The "guts" of a standard 9V battery
Have you ever wondered what is inside the familiar 9-volt battery (often
referred to as a "transistor radio battery" in the last century)? I have read about there
being AAAA cells (that's right, quadruple−A, A-A-A-A), but wanted to see for myself. So, I used a small
screwdriver and a pair of pliers to remove the outer metal case. This first picture shows
the six AAAA cells bundled together and contained with heat-shrink tubing.
In the bottom photo, you can see that all six AAAA cells are connected in series. Each
individual cell is 1.5 volts, so 6 x 1.5 = 9.0 volts.
For a size comparison, a standard triple-A (AAA) cell is shown next to one of the AAAA
Here are the specifications for the Duracell Ultra 9V battery:
Battery Capacity: 550 mAh
Battery Technology: Alkaline (Single Use)
Depth: 17.0 mm
Height: 48.5 mm
Voltage: 9.00 V
Since the cells are connected in series, than means the overall current rating for the
battery assembly is the same for each AAAA cell. So, each AAAA cell is rated at 2.1 amps with
an energy capacity of 550 mAh (milliamp-hours).
Prior to the advent of miniature wireless devices like Bluetooth headsets, wireless mice,
stereo remote controls, etc., almost nobody had ever even seen a AAAA cell. Still, probably
the vast majority of people do not know that the familiar, ubiquitous 9V battery is composed
of six of them.
Now you know.
Posted March 14, 2023
(updated from original post on
Related Pages on RF Cafe:
or Li-Poly Battery Characteristics
Inside a 9-Volt Battery
How Many AA Batteries Would to Take to Power a Human?
- Ray-O-Vac Ad, August 25, 1945, Saturday Evening Post