Thanks, I will file that under the many things I didn't know. I assume majority of laptop batteries are lithium?
These days, that would be a correct assumption.
Not just laptops, but cell phones, pagers, etc.
If the battery is flat and wide, it's a lithium. If it's round, it'll say what chemistry the battery uses. (dry cell, alkaline, nicad, nimh, lithium, etc.)
All round lithium cells incorporate the protective circuitry, so they're pretty safe.
Some flat lithium cells do, some don't. Sometimes the manufacturer will incorporate the protective circuitry into the charger. So, it's the flat cells you have to watch out for.
The absolute worse thing to do is to use a non-lithium charger on lithium cells. Neither the voltages nor the current (amps) will match.
As I wrote above, unlike all other battery technology, lithiums are sensative to both voltage and current (amp) errors. If you use a charger with voltage too high, or if the charging current exceeds 1C/cell (single-cell capacity), or if you overdischarge the cell, expect a puffed pack, followed shortly by a toxic, corrosive white cloud, followed shortly by an intense, spitting flame.