Electrical & ElectronicsHTML guide
Battery Basics
A guide to battery runtime and charge-time estimates, focused on turning capacity and current into sensible planning figures without overstating what a quick formula can promise in real use.
Key formulas
Runtime estimate
runtime = battery capacity / load current
Charge-time estimate
charge time = battery capacity / charge current
Why battery estimates need caution
Battery maths is useful for first-pass planning, but real runtime and charge time depend on chemistry, temperature, discharge profile, charger behaviour, and system losses.
That means the quick result is best treated as a planning estimate, not a guaranteed operating figure.
Common mistakes
- Treating nameplate capacity as if all of it will be delivered under every load condition.
- Ignoring conversion losses in the wider system.
- Assuming a charge current stays constant from empty to full.
- Reading runtime estimates as exact promises rather than broad planning figures.
Related calculators
Apply the topic straight away.
Battery Runtime Calculator
Use the Battery Runtime Calculator for practical circuit and electronics work involving battery runtime.
Electrical & ElectronicsOpen
Battery Charge Time Calculator
Use the Battery Charge Time Calculator for practical circuit and electronics work involving battery charge time.
Electrical & ElectronicsOpen