Yesterday afternoon, I turned my 21 year old Chevy (Isuzu) 6.6 Liter Duramax Diesel into a plug-in hybrid.
Okay, not really.
I just became annoyed with the process of plugging in the block-heater during the sub-zero temperatures: kneel down in front of it, use both hands to carefully pull of the dust cap, plug in the extension cord. Then when I want to leave, use both hands to unplug the extension cord, then both hands again to put the dust cap back on the pigtail.
Too much effort.
The fix was to add a weather-resistant bulkhead power inlet. I can now — more easily, and single-handedly — just plug in the extension cord.
Future addition is to add a Battery Tender so it keeps the batteries in a peak state of charge.