Boondocking Battery Math: What Your Smart Lock Really Costs Overnight
Short version: it's small — and it's predictable. Here's the no-nonsense math.
The 2 Numbers That Matter
- Standby draw (W): often 0.2–0.5 W, 24/7.
- Actuation energy (Wh): brief motor pulses per day.
Back-of-Napkin Example
Standby 0.3 W × 24 h = 7.2 Wh/day. Actuation 3 W × 8 s/day = 24 W·s = 0.007 Wh/day (yep, tiny). Total ≈ 7.2–8 Wh/day including converter losses.
Battery Impact
At 12 V: 8 Wh ÷ 12 V = 0.67 Ah/day. On a 100 Ah usable battery, that’s ~149 days… if the lock were the only load (it isn’t, but you get the picture).
Solar Reality
To break even: Panel W ≥ Wh/day ÷ (sun hours × derate). If you get 4.0 peak sun hours and 0.75 derate: 8 ÷ (4×0.75) ≈ 2.7 W. A 5–10 W panel is plenty.
Use the Energy Calculator with your actual numbers. Keep parasitics (lock, router, sensors) honest and you’ll stretch boondocking days.
Related Reading
- Parasitic Loads Audit — Measure all your standby draws.
- RV 12V Smart Lock Wiring — Efficient power delivery.
When Numbers Jump
- High standby >0.5 W → consider firmware settings or different model.
- Converter inefficiency → upgrade buck or shorten cable runs.
- Cold weather → batteries lose effective capacity. Add buffer.