As PP's have said grab a fuelrod. The vending machines for them are everywhere. Then you can swap it out for free any time you need a fresh charge and you'll have it for future visits as well.
It is pricey but hey its a good option for you.
By the way, it looks like Disney has not updated their page in a bit. The kit now comes with a micro-USB adapter, a Type-C adapter, and an Apple Lightning adapter. It no longer comes with the older Apple 30-pin adapter or an RS232 serial cable.
Idk if this is too late but as the other posters have said, fuel rods are offered in the parks, they can be quite pricey but they're a good option. Some of the machines I know of are in the gift shop of the lower level at Polynesian and near the bathrooms outside of once upon a toy in Disney Springs.
I first saw a Fuel Rod kiosk in Fantasyland a couple years ago. Seems like I saw prices around $20 ... not sure the cost for recharged replacements.
But, if you fly down, lithium-ion batteries are not allowed in checked baggage. So be sure to put any devices with lithium batteries (phones, computers, tablets, batteries, etc.) in your carry-on.
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