Concur with Gahhhrrrlic.
A '12v 4A Plug' means very little to me, it could be anything.
Lithium batteries can and do explode very violently if you get the charging wrong, I narrowly escaped loosing my sight (and it could have been far worse) when one exploded in a large fireball a few years back.
If you want to charge a Lithium battery, buy a charger that is explicitly designed for the job, do not use random power supplies as a replacement.