Calculators · AP Design Labs

Calculators

Free tools that run in your browser. The values below are an example ESP32 sensor node. Change them to match your build.

Battery life

Battery

Capacity

mAh

Usable

Allows for ageing, cold and cutoff voltage

Awake current

Awake for

Sleep current

µA

Wakes every

min

Self-discharge

%/mo

Estimated runtime

–

Average current: –
Usable energy: –
Wakes per day: –

Where the charge goes

AwakeAsleepSelf-discharge

LoRa airtime

Time on air for one packet, using the Semtech SX127x/SX126x formula. Longer airtime means more battery used per message and more chance of collisions on a busy mesh.

Spreading factor

Bandwidth

Coding rate

Payload

bytes

Preamble

symbols

Awake current

mA TX

Time on air

–

Symbol time: –
Payload symbols: –
Low data rate optimise: –
Bit rate: –
Charge per packet: –

Each step up in spreading factor roughly doubles airtime, which buys range but costs battery. Check your local MeshCore preset before changing radio settings, because every node on the mesh has to match.

Voltage divider

Scale a battery voltage down to an ADC pin, and see how much current the divider itself draws.

Input voltage (max)

R1 (top)

kΩ

R2 (bottom)

kΩ

ADC limit

ESP32 at 11 dB attenuation is about 3.1 V

Output voltage

–

Ratio (multiply reading by): –
Divider current: –
Headroom to ADC limit: –