# What is the truth about 1.5 V “lithium” cells?

At least one manufacturer out there is marketing "Lithium" cells in familiar AA and AAA sizes, as direct replacements for those standard 1.5 V sizes, boasting the typically better than alkaline longevity you'd expect from lithium.

But we all know the range of lithium technology cell voltage is expected to be 3 V for single use cells, up to a max of around 4.2 for li-Ion variations of rechargeable at max charge. All my attempts to research what the truth is (short of buying and cutting one open) have resulted in little more than manufacturers hype. Can anyone shed light on what is going on with these? A stretch to think perhaps they actually have embedded buck converters under the hood? Or has a genuine 1.5 V lithium technology actually been invented?

I've included one manufacturer's photo as a reference

• But in general, look for differences in the range of temperature of operation, usable discharge rates, self-discharge rates, energy density (by volume and/or mass), manufacturing costs, and shelf life. – jonk Dec 23 '16 at 17:58
• There are several 1.5V lithium battery chemistries. – Ignacio Vazquez-Abrams Dec 23 '16 at 19:10
• Sorry... I was trying to avoid the appearance of endorsing any manufacturer. Here's good reference photo though – Randy Dec 23 '16 at 20:19
• It's time for a good ole Christmas Battery Showdown – neonzeon Dec 25 '16 at 17:03
• @Randy, there is no need to avoid mentioning a particular manufacturer if you have a legitimate question regarding a product made by said manufacturer. As long as it isn't evident you're spamming, we're not going to think you're endorsing the manufacturer, nor are we going to flag your post as spam. – bwDraco Jan 3 '17 at 11:37

Lithium batteries come in many different chemistries, and it is the chemistry that governs the voltage. The most common chemistries are on the order of 3-4V, but there are chemistries which have a 1.5V terminal voltage.

The wiki page for Lithium batteries has a list of many different chemistries and their voltages. A Lithium anode with an Iron Disulphide cathode ($\mathrm{Li-FeS_2}$) is one such example of a 1.5V terminal voltage, and is the chemistry used in the AA replacement batteries as per the datasheet link on the Wiki page, and in @pjc50's answer.

• Yep. This is a lithium primary battery - meaning not rechargable. Very common to hear of lithium secondary batteries - the typical lithium-ion rechargeable you'll find in a phone, etc. It's easy to confuse the two, but they are completely different. These lithium primary batteries have great long-term storage, work well when very cold, and can put out a high current while having lower voltage drop over their life. Useful for emergency flashlights in your glove box, and high-draw gadgets like photo flashes. – Aaron Kondziela Dec 24 '16 at 18:41
• One other advantage of the lithium primary batteries - at least the brand I was using - is that they were lighter than the alkaline versions. When I was using a Nikon f5 SLR, which used 8 AAs, the weight saving was noticeable - especially when used with a flash that used another four. The higher capacity (longer in-use life) was also handy. – JerryTheC Dec 24 '16 at 19:40

Different chemistry: Lithium Iron Disulphide. Open circuit voltage of 1.8V, drops to about 1.5V under load.

If it is rechargeable Lithium 1.5V, one company with Chinese patent uses 3.7V Lipo with smart embedded buck converters into an AA/AAA cell to output 1.5V with a cost of about 5~10 cents per cycle.

Note the dual anode (+3.7,+1.5V) requires their special charger for 500~100 cycles with 80% DoD.

http://www.kentli.cn/product/show.php?id=1#

Bottom line.

Only use proven, documented reliable sources for batteries and capacitors.

Too many fly-by-night battery vendors should make anyone skeptical. This takes years of proven Quality track record with many initial failures.

Making a good battery with high Capacity, low ESR at low cost is hard.

It may worth investing in these to verify yourself.

• Thanks. I was only joking about the buck converter, but I'm amazed to find a company actually doing this. I looks like something I'd want to obtain just for curiosity! – Randy Dec 23 '16 at 20:21
• I too was surprised but as Lithium costs come down, this makes more sense. usually Alkaline at 10c except in impulse shelves by cashier then 2/\$1 or more. The 9V Lithium cells are best bet for portable gas/smoke detectors so it will last for years . – Sunnyskyguy EE75 Dec 23 '16 at 20:31
• Are you suggesting Energizer Holdings Inc, one of the largest battery manufacturers in the world operating for over 100 years is a fly by night operator? – Paul Uszak Dec 23 '16 at 21:55
• What made U think that? Nothing I wrote suggest they were; youtube.com/watch?v=7WWnY5PGYmQ – Sunnyskyguy EE75 Dec 23 '16 at 22:05
• @PaulUszak - the image of the Energizer batteries was added to the question in an edit after Tony wrote his answer. – Periata Breatta Dec 23 '16 at 23:07

The truth is that the Energizer lithiums are probably the best small batteries you can buy. And yes they are a direct replacement for standard pencil batteries. And no, they don't have little bucks inside them.

The AA type present 1.72V open circuit, and can source >4 amps shorted. They also work very well in extreme cold, although the standard advice is to keep them inside your clothing /sleeping bag. The only type I carry for survival gear. Expensive though. They top the list for total storage capacity but you pay for it. Good quality alkaline batteries are good for daily use and they can be bought in industrial bulk quantities (Duracell Procell). I would suggest that lithium only makes financial sense for survival /tactical situations like GPS or gun sights.

Life saving tip: Never use rechargeable anything in survival /tactical situations as they are very unreliable. You'll look really stupid in the middle of the Gobi desert trying to fix the buck converter in your dodgy rechargeable lithium batteries.

Update:

I've reviewed two relevant (and official) datasheets, one for the above lithiums and one for standard Energizer alkalines. I have to admit to being surprised as to the difference in capacity. I honestly thought that it would be greater.

So for lithium, we have:-

and for a standard alkaline, we have:-

You'll notice that Energizer cunningly have two different styles of graph. So conspiracy theorists might think that this is to obfuscate an easy comparison of capacities. Not me though. The only common discharge profile is at 100mA, giving capacities of ~3500mAh and ~2500mAh respectively. That's only an improvement of 40% over common alkaline chemistry.

Other interesting comparisons can be determined like (lithium v alkaline):-

Energy density: 233 mAh/g compared to 109 mAh/g (+114%)

Money density: 8.7 pence/g compared to 1.6 pence/g (+448%) - based on March 2018 Amazon(UK) prices.

• Yes... definitely very pricey. As a musician I've considered them for some of my wireless devices, where using an AC powered wall supply doesn't make sense. Currently they cost much more than their equivalent multiple cells to make up the same mA-hour rating. But my limited understanding of lithium chemistry had me wondering if the company used the word "lithium" as hype. Since it is apparently for real, I'm hopeful they'll get some competition. And that China made rechargeable that DOES have a buck converter looks very interesting too! – Randy Dec 24 '16 at 22:17
• @Randy you can get an idea of the cost per Ah (at 200mA discharge rate) – neonzeon Dec 25 '16 at 16:59
• @Paul Uszak - Where Lithium primaries really shine is at cold temperatures or high discharge rates, and that is why photographers use them -- they are likely to be using them a little colder (outside) and harder (charging the flash) than alkalines. The other major benefits being that they are much lighter, and also less likely to leak and ruin your expensive equipment. But at LOW discharge rates, you are right -- there is not as much benefit. I would still put one into my smoke detector for the longer life and the reliability (are not likely to leak as they get to end-of-life). – MicroservicesOnDDD Feb 19 at 14:17

This is a lithium-iron disulfide (Li-FeS2) battery. It is a primary (non-rechargeable) chemistry that is sometimes referred to as lithium metal; do not confuse these with rechargeable lithium-ion batteries.

It has a nominal voltage of 1.5V and an open-circuit voltage of 1.8V when new, making it a suitable replacement for alkaline batteries in many applications. The Li-FeS2 chemistry provides very long shelf life (up to 20 years) and long runtime under a variety of discharge conditions (especially under moderate to high drain). Most notably, it is far less affected by low temperatures than most other battery chemistries, capable of delivering nearly an order of magnitude longer runtime than alkaline batteries at 0 °C (32 °F), hence the "up to 9x longer lasting" claim, and can deliver near-full performance at subzero temperatures (-20 °C or lower) where other batteries would fail. It is also considerably lighter in weight than a comparable alkaline battery.

The main drawback is its significantly higher cost compared to alkaline batteries. This is due to the use of expensive lithium metal as well as complex physical construction more similar to that of rechargeable batteries than alkaline batteries. As such, it is best suited for applications where the device must continuously operate in a very cold environment, where the longest possible service life between replacements is required, or where battery replacement is inconvenient, such as in a smoke or carbon monoxide alarm.

For more technical information about these batteries, see Energizer's application manual.

• yes, great batteries. And they never leak and ruin your nice led flashlight like alkalines often do. – electrogas Mar 17 '18 at 3:05

About non-rechargeable lithium batteries, is a matter of chemistry: the Energizer you posted are Li-FeS2 with a voltage of 1.8 V (1.5 V under load).

Reference: Energizer Ultimate Lithium AAA (L92)

The rechargeable version of Kentli is the well-known 3.7 V Li-Po version with an internal circuit. Take care that the capacity in the specification is measured in mWh and not in the usual mAh, probably a "commercial" trick - because mWh is greater than mAh. Those batteries needs a specific charger.

Reference: Kentli AA 2800mWh (Blue)

The new lithium poly batteries are GREAT. You can get them in AAA, AA. C, D all at 1.5/1.6V and the PP3 at 9V. Using a 5v source (USB) to charge a 3.7v battery inside and then using either buck or boost converter to produce the 1.5V/9V up to a specified current. The output voltage is constant (zero Output resistance) throughout the discharge cycle but suddenly switches off at the end of discharge. The perfect battery? The efficiency must be good as it doesn't seem to get warm during either charge or discharge.

The only drawback is the price (e.g. £7.50 per PP3) but with up to 3000 charge cycles it only works out at 0.25p per battery (i.e per discharge cycle).

!'m sure the price will come down in time.

Dingus

• Yes, but that's not what is shown in the question. – Ignacio Vazquez-Abrams May 26 '17 at 15:46