[Frank Carter]

I have 1600 Samsung Galaxy tablets deployed and, over time, the batteries are understandably running out of juice. I'm looking for a way to test the health / condition of the battery before I redeploy them to the field. Not just that they are fully charged, but are they capable of receiving a full charge, how many more times can they be charged before they start depleting capacity? Maybe too much to ask....

[Rukbat]

There's no way to determine those things with a lithium battery. About the closest you can come is to condition the battery (3 full charges, 3 full discharges), then fully charge it and see how long it lasts to 50% with a fixed load.

Discharging much lower than 50% will ensure that the battery doesn't last too long. Charging or discharging above or below the rated temperature will too. Read How to Prolong Lithium-based Batteries - Battery University then the rest of the site to get more information.