zombo

Hey guys,

So I want to make a battery backup for my alarm, I was wondering can I simply just get like a 12 volt gel cell like this

http://buckenvy.com/images/12vb-1.jpg

and hook it up to my positive and negative from my main battery? or do I need some kind of circutry?

cheers!

83customcivic

2 different kinds of battery back ups for the siren (listed in your subject) & the alarm itself (listed in your post).

Battery back up for the siren keeps just the siren wailing in case all power is lost to the alarm. The internal battery is inside the siren housing itself. It is shut off by a key. DEI 515R is the best choice IMO

That battery that you linked would work good for back up power for the alarm itself. Just parallel the + and - off the main alarm to the + and - of the back up battery

zombo

Sweet yeah what I want to do is add a battery to my existing setup to help backup the siren, I was thinking of just wiring up the gel cell to the positive and negative feed that is on my amp in the boot (comes from the battery), is that going to work?

nsxxtreme

Actually you don't want to parallel them. The purpose of a back up battery it to isolate the reserve battery from the main electrical system. That way if somehow a theif figures out how to wipe out your main battery (by shorting + and - together along with other ways) your back up will survive.
The way tis is done is with diodes. only allowing the main electrical sytem to charge the reserve battery. The reserve battery then will be protected and able to supply current to the alarm if a fault was to occur. Its a simple circuit to build as simple as it gets. But for most people its just easier to buy a DEI backup battery. Toss out the battery and buy a good quality lead acid battery.

83customcivic

While I believe in the proper way of securing even back ups, most of the time a thief is just going to unhook/cut either 1 of the main batteries + or - or both rather than short, thus just paralleling would work. But the proper way would be as you described.

Also.. to address the OP about connecting the back up to the main at the main battery itself, I disagree. If the thief does disable the main battery, all connections that are made there are going to be cut. Thus I recommend the connection be made inside at the main alarm.

83customcivic

Back up the alarm itself which will keep your siren going off.

Explain "amp in the boot"? If you are referring to car audio amp, No.
Make the connection to the alarm main + and - inside