Most of my author friends go to conventions to be on panels and to sell books to people they meet. Some sell books using a cash-only approach, while others use phone-based credit and debit card devices to accept payments.
Getting 120v power to your booth can range from free to twenty bucks for the con to several hundred dollars for the duration of the event.
I just found out — most conventions do not accept the most common form of author and artist payment, better known as “exposure”. Imagine my surprise!
Because of the proximity of tens of thousands of cell phones for huge Comic Con-type events, your cell has to shout to be heard by the tower. This means your cell is typically running at the highest transmitting power it has available. No wonder your poor cell runs out of juice six hours into the first day!
There are two general methods I use when running a booth. The first is to use a small booster battery that you can find for around fifteen bucks or less. I have four of them with an octopus cable that allows them to recharge Apple (Lightning and the old style), Mini-USB, and Micro-USB. This covers most of the phones in the booth.
These small battery boosters are good for around one full recharge and maybe a quarter additional charge if you’re lucky.
The other (and best) way to handle keeping all the cell phones in the booth fully operational is to invest in a large external battery, something that can pull double duty if you left your headlights on in your car.
The image above is an inexpensive car battery emergency jumpstarter kit. This one is from Harbor Freight. I have an older type, but it’s basically the same thing.
The battery in this beast is good enough to charge your phones, cameras, or any other portable devices and still have plenty of juice to crank over an old Pontiac engine a few times. This newer model shown above already comes with a built-in USB port. Just plug in your cable and charge your device. The older one I have does not have a USB port, but it does have a nice 12v cigarette lighter-style power outlet, and I popped in a two-port USB charging unit that is normally used in cars. This kept all of the phones purring throughout big conventions like Denver Comic Con and Salt Lake Comic Con.
As a bonus, in case the power goes out, there is a built-in flashlight that can run for hours and hours. When it needs to be recharged, these battery jumpstarters come with a cable that plugs into a regular outlet.
This is the setup that I recommend for folks who go to lots of conventions. The vendors on either side of you will appreciate the help if their cell dies, and your author friends will be happy there is a safe place for them to recharge their phones without leaving it against the wall of a panel room. Plenty of kudos and good karma to go around!