I have a dual -3500 setup in my RV-7A. Normally they work great. But on very cold days when I start the plane, the AFS screens will not turn on - no sign of life whatsoever. Do you know why this happens?

Above roughly -5 deg Celsius both screens always work great. Below -15 deg Celsius both screens are always dead. In between (which is normal for the entire winter here!) it is anyone's guess - in fact sometimes one screen will work but not the other.

Is there any way to improve the cold weather performance? e.g. will a new efis battery help? Or would an upgrade to -4500 eliminate the problem component(s)? Pre-heating the cabin works fine, but that luxury is often not available when we travel.

As much as I love my AFS units, it is hard to recommend them to any other local builders when I know they won't even turn on 3 months per year! Would love to see this fixed!

Thanks!