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300Ah battery runtime at 50 watts
300Ah 12V lithium battery running 50W (AC, 90% inverter) · 32 h 24 min on lead-acid/AGM
300Ah battery at 50W – by battery type
| Battery type | Usable energy | Runtime (AC load) | Runtime (DC load) |
|---|---|---|---|
| LiFePO4 lithium (90% usable) | 3,240 Wh | 58 h 19 min | 64 h 48 min |
| Gel (80% usable) | 2,880 Wh | 51 h 50 min | 57 h 36 min |
| Lead-acid / AGM (50% usable) | 1,800 Wh | 32 h 24 min | 36 h 00 min |
Battery current 4.6 A (0.02C). Energy = 300Ah × 12 V = 3,600 Wh.
Same battery, other loads
FAQ
How long will a 300Ah 12V battery run a 50W load?
A 300Ah 12V lithium (LiFePO4) battery stores 3,600 Wh and, using 90% of it through a 90% efficient inverter, runs a 50W AC load for about 58 h 19 min. A lead-acid or AGM battery limited to 50% depth of discharge lasts about 32 h 24 min.
How many amps does a 50W load draw from a 12V battery?
About 4.6 A from the battery through a 90% efficient inverter (4.2 A for a DC load with no inverter).
Why is the real runtime shorter?
High discharge currents reduce usable capacity (Peukert effect in lead-acid), cold weather cuts capacity, batteries age, and many appliances draw more than their label while starting. Treat the number as an upper estimate.
Other battery sizes at 50W: 50Ah · 100Ah · 200Ah · battery runtime calculator · all combinations
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