Battery backup for alarm, have battery
Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=45575
Printed Date: October 31, 2025 at 8:23 AM
Topic: Battery backup for alarm, have battery
Posted By: Chiana
Subject: Battery backup for alarm, have battery
Date Posted: December 19, 2004 at 11:49 PM
I have a few 12volt batteries from PC battery backups. I wold like to wire one of these batteries in so that it will power the alarm in the event that the car's battery is damaged. However, I don't want the battery to power the rest of the car. How should I wire this battery into my alarm?
-Chris
Replies:
Posted By: xtremeaudio
Date Posted: December 20, 2004 at 3:27 AM
you need put a diodes on 12volt to your alarm and put your pc battery after the dioes they will work . dioes only let the elcetrec go one way and your pc battery on power you alarm
Posted By: Chiana
Date Posted: December 20, 2004 at 9:19 AM
Ok. Do I need to put diodes on the pos and neg or just teh neg?
Posted By: Chiana
Date Posted: December 20, 2004 at 9:39 AM
Oh yes.... how the heck do I get this battery to recharge off the car's electrical system?
I think this is teh general idea:
For power to the alarm:
Ground the neg from the battery to the chasis, no diodes there. Run a positive to the car alarm. Put a diode in the line for the car alarm, before where the PC pattery comes in.
To recharge the battery:
Run a pos line form the car to the battery, putting a dioded in the line to allow power to only flow to the battery for charging.
How does that sound?
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