A few minutes ago, I spoke to my friend, who happens to be a chemist turned
software developer, and he said that we are generally overly paranoid about
hydrogen.  He said that whereas the car batteries had vents, most new ones
are closed systems that don't require that you add water and have a catalyst
to recombine the hydrogen and oxygen.

He went on to say that most of the battery backup electronics, including
his, has low voltage detection so that power is turned off when battery
voltage drops below 11.5V.  He countered most of the concerns so I'm left
once again thinking it may be a good idea.  Perhaps the smart thing would be
to watch his system for a while to see what happens.

Please don't shoot the messenger, but any counters to his arguments?  Anyone
else doing this already?

Thanks,
Ed


-----Original Message-----
Subject: Re: [EE:] battery backup


Ok.  Not a good idea.

A friend had recently done this and I wanted to research it before I
followed suit.  Thanks for stopping a mistake (and ruined carpets).

Ed

-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of David Schmidt
Sent: Wednesday, March 31, 2004 1:26 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [EE:] battery backup


- hydrogen gas generation
- Corrosive sulfuric acid fumes released during discharging.  This will wet
any dust that collects on the top of the batteries, and will eventually drip
onto you floor and eat holes in your carpet.
- having to check fluid levels
- sulfation - I don't think the charging technique is suitable for a wet
cell.
- your home owner's insurance being void when you make a claim :-)

Dave
> Can anyone think of a reason not to attach a car battery in place of the
> sealed battery in a battery backup system?  I've got a few of these

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