Need some help
 

As I said in a ealier thread I got this Pro mast l120 light and its pretty good I cant get my new lights until the end of the year so I need to make it last a bit. I am having a weird problem though. when I got it I put in batteries (energizers from one of those big packs) I went in my first job and it was great I went on my second job with it and it was great I started to wonder how long the batteries would hold out so I changed them with 4 others from the same pack. now after a few minutes the light starts to flicker so I tried other batteries from that same pack and I got the same results I tested all the batteries they were reading 1.6 volts or more the ones I took out were rading 1.35 ish I put them back in and its fine. I know sooner or later those batteries will die and im going to have to deal with this. Any ideas???