All batteries put out the voltage that they say they do when they are new but some put out the voltage for a longer period of time before it begins to taper off. Your detector goes "dead" from used up batteries because the voltage of the battery pack falls below the lowest level the detector can operate on.
The lowest voltage the detector can operate on is determined by the Voltage regulator, a chip in the detector's circuitry. Typically they are 8 volts, so the power from your battery pack may put out 12v to the detector and the regulator slows it down to the 8 Volts that the detector uses.
As you are humming along in the field your battery pack will be above 12v. when it is fresh and some hours later (the mfg usually states how long) the batteries get used up and getts near 8 Volts and the detector shuts off or loses performance.
Disposeable:
If you use disposables get Alkaline. Don't fall for "Heavy duty" or any other wording, as long as it says alkaline those are the best because they will stay at there voltage longer than cheaper batteries.
Brand names make no difference in batteries as long as you are buying Alkaline. So skip the Duracell and go for the dollar store.
Rechargeables:
Recharge-ables are what I use. They put out less voltage 1.2 Volts instead of 1.5 volts like alkalines,
but you can recharge them up to 1000 times. Typically a re-chargeable will have 1.3 volts when it is a fresh charge and 1.3v x 8 batteries ( in a White's and Minelab pack) is 10.4 volts which is way more than the 8 volts a detector requires.
The rechargeable batteries will put out that 10 Volts until they finally go dead.
The MAH rating on recharge-ables determines how long they will last
The higher number the better. 2600 mah is fantastic Lets say a detector runs on 200 Milli-amps ( which is a total battery hog) Than take 2600 and divide by 200 and you get 13 hours of use.
As long as you keep them charge you wont lose any performance IMO, plus you can save about $700 by using them
I hunt in the park so if I was hiking in gold country which is completely different I would go with those dispose-able Lithium batteries
because they are light weight and really do last 8x longer. for 3x the price.
I am no expert but have looked into this stuff for a while and use rechargeable 90% of the time.
If I was going where power for days on end really mattered I would spend the money and buy those dispose able lithium.
Alkalines that can be picked up for a rock bottom price are a great deal (completely ignore brand name)
Batteries that say Heany duty, or long lasting are crap unless they specifically say Alkaline on them[size=medium][size=large][size=medium][/size][/size][/size]
The Guy in the article on the link you gave IS basing an important opinion on only one example. His batteries where defective, or old or maybe he left his new machine on overnight. I wouldn't run out to buy panasonic industrials after reading it either, but I wouldn't be buying four packs of Enigizers for $7 with out looking for much cheaper alternatives.
