wrote:
Steve Foley wrote:

"RST Engineering" wrote...


Trivial to design and build.

Jim

Not for me


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Yes, even for you :-)

Although he hasn't stated it very well, the original poster is probably
looking for a voltage comparator.


Unfortunately, the original poster's use of the term 'charging' needs
to be defined in electrical terms, and the chances off finding exactly
what he wants in an off-the-shelf package is probably somewhere between
slim and none. But there are numerous examples of such circuits out
there, assembled as well as kits.

-R.S.Hoover


The voltage comparator is straight forward enough, and you could also
probably modify an existing automtive regulator to get the job done.

If he really needs something more upscale, there are low voltage cutout
circuits available. There are some listed he

http://home.cogeco.ca/~rpaisley4/xLowBattery.html

But these are probably beyond a beginner.

I admit I am operating off of almost no sleep and may be missing
something, but to keep it dead simple, why not just put a large diode
between the alternator charging post and the battery. Wire the
accessories behind the diode directly to the charging post. There would
be some forward loss of probably half a volt, but I can't figure it
would mess with the internal regulator as the voltage/current is already
passing through a full wave rectifier. If you have a three wire
alternator with remote voltage sensing, it wouldn't affect it at all.
For that matter, you can get the thing ready wired by buying a battery
isolator from JC Whitney. No need to worry about voltage levels and
whatnot. If the alternator isn't producing a charge your accessories
aren't getting juice -- pretty simple.

Charles