Tricky start 2007 ML350
 

I recently received purchased a 2007 ML350. Lots of problems. My current problem is that now that it is cold out when I try to start it I turn the key and it will act like a bad battery. It may click or do nothing. If I immediately turn the key again it will start no problems. It shows no signs of dying while driving down the road. I have driven 15 to 20 miles several times no problem. The battery, engine off, tests at 12.5 volts. The alternator tests at 13.7c volts. I have not checked the battery connections yet. Is there anything I should be looking at? It occurred to me a locksmith made new keys for me and he got a code of terminal 30 not present procedure for establishing test preconditions. Again any ideas that could help me?