Alternate 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=14
Printed Date: May 07, 2024 at 3:39 PM

Topic: Alternate Battery

Posted By: hot_shot_guy123
Subject: Alternate Battery
Date Posted: March 09, 2002 at 11:57 AM

Hi I would like to connect an alternate battery to my alarm but I have no clue how to do it! I know where the power wire is going to my alarm so I figure that, that wire goes to the power and then I'd run another wire grounded to the chasis. The alarm uses current and so I'd have to run a wire to the alternator right to charge the seperate battery. How do I do this, I think this would be the biggest problem I'm facing. I have a 1990 dodge shadow if you needed to know. Thanks in advance

Replies:

Posted By: the12volt
Date Posted: March 09, 2002 at 12:42 PM

Hi hot_shot_guy123, the simplest way to add the alternate battery (if not a back-up battery) is to connect it parallel to the existing battery in the vehicle. If your concern is someone disconnecting the main battery, you can connect the positive terminal of the new battery to the B+ side of the alternator at the alternator (B+ side of alternator connects to positive terminal of existing battery) and connect the negative terminal to the chassis of the vehicle, then connect the 12V B+ lead of your alarm (and accessories/sensors) directly to the alternate battery.

If you're looking for a back-up battery for your alarm, there are many available and often at a fraction of the cost of a nice car battery. Either option is an easy install.

the12volt

Posted By: hot_shot_guy123
Date Posted: March 09, 2002 at 6:51 PM

Thanks for the reply but I kinda have a few more questions about the hook-up. First does it matter what size wire I run from the B+ side of the alternator and how should I attach it to the alternate battery could I solder it to the battery or should I go out and buy some terminals? Also where would be a good place to locate this alternate battery for my alarm? Can you buy back-up batteries that that have the same power as a regular battery but are flat? I was thinking of putting it between the panels in my trunk so it is hidden.

Posted By: the12volt
Date Posted: March 11, 2002 at 5:32 PM

Hi hot_shot_guy123,

I'd recommend at least an 8 gauge lead or better if you mount it in the trunk to keep it charged, by the way the trunk would be my first choice mainly because of size and the ability to conceal it. Yes, I would use terminals instead of attempting to solder directly to the battery. The B+ side of the alternator has a lead going directly to the positive terminal of your exisiting battery and I'd connect the second battery's positive terminal to it if you do not want to connect to the existing battery's positive terminal. Either connection will keep the second battery charged. Connect the second battery's negative terminal to the chassis. If you add this second battery, be sure to fuse the lead at each end where you connect to the alternator or existing battery and at the new battery itself.

For back-up batteries, they come in a variety of small sizes that are easily installable in the interior of the vehicle that are adequate in supplying power to an alarm system. I'd first check with the manufacturer of the alarm you currently have before looking elsewhere.

the12volt

Posted By: hot_shot_guy123
Date Posted: March 11, 2002 at 9:28 PM

Thanks for your help, I'll be starting on that little project shortly.

Sandro.