Cylindrical Compared With Prismatic LiFePO4 Cells

Same Chemistry Different Package

Both formats are lithium iron phosphate at 3.2V nominal with a 3.65V charge voltage and a published cycle life above 2000 at 80% DOD. What changes is the can.

Cylindrical Cells

Wound into a steel can in fixed sizes: IFR18500 at 850mAh, IFR18650 at 1400mAh and 1500mAh, IFR26650 at 3000mAh to 3500mAh, IFR32600 at 4000mAh, IFR32700 at 6000mAh and IFR42110 at 10Ah. Many small cells make an irregular shape easy to fill and spread heat well, at the cost of more welds.

Prismatic Cells

Flat aluminium or plastic cased cells from LFP1868117 at 10Ah up to LFP60260320 at 300Ah. Fewer cells, fewer welds, better use of a rectangular enclosure, and the practical choice for storage banks.

Choosing By Capacity

Below about 20Ah a cylindrical pack is usually simpler and cheaper. Above about 50Ah the parallel count on cylindrical cells becomes the problem, and prismatic wins. Between the two, the enclosure shape usually decides.

Choosing By Current

Our published prismatic cells reach high rates: the 3.2V 200Ah cell is rated 600A maximum discharge at 3C. Cylindrical cells reach the same total current by adding parallel strings.