The battery holder/magazine with 8 newly charged eneloops is only putting out 5 volts. the light is less than a year old with a total of 3 hours run time.
I've tried different batteries , its not the batteries.
Should put out 5.6v on fresh ni-mh. The batteries are run 4s 2p so don't expect anything more than 5.6v (1.4v x 4). The battery carrier can't make that 0.6v disappear so it's either your batteries, charger or voltmeter.
As Jash said, its 4s 2p, so freshly charged and healthy nimh's would give you about 1.3x4 = 5.2v. Not very freshly charged or not healthy batteries would give you less than that.