Lighting issue

Hi everyone. I have an Arctic Cat 400 VP. Recently it has developed some kind of lighting issue. When I turned on the lights the other day it took about 2 or 3 minutes for the machine to die. I thought maybe it was a dead cell in the battery so I bought a new one. Again I went for a ride at night and turned the lights on and again the machine died but it took a little longer with the new battery. What I have done so far is check all the fuses, removed the negative wire and checked with a test light to see if there is a short with the ignition off and I metered the battery with the key off and key on. With the key off it registered 9.87 volts and when I started the machine it dropped to 6.93 volts. Can I meter the charging system somehow? I might add the machine is still under warranty but I really dont want to lose it for 2 or 3 weeks during this spring and summer season. Cheers Daniel