I have a small battery thats used on Lo-Jack systems, and Im thinking about routing it in to my alarm. Would a battery of this size be enough to power a siren for more then 10 min ? I will take a pic of it later on today. Its a Portalac PE12v1.2 ah.

 

You guys positive on that ? This battery isnt all that small. Seems to me that it should at least sound the siren for 5 min. Still something if you ask me.

Here is a pic of the battery, btw, thats not the fluids leaking out its ducked tape remainders.

 

Considering that this battery was free, then I guess I will go ahead and use it. Im thinking about only using the battery to operate just the siren alone, meaning when the alarm is triggered, and they find the brain and cut it, the battery will only power the siren, and not the lights.

 

I don't know about that, 7.2AH is a pretty hefty battery. I think that is pretty overkill myself. The ones DEI sells are .7ah and the one I have is 1.3ah, plenty of juice IMO. One of the big reasons for a battery backup, IMO, is to scare off the thiefs when they cut your main batt.

 

Is your 1.3 amp battery is giving you descent backup time ? If you dont mind me asking, how do you have it wired in ? Im still not descided on which way Im gonna run it.

 

My battery looks exactly like the one pictured (same size) and is 1.3ah. A 7.2ah battery would be considerably larger and heavier. I haven't tested backup time, running a lead acid battery dry is not good. If your battery is old spend the $18 to buy a new one at partsexpress. Better yet, just buy their battery backup kit which includes a module that triggers the alarm and switches power when the main battery is cut.