LiFePO4 vs Lead-Acid Batteries for Off-Grid

The choice between LiFePO4 lithium and lead-acid (FLA or AGM) batteries dominates off-grid system design. Lithium is more expensive upfront but cheaper per-kWh-cycled over 10 years.

LiFePO4 Lithium (Battle Born)

Pros

  • 3,000-5,000 cycle life (10+ years)
  • 80-100% depth of discharge usable
  • No maintenance
  • Lightweight (1/3 of lead-acid)
  • Faster charging
  • Built-in BMS

Cons

  • Higher upfront cost ($900-
    ,500 per 100Ah 12V)
  • Cold-temperature charging limitations
  • BMS can shut down in extreme conditions

Verdict: Best for new off-grid builds. Total 10-year cost is lower than lead-acid despite higher upfront. The default choice in 2024+.

AGM/FLA Lead-Acid

Pros

  • Lower upfront cost (00-$500 per 100Ah)
  • Charges in cold weather
  • Familiar technology
  • No BMS failures

Cons

  • 300-1,500 cycle life
  • Only 50% depth of discharge usable
  • Requires equalization charging (FLA)
  • Heavy
  • Ventilation needed (FLA outgasses)
  • 5-7 year typical lifespan

Verdict: Mostly obsolete for new off-grid builds. Still works for occasional-use backup systems where capital is tight.

Frequently Asked

Is LiFePO4 worth the extra cost?
Yes for any year-round use. Total cost of 10-year operation is lower for LiFePO4 despite ~3x upfront. Lead-acid only makes sense for backup systems used a few times per year.
How long does a LiFePO4 battery last?
Typical 100Ah LiFePO4 batteries are rated 3,000-5,000 cycles at 80% DoD. At one cycle per day, that's 8-14 years. Battle Born's 10-year warranty reflects this.
Can I charge LiFePO4 below freezing?
No — most LiFePO4 batteries' BMS will block charging below 32°F (0°C) to prevent damage. Discharge is fine to -4°F. Heated battery boxes solve this issue.
Are AGM batteries still good for off-grid?
Only for backup systems used infrequently. For daily-cycled off-grid use, LiFePO4 is cheaper per-kWh-cycled over the system lifetime.