Performance test

We’ve had this lantern for many years. It used to have a fluorescent tube and was powered by a lead acid rechargeable battery.
Performance was ordinary at best and whenever needed the battery seemed to be flat.
I had a 12v NiMH battery pack from an old car vacuum cleaner, a 12v led bulb (from the trailer tent) and bought a bulb holder.
Put it all together yesterday and after an overnight charge it is on test. So far it has been on over two hours. Could be a result!