Extra battery attached to an amplifier and speaker

an auxiliary battery with an amplifier and speaker in a package a little bigger than a soda can. Inside the Charge is a rechargeable 6000 milliamp-hour (mAh) lithium-ion battery. Milliamphours are a measure of how much energy a battery can hold. Many smartphones have a 1400 mAh battery. By that measure, the Charge could refill a phone battery almost four times.

That battery gives the Charge the capacity to play music for 12 hours at a time, according to the manufacturer, Harman International Industries. At that rate, it would outlast the phone or tablet that it was connected to.

In a test, it easily connected to a phone using Bluetooth. The Charge also has a 3.5 mm jack for a wired connection, which slows the battery drain from the device providing the music. Behind the grille are two speakers, and at one end is a bass port to improve reproduction of deeper tones. The Charge produces a lot of volume for a 6-inch-tall music dock.

It is available in black, green and blue for $150 through JBL.com. Wi-Fi, and have downloaded the free app from iTunes. Originally a research initiative at Nokia, the project has been spun off as an independent company.

If the app is free, what’s the catch? The current library has only 26 books. The story-sharing requires that both parties have the app started on the iPad and have previously sent a friend request to each other by email.

The book and webcam images of both people appear on the screen, and either party can turn the page (although the actual page-turning can be slow).

I was able to share a New Jersey kindergarten teacher’s reading of “Peter Rabbit” with a group of educators in Utah. Not only could we see one another’s faces, we could easily converse.

The best part was that we could see a ghost image of the teacher’s hand when he was pointing at a picture or getting ready to turn a page.

Keeping costs down means stripping out all the frills. The tablet does come with a recent version of the Android operating system, Jellybean 4.1 (only Jellybean 4.2 is newer). That means you would get access to all of the Google services, like Gmail, Google Play, Google Now, Chrome, Maps and YouTube, as well as recent versions of thirdparty apps.

The tablet’s hardware is good, but streaming videos over Wi-Fi lagged a little. (The tablet is Wi-Fi only.) The screen has a subtle blue tint, which you probably won’t