It's just an opinion but I agree with BFL. I have a 3 way and twice it has run the battery too low, once when I ran out of LP and once when I forgot to turn the LP on. It automatically switches to 12V with no notification indication.
Yes, I know who's fault it was. Could be mental acuity. Maybe it will never happen as you're alot sharper than me, but...
The point is, if it didn't have the 12V option it would have stopped cooling and the alarm would start telling me the burner was out rather than waiting until the battery was too low to sound the alarm.
Once that happens, it's too low to crank the generator without a jump unless it can be plugged in.
If we didn't hear the alarm, the temperature would have started to increase but I'd rather loose some food than run the battery too low. That's maybe $25 versus $200 for batteries.
