Lithium and LED Life

[Harmless]

I've read that Lithium cells put out slightly higher voltage than alkaline cells. In theory, a LED that was designed for 3V could have a shorter life with 2 Lithium cells than 2 alkaline cells.

Anyone have an experience with unexpected burn-out of a LED using Lithium batteries, or is this risk theoretical only?

[MuddyWaters]

It depends on the led, and the light, and the battery.But pretty much...no for energizer lithium and a good led like cree xpg2

Your good lights will have current regulation circuitry so the light is constant, and not bright at first and dim as battery discharges. The downside to this is they go dead suddenly. Sometimes you turn one off and its too dead to turn back on.

But when it comes to the expensive real Li batteries, yes, they are much higher voltage and will shorten life if not used with a properly rated light. In some cases its heat that kills the circuitry, not the led. The AA size 14500 has 3.6 Vper cell.

[rafe]

As far as I know lithium cells aren't interchangeable with ordinary alkaline batteries or NiMH. Alkalines are around 1.5 volts nominal whereas lithium is around 3.7 volts.

[nsherry61]

Lithium AA and AAA batteries, now days, are specified to have 1.5 V just like AA and AAA alkaline batteries. Minor voltage differences between alkaline and lithium batteries in the past have been an issue with older batteries and LED lights, but these days, most all modern lights manage the input voltage just fine. Heck, my BlackDiamond Ion headlight came stock with lithium batteries in it.

[Starchild]

Lithium AA and AAA batteries, now days, are specified to have 1.5 V just like AA and AAA alkaline batteries. Minor voltage differences between alkaline and lithium batteries in the past have been an issue with older batteries and LED lights, but these days, most all modern lights manage the input voltage just fine. Heck, my BlackDiamond Ion headlight came stock with lithium batteries in it.

Not really, but there is the special case of Energizer Lithium batteries (and only them) that compete with Alkaline and have apx 1.5 volts and is commonly available. But there are many 3.7 V lithium batteries that are sized AA and AAA (mainly because it's a common form factor) available usually for industrial purposes.

[zelph]

Some info about LED's

Power sources[edit (https://en.wikipedia.org/w/index.php?title=Light-emitting_diode&action=edit&section=39)]

Main article: LED power sources (https://en.wikipedia.org/wiki/LED_power_sources)
The current–voltage characteristic of an LED is similar to other diodes, in that the current is dependent exponentially on the voltage (see Shockley diode equation (https://en.wikipedia.org/wiki/Shockley_diode_equation)). This means that a small change in voltage can cause a large change in current. If the applied voltage exceeds the LED's forward voltage drop by a small amount, the current rating may be exceeded by a large amount, potentially damaging or destroying the LED. The typical solution is to use constant-current (https://en.wikipedia.org/wiki/Constant_current) power supplies to keep the current below the LED's maximum current rating. Since most common power sources (batteries, mains) are constant-voltage sources, most LED fixtures must include a power converter, at least a current-limiting resistor. However, the high resistance of 3 V coin cells (https://en.wikipedia.org/wiki/Button_cell) combined with the high differential resistance of nitride-based LEDs makes it possible to power such an LED from such a coin cell without an external resistor.[123] (https://en.wikipedia.org/wiki/Light-emitting_diode#cite_note-123)

[Dogwood]

Have been using Energizer Lithium AAA batteries to power my various LED headlamps as a matter of choice for more than 6 yrs. Anecdotal, but I see no burning out of my LED headlamps doing this.