Re: 9v battery min voltage

jasen wrote:
On 2006-12-31, lerameur <lerameur@xxxxxxxxx> wrote:
HI

I am building a unit that will have a small 9v battery for power. I
will put a voltage comparator and it will activate a led to warn for a
low voltage battery. Iwould like to know at what voltage dos the
battery need to be change, when is it dead ? is it 7.5 v ? or 8?....

if it's non-rechargable when it's too weak to use.
if rechargable when the voltage drops 1.2V below the full charge
voltage.

A bit of a challenge here: if the battery can power the led, then perhaps it isn't really dead.

An alternative approach is to use the led to indicate a "low" battery, rather than a dead one. It is much better (usually) to know that changing the battery is now prudent, than to know that the battery should have been changed earlier because it is now dead. ;-)

If you take that route, 7.5 or 8 volts might be just enough to operate your device and indicate time for a battery change. If I recall, battery voltage drops fairly quickly once the battery begins its decline in earnest.

Chuck

----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----
.