Battery Charging Time
Calculate battery charging time based on charger current
Typical values: 5A, 10A, 20A
Lead-acid ~85%, LiFePO₄ ~95–98%
Charging time
Real time is longer due to charging efficiency losses. Lead-acid batteries also have an absorption phase.
How does it work?
Ideal charging time = charge to add (Ah) / charger current (A). For example, charging 80 Ah at 10 A: 80 / 10 = 8 h.
Real charging time is longer due to charging efficiency losses. Lead-acid: ~80–90% efficient. LiFePO₄: ~95–98%.
Lead-acid charging phases: Bulk (constant current) → Absorption (constant voltage, tapering current) → Float (maintenance). The absorption phase adds 2–4 hours and is not fully represented in this calculator.
Example
Example: 100 Ah lead-acid, 20% → 100%, 10 A charger, 85% efficiency.
Charge to add: 100 × 0.80 = 80 Ah
Ideal: 80 / 10 = 8.0 h
Real: 8.0 / 0.85 = 9.4 h
Assumptions
- •Charger delivers constant current throughout
- •Efficiency is constant (decreases in practice during absorption phase)
- •Lead-acid absorption phase not separately modelled