Overview
This covered box holds four AA cells and delivers their combined voltage through red and black wire leads, with a built-in on/off switch so you can cut power without pulling a battery. It is the classic portable supply for small robots, servo projects, and anything that needs more than a coin cell but less fuss than a lithium pack.
With the cells in series, four alkaline AAs give about 6 V and four NiMH rechargeables about 4.8 V. That 4.8–6 V window is what hobby servos and small DC gear motors are built for, and it suits the 5V/VIN input of most ESP32 dev boards. It is a less comfortable match for a 5 V Arduino or a Raspberry Pi Pico, which is where this manual spends most of its time.
The holder has no regulator, fuse, or reverse-polarity protection, and it does not charge batteries. Confirm polarity and voltage with a multimeter before the first connection — the supplier leaves that check to you.
At a Glance
Specifications
| Parameter | Value |
| Cell format | 4 × AA (alkaline, NiMH, or lithium primary) — not included |
| Cell arrangement | Four cells in series (typical for two-lead holders — confirm with a meter) |
| Output, alkaline | About 6.0 V nominal, a little higher when fresh |
| Output, NiMH rechargeable | About 4.8 V nominal, a little higher straight off the charger |
| Output, lithium primary | About 6.0 V nominal; up to about 7.2 V open-circuit when new |
| Do not fit | 14500 lithium-ion cells (3.6–3.7 V each, about 14.8 V total) |
| Switch | Built-in on/off switch |
| Leads | Red and black wire leads |
| Enclosure | Covered box with removable cover |
| Dimensions | Not published |
| Current rating | Not published — plan for modest loads and measure the voltage under load |
| Protection | None: no fuse, regulator, charging, or reverse-polarity protection |
Wiring Guide
Check the pack before it meets a board. Fit four cells following the + and − marks in each bay, switch on, and measure across the bare lead ends with a multimeter: the red lead should read positive, and the voltage should match four cells in series (about 6 V alkaline, about 4.8 V NiMH). Only then connect it — the right pin depends on that reading.
Arduino Uno and Nano
Which pin you use depends on the cells. The 5V pin bypasses the regulator and must stay at or below 5.5 V; VIN goes through the regulator, which is recommended for 7–12 V and needs headroom above 5 V.
| Cells Fitted | Connect To | Result |
|---|---|---|
| 4 × NiMH (about 4.8 V) | Red → 5V pin, black → GND | Works well once the pack reads 5.5 V or less — freshly charged cells can start slightly higher |
| 4 × alkaline (about 6 V) | Red → VIN, black → GND | Runs light sketches, but 6 V is below Arduino’s 7–12 V range, so expect resets as the cells sag |
| Any cells through a 5 V regulator module | Regulator output → 5V pin, GND → GND | The most reliable option for alkaline cells |
ESP32 Dev Boards
Most ESP32 dev boards step their 5V/VIN pin down to 3.3 V with a small linear regulator that needs a little over 1 V of headroom, which makes a 4×AA pack a good match.
| Holder Lead | ESP32 Pin | Notes |
|---|---|---|
| Red (+) | 5V / VIN | Needs roughly 4.6 V or more at the pin for a stable 3.3 V rail |
| Black (−) | GND | Common ground |
Raspberry Pi (Regulator Required)
Raspberry Pi computers need a stable 5 V supply. A 4×AA pack is above that when fresh and sags under load, so it cannot be wired straight to the board.
| Option | How | Notes |
|---|---|---|
| 5 V regulator module | Pack → regulator → the Pi’s 5 V input | Check the regulator’s current rating against your Pi model |
| USB power bank | Plug into the Pi’s power port | The simplest portable supply for a Pi |
| Raspberry Pi Pico | See the Pico tab | Needs far less power than a Pi computer |
Raspberry Pi Pico
VSYS accepts 1.8 V to 5.5 V. Four alkaline cells start above 6 V, so this pack needs a little help before it meets a Pico.
| Cells Fitted | Connection | Notes |
|---|---|---|
| 4 × NiMH | Red → Schottky diode → VSYS (pin 39), black → GND (pin 38) | The diode drop brings a freshly charged pack down toward the 5.5 V limit — measure to confirm |
| 4 × alkaline or lithium | Pack → 5 V or 3.3 V regulator → VSYS | A fresh pack is over 6 V: too high for VSYS, even through a diode |
| A smaller pack | A 2×AA or 3×AA holder directly on VSYS | The Pico datasheet names three AA cells as a good fit |
