Cold weather no start
I have a 2006 CLS55 AMG. It is currently -10 F outside and my car does not want to start. It will crank but not turn over. My battery voltage is a bit low at 11.9 volts when the car is off. If I can get it to finally turn over (most days it won't start) the voltage is 13.9 and I get the "low battery conven functions temporarily unavailable" error for a few minutes. If I leave the battery on a tender that car will start up without issue. The car only has this issue when the temperature is below 15 F. Anything warmer than 15 F and it starts beautifully.
I replaced my alternator, crank position sensor, starter, and both batteries over the summer. I have had both batteries tested multiple times at different places and they are good.
I am not sure where to start troubleshooting from here. Could there be a parasitic draw? Should I get a better battery designed for cold weather? I do not think it is fuel related. I have good pressure at the rails.
Any suggestions/input would be appreciated. Thanks!





