On Jul 10 2018, at 12:30 am, Victor Odhner <email@example.com> wrote:
My wife has a tablet (Sansung SM-T530NU Nook) that can be charged in my truck. But it rejects every attempt to load from the Macbook via USB cable or BlueTooth — the devices see each other, but can’t quite get a connection.
Only remaining possibility seems to be a micro SD chip.
Many of the tablets do special negotiation on power, and the chargers and others expect that. I'd recommend having a USB condom in general, but in this case it'd probably also solve the negotiation problem. These are the ones I use.
Also there are many extended charge batteries provided by Anker which may work for your needs. I was looking at buying this one for my Dad who has a CPAP machine and would like to be able to camp. I imagine a smaller one would work depending on what you want.