1---
2app_version: 0.7.0
3precision: 3
4form_title: Battery Runtime (POTA / SOTA / Field Day)
5form_description: Will this battery get you through the activation? Enter its capacity, your radio's RX/TX current draw and how much of the time you're actually transmitting.
6form_inputs: Battery capacity (Ah)|capacity_ah, Usable capacity (%)|usable_pct, RX current (A)|rx_a, TX current (A)|tx_a, Transmit duty cycle (%)|duty_pct
7form_outputs: Usable capacity (Ah)|usable_ah, Average current draw (A)|avg_a, Runtime|runtime
8---
9# Battery Runtime (POTA / SOTA / Field Day)
10// "Will this battery get me through the activation?"
11
12capacity_ah = 10 // nominal battery capacity, e.g. a 10 Ah LiFePO4 pack
13usable_pct = 80 // LiFePO4: stop well above empty; lead-acid: ~50%
14
15rx_a = 0.5 // receive current draw
16tx_a = 5 // transmit current draw at your usual power level
17duty_pct = 25 // % of operating time actually transmitting (SSB/CW mix)
18
19usable_ah = capacity_ah * usable_pct / 100
20avg_a = rx_a * (1 - duty_pct / 100) + tx_a * (duty_pct / 100)
21
22// Ah divided by A is hours; times 1 h it shows as hours and minutes.
23runtime = usable_ah / avg_a * 1 h
24
25"Usable capacity (Ah)": usable_ah
26"Average current draw (A)": avg_a
27"Runtime": runtime
28"Runtime in decimal hours": runtime in h
29
30// A second radio or a phone charging off the same battery — add its average
31// draw here to see the runtime hit before you pack it.
32accessory_a = 0.2
33runtime_with_accessory = usable_ah / (avg_a + accessory_a) * 1 h
34"Runtime with an accessory load": runtime_with_accessory
35