Answer: In general, the answer to this question is "No", but this answer requires a little more information, so you can better understand the possible consequences of using a wall power adapter with a different output voltage. The voltage required by the electronic device can be determined by the number of batteries it takes. Each battery generates a voltage of 1.5VDC, so to determine the required voltage, simply multiply 1.5VDC by the number of batteries (batteries are connected in "series"). This procedure is valid for electronic devices that use AAA, AA, C and D size alkaline batteries. The graphic below illustrates the series connections and voltages for 1, 2, 3, 4 and 6 batteries. As an example, suppose you have an electronic device that uses 3 x D batteries. The voltage required by the electronic device is 3 x 1.5VDC = 4.5VDC which means you would need a wall power adapter that generates 4.5VDC. Almost all battery powered electronic devices are designed to operate at voltages slightly higher than 4.5VDC and substantially lower than 4.5VDC. A good rule of thumb for the high-end operating voltage is to add 20%, so for this example, multiply 4.5VDC by 1.2 (20% higher); therefore, the high-end operating voltage is 1.2 x 4.5VDC = 5.4VDC. This means that electronic devices that use 3 x alkaline batteries will operate from wall power adapters that generate output voltages of 5VDC which is the same voltage supplied by USB power sources. The low-end operating voltage for battery powered electronic devices is determined by multiplying the battery's end-of-life voltage (voltage when it's considered dead) by the number of batteries used. Almost all AAA, AA, C and D size alkaline batteries have an end-of-life voltage of about 0.75VDC, so most electronic devices are designed to operate at a slightly higher low-end operating voltage of about 0.8VDC per battery. A couple of graphs illustrating the typical discharge curves for a AA cell alkaline battery can be seen below. Notice that when the battery is new, its open-circuit (no-load) voltage can be as high as 1.65VDC to 1.75VDC, and at the end of its useful life, it has discharged down to about 0.8VDC. The typical discharge curves shown below are for AA cell alkaline batteries for constant load currents of 5mA up to 1000mA. For an electronic device that uses 3 x alkaline batteries, the low-end operating voltage is 3 x 0.8V = 2.4VDC. Even though a 3-cell battery powered electronic device might work at voltages this low, you really don't want to use a wall power adapter that generates 2.4VDC, 3.0VDC or even 3.3VDC because the electronic device might exhibit undesirable behavior such as reduced brightness, slower speeds, lower volumes, etc. It's best to select a wall power adapter that supplies an output voltage close to the high-end operating voltage which was determined in this example to be between 4.5VDC and 5.4VDC, so a wall power adapter that supplies 4.5VDC or 5VDC would be a good choice. Some electronic devices may actually have internal circuitry that disables the electronics in the event that the input voltage is too high or too low. This is done in order to protect the electronics from potential damage caused by attempting to operate at voltages outside of its operational range. Also, you want to avoid using a wall power adapter that has an output voltage greater than the device's high-end operating voltage because the internal circuitry may be damaged or even permanently destroyed. The table below summarizes the voltages and recommended wall power adapter output voltages for 1, 2, 3, 4 and 6 alkaline batteries (AAA, AA, C and D sizes).


Typical AA Alkaline Battery Discharge Curves (Voltage vs. Time) for Various Constant Load Currents from 5mA up to 1000mA

Graphic Illustrating Series Connections for 1, 2, 3, 4 and 6 Alkaline Batteries (AAA, AA, C & D Sizes)


Table Summarizing Voltages & Recommended Wall Power Adapters for 1, 2, 3, 4 & 6 Alkaline Batteries (AAA, AA, C & D Sizes)