[Elecraft] KXBC3 charger question

[Josh Fiden]

You’re supposed to replace the smoke detectors every 10 years because they lose sensitivity. In my experience, 9v alkalines in the AC powered models last nearly that long. I assume it’s just the shelf life of the battery. 

73
Josh W6XU

Sent from my mobile device

> On Oct 5, 2021, at 1:22 PM, jerry <jerry at tr2.com> wrote:
> 
> I have a related questions about batteries discharging... Not really about ham radio, all please feel free
> to delete...
> 
>  We have a *lot* of smoke detectors.  They are the kind that runs off the AC, but each one has a backup
> battery.  The other day, one started beeping...and beeping...and beeping.  That momentary beep that says
> "change my battery!".
> 
> Amazon couldn't get me batteries the same day.  And the beeping makes it hard to sleep.  So I went to the garage
> and got one of a set of rechargeable lithium 9V
> rectangulars that I had bought for test equipment - DMMs and such.
> 
>  The old battery in the smoke detector was 7.88V.  The lithium - 9.4.  Installed it...and no beeps!
> 
>  It's tempting to just load all the detectors with lithiums.  The alkalines last a couple years.  Maybe a fully-charged
> lithium would last as long... and then you recharge it?  If so, they'd be a good deal.  If OTOH they only last a couple months,
> that's NOT a good deal, because I'd have to get out the ladder etc every time.
> 
>              ??
>                   - Jerry KF6VB