[wayne]

Bryan,

Although I have not discussed the internals with the engineers at Pentax, I have with engineers from Canon and Sony. They have internal power conversion circuits (multiple) to handle the various requirements. For the most part, they use either buck (step down) converters or boost (step up) converters rather than linear regulators. For example, the CPU for most digital cameras runs on less than 3V while the motors are typically run off the battery power. Backlighting also requires a different voltage (the original designs used a CCFL tube, much like those used in laptops and LCD monitors) while newer designs may use white LEDs. Another interesting point, the back light color differs from market to market (cooler or warmer, depending upon the region preference - there really is a difference between the Japan model vs say a US model).

Getting back to the regulation issue, they also design in local regulators. These are typically low drop out designs which provide noise free power to sensitive circuits. They also allow you to turn off functions (such as anti shake) to conserve power. Some of these may be incorporated into the custom IC's used in the camera, or they can be individual circuits (which can be as small as a SOT-23 package (very tiny).

Depending upon the design of the power circuitry, the engineers may have been counting on a certain range of input voltage to maintain regulation. Getting back to the buck/boost converters, unless you design in a complex design which combines both functions (more parts, larger board or flex area), your basic step down converter wants the input to be higher than the output while the boost converter wants the input to be lower than the output (there are other methods, but that is not for this discussion).

So, the input to the camera should be between a range of voltages determined by the designers. If you fall outside of that range, you could have a problem. If the manufacturers says that an RCR-V3 battery may damage the camera, then I for one would not use them (my camera is worth more than a desire to have rechargable RCR-V3's). Oh, again, as many have stated, don't ever mix battery types. It is more than the voltage that you need to consider (internal resistance of the cells, discharge rates, thermal ratings, etc).

Wayne