How To Choose Between LiFePO4 And Lithium Ion

Start With Cycles Not Capacity

The two chemistries we ship most differ in one number that decides most projects. A LiFePO4 cell is published at more than 2000 cycles with 80% capacity left at 100% DOD. An ICR18650 lithium ion pack is published at around 500 cycles. If your product cycles daily, that is the difference between a pack that lasts five years and one that lasts eighteen months.

Then Look At Voltage Per Cell

LiFePO4 sits at 3.2V nominal and charges to 3.65V. Lithium ion sits at 3.7V nominal and charges to 4.2V. Four LFP cells give 12.8V, which is why LFP drops into lead acid systems so cleanly. Three lithium ion cells give 11.1V, which is what most 12V labelled tools actually run.

Weight And Space Go The Other Way

Lithium ion carries more energy per gram, so for the same run time an 18650 pack is smaller and lighter. In a hand tool or an e-bike that matters more than calendar life. In a pole box that nobody visits for five years it does not.

Temperature Window

Our LiFePO4 packs discharge from -20℃ to 60℃ and charge from 0℃ to 45℃. That charge floor matters in outdoor installations: the controller should not attempt to charge a frozen pack.

A Simple Rule

Daily deep cycling, outdoor installation, lead acid replacement: LiFePO4. Weight critical, intermittent use, tight housing: lithium ion. Thin flat space in a consumer device: lithium polymer. Locked to a 1.2V cell size: Ni-MH.