My Sony Vaio laptop has a built-in program called "Sony Battery Care" which provides a functionality to hold battery at certain levels of charge while operating. For example, I've set it to 50% and the battery is always kept at that level while on AC power. This mode prevents battery degradation and is more effective as I usually use my laptop with AC power.
I'm looking for a similar program to use with other laptops with Windows OS; preferably a free one.
To push Sparr's comment into an answer, he's completely right. Charging circuitry is typically pretty dumb and can't be controlled via software. There may be a hardware solution that would go between the wall socket and the power adapter, but that's unlikely.
As a man who troubleshoots the power boards in old laptops for fun, I haven't seen this sort of feature (or chip to support that feature) in any brand before. There doesn't seem to be a generic solution yet. Maybe the industry will change.
On recent Lenovo Thinkpad laptops you can use the System Management API tools to set the charging threshold and limit, in the same way that the Sony tools do.
There is a command-line option to change various power options on Windows computers that might do what you want.
General info: Turn off power saving options via command line
Try powercfg /? and notice the export and import options. Try exporting your "VAIO Maximum Battery" power scheme GUID, then import it onto another Windows computer, thereby duplicating all its settings.
I only have Vista so I can't speak for XP or 7 and if you can export and import across versions of the OS. Also, it's unknown if VAIO has software or hooks it added for power capabilities, but I bet it does because I uninstalled all the VAIO add-ons once and the power scheme stopped working, and I couldn't even delete it without the powercfg command-line tool, so I'm guessing this answer won't work, but it's worth a try.
