Offline Tool
Battery Runtime Calculator
Field radios die from optimistic amp-hour math. Enter load current, battery size, and an efficiency factor; this calculator estimates runtime so a go-kit LiFePO₄ is sized before the net.
Estimate battery runtime from Ah capacity and load current. Field power planning for go-boxes and emcomm. Works offline after your first visit.
Field radios die from optimistic amp-hour math. Enter load current, battery size, and an efficiency factor; this calculator estimates runtime so a go-kit LiFePO₄ is sized before the net.
A 5 W HT at 1.5 A transmit and 0.2 A receive, 10% duty cycle, on a 12 Ah LiFePO₄, runs far longer than the same radio on a 7 Ah SLA that you must not discharge below 50%. LiFePO₄ usable capacity is most of the rating; SLA usable capacity is roughly half. Winter in the Tri-Cities also sags lithium-ion (not LiFePO₄) — see the winter go-kit power note.
Add a margin for lights, a hotspot, and a laptop if the kit supports digital. Pair this math with LiFePO₄ vs SLA, power system sizer, and solar sizing. The field power hub groups those tools.
Numbers are estimates. Meter the real current on your radio at the volume and power setting you actually use.
See also: Emcomm go-bag
Estimate load in amps, multiply by required hours, add a safety margin — LiFePO₄ allows deeper discharge than SLA.
Not all rated Ah is usable — SLA is often limited to ~50% depth of discharge; LiFePO₄ can use most of the pack safely.
0.8 is a reasonable starting point for inverter or wiring loss. Use 0.95 for a radio wired straight to a LiFePO₄ with fat leads.
Peak current is high. Size for transmit current × duty cycle plus headroom, or you will brown out on voice peaks.
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