110Views5Replies

Author Options:

Just to make sure! 30A to charge battery? Answered

Hey! I have an old home alarm system which is broken beyond repair. I just wanted to make sure if it is OK to charge the 12v battery at 2.1 or2.4 Ah with an ATX PSU at 30A? Will the battry just take 2A from it? If not I have the transformer that came with the Alarm, would that be safe to charge with? It's 12v BTW. Thanks. Never can be too careful. Also, I'm using it on a scanner light tube, this will be fine, yes? I have the starter, it is not a problem. It's weird though, when it is lit, you can pull out the ground on the light tube, not the starter and ut still stays lit. Weird. Thanks in advance!

5 Replies

user
NachoMahma (author)2007-08-05

. To charge batteries you need some type of current limiting to keep from damaging the battery. As such, a computer PSU, by itself, does not make a good battery charger. . I'm with LV, if the battery is more than a few years old, it's probably bad. . . Not sure about why you don't need the ground on the light tube, but stand under some high-tension lines at night with a bare florescent tube and watch what happens.

Select as Best AnswerUndo Best Answer

user
LasVegas (author)2007-08-04

You cannot use an ATX power supply as a battery charger. It's not designed for that purpose and would likely destroy the power supply, the battery or both.

Select as Best AnswerUndo Best Answer

user
Josho (author)LasVegas2007-08-04

OK then, what about a standard Mains DC charger? It's 12v, don't know about the watts. It came with the alarm, so I dunno.

Select as Best AnswerUndo Best Answer

user
LasVegas (author)Josho2007-08-04

Oh wait! It came with the alarm? It should work then. Sorry.

Select as Best AnswerUndo Best Answer

user
LasVegas (author)Josho2007-08-04

It depends on the composition of the battery. Different battery types require different charger designs. If it's lead/acid or a "gel cell," you could charge it with a car charger. A gel cell looks like a rather large plasic block with two terminals. I wouldn't use the quick charge setting on a gel cell though. A lithium battery requires an entirely different charger setup as do NiCad or NiMH batteries. I'm assuming then that the charger section of the alarm system is failing? Could it also be that the battery itself has failed? The battery can be replaced if that's the case. If it's a gel cell, as I suspect, if it shows a very high current when attached to a car charger you should replace it.

Select as Best AnswerUndo Best Answer