OK, not sure if this belongs here but here goes.
I bought a bunch of rechargeable batteries for my 396xt, and noticed that they all have different mAh designations. I have 2600, 2500 RS, 2250 came w/scanner, and 1900 costco. All batteries are 1.2V. My question, is there a differance in the use times, charge times or length of life in the different numbers? Can they all be charged together.? Can they be mixed in the charger? Last but not least, Which is the better choice??
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Because you specifically mentioned the 396xt, My answer is specifically related to the 396xt.
Keep the NiMH batteries in the scanner the same brand / series/ mAhr if you are using the scanner as the charger for the batteries. Higher number for mAhr (milliAmpere hour) means more battery capacity and with the constant fixed load of the scanner, it is safe to say that the higher mAhr batteries would last longer for use. However, as the batteries age and/or are subjected to numerous charge/discharge cycles, the capacity over time will decrease and battery life will diminish. My scanner when purchased new came with GP 2250mAhr batteries. Therefore, I would not recommend putting a NiMH battery with less mAhr capacity in the scanner. Hopefully, Uniden thought out the possibility of replacing the GP batteries when they die with other brands of batteries when designing the charger portion of the scanner.
If you use an external charger instead of the scanner, Always charge the same brand / mAhr batteries with the charger made by the same manufacturer specifically designed for that particular series of battery where possible. NiMH chargers are time based not because of some specific time it takes to charge, but because that is the cheap and dirty way to regulate the internal temperature of the battery cell is by switching the battery current of the charger on and off throughout the charging regime. In a NiMH battery, the temperature inside the cell is more critical to monitor than Ni-Cad batteries so temperature regulation is critical. Because there are no thermal sensors in a standard AA battery to sense temperature, on-off switching of the battery charging current with internal digital timer circuits in the charging circuitry is how the battery charger designers regulate the temperature. Different battery manufacturers have slightly different chemical compounds and because of this, the battery capacities, temperature properties and the internal impedance of the battery can be vastly different between two different manufacturers and therefore the charging regime has to be adjusted to prolong battery life.
Literally, the chemical formulas and batch process manufacturing is tightly controlled when making the battery cell for consistency between different batteries bearing the same label as well as the battery chargers are specifically designed around a battery cell made to the strict manufacturing standards in order to both charge a battery to full capacity without damaging the battery during the charging process as well as prolong the overall lifespan of the battery as long as possible.
In reference to the guy who mentioned using akalines in the 396xt, Yes, you can but you have to remember to slide the switch in the battery compartment over to "akaline" in order to disable the charger feature of the scanner before placing the akaline batteries inside the scanner.