Real time clock basics

Hi Dan,

Thanks for reply...do internal battery need charging, how long do they last??

Thanks

Some have internal batteries and some require external batteries

Sometimes a very large value capacitor is used in place of external batteries

Dan

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Dan Hollands
1120 S Creek Dr

Hi Rich,

If you can read properly.....the thread is posted in

*sci.electronics.basics* not sci.electronics.design!!!! Dosen't that makes any difference....and turns what all you said useless!!!!!

I don't know - never used one - just saw one at some point in a catalog

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Dan Hollands
1120 S Creek Dr

You'll have better luck with a question like this if you actually use the other side of google - the web search.

Try various things in the search box, like "Real Time Clock Batteries" or whatever search phrase you want to make up - you will be amazed at what's already out there.

Admittedly, that's a lot colder and less fun than interacting with actual real live people, but huff! This is the sci.electronics.design group, not the sci.electronics.basics group, so we're all insufferable arrogant prigs who mercilessly flame anyone who asks an impertinent question. Was everybody able to discern that that was a joke? ;-)

But in answer to your question, the only honest answer is, as usual, "It Depends." :-)

Good Luck! Rich

yes.

some are encapsulated with the battery,

other use an seternal battery. these days a 3v lithium disc cell or a large capacitor is commonly used,

In the past on-board NiCd rechargables and external battery packs been used as well.

Amstrad even made a computer with an external battery compartment.

Bye. Jasen

no, when the battery fails the unit must be replaced (or opened and the battery replced)

about 5 years.

the first signs of a failing battery is that the PC's real time clock starts losing time and then stops

As the clock chip also stores the BIOS configuration info the next sign is corrupted config info.

Bye. Jasen

Sorry, I won't bother you with any replies next time.

Good Luck! Rich

We are now using a 1 Farad super capacitor with our RTC. If you do not expect long power outages (like several weeks), the super cap is a nice way to go. It does not require replacement like a battery and can be permanently installed.

On the other hand, if there are few power outages, a lithium battery would also work well since it has such a long shelf life. The supercap/RTC combination we use retains the time for outages well over one month.

Lou

Hey Rich......I've no such intention, so keep posting!!