[aprssig] Automatic power off device

James Jefferson Jarvis jj at aprsworld.net
Wed Apr 13 11:55:51 EDT 2005

Hi group,

Last July I shared some details on a project of mine that was designed to 
protect a vehicle battery from being discharged from APRS equipment. At the 
time there was a fair amount of interest, but I didn't have any kits 
available. Now I have some kits and pre-assembled units made so I thought I 
would let everyone know again.  

The website for the project is:

From the website:
"The APO2 is designed to protect a vehicle battery from being discharged when 
the vehicle is turned off. It will turn off a DC load when the battery 
voltage drops below a voltage set point and after a timer has elapsed. There 
are two set points which can be selected with a jumper, 13.05 volts and 12.1 
volts. The 13.05 volt threshold is designed so the DC load will turn off 
approximately 15 to 20 minutes after the vehicle ignition turns off. The 12.1 
volt threshold is designed to protect a battery from permanent damage.

The APO2 is enclosed in a ABS plastic enclosure with mounting tabs. It is 
inexpensive and light weight so it can be used in a variety of locations and 



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