Chip presets (fills sleep/active currents — adjust freely):
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⚠ When NOT to use this calculator. It models a rectangular duty cycle (wake → sleep) and datasheet-typical currents. It does not model: regulator quiescent current (often 5–100µA — the hidden killer), battery self-discharge, cold-weather capacity loss (Li-ion can lose 20–50% at 0°C), WiFi retry storms, or brownout margin. Treat the output as an order-of-magnitude planning number and measure your board's sleep current with a µA meter before shipping.
Worked example
A soil sensor wakes every 30s (2,880×/day), reads for 500ms at 80mA, sleeps at 10µA, on a 2000mAh LiPo (80% usable):
Active charge = 2880 × 0.5s × 80mA = 32mAh/day · Sleep charge = 24h × 10µA ≈ 0.24mAh/day → ≈48 days? No — check the math yourself with the tool: the point is active energy dominates. Double the wake time → runtime nearly halves. Cutting sleep current in half barely moves the needle.
Active charge = 2880 × 0.5s × 80mA = 32mAh/day · Sleep charge = 24h × 10µA ≈ 0.24mAh/day → ≈48 days? No — check the math yourself with the tool: the point is active energy dominates. Double the wake time → runtime nearly halves. Cutting sleep current in half barely moves the needle.
FAQ
How long will a 2000mAh LiPo run an ESP32 deep-sleep sensor?
For the default scenario (2,880 wakes/day, 500ms at 80mA, 10µA sleep): about 50 days from a 2000mAh cell. Active energy dominates — reduce wake time before anything else.
What deep-sleep current does the ESP32 actually draw?
Bare chip: ~5–10µA. Dev boards: 20–150µA (USB-serial chip + regulator). Some boards never truly sleep — measure.
Why does my battery die faster than the estimate?
Regulator quiescent current, WiFi reconnects, cold weather, or an aging cell. The calculator shows the ideal; reality subtracts 20–50%.
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