There are two ways to power your Circuit Playground: you can use the USB connector to connect to a computer or portable USB power pack or you can plug in a battery pack. USB can be used to power and program. The battery connection can only be used for power - but it's great for when you want to take your Circuit Playground out into the world
This is the Battery Power Jack:
The technical specifications for the jack is:
JST PH type 2-pin connector Pin #1 Power and Pin #2 Ground
You can use this with any battery pack that can provide at least 3.5V DC and up to 6.5V DC. In particular it works really well with 3 x 1.5V batteries, like this 3 x AAA battery holder
Advanced users can connect up a single-cell rechargeable lithium ion or lithium polymer battery
Lithium Ion or Polymer batteries are more difficult to use and require much more care than rechargeable AAA's so we don't recommend them.
Circuit Playground does not have battery charging built in so no matter what rechargeable battery you have, you will need a separate charger as well.
Circuit Playground is designed for beginners so it has some protection and regulation circuitry so that it is flexible about how it is powered. In particular there is a polarity protection diode (to avoid destroying the board if you have a backwards-connected battery). It also has an onboard 3.3V Power Supply:
This means you can power it from anywhere between 3.5V up to 6.5V and it will automatically regulate it down to a clean 3.3V
Think of it like a barber. When you go to the hair salon, you have long uneven hair (just like the large, uneven power that is fed into the Circuit Playground from a battery pack). The stylist takes out the scissors and says OK how long do you want your hair? and you reply 3.3 inches long!
>snip snip< and your hair is cut straight off, leaving a very clean line.
Just make sure all of your hair, err... battery voltage is at least 3.5 Volts because the regulator needs some extra length to work with.
When powering Circuit Playground, you can draw at most 500 milliAmps of current. This is not a guarantee because you also have to make sure that the regulator doesn't overheat. If you're using some other voltage input, the max current you can pull continously is approximately
250 milliWatt / (Input Voltage - 0.3 - 3.3 V) = in milliAmps
So for 5V USB in, the max for continuous current is 250/(5-0.3-3.3) = 178 milliAmps
This is just a rough estimate and depends on if the power usage is continuous or just once in a while.