On Jul 10 2018, at 12:30 am, Victor Odhner 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. https://smile.amazon.com/PortaPow-3rd-Data-Blocker-Pack/dp/B00T0DW3F8/ (https://link.getmailspring.com/link/1531227692.local-5b3fbd6e-e96b-v1.2.2-96fb3a99@getmailspring.com/0?redirect=https%3A%2F%2Fsmile.amazon.com%2FPortaPow-3rd-Data-Blocker-Pack%2Fdp%2FB00T0DW3F8%2F&recipient=cGx1Zy1kaXNjdXNzQGxpc3RzLnBoeGxpbnV4Lm9yZw%3D%3D) 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. https://www.anker.com/deals/powerhouse2 (https://link.getmailspring.com/link/1531227692.local-5b3fbd6e-e96b-v1.2.2-96fb3a99@getmailspring.com/1?redirect=https%3A%2F%2Fwww.anker.com%2Fdeals%2Fpowerhouse2&recipient=cGx1Zy1kaXNjdXNzQGxpc3RzLnBoeGxpbnV4Lm9yZw%3D%3D) Ted