Frequently Asked Questions
How do I estimate battery charge time?
Hours ≈ (Ah to replace ÷ charge current A) × inefficiency factor. A 100 Ah LiFePO₄ depleted to 20% needs 80 Ah; at 40 A charge × 1.15 inefficiency ≈ 80 ÷ 40 × 1.15 ≈ 2.3 h.
What inefficiency factor should I use?
LiFePO₄ round-trip is ~95% (use 1.05–1.15). AGM ~85% (use 1.15–1.25). Flooded lead-acid ~80% (use 1.25–1.4). The factor accounts for charging losses, not the deeper discharge inefficiency.
Why does charge slow down near full?
Lead-acid switches from bulk (constant current) to absorption (constant voltage) at ≈ 80% SOC, and current tapers for hours. Lithium stays near full current until ≈ 95% SOC then tapers briefly, so it charges much faster.
Can I charge faster with a bigger charger?
Only up to the battery's C-rate limit. LiFePO₄ typically allows 0.5 C continuous (50 A for a 100 Ah), some up to 1 C. Lead-acid is limited to 0.1–0.2 C without overheating or shortening life.
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Estimates for informational purposes only.
Important Disclaimer: Estimates for informational purposes only.
This calculator provides estimates for informational purposes only. Results are based on assumptions and may not reflect actual outcomes. Consult qualified professionals in relevant fields before making important decisions based on these results.