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Old Jul 10, 2007, 12:15 PM   #1
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Hello all --

I have a question that I'm sure most of you know. I have a Panasonic point & shoot camera; don't remember the model number, but it's a 6 megapixel, 6x zoom camera that runs on 2 AA cells. I also have a Pentax K100 D that runs on 4 AA cells. The Panasonic camera came with 2 Panasonic "Oxyride" batteries, that, if I remember correctly, were rated at 1.6 volts each. The manual recommends using Oxyride batteries, but says that the camera will also function with ordinary alkalines (which are rated at 1.5 volts)or NiMH rechargables (rated at 1.2 volts). I have only used NiMH batteries in the Pentax camera, but it too can supposedly operate on several types of batteries, with varying voltage outputs.

So how does a camera operate properly with such a wide variation in battery voltage? It've always read that digital cameras have very sensitive circuitry, but somehowmy Panasoniccan operate with their power source ranging from2.4 to 3.2 volts?And with 4 AA cells, the operating voltage of the Pentax could be anywhere from 4.8 to 6.4 volts. Seems hard to imagine. Can anyone explain?
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Old Jul 10, 2007, 9:33 PM   #2
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Digital cameras (and most battery powered electronics) use a DC-DC converter in the power supply to change the battery voltage into the several different votages used by the various components. As the battery voltage decreases, the converter has to "work harder" to supply everything.

The votage level of batteries decreases under load. Alkaline batteries more so than NiMH, though they start slightly higher. Alkalines show a more gradual no-load votage drop from full charge to discharge than NiMH. It becomes a challenge to design a power supply which takes all these factors into consideration, but will shut down the camera without damage when the battery is nearly discharged.

Hope this helps.

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Old Jul 12, 2007, 9:25 AM   #3
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Thank you Brian -- that makes complete sense. Another mystery solved.
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Old Jul 20, 2007, 11:15 AM   #4
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Hello Vermont,

Another thing to keep in mind is what the voltages refer to.

Alkaline cells start off slightly above 1.5 volts and go down from there.

NiMh cells start off at around 1.42 volts, but spend a large portion of their discharge time in the 1.2 volt range. The discharge curve for NiMh cells is much flatter than that for Alkaline cells.

While both chemistries start off at similar voltages, the NiMh cell can actually deliver a higher voltage (depending on load) than the Alkaline cell.

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