FNB-66LI Battery Pack:

The FNB-66LI for the VX-1210 is a sealed 14.8 volt 4.8 Amp-Hour Lithium-Ion battery pack. It is charged by the PA-26/CD-17 charger, and can be charged without removing it from the radio. 

This pack will operate the radio for 10 hours in normal SSB operation, and approximately 24 hours in receive only.

One aspect of the Lithium-Ion chemistry is that there is a fixed service life independent of the number of cycles. Just like modern laptops, there is typically noticeable degradation in 3-4 years, and many have seen pack failure in the 4-5 year timeframe.

The pack is composed of individual cells, and has successfully been rebuilt. This is critical as the 1210 is technically out of production, and there is a concern that remaining factory battery packs in the parts system are also approaching end of life due to age.