Makita MAK-196810-2 36V to 18V Li-Ion Battery Adapter - Atlas-Machinery
Amazon.com: Power Wheel Adapter with Fuse & Switch, Secure Battery Adapter for Makita 18V Lithium Battery, with 12 Gauge Wire, Good Power Convertor for DIY Ride On Truck, Robotics, RC Toys and
Someone dug around Makita's new patents, found a 2x18V to 40V adapter : r/Tools