I am wondering if you have done any tests with the FP23 and lithium AA batteries? Will it work and will it give longer recording times?
Without phantom power activated, the current draw of the FP23 is approximately 50 milliamps. The milliamp/hours rating of a typical alkaline AA battery is 1,200. 1,200 divided by 50 equals 24 hours of FP23 operating time.
If a lithium battery provides more than 1,200 milliamp/hours, it will power the FP23 for a longer time than an alkaline AA battery.