Left the D26-1600 running with a camera on it. This time it ran for almost 3 hours. When the indicator started flashing red (less than 5%) I turned it off, took out the battery and check the voltage. The battery was at 2.98V. The specs for the light say it needs 2.75V minimum. So everything seems to make sense.
However, my camera died and I only captured 44 seconds. So I put a new battery in the D26-1600, put a new battery in the camera, turned the light on and within seconds, the indicator starts flashing red. It is a fully charged, new battery. I pull the battery and check it with the volt meter. It is fine.
So occasionally the light works fine but most the time it turns off in minutes, some times seconds. I'd hate to be using this on a dive and have it start failing 5 minutes into the dive.
I might have thought it was the batteries I'm using but I can take the failing battery from the D26-1600, put it in my D26 Whale and it works fine.
I've send a message off to my contact at XTAR to see if she can get me in touch with someone in support. Right now the light has worked once correctly. All other times it fails to keep working within minutes. I'm DEFINITELY not using this light until someone can explain what is happening and how to fix it.
EDIT:
I charged a battery to 100%, put it in the D26-1600, turned on the camera. Turned on the D26-1600. Let it run. Within 2 minutes the D26-1600 turned off. I review the camera and it ran for a total of 1:38. I took the battery out of the D26-1600, put it in my D26 Whale, turned on the camera, turned on the D26 Whale. After 15 minutes the D26 Whale is still running at full brightness (1100 lumens, I believe). This is the same battery which will not even turn on the D26-1600.
Next attempt will be to take the battery used when the D26-1600 ran for almost 3 hours. I'm charging this battery right now. Once it is fully charged, I'll try it in the D26-1600 again. Maybe only that one battery works with the D26-1600. Still a problem for me, all the batteries work fine in the D26 Whale. Why don't they work in the D26-1600?