repeater.
- Schedule check-ins instead of monitoring. A household that agrees to listen at the top of every hour for five minutes, then powers down, uses a tenth of the battery of one that leaves every radio on. The family communication plan is where those times get written down.
- Set the squelch so the speaker is silent between calls. An open squelch plays static all day, and the audio amplifier is a real load.
- Dim or time out the display and drop the volume. Small individually, meaningful over 12 hours.
What to stock, and why three kinds
Batteries for handhelds.
Four chemistries do all the work in a household radio kit. Each has one job it does better than the others.
Alkaline AA and AAA
The cell every store sells
Weather radios, most FRS pairs, and many GMRS handhelds run on them. Alkalines hold their charge for years on the shelf and can be bought at any gas station that still has lights on. Their weakness is inside the radio: a cell left installed for years can leak and corrode the contacts. Store the cells in the kit beside the radio, not in it, and write the purchase date on the pack.
Lithium primary AA cells (not rechargeable) cost more, weigh less, and tolerate cold far better. Worth it for the vehicle kit and the radio that lives in an unheated space.
NiMH rechargeable AA
The daily-use cell
Modern low self-discharge NiMH cells hold most of their charge for a year and can be recharged hundreds of times. They run at 1.2 volts rather than 1.5, which every radio designed for AA cells tolerates. Buy them for the radios you actually use each week, and charge them on a smart charger that stops when full.
Keep a set charged in the kit and a set in rotation. A NiMH cell that has sat for two years uncharged may be flat when you need it; alkalines cover that gap.
Lithium-ion packs
What most modern handhelds use
Ham and GMRS handhelds ship with a proprietary lithium-ion pack: light, dense, and useless if it is the only one you own. Buy one spare pack per radio and rotate them. Buy the manufacturer's pack or one it approves; the CPSC's guidance on lithium batteries is blunt that a pack or charger which merely fits is not the same as one that is safe.3
Prefer radios that charge over USB-C. It removes the proprietary cradle from the chain and lets any power bank in the house recharge the radio.
The AA battery tray
The most underrated $15 in radio
Many handheld makers sell an empty battery case that clips onto the radio in place of the lithium pack and takes ordinary AA cells. Power output usually drops a step, and the radio still works. It turns a dead proprietary pack from a crisis into a trip to the kit drawer. If your radio has one available, it belongs in the kit beside the spare pack.
Check the tray's rating; some are for alkaline only, others accept NiMH.
Charging lithium safely: the CPSC's rules
Lithium-ion fires are rare per battery and rising in total because the number of batteries in a house keeps growing. The Consumer Product Safety Commission's consumer guidance fits in six lines, and it applies to radio packs and power banks alike.3 4
- Charge with the charger that came with the device, or a replacement the manufacturer approves.
- Be present while charging. Do not charge while asleep, and unplug when the charge is complete.
- Charge on a hard, flat surface away from anything that burns, not on a bed, couch, or pile of paper.
- Never modify, disassemble, or use a damaged, wet, or swollen pack. Stop using any battery that gets hot, changes shape, leaks, or smells.
- Do not put lithium batteries in the trash. Take them to a battery drop-off.
- If a lithium battery catches fire, leave and call 911. The CPSC's guidance is not to fight it; these fires spread fast and can reignite.
One connector for everything small
The USB-C layer.
Phones, satellite messengers, Meshtastic nodes, headlamps, and a growing share of handheld radios all charge from USB-C. That makes the humble power bank the most important piece of communications power equipment most households will own, and the one where a little arithmetic saves real money.
Power banks are sold by milliamp-hours, which is a measure of the cells inside at 3.7 volts, not of what comes out the port. To get watt-hours, multiply the mAh rating by 3.7 and divide by 1,000: a 20,000 mAh bank holds about 74 watt-hours. Expect to get 60 to 65 of those out after conversion losses. Against the table above, that is four or five handheld pack recharges, or three phone charges, or a satellite messenger for a week. Two banks that size cover a household's small devices for a three-day outage.
What to look for: at least one USB-C port that both charges the bank and delivers power, a capacity in the 20,000 to 27,000 mAh range (the practical ceiling for air travel), and a brand that publishes its safety certification. Recharge the bank from the wall every few months, because lithium cells lose charge sitting on a shelf. The Energy section's battery systems guide covers power banks in the context of the whole house; this page is only about what they do for radios.
Where the hand crank fits
Emergency weather radios advertise a hand crank, and it works, in the sense that a minute of cranking buys some minutes of listening. Treat it as the layer under the last layer. A weather radio that also takes AA cells and charges over USB will run for days on either before anyone has to crank. Buy the crank as insurance and the batteries as the plan.
For mobiles and base stations
Twelve volts without the grid.
Mobile radios are designed for a vehicle's 13.8 volt system, and they tolerate a range around it; most manuals allow roughly 12 to 15 volts. Anything that delivers that voltage and enough current is a candidate. Four options, in order of how well they suit a household base.
1. A dedicated LiFePO4 battery
Lithium iron phosphate (LiFePO4) batteries are the current standard for this job. They rest at about 13.2 volts, squarely in a mobile radio's range, hold that voltage until nearly empty, weigh a third of a lead-acid battery of the same capacity, and are rated for thousands of charge cycles. Every reputable one has a built-in battery management system, or BMS, that shuts the battery down before it is overcharged, over-discharged, or short-circuited. Buy only batteries that say so on the spec sheet.
Size it from the table in section one. A 50 Ah battery runs a 50-watt base for a day of continuous monitoring with a 10 percent talk share; 100 Ah covers two days with margin, and drops to well under a day's use if you set the radio to 25 watts and schedule listening windows. Prices for a 50 Ah LiFePO4 with BMS run roughly $130 to $250; 100 Ah roughly $200 to $400. Add a matching lithium-profile charger, usually $40 to $80, and a fuse holder.
2. A portable power station's DC output
If the household already owns a portable power station for the refrigerator and the phones, it can run the radio too, with one check first. Use the 12-volt DC output, not the AC inverter; running a 12-volt radio through an inverter and then back through a 12-volt power supply wastes 20 to 30 percent of the energy. Then read the current rating on that DC port. Many cigarette-lighter style outputs are limited to 10 amps, and a 50-watt radio draws about 11 on transmit, which will trip the protection every time you key up.2 Use a higher-rated DC port if the station has one, or run the radio at a lower power setting.
3. The vehicle
A vehicle is a 12-volt battery attached to a charger that makes several hundred watts. A mobile radio installed per the installation guide runs from it directly. Two cautions. A starting battery is built to deliver a huge current for a few seconds, not a small current for a day; an hour of monitoring with the engine off is fine, an overnight is a gamble on whether the car starts in the morning. And the engine must only run outdoors: the CDC's rule is never to run a car or truck in a garage attached to a house, even with the door open, because carbon monoxide reaches lethal levels.5 Park in the open, run the engine for 20 minutes an hour when you need to recharge, and keep enough fuel to still leave.
4. Lead-acid, with reservations
A spare car battery or a deep-cycle marine battery works electrically, and many stations ran on them for decades. The reason LiFePO4 replaced them is partly weight and cycle life and partly safety: a flooded lead-acid battery gives off hydrogen gas while charging, which is an explosion hazard in an enclosed space, and it contains sulfuric acid.6 7 If a lead-acid battery is what you have, keep it in a vented battery box, charge it in a ventilated space away from sparks and living areas, and treat it as the interim solution it is. A sealed AGM battery removes most of the gassing concern but not the weight or the short cycle life.
Wiring rules that do not change with the battery
- Keep the radio's fused power cable intact. The manufacturers are unambiguous: never cut off the fuse holders and never fit a fuse of a different rating.8 The fuses protect the wire, not just the radio.
- Fuse at the battery. A battery that can deliver hundreds of amps into a short deserves a fuse within inches of its positive terminal, sized for the wire. Use a proper inline fuse holder, not a bare fuse and tape.
- Use connectors, not bare wire. Anderson Powerpole connectors are the amateur radio standard and let any radio plug into any battery in the house. Red to positive, black to negative, every time; reversed polarity is the most common way a radio dies.8
- Cover the terminals. A wrench dropped across a 100 Ah battery's terminals welds itself in place. Use terminal covers and keep tools away from the top of the battery.
Putting it back
Recharging during an outage.
A battery is a bucket. In a two-day outage a full bucket is enough. Past that, you need a tap, and there are three.
Solar
A folding 100-watt panel in decent sun produces on the order of 400 to 500 watt-hours over a day, which is close to the 450 watt-hours the 50-watt base uses in a day of monitoring. That is the whole design: a panel roughly matched to the daily load, a battery sized for two days, and the household stays on the air indefinitely as long as the sun cooperates. Two things the panel needs between it and the battery: a charge controller, and for LiFePO4, one with a lithium charging profile. Power stations have the controller built in. Standalone batteries do not.
Sizing, mounting, and the difference between a panel's rated watts and its real output are covered in the Energy section's solar basics guide and its 200-watt portable solar build. A radio operator does not need to know more than those two pages contain.
The vehicle, again
With the engine running, a vehicle's alternator can recharge a LiFePO4 battery or a power station through a 12-volt outlet or a dedicated DC charger, and USB-C car adapters recharge everything small. It is the fastest tap most households own and the one they forget. The rules from the previous section stand: outdoors only, never in an attached garage even with the door up,5 and keep the tank above the point where the vehicle stops being an evacuation option.
A generator, if you have one
A generator recharges radio batteries the same way it runs a refrigerator: plug the charger into it. Two radio-specific notes. Run the battery chargers during the hours the generator is already running for other loads rather than starting it for the radios alone, and never let the generator's placement drift indoors or toward a window because a radio battery is low. The generator safety guide has the placement rules, and they do not bend for communications.
What sits in the drawer
The radio power kit, and its calendar.
Three tiers, matched to the three tiers of radio the rest of this section describes. Stop at the tier that covers your radios.
Tier 1 · Weather radio and FRS pair
$30 to $60
- Two full sets of AA cells per radio, stored outside the radios, dated
- One 10,000 mAh USB-C power bank
- USB-C cables for every device, plus one wall charger
Tier 2 · GMRS or ham handhelds
$100 to $200
- One spare lithium pack per radio, rotated monthly
- An AA battery tray per radio model, if the maker offers one
- Two 20,000 mAh USB-C power banks, recharged every three months
- A 12-volt car charger or adapter for the radio's cradle
- A small folding solar panel with USB output, 20 to 30 watts
Tier 3 · Mobile or base radio
$250 to $600
- 50 or 100 Ah LiFePO4 battery with BMS, or a power station with a DC port rated over 12 amps
- Lithium-profile charger, inline fuse at the battery, terminal covers
- Powerpole connectors on the radio and every battery
- 100-watt panel and charge controller, or a power station that accepts solar input
- A plug-in voltmeter so you know what is left
The calendar
Batteries fail quietly. The only defense is a schedule, and it takes less time than the average software update.
Monthly
Swap the lithium pack in each handheld with its spare and charge the one you removed. Turn on each radio and make one contact. Top off the LiFePO4 battery.
Quarterly
Recharge every power bank. Check the AA stock for dates past three years and for any cell that looks swollen or crusted; replace and recycle. Run the base radio from battery for an hour with the wall charger unplugged.
Yearly
Replace NiMH cells that no longer hold a charge. Run the whole kit through one full simulated outage day: radios on battery from breakfast to bedtime, solar panel out, nothing plugged into the wall. Write down what ran out first.
Learn from other people's outages
Common mistakes.
One battery per radio
The pack in the radio is the one that is dying. The spare is the plan. A handheld with one pack and no AA tray is a radio with an expiration time printed on it.
Alkalines left in the radio for years
The kit radio gets opened in the storm and the contacts are green. Store the cells beside the radio, dated, and rotate them.
Running a 12-volt radio through an inverter
Battery to inverter to wall-wart power supply to radio throws away a quarter of the energy and adds two points of failure. Radios are 12-volt devices. Feed them 12 volts.
Idling the car in the garage to charge things
It is a recurring cause of carbon monoxide deaths in winter outages. Outdoors, in the open, every time, even with the door up.
Charging while asleep
Radio packs and power banks go on the counter in the morning, not on the nightstand at night. The CPSC's guidance is to be present while lithium batteries charge.
Never testing on battery
A base station that has only ever run from the wall has never been tested. Unplug it for an afternoon each quarter and find out what the battery actually does.
Where to go from here
Power is the floor. Build on it.
Antennas and Radio Installs
Height beats watts. The other half of a base station, including the vehicle wiring these batteries feed.
Read the guide →
Battery Systems
The Energy section's guide to power banks, battery stations, and UPS units for the whole household, not just the radios.
Read the guide →
Communication Layers
Where each radio, and its battery, fits in a plan with a primary, an alternate, a contingency, and an emergency layer.
Read the guide →
Sources
Where this information comes from.
All sources accessed September 5, 2026. Current draw and battery figures come from manufacturer specifications; safety guidance comes from the CPSC, CDC, and OSHA.
- Yaesu. FT-65R product page: 7.4 V, 1,950 mAh lithium-ion pack, over 9 hours of operation on a 6-second transmit, 6-second receive, 48-second standby duty cycle. yaesu.com
- Yaesu. FTM-300DR/DE Operating Manual, specifications: current consumption approximately 0.5 A receive, 11 A transmit at 50 W; supply voltage nominal 13.8 V DC. yaesu manual (PDF)
- U.S. Consumer Product Safety Commission. "Lithium-Ion Battery: A Consumer Safety Guide." Charger compatibility, attended charging, damaged batteries, and what to do in a battery fire. cpsc guide (PDF, hosted by NY DHSES)
- U.S. Consumer Product Safety Commission. Battery charging safety public service announcement: be present while charging, never while sleeping, use the supplied charger, unplug when done, never trash lithium batteries. cpsc.gov
- Centers for Disease Control and Prevention. "Carbon Monoxide Poisoning Basics." Never run a car or truck inside a garage attached to a house, even with the garage door open. cdc.gov
- Occupational Safety and Health Administration. Standard interpretation, June 20, 1997: lead-acid batteries have the potential to emit hydrogen gas, which may result in fire or explosion upon ignition, and to leak or spill acid. osha.gov
- Cornell University Environment, Health and Safety. "Battery Charging": lead-acid batteries generate hydrogen gas during charging, an explosion hazard, and contain corrosive liquid. ehs.cornell.edu
- Yaesu. FTM-300DR/DE Operating Manual, safety precautions: never cut off the fuse holder of the DC power cord, do not use fuses other than those specified, do not reverse polarity. Same document as source 2.