Azhar Ali Chohan asked:
"1, What are the constant voltage type batteries."

IJAZ AHMED replied:
"1) Almost all batteries are CV type."

This is true, but I'm not sure if that's what Azhar really wanted to know:
Azhar: do you want to know what batteries are CV, or are you really asking what batteries need a constant-voltage charger?
This is a very different question, and using the wong method can be VERY DANGEROUS - incorrectly charged batteries can EXPLODE!