The Ryobi inverter was on sale one day. Out of curiosity, I checked the reviews. No one had tried to use it as a mobile 18V vehicle charger. Ryobi does offer bigger Watt inverters. I wanted s small one to use under the hood. No more electrical cord to trip over. It was surprising to hear a small fan kick on to cool it internally. I guess the large Battery Tender does get close to the 1.25 A inverter capacity. Soon, I'll take the 700 mA battery tender off my '83 C10 and try it out. The smaller charge could probably work for hours off a 9 aH 18V battery.

__________________
'06 X5 3.0i - bought @143,123 miles (12/26/20)