Most Helpful Customer Reviews
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99 of 101 people found the following review helpful:
5.0 out of 5 stars
Match those batteries with the correct application for best results, January 1, 2008
The Energizer L91 Lithium AA cell is a fantastic power source. For high-drain applications, it offers great advantages over ordinary alkaline cell and rechargeable NiMH cell. However, it is also very expensive as a disposable battery. So it is important to recognize the strength of L91, and use it only in applications that give you the best results. Otherwise you'll be wasting your money.
According to data sheet published by Energizer, the capacity of the Lithium AA cell (L91) is 3000mAh. This number remains nearly constant with load current. In comparison, the ordinary Alkaline battery (such as the Energizer E91 AA) is rated as 2800mAh, but only at a very light load of 25mA. At a heavy load of 1000mA (typical for a digital camera or flash unit), its capacity drops to below 1000mAh. This number gets even worse at low temperature. At zero degree C and 1000mA load, the L91 can provide about seven times more energy compared to the E91. This is where the marketing claim of "Last up to 7 times longer" comes from.
When used in a digital camera at room temperature of 25 degree C, the L91 is more likely to last 3-4 times longer than alkaline. This is enough to justify its price, which is also around 3-4 times higher than alkaline. However, in low-drain applications (such as smoke detector, wireless mouse or remote control) alkaline cells will last just as long at a fraction of the cost.
The L91 also contains much higher energy when compared to an ordinary rechargeable NiMH cell such as the Energizer NH15-2500. This is partially due to its higher terminal voltage of 1.5V, which is 20% higher than that for NiMH.
Energy stored in NH15-2500 : 2.5Ah * 1.25V = 3.125Wh,
Energy stored in L91 : 3Ah * 1.5V = 4.5Wh (44% higher).
Higher terminal voltage for L91 is especially advantageous in digital camera applications, because your camera flash will recharge up to 20% faster. An added benefit is that the L91 weighs only 14.5 grams (0.5 oz) each, compared to 30 grams (1 oz) for NiMH. So your camera becomes much lighter.
The NH15-2500, like all ordinary NiMH cells, suffers from rapid self-discharge problem. If you charge up a set of those cells and leave them in your camera for a few weeks, you're likely to be greeted by 'Low Battery' sign when you try to take a photo. The new generation of 'ready-to-use' NiMH cells such as SANYO eneloop and Rayovac Hybrid solved this problem by having very low self discharge rate. But they have lower capacity of only 2000-2100mAh.
Bottom line: If you need AA batteries for a long hiking trip, then L91 is obviously your best choice. For most other situations, I recommend using low self-discharge NiMH cells for lower operating cost.
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25 of 26 people found the following review helpful:
5.0 out of 5 stars
Lightweight power source for your survival kit and special applications, January 3, 2008
These are "niche" batteries. They weigh half their Alkaline and NiMh brothers, store more energy, work in very low temperatures, and sit on the shelf for a decade without losing their charge.
As everyday consumables they make no sense (for that, look into Eneloop rechargeables). But as the cells that power your emergency flashlight, your GPS on the Inka Trail, or your radio during a blackout, they are a godsend.
Note that the voltage of these cells is slightly higher than regular AA's. Therefore, some devices actually *won't work*, at least not when the cells are fresh and fully charged! For example, people have posted problems with Garmin's Gpsmap 60csx or some regulated LED flashlights. I'd recommend you check with the manufacturer and test your device with those cells before placing them in your survival kit.
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16 of 17 people found the following review helpful:
5.0 out of 5 stars
Best batteries are not without their caveats., July 31, 2006
Aside from the ludicrous pricing, Lithium cells do vent small amounts of gas when you use them. This is normal in case you smell something when you open your device. Don't inhale the gas.
Check out their web site and you will find not all devices run 7 times longer, it depends on the drain of the device. These batteries do NOT hold 7 times the mA power.
Let's put it in perspective. A typical Alkaline AA holds about 2565 mA of power. Though 1.5v is nominal, they actually measure 1.6v when fresh. Voltage naturally drops as you use the battery.
Lithium AA's hold about 2900 - 3000 mA. Again, 1.5v is nominal, but they measure about 1.7v - 1.8v. Lithium also has a naturally straighter discharge curve and sustains usable voltage for longer periods of time. This is partly due to Lithiums having a higher wattage capacity than Alkalines.
When an Alkaline measures 0.9v and heads for the dead zone, it may still hold 1/3 of its' power, or more. This goes to waste as most devices simply stop when the voltage drops too far. Lithium not only has a higher mA rating, but they sustain higher voltage for longer times, and thus, drain much more deeply.
In a low drain device, this appears to last 7x longer. In reality, Lithium AA holds about 20% more power than Alkaline, and thus you may only see +/- 20% of extended run time. All depends on the device.
While your AA Lithium will eventually die, you could probably get some more use out of it in a good LED flashlight - though at reduced light output. Don't drain them too deeply, or they can explode like any other battery. When you stop getting usable light, replace the batteries.
Their resistance to heat and cold and longer life make them ideal for vehicle emergency devices, such as flashlights.
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