Tool

Will my 12 V lithium setup last?

Enter your bank, daily use, and daily charging to see how many days it lasts. One 100 Ah 12.8 V LiFePO4 battery plans as 1,152 Wh usable calculated. Everything runs in your browser. Updated Oct 18, 2026.

Battery capacity (Ah, 12 V)

Batteries in parallel

Daily use (Wh, battery side)

Daily charging (Wh)

Days you want to last

Works on energy, with margin. Bank: 1,280 Wh rated, 1,152 Wh planned usable (90%). Lasts about 1.6 days.Energy only. It does not check charger voltage, BMS current limits, cold-weather charging, wiring, or fusing.

What this checks today

This first version checks energy only. Component checks are next: charger voltage against the battery's charge window, inverter current against the BMS rating, and cold-weather charging. The methodology lists every formula and assumption.