How Long Will a 300Ah Battery Last?
A 300Ah battery is a mid-range capacity commonly used in larger RV systems, small home backup, and off-grid cabins. At 48V, it provides over 15 kWh of total energy — enough for meaningful overnight home backup or multi-day camping.
Energy by Voltage
| Voltage | Total Energy | Usable (80% DoD) |
|---|---|---|
| 12.8V | 3,840 Wh | 3,072 Wh |
| 25.6V | 7,680 Wh | 6,144 Wh |
| 51.2V | 15,360 Wh | 12,288 Wh |
Runtime Formula
Runtime Table: 300Ah 48V LFP
At 80% DoD and 92% efficiency, a 300Ah 48V LFP battery provides 12,288 Wh of usable energy:
| Load | Power (W) | Runtime |
|---|---|---|
| Router + lights + phone | 50 W | ~226 hours |
| Fridge + essentials | 150 W | ~75 hours |
| TV + laptop + lights | 250 W | ~45 hours |
| Small AC unit | 800 W | ~14 hours |
| Electric kettle | 1,500 W | ~7.4 hours |
| Microwave + fridge | 2,000 W | ~5.5 hours |
Scenario: Home Backup
For overnight home backup with essential loads:
Given: 300 Ah at 48V LFP, 80% DoD, 92% efficiency
Loads: Fridge (60W) + router (10W) + 4 LED lights (24W) + phone (15W) + CPAP (30W) = 139W
Usable energy:
Effective load:
Runtime:
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How long will a 300Ah battery run a house?
A 300Ah 48V LFP battery stores 15,360 Wh total, with 12,288 Wh usable at 80% DoD. For a home consuming 10 kWh/day, this provides approximately 1.1 days of autonomy. For essential loads only (2–3 kWh/day), it lasts 4–5 days.
How long will a 300Ah 12V battery last camping?
At 12.8V, a 300Ah LFP battery provides 3,072 Wh usable at 80% DoD. For typical camping loads (fridge 50W, lights 24W, phone 15W = 89W), runtime is approximately 31 hours — enough for a 3-day camping trip without recharging.
How many solar panels to charge a 300Ah battery?
A 300Ah 48V LFP battery stores 15,360 Wh. With 5 peak sun hours, you need approximately 3,072W of solar panels (before losses). A 3.5–4 kW array accounts for system losses and cloudy-day margin.
Is a 300Ah battery good for home backup?
A 300Ah 48V LFP battery (15.36 kWh) provides excellent overnight backup for essential loads. It can power a fridge, router, lights, and medical devices for 12+ hours. For multi-day backup, consider parallel batteries or a larger bank.