AGM vs LiFePO4 battery bank
Quick answer: Lifeline says to keep an AGM battery's average depth of discharge at 50% of its 20-hour rating. With this site's 0.50 AGM and 0.80 LiFePO4 factors, 1,000 Wh a day for 2 days at 12 V needs about 417 Ah of AGM or 260 Ah of LiFePO4: four 64 lb Lifeline GPL-31Ts or three 31 lb Battle Born BB10012s.
Run one load both ways
Formula (this site's calculator settings): Wh/day × days × 1.25 ÷ volts ÷ DoD factor. The 1.25 margin and the 0.50 / 0.80 factors are this calculator's settings, not a battery maker's spec. Battery counts use 12 V batteries in series and parallel, rounded up.
The two batteries side by side
| Lifeline GPL-31T (AGM) | Battle Born BB10012 (LiFePO4) | |
|---|---|---|
| Voltage | 12 V | 12 V |
| Capacity | 105 Ah (20-hour rate) | 100 Ah |
| Weight | 64 lb | 31 lbs |
| Depth of discharge | Lifeline: keep average at 50% | This calculator uses 0.80 |
| Cycle rating | See Lifeline's technical manual (depends on depth of discharge) | 3,000 to 5,000 cycles |
| Source | GPL-31T product page, Lifeline technical manual | BB10012 manual |
What changes between the two
For the same daily load, the AGM bank is larger in amp-hours because you only plan to use about half of it. It is also much heavier. The LiFePO4 bank is smaller and lighter, and Battle Born rates it for thousands of cycles. Charging voltages differ too: the AGM battery guide covers Lifeline's absorption setting, and the 12V LiFePO4 spec chart covers the lithium side.