Probably not a good idea either.
The backup battery in the bell box is charged from the 13.8V through a
diode,
 In all the alarm systems I have seen

Peter Cousens
cousens@biscit.biz

> -----Original Message-----
> From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU] On
> Behalf Of Jinx
> Sent: Monday, August 18, 2003 12:25 AM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [EE:] 24vdc from a 15vdc psu
>
> > Conventional and 10 year life sealed batteries require 2.27
> > vpc -3mV / Deg C temp compensation for static charging for
> > maximum life (Yuasa Clhoride Sonnenshine) not so sure
> > about American ones (Power Gnb Johnson ect)
>
> > In this type of app. Where the charge is almost never
> > interrupted, I recommend 13.5V, this gives you 2.25 Volts
> > per cell
>
> If the graf halph-way down is typical
>
> http://www.stealth316.com/2-dynabatt.htm
>
> then 13.8V would be more or less right for NZ's 10-20C
> temperature range. However, I think I'll trim them back the
> merest tad when I come across them on service calls to
> make allowance for summer temps (which rarely get over
> 25C BTW)
>
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