For those whose thoughts about external batteries go beyond simply recharging a cell phone, the market is offering some interesting options. In the past, I've written about the Vagabond mini AC inverter, a device about the size of a brick that can supply about 100 Whr (that is, 100W for about one hour or 20W for about 5 hours, etc.) of wall-plug quality AC power: http://forum.tabletpcreview.com/threads/vagabond-mini-self-powered-ac-inverter-user-review.56197/ For TVs, laptops, tablets and even small appliances, the compact Vagabond can supply enough power to provide multiple rechargings or a few hours of operation in the wild. You can even swap out the battery with a fresh one to extend the period of operation But time moves on, and at this year's CES, Anker introduced the PowerHouse 200 (200Whr) portable battery with multiple power taps (USB, USB-PD, 12V power socket and AC, likely modified sine wave(?)): https://liliputing.com/2018/01/anke...sive-battery-that-charges-all-the-things.html (Courtesy of liliputing site) The PowerHouse 200 has a bigger brother, the Anker PowerHouse with 400+ Whr of capacity. I've never used an Anker product, but they seem to have a solid following and I have no doubt that they make a good product. However, this brought to mind a brand that I do have experience with, Goal Zero. Goal Zero makes a line of portable / outdoor power products including portable batteries, solar panels (to recharge in the wild) and light products including a slick flashlight, the Torch 250, that should be in everyone's glove compartment. In particular, Goal Zero makes the Yeti 150 and the Yeti 400 and 400 Lithium (150 Whr, 400 Whr and 430 Whr respectively) which are somewhat equivalent to the Anker products: http://www.goalzero.com/?gclid=EAIaIQobChMImLPUgf_L2AIV2BWBCh361QPrEAAYASAAEgLZpPD_BwE I can say that the Goal Zero products are well designed and the 400 and 400 Li feature true sine wave AC whereas the Anker products appear to be modified sine wave AC (see my Vagabond write-up for an explanation of this). Now, all of these products are large, heavy and expensive, but if you need portable power these are options that didn't exist just a few years ago. And it's nice to have options...!