Looking to do this when I get the Compustar installed. How do I hook it up right? I understand teh purpose jsut not sure of whats invloved with it. I know there are a couple people on here with back up batteries. If anyone has a nice place to hide it let me know by PM. I know people dont want their setups all over the internet. Also wondering where to buy one. Thanks guys

 

any old battery will work... you could get 2 lantern batteries at walmart.

Method 1:
hook up 2 diodes to the power wires. The diodes ensure that there will be no way for the backup power to power the rest of the car. You will need to find a 1A diode, or put many smaller ones together.

Put the side with the line on it away from the power source. you need 1 on the battery -> alarm connection and 1 on the backup -> alarm connection.

You can put the battery in the trunk spare tire well. or behind the sterio just ensure it's a 12V.

method2:
hook up a relay next to the alarm, so that when battery power is lost, it turns off and switches power to the alarm from the 1st battery to the 2nd battery.




Here's a picture to illustrate what i'm talking about. the one on the left shows 2 diodes. the one on the right shows the relay hooked to the battery. when the battery is cut off, the relay looses power and switches to the spare battery.
Attachment 177

This is just for the power wire. Ground the negative spare battery cable to chassy ground. All other wires are hooked up as normal.

 

if i were you i would get one of the siren/backup battery all in one type things. i kind of wish i would have done that now...

http://cgi.ebay.com/ebaymotors/DEI-515R-BA...1QQcmdZViewItem

just makes the install easier and its a little more secure.

 

Ya that makes sense. A LOT less of a hassle it looks like. Im going to have to check into those

 

^^ so you're going to buy a 2nd alarm? What i'm talking about costs $1 at radio shack.

it's also exactally what you want. 2nd battery backup for your alarm. if you buy 2 lantern batteries, it would cost you $10.