About 18 h 11 min at 210 W. That covers your 12-hour target.
Backup time
18 h 11 min
210 W load · 0.8 days
Usable energy
4.61kWh
5.12 kWh nominal × 90% DoD
Battery drain
253W
incl. 11% inverter loss + 20 W idle
Discharge current
19.8A
0.05C at 12.8 V
Runtime without Peukert
18 h 11 min
lithium: negligible
Energy delivered to loads
3.82kWh
Capacity for 12 h
3.3kWh
256 Ah at 12.8 V nominal
Temperature / age factor
100%
25 °C, 100% health
Runtime at other loads
| Load | Battery drain (W) | Current (A) | Runtime | C-rate |
|---|---|---|---|---|
| 25 W | 48 | 3.7 | 96 h 27 min | 0.01C |
| 50 W | 76 | 5.9 | 60 h 59 min | 0.01C |
| 100 W | 131 | 10.2 | 35 h 09 min | 0.03C |
| 200 W | 242 | 18.9 | 19 h 01 min | 0.05C |
| 300 W | 353 | 27.6 | 13 h 02 min | 0.07C |
| 500 W | 576 | 45 | 8 h 00 min | 0.11C |
| 750 W | 853 | 66.7 | 5 h 24 min | 0.17C |
| 1,000 W | 1,131 | 88.4 | 4 h 04 min | 0.22C |
| 1,500 W | 1,687 | 131.8 | 2 h 41 min | 0.33C |
| 2,000 W | 2,242 | 175.2 | 2 h 00 min | 0.44C |
| 3,000 W | 3,353 | 262 | 1 h 20 min | 0.65C |
Selected loads
| Device | Average W | Share |
|---|---|---|
| Refrigerator | 60 | 29% |
| Wi-Fi router + modem | 15 | 7% |
| LED lighting (5 bulbs) | 45 | 21% |
| TV 50" | 90 | 43% |
- Average power matters, not nameplate power: a fridge rated 150 W cycles on and off and averages 40–80 W; start-up surges affect inverter size, not runtime.
- Lithium batteries keep nearly full capacity at moderate currents, so Peukert effects are minimal (k ≈ 1.02–1.05).