Battery charge time calculator
The ideal energy calculation is useful, but real devices taper power near full charge.
Wh
%
%
W
%
Ideal charge time
0.94hours
- Ideal charge time
- 56 minutes
- Energy stored
- 36.00 Wh
- Energy drawn before standby losses
- 42.35 Wh
Show the working
- Battery capacity = 60
- Starting charge = 20
- Target charge = 80
- Charger power = 45
- Charging efficiency = 85
- Energy stored = 60*max(80-20,0)/100 = 36
- Energy drawn before standby losses = 36/(85/100) = 42.3529
- Ideal charge time = 42.3529/45 = 0.941 176
- Ideal charge time = 0.941 176*60 = 56.4706
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- time = required battery energy / (charger power x efficiency)
Fast charging normally tapers near full, so 0-100% takes longer than this constant-power estimate.