Calculate capacitor discharge time, energy storage, and hold-up time for automotive ECU and memory keep-alive circuits.
Input Parameters
Results
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Hold-Up Time
s
--
Stored Energy
J
--
Usable Energy
J
--
Time Constant (RC)
s
Note: Supercapacitors (1-10F) provide seconds of hold-up. Electrolytic capacitors for millisecond-range backup. Derate capacitors 20% for temperature and aging.
Reference
Hold-Up Time = C × (V_initial − V_cutoff) / I_load
Stored Energy = 0.5 × C × V²
Usable Energy = 0.5 × C × (Vi² − Vc²)
Time Constant τ = R × C
R_equiv = V_initial / I_load