[aprssig] Tracking my trip

Stephen H. Smith wa8lmf2 at aol.com
Fri Aug 18 17:50:50 CDT 2006

Ryan.Tourge at sheriff.co.warren.ny.us wrote:
> Slightly off topic of this thread but...
> I have a 2003 Honda Civic. I notice that the voltage switches from 14.4
> to ~12-13 volts intermittently. I assuming its some high tech battery
> maintenance idea but it it's a real pain trying to configure my OT to
> act on voltage changes.
> Anyone experienced anything similar?
> Ryan

This is a perfectly normal voltage variation for a so-called 12-volt 
system when the engine is running.  Typically the voltage will start out 
high just after the engine is started (and the battery voltage is low).  
Then after the initial charging rush, the voltage will drop somewhat.    
[Note that most mobile transceiver power output specs for 
"12-volt-operated" radios are quoted at 13.8 VDC since this is more 
typical of a mobile with the engine running..]

A healthy 12 volt car battery will drop to something like 12.6-12.7 
volts after the engine is shut off for a few minutes.  

If you are trying to sense engine-on-and-running vs 
engine-off-and-parked, you need to set  the voltage detect threshold at 
about 12.9 volts.  


Stephen H. Smith    wa8lmf (at) aol.com
EchoLink Node:      14400    [Think bottom of the 2M band]
Home Page:          http://wa8lmf.com

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