K20D - Clock

When you take the battery out for recharging, the clock keeps running. I dont know for how long?

Is there a rechargeable battery stashed away in there somewhere, how long does it last, and where is it?

It would appear that it is not possible to recharge the battery while its is in the camera, so batteries have to be removed.

It's no different to a video recorder holding its time info during a power cut - there has to be a power source that recharges whilst the power is there. I don't know about the K20D because I always put another battery straight in - I rotate three per camera - but some cameras lose their time info after 24 hours or so.

It's probably a capacitor that stores enough charge to keep the settings and the clock running for a while.

SD cards probably work in the same way? I dunno?

Even Gameboy game cartridges had this facility (or at least Pokemon Crystal did, to keep its game-specific clock to time) so it isn't all that surprising for a £500+ camera in 2010 to have it

SD Cards are solid state, and the memory is retained when removed from the system. But they could not continue to "Clock" when removed from power or the system.

I had a Video camera that had a button battery that kept the clock going, was also recharging, computers also have a small button battery to keep the clock going. They only last about five years or so.

My point and shoot recharges with the battery in camera, but when I remove the battery for any reason I have to reset the clock.

The manual for the K20D states that if you take a battery out for a long time the clock will stop. It doesnt say how long.

Must be as suggested above some sort of capacitor, that keeps a trickle charge going for a while.

I went an checked and indeed the memory in an SD card does not require power to retain the data.

Although the circuitry inside the camera is all solid state too.

SD cards are "non-volatile" memory, so they don't lose their information, but then everyone who has several cards knows this.

However, if left for a very long time the information can become corrupted and unreadable, so they are not suitable for archival storage. I would imagine that a "very long time" means months and years, but I've never seen it defined.

http://www.kingston.com/products/pdf_files/FlashMemGuide.pdf

Up to 10 years data retention (so it can as well be 1 day )

Don't confuse the two things

Real Time Clock: requires some power to keep the clock 'ticking'. Usually they run on a very slow oscillator (32.768kHz) and require micro-amps of power to keep going. The memory registers that keep track of the date and time, as well as the electronics are all CMOS circuits. Sometimes a Lithium cell is soldered to the PCB - typical life span is ten years (the real time clock often takes so little power that the battery will last as long disconnected as powering the clock!). Alternatively the RTC can be run from a capacitor with very low self-discharge characteristics. This will give perhaps a day, perhaps a week. When the power is disconnected from the RTC chip the time will reset.

Memory: SD cards and CF cards all use NAND Flash technology. This memory chip requires no power to keep the contents. The contents should stay preserved for a minimum of 10 years - although clever error correction and detection mathematics can extend this time substantially (when the device is booted up after that time the maths allows any changed bits to be detected and reset to the correct values).

But, going back to the OP, the options are:

1. Don't worry about it. Just check the clock and custom options when you put the charged battery back in You'll probably be absolutely fine!

2. Get a second battery and cycle the batteries. This is my preferred option - you've always got a spare if you're out and about

Matt

[EDIT] Missed a decimal point

I now have five batteries and two chargers for the K20 alone.

Am I paranoid, should I be worried Doctor Matt?

Only if you try to put them all in at once!

It's a capacitor (Super Cap) typically 1 Farad or more. Have a look at Farnell. Some car radio's use them as well as many other applications.

Best regards

Paranoid? Ask the voices in your head!
Matt

There are too many

A 1 Farad capacitor is not an electronic component.

It is a weapon.