Different battery types have different output voltages…a function of their internal chemistry. Among common household batteries — the kinds you might find at the grocery store — there are two major types:
Rechargeable nickel metal hydride (NiMH) cells output 1.2 Volts, as do nickel cadmium (NiCd) cells. The latter have fallen out of favor for a number of reasons, but maybe you still have a few around the house.

These cells are more expensive up front, and require a charger. But for frequent use, they can be more economical in the long run.
Single-use, disposable alkaline cells output 1.5 Volts.

Though not reusable, for occasional use they may be more economical. But the main benefit is their ubiquity — replacements can be bought almost anywhere, important when you’re away from home and a charger.
(We’re using approximate numbers here. Actual output will vary by some fraction of a volt depending on the cell’s age, state of discharge, temperature and other factors. For most casual projects, these small factors can be ignored for simplicity’s sake.)
When cells are wired in series (joined end to end, as when installed in our 4X AA battery holder), add up the voltages to determine the total output:
4 NiMH cells = 4.8 Volts total. That’s right in our target voltage range, making it perfect for the LED strips! If you’re using rechargeables, the 4 cell holder can be used directly to power your project.
4 alkaline cells = 6.0 Volts total. Uh oh…that's too much! If connected directly to an LED strip, this will burn it out. Fortunately, there’s an easy workaround…

This guide was first published on Jul 29, 2012. It was last updated on Jul 29, 2012.

This page (About Batteries) was last updated on Jul 24, 2012.

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