Lithium Phosphate (LFP) batteries, like the Fortress Power eFlex 5.4 G2 Lithium Solar Battery 5.4 kWh or the Fortress Power eVault Max 18.5kWh LFP Battery Storage, can be discharged up to 90% without causing significant harm to the battery. We recommend 80% (as most LFP manufacturers) but this still provides a wider discharge range compared to SLA batteries.

Additionally, LFP batteries tend to have a longer lifespan compared to SLA batteries. For example, our eFlex 5.4 battery is rated up to 8000 cycles (or 10-year warranty). I would suggest you compare this to the SLA battery cycles. I have seen a range between 300 to 700 cycles for SLA batteries.

Lastly, while it is not directly related to capacity, I strongly recommend that customers understand the maintenance requirements. LFP batteries are virtually maintenance free, whereas SLA will require periodic maintenance.

In summary, when comparing LFP to SLA batteries here are a few things to consider:

• Depth of Discharge range
  • LFP – 80% vs SLA – 50%
• Cycle Count
  • LFP 8000 cycles vs SLA 300-500 cycles
• Warranty Term/Lifespan
  • LFP 10 years vs SLA 1-3 years (?)
• Maintenance Requirements
• LFP – maintenance free vs SLA – periodic maintenance required

To compare the cost of an SLA battery bank to a lithium phosphate battery bank, use this resource link: How to Calculate the Energy Cost of Different Battery Chemistries