How hard would it be to make an adapter to charge my VHF Radio?..hmmmmmm
Most modern VHF radios use lithium ion batteries for their superior energy storage capacity. VHF’s 5 watt transmission power requires a large current capacity battery. Unlike NiMH or NiCAD, lithium ion will not accept a fast charge. You will need to turn that little crank for about 4 hours to charge up your typical modern VHF battery.
I think a flexible Brunton Solaroll or equivalent solar product is better suited for your intended purpose. The current need to charge the lithium ion battery is typically low but the charge time is long.
Lots of solar chargers/power supplies out on the web intended just for that purpose. They even have jackets with flexible solar panels sewed on to them with a storage cell built in and power jacks for cell phones or computers. Would what you pointed out work? … depends on the milliamp output compared to what is needed to recharge. Your charger should have the output marked on it.