Can a low voltage set off a car alarm?

[Fallout]

I had to rewire my stereo in my new (2001) Passat recently, as the previous owner had probably had a million accessories and therefore hashed up the writing. In all, it took me about 5 or 6 hours over two days, testing wire voltages, trial and error etc etc. until I had all the wires going to the right place. Finally had it working, then went to start the car and the battery was almost flat, so couldn't. I would've charged it, if my Dad hadn't borrowed my car charger before xmas and never returned it. So currently it's charging on an OptiMate, but the ETA on that is about 3 days to charge ...

Anyway, the first night I had the car it was fine. The second night I had it, the alarm went off at 2am for no reason. This corresponded with the first day I started rewiring the thing. Then last night the alarm went off randomly at midnight. It was hooked up to the optimate when that happened. Tried to start the car this morning, and there is more juice, but not quite enough to crank it properly (that's 8 hours of optimate charging used up!!!).

My question is, does anyone think my battery issues could be related to the alarm issue? I'm wondering if the alarm detects the voltage drop or something. I've bullied the old man into coming up and returning my charger, so I should be able to give it a proper charge soon, but if a low voltage battery is gonna keep setting off my alarm, I may bite the bullet and buy a new battery.

Any ideas my mechanically inclined brethren?

Originally Posted by Fallout

I'm wondering if the alarm detects the voltage drop or something.

Yes, some do.

Originally Posted by Jabba

Yes, some do.

The cold weather this week wont help much either, that causes the battery to be less efficient and the alarm thinks someone is trying to tamper with it.

had a loan bike that did this to me several years ago, 2am it would go off, and shutting it up was not easy.

[Fallout]

Seems to be going off now and then. It went off earlier today, kinda coinciding with me having a go at starting it (and failing). I've got a proper car charger on it now and it just went off again. I suspect the voltage going up maybe set it off. Maybe there's a threshold it keeps crossing??