Rating batteries

[alpineranger]

For a long time I've thought that rating non-recharagable batters in terms of mAH would be a great idea. I've seen battery reports in Consumer Reports (yeah, I know, ugh, but no one else seems to do ratings like that), and I was very unsatisfied with the way they conducted the tests. A nice numerical result would make a lot more sense to me. Perhpas there is some reason why people don't do these sort of tests, but I can't think of why not.

 

[gopunk]

mah is a bad indicator in the first place, but even worse for different battery types. an nimh batt of 1200 would take more photos than an alkaline of 2800, because alkalines only deliver a small fraction of rated capacity when powering high drain devices.

 

[RossMAN]

Here is a great rechargeable battery review which is definitely bookmark worthy.

 

[Jerboy]

Both Duracell and Everready have ALL their batteries rated in mAh.

 

[sharkeeper]

All batteries are rated in ampere hours. The ratings are misleading because the ratings are often at the 1/10 or even 1/20C rating. This means dividing the rating by 10 or 20 for your continuous draw respectively. This works with constant loads at low currents. Most primary (meaning non rechargeable) cells have much higher internal impedance than secondary (rechargeable) cells. Also, most primary cells will increase in impedance faster when discharged heavily. The impedance will drop back down with a rest period. This is why your alkaline powered flashlight will be bright in the morning after a long night's use. Most secondary cells (Pb and Li are 2/3 respectively) have a lower voltage (1.2 volts vs. 1.5 volts) per cell but the voltage is much more "flat" across the life of the charge. Alkalines have a sloping voltage discharge characteristic.

What this boils down to is a 1000 mAh nimh battery can often give more useful life per charge than a 1500 mAh alkaline. As long as the device is designed to run on the lower starting voltage, you should be ok.

Cheers!