Most Helpful Customer Reviews
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91 of 92 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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23 of 23 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 test your device with those cells before placing it in your survival kit or backpacking in Peru.
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22 of 23 people found the following review helpful:
5.0 out of 5 stars
More reliable than rechargables, July 12, 2007
I've found that rechargable batteries don't hold the charge very long--if my digital camera stays in my backpack with no shooting for several weeks, I can't depend on them. Regular alkaline batteries hold their charge but get used up quickly with a lot of heavy use like zooming, viewing pictures, etc. Li batteries seem to last months and months in terms of both holding their charge and surviving through heavy use. Also, I've read (don't know for sure) that Li batteries can function in wider extremes of temperature than alkaline.
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