LiFePO4 Cells

Lithium iron phosphate

Background

NCA/NCM vs LiFePO4/LFP

• LiFePO4/LFP is commonly called the iron phosphate

  • Has a nominal voltage of 3.2V per cell

  • Takes 16 of these cells to make a 28V pack while NCA/NCM only require 13 to hit that voltage

  • Is considered the most fire safe

  • Last about twice as long as the common NCA/NCM 18650-cell packs

  • A 4S pack of LFP is the most common replacement for a 12V lead-acid battery pack (4P x 3.2V = 12.8V nominal)

• NCA/NCM in the 18650 format cells have a much better selection of choices and provide high power and long-range in a small package that is affordable

• LFP can be found in flat pouch cells and 26650s and large cylindrical cells (these are big)

• Open

  
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Li-ion VS LiFePO4

• Specific energy of 90/120 watt-hours per kilogram, Li-ion is 150/200 Wh/kg

• Discharge rate is much better (find numbers!)

• 1000-10000 cycles, Li-ion has about 500-1000

• Li-ion lifecycle is more affected by the working temperature of the electronics/components whereas LiFePO4 can handle high temperatures with minimal degradation

• 350 day shelf life whereas li-ion only has about 300 day

• Lithium Iron Phosphate Vs. Lithium-Ion: Differences and Advantages

RELion’s low temp LiFePO4s

• Probably dont need need low temp capabilities?

• Can be safely charged at -20 to 60 Celcius

• Regular batteries: charging below 0 celcius - should reduce charge current (by how much?), will only suffer about a 10% loss in capacity when charging below 0, lead acid will lose 50%

• These batteries has internal heating and monitoring systems to combat this and allow it to be charged down to -20 C