Cell Break-In?

I've read in a couple of papers that lithium iron phosphate (LiFePO4) calls have a break-in period. I decided to pull a cell out of stock and see how break-in might look.

The cell I tested is a cylindrical 40138 cell. It's 40 mm (1.6 in) in diameter and 138 mm (5.4 in) long. Nominal voltage is 3.2 and nominal capacity is 10Ah. These cells can handle up to a 100A surge.

I used a West Mountain Radio CBAII for the discharge load and data logging. I recharged each cell with at least one Voltphreaks single cell charger. Ambient temperature was 75 to 77 degrees F. Low voltage cutoff was set to 2.1V. The cell was loaded with 10A for the early tests, though later tests included 20A and 25A.

Here are the numbers:

1. 9.63
2. 9.76
3. 9.91
4. 9.92
5. 9.91
6. 10.01
7. 9.89
8. 10.10
9. 10.21
10. 10.10 (20A discharge)
11. 10.21 (20A discharge)
12. 10.05 (25A discharge)
13. 10.04 (25A discharge)

I'll run a few more cycles at 10A to see if nine cycles is a reasonable break-in period or if there's more capacity available.

For more information:

West Mountain Radio CBAII (http://www.westmountainradio.com/)

Voltphreaks single cell charger (voltphreaks.com)