ORIGINAL: speedster 1919
That way still sounds iffy.........So to play it safe I went to Harbor Freight and bought a 110v converter and pluged in my Hangar 9 wall field battery charger. Seams to work OK. The inverter is suppose to shut off if car batt gets to low. Funny but my cig plugs only works when van is running......... Also I checked the price of the inverter off the net from Harbor Frieght and it was $19.95 at the store it was $29.95. I asked why the big difference in price and was told I was paying for the store front. But I could go home order and pay the frieght for $19.95.
So you take 13.8 volts DC from the automotive system convert it to 120 VAC and then convert it back down to 13.8 volts VDC.
[
] Sometimes it helps to think about what you are doing. Again I say the field box battery doesn't know where it getting its voltage from and doesn't care.
John