Your better off getting a spare battery or two. Charging an e-bike battery from a Jackery or similar, even a 1000 or 1500 will drain nearly your entire battery. Personally I would invest in either solar panels or portable generator, something small like a 1000w or 1500w, which will likely weigh less than a 1500 Jackery. That way you can have that running and charging the spare battery, leaving you the ability to get out and enjoy yourself while it's charging.