Battery Power Supply

Battery holders and battery power supplies provide portable, cordless DC power for LED projects that need to go where wall outlets cannot.

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Battery holders and battery power supplies provide portable, cordless DC power for LED projects that need to go where wall outlets cannot. Model railroad rolling stock, wearable LED costumes, LED jewelry, holiday ornaments, science fair displays, portable prop lighting, geocache markers, LED throwies, and remote-location accent lighting all rely on battery power. Our selection includes holders for AA, AAA, and CR2032 coin cell batteries in various cell counts, giving you voltage options from 1.5V (single cell) to 12V (8-cell holders) and current capacities from the ~220mAh of a coin cell to the ~2500mAh of a quality AA alkaline.

Voltage options by cell count: The output voltage of a battery holder depends on the number of cells wired in series (each alkaline cell provides 1.5V nominal). A 2-cell holder (2xAA or 2xAAA) provides 3V — enough to directly power a single blue, green, white, or UV LED (which have a ~3.0–3.2V forward voltage) with little or no resistor needed, and enough to power red, orange, or yellow LEDs (~2.0V Vf) with a small resistor. A 3-cell holder provides 4.5V — a versatile voltage for small LED arrays with current-limiting resistors. A 4-cell holder provides 6V — matching our 6V pre-wired LEDs. Higher cell counts (6xAA = 9V, 8xAA = 12V) power longer runs of LEDs or match higher-voltage pre-wired LED products like our 9V and 12V pre-wired LEDs.

Coin cell holders (CR2032): CR2032 lithium coin cells (3V, ~220mAh) are the standard power source for ultra-compact, ultra-lightweight LED applications. A single CR2032 powers a blue, green, white, or UV LED directly (no resistor needed because the cell’s internal resistance limits current) and powers red/yellow LEDs with a small resistor. Coin cell holders are used for LED throwies (an LED taped directly to a coin cell with a magnet — the simplest possible LED project), miniature model lighting (model railroad rolling stock, architectural models, dollhouse fixtures), wearable LED accessories (earrings, pins, costume accents), greeting card LEDs, and geocache markers. Battery life depends on the LED’s current draw: a low-current (2–5mA) LED on a CR2032 runs for 40–100+ hours; a standard 20mA LED runs for about 10 hours.

AA vs. AAA cells: AA and AAA cells have the same 1.5V nominal voltage per cell but differ in capacity and physical size. A quality AA alkaline has approximately 2500mAh of capacity; an AAA has approximately 1000mAh. For the same LED load, AA batteries last 2.5 times longer than AAA. Choose AA holders when runtime matters and physical size is not the primary constraint — model railroad layout power, science fair displays, prop lighting for extended performances. Choose AAA holders when space and weight are limited — wearable costumes, small ornaments, lightweight portable fixtures. Rechargeable NiMH cells (AA: ~2000mAh, AAA: ~800mAh at 1.2V nominal) work in all of our holders and reduce long-term battery costs for frequently used LED projects.

Built-in switch options: Some of our battery holders include an integrated on/off slide switch, which eliminates the need for an external switch in the LED circuit. This is convenient for projects where the battery holder is accessible and you want simple, tool-free on/off control — holiday ornaments, display case lighting, portable props, and children’s projects. For projects where the switch needs to be mounted remotely from the battery holder (panel-mount toggle switches, pushbuttons, key switches), choose a holder without a built-in switch and wire an external switch from our switches and connectors category into the circuit.

Estimating battery life: Divide the battery capacity (in mAh) by the total LED current draw (in mA). A 2xAA pack (2500mAh) powering five 20mA LEDs in parallel (100mA total) lasts approximately 25 hours. A CR2032 (220mAh) powering one 5mA LED lasts approximately 44 hours. These are theoretical maximums — actual runtime is 10–20% less due to voltage dropoff at end of life (LEDs dim gradually as the battery voltage decreases below the ideal operating range). For the longest runtime, use the lowest LED current that provides acceptable brightness. Many indicator and accent lighting applications look fine at 5–10mA, which doubles or triples runtime compared to the standard 20mA drive current. Reduce current by increasing the resistor value.

Pair battery holders with our component LEDs, pre-wired LEDs (matched to the holder’s output voltage), resistors, and wire and connectors. For projects that start on battery power during prototyping but transition to permanent wall power, see our AC-to-DC power supplies — a 6V adapter replaces a 4xAA holder, a 9V adapter replaces a 9V battery or 6xAA holder, and a 12V adapter replaces an 8xAA holder. Use our LED Resistor Calculator to find the correct resistor for any battery voltage and LED combination. New to LEDs? Pre-wired LEDs are the easiest starting point — the resistor is already built in, so you just connect power and ground.

Frequently Asked Questions

Divide the battery capacity by the LED current. A 2xAA pack (2500mAh) powering a single 20mA LED lasts approximately 125 hours. Powering five LEDs at 20mA each (100mA total): about 25 hours. A CR2032 coin cell (220mAh) powering a single 20mA LED lasts about 11 hours; at 5mA (reduced brightness), about 44 hours. Actual runtime is 10–20% less than the calculated value because LEDs dim and effectively stop working before the battery is fully depleted.
In most cases, yes. A current-limiting resistor is needed whenever the battery voltage exceeds the LED’s forward voltage. The one common exception is a CR2032 coin cell (3V) powering a single blue, green, white, or UV LED (~3.0V forward voltage) — the cell’s high internal resistance naturally limits current to safe levels. For red/yellow LEDs on a coin cell (2.0V forward voltage), a small resistor is recommended. For AA/AAA holders at 3V or higher, always use a resistor. Pre-wired LEDs have the resistor built in.
The battery voltage must be higher than the LED’s forward voltage. Red, orange, and yellow LEDs need at least 2.0–2.2V — a 2xAA holder (3V) works well. Blue, green, white, and UV LEDs need at least 3.0–3.2V — a 2xAA holder (3V) works with minimal headroom, or a 3xAA holder (4.5V) gives more comfortable headroom for a resistor. For pre-wired LEDs, match the battery voltage to the pre-wired LED’s rated voltage (6V, 9V, or 12V).
Yes. NiMH rechargeable cells (AA: ~2000mAh at 1.2V; AAA: ~800mAh at 1.2V) fit standard battery holders. Note that NiMH cells are 1.2V per cell instead of 1.5V, so a 4xAA NiMH pack provides 4.8V instead of 6.0V. This slightly lower voltage reduces LED brightness marginally but is generally acceptable and saves money over hundreds of charge cycles. Recalculate your resistor value using the NiMH voltage if precision matters.
An LED throwie is the simplest possible LED circuit: a 5mm or 10mm LED pressed directly onto a CR2032 coin cell (3V), held in place with tape, often with a small magnet attached so it can be thrown onto metal surfaces. Blue, green, and white LEDs (3.0–3.2V forward voltage) work best — the coin cell’s internal resistance limits current naturally, so no resistor is needed. A throwie glows for 1–2 weeks on a single CR2032. They are popular for art installations, parties, and guerrilla lighting projects.
Yes. Replace the battery holder with a wall adapter that matches the battery voltage: a 6V adapter for a 4xAA holder, a 9V adapter for a 9V battery or 6xAA holder, or a 12V adapter for an 8xAA holder. Connect the adapter’s output to the same positive and negative points in the circuit. The resistor values and LED wiring stay the same because the voltage is the same. This is a common transition for LED projects that start as portable prototypes and become permanent installations.