RadioWiki · Tools · Off-grid

🔋 Battery runtime & solar sizing

How long a battery runs your handheld, mobile or mesh node - and whether the panel keeps up in winter.

What's drawing power

Receive / idle currentA

Transmit currentA

Time spent transmitting%Net control ≈ 30%, monitoring ≈ 5%, a mesh node ≈ 1%

Battery

CapacityAhChemistry90% usable before it's hurtNominal voltageV

Runtime

Average draw: 275.0 mA; 3.5 W average
Runtime: 65.5 h; 18.0 Ah usable
Per day: 84.5 Wh; 6.6 Ah/day

Solar (for a node or a go-box left in the field)

Panel ratingWPeak sun hours per dayhOklahoma winter ≈ 3, summer ≈ 6

Harvest per day: 67.5 Wh; after ~25% controller & wiring loss
Balance: -17.0 Wh/day; battery drains over time
Days of cloud it survives: 65.5 h; from a full battery, no sun at all

Cold cuts capacity (lead-acid loses roughly a third at freezing; LiFePO4 mostly keeps its capacity but must not be charged below 0 °C without a heater). Size the panel so winter still balances, and give a mesh node at least 3-4 days of dark.