How long will a 48V 100Ah battery last?
A 48V 100Ah battery provides 4.8kWh of energy (48V × 100Ah = 4800Wh). Its runtime depends on the load’s power draw: Duration (hours) = Battery Capacity (Wh) / Load Power (W). For example, a 500W load yields ~9.6 hours. Actual runtime is reduced by inefficiencies (e.g., 90–95% discharge efficiency for lithium batteries) and environmental factors like temperature.
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What factors determine a 48V 100Ah battery’s runtime?
Key factors include load power, discharge efficiency (typically 85–95% for lithium-ion), ambient temperature, and battery health. Higher loads or extreme temperatures reduce usable capacity.
Runtime calculations start with the formula 4800Wh ÷ Load Power. A 1200W solar inverter would drain the battery in 4 hours (4800Wh ÷ 1200W = 4h), but real-world results drop to ~3.6 hours after accounting for 90% inverter and 95% battery efficiencies. Pro Tip: Always derate capacity by 10–15% for lithium batteries to avoid deep discharges that accelerate aging. For example, electric golf carts drawing 800W typically achieve 5–5.5 hours of runtime instead of the theoretical 6 hours.
How does load current affect runtime?
Current draw directly impacts runtime: Duration = 100Ah ÷ Current (A). A 20A load yields 5 hours, while 50A cuts it to 2 hours.
This linear relationship assumes constant current, but Peukert’s Law reveals hidden losses. Lead-acid batteries lose 40% capacity at 50A vs 20A, while lithium variants maintain >90% above 1C rates. A 48V 100Ah LiFePO4 battery powering an e-bike with 15A average draw delivers ~6.3 hours (100Ah ÷ 15A × 95% efficiency). Practically speaking, regenerative braking can extend runtime by 5–8% in hilly terrain.
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| Load (A) | Theoretical Time | Actual Time (LiFePO4) |
|---|---|---|
| 10 | 10h | 9.5h |
| 25 | 4h | 3.8h |
| 50 | 2h | 1.9h |
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FAQs
Can I connect multiple 48V 100Ah batteries for longer runtime?
Yes—parallel connections increase capacity (e.g., two batteries = 200Ah/9.6kWh). Use identical batteries and a balancing BMS to prevent uneven discharges.
Why does my 48V battery die faster in winter?
Lithium batteries lose 20–30% capacity below 0°C. Insulate battery compartments and maintain 15–25°C for optimal performance.
