Brighter or not?

Just a general question. Do Lithium batteries make an LED shine brighter than Alkaline batteries? Or are they recommended just because they keep supplying power more consistently than Alkalines?

Generally speaking, lithium's are recommended because they aren't prone to leaking if left in a light for a long time. BTW, welcome to the forum!

If a light was designed to run on 1,5 Volt Alkaline or NiMH batteries, then yes, a light will shine brighter when using a 3,7 - 4,2 Volt Lithium Ion cell, because it is being "over driven". It may also destroy the light if it cannot handle the higher voltage. Many lights today are designed to run on a range of voltages; in case of Flashlights designed to run on an AA or AAA battery, they may accommodate voltages up to 4,2V. This way they are able to be driven by both an AA 1,5V Alkaline/NiMH OR a 3,7V 14500 Li-ion battery.

For lights that use 3V Lithium batteries such as CR123s, this is also true. But again, it is important not to use Li-Ion cells in lights that are not designed for them, as it may destroy the flashlight. When a light can accommodate Li-ions, the manufacturer will usually mention this.

In case of lights that run on multiple batteries, such as 2X CR123s (and are NOT designed to run on Li-Ions), it will always be safe to use a single Li-Ion 16650 or 18650. When used with this Li-Ion cell, the light will now usually shine LESS bright. This is because 2X CR123s will drive the light at roughly 6V compared to only up to 4,2V of the single Li-Ion cell. Many 2X CR123 Flashlights these days are designed to take both the 2X 3V lithium cells, as well as a 18650. In this case the light will usually archive higher brightness when used with the Li-Ion cell. This has to do with the electronics inside the flashlight, the higher capacity and drain of 18650s compared to CR123s, and current control circuits. The voltage is important when it comes to changes in brightness, not the battery chemistry. More Voltage = higher brightness OR a destroyed flashlight. Always inform yourself if it is safe to use higher voltage batteries in your particular flashlight.

I hope this helps.

Thanks, guys. Good info, and yes, it does help.

Oh, and thanks for the "welcome".

Chris C said:

Just a general question. Do Lithium batteries make an LED shine brighter than Alkaline batteries? Or are they recommended just because they keep supplying power more consistently than Alkalines?

Click to expand...

The answer is probably YES

But it really depends what your question is exactly.

By "Lithium" do you mean the AA or AAA silver Energizer Lithium batteries? Or are you meaning something like a CR123a Lithium or maybe even a Li-ion rechargeable battery?


There are several things to consider. Firstly the battery power and performance. And then how the light is designed to operate.


1. If we look at the battery first.

A normal Alkaline battery like a Duracell or lots of other makes. These have 1.5v (v for volts) when resting. This is true for AAA, AA, C or D cell sizes. The 'bigger' the battery, the longer it lasts, i.e. it has a higher capacity or mAh.

The trouble with alkaline batteries is, firstly they leak and ruin things, so should generally be avoided. But when you apply "load" to the battery, i.e. having a torch on, especially a high output mode. The voltage sags (gets lower). And they don't generally allow much current.

This means that very soon after turning a light on, the battery will sag and cause a performance drop. They also get considerably worse as they reduce capacity. This means for any 'high output' device, they perform really badly, such as torches, digital cameras, etc.


A Lithium battery like an Energizer Lithium is a direct replacement. They also make 1.5v but they key differences are, they don't leak. They don't mind the cold, they have a really long shelf life. But most importantly they allow more current and sag a lot less. This means you will generally get much better performance from these. More current in some lights could mean more output (depends on the light). And more stable voltage should give more consistent light for longer. So better runtimes. Sadly this isn't always true as some torch makers program their lights to not take advantage of this. But a lot do.

A good NiMH rechargeable AA/AAA is only 1.2v but exhibits potentially even better consistency, although ultimately less capacity. But will generally easily output perform an alkaline battery.


Something like a CR123a has 3.0v, so a lot more punch. Plus the good consistent current and little voltage sag. Although there isn't a direct alkaline alternative. So few lights will run on this or alkaline.


Li-ion is rechargeable. These have 4.2v, so considerably more punch. And again don't sag like alkalines. So these will generally offer a lot more light, but it does depend. The higher voltage can also fry torches not designed for 4.2v, so you need to know if your torch is compatible. However there are some torches that allow you to run 3 x AA or 1 x 26550 Li-ion, the latter is massively better.



2. Torches generally have 'drivers' that control the modes and output of a light. These can be boost drivers where the battery voltage is lower than needed, so the driver will need to pull current from the battery to make the LED work and feed it the correct voltage. There are buck drivers where the voltage is higher than needed and the driver will lower it down, but not need as much current normally. Efficiencies of these can vary wildly. Or you can get linear drivers which make about the right voltage from the battery for the LED. These will often allow the LED to be 'direct driven' from the battery. Which means it is all down to how the battery performs on how much light is produced.

Drivers can also be programmed to limit current, dim the light or step down. This can be after a period of time, thermal limits or even battery sag levels. So the answer isn't 100% unanimous for all situations. for example, Maglite (and I think Led Lenser) often program their lights to dim, to maximise performance on alkaline batteries. Putting a 1.5v Lithium AA in them will not improve performance, because the driver program will negate the benefits of the battery. But you may still experience better total run times and no leaks. So they are still worth it.

As you have read, your simple question involves complex answers.

Since this topic of "regulation" pops up periodically, I'll link up a couple of primers below, for those interested to read further ....

https://www.candlepowerforums.com/v...n-regulation&p=2632695&viewfull=1#post2632695

https://www.candlepowerforums.com/v...oost-and-PWM&p=2799081&viewfull=1#post2799081

Some history CD: op has a (direct drive) Coast HP7 and is struggling with Duracells not keeping up with demand.
It's not easy to get google to find old reviews that show the ole HP7 would dim dramatically as quickly as 30 seconds on duracells. Like you turn it on and literally watch it dim.

I bought eneloop pros for mine based on reviews back around 2015. They hold steady output for 10-20 minutes depending on whether using the 207 lumen version, the 251 or the 360. They actually perform better with the 360 lumen version.

Duracells in a Coast HP7 is like drinking a chocolate milkshake through a coffee stirrer. Yet they come with duracells installed. Nowadays I use my HP7 in short bursts of a few minutes at a time with Blue wrapper Rayovacs. Red wrapper (Fusion) work better but aren't as readily available as the blue kind. Ultimate lithiums being pricey are actually better but my experience with high drain aaa lights like a Coast HP7 is the Eneloop Pro is the best option. I have the 207,251 and 360 lumen versions. My favorite is the 251 version.

Chris C, if you have $20 burning a hole in your pocket a Maglite ML25 is a fine upgrade for the HP7. Better fuel mileage, regulated output and a great beam. Plus it's built in America.

I've got one of the old 4 D cell Maglights. Always liked it.................but it's kind of hard to slip into a coat pocket on a walk. The ML25 uses 2 C cells, but it's output is only 177 lumen. My Coast is 410 lumen.(and easily slips into my pocket) How is the Maglight an upgrade??? Besides, I have two Wsiiroon 1600 Lumen XML-T6 lights, so I'm not really looking to upgrade.
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Chris C said:

I've got one of the old 4 D cell Maglights. Always liked it.................but it's kind of hard to slip into a coat pocket on a walk. The ML25 uses 2 C cells, but it's output is only 177 lumen. My Coast is 410 lumen.(and easily slips into my pocket) How is the Maglight an upgrade??? Besides, I have two Wsiiroon 1600 Lumen XML-T6 lights, so I'm not really looking to upgrade.

Click to expand...

I quite like the Maglites as well as Led Lenser and I even have a Coast light (not very common in the UK). They can all be fun and usable. But they all massively under perform compared to what else is out there.

For instance a C8 has a similar sized reflector to a C cell Maglite, but is much smaller and lighter and runs on a single 18650 battery.

You can also get a huge array of different emitters. An XP-L HI will easily out throw the Maglites and with much higher lumen output.

Or if you want total lumens, there is an XHP50 C8 with well over 2000 lumens available.

C8's cost from $15-30 such as Convoy or Astrolux.