Newbie Battery Question ?

My home alarm needs a new backup battery.

The old battery is a Union Battery 12V 4Ah rechargeable.

I purchased the new replacement battery at Radio Shack. They did not have the exact battery, but the guy told me this one would work fine -- a Radio Shack 12VDC 5Ah rechargeable.

My questions: Was the Radio Shack guy correct?

Is it okay to replace my old Union Battery 12V 4Ah with a Radio Shack 12VDC 5Ah as to not cause any damage or danger?

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Thank you.

Sounds like a gel cell. Yes the larger one should be ok, if it physically fits in the unit.

Yes, it will fit.

In fact, is it almost the same size as the battery it will replace.

By the way, what's a "gel cell"?

Thanks.

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DavidTHR said:

By the way, what's a "gel cell"?



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It's a lead/acid battery, two Volts per cell, just like the bigger one in your car, except that the electrolyte (the acid part) is a gel (like Jello), rather than liquid like in the auto battery.

Just like your car's replacement from Sears, minor changes in capacity don't matter all that much. As we used to say in the dynamite business, 'if some's good, more's better'.

Doug Owen

A related question:

When the back-up battery is low, my alarm pad flashes a warning light.

I installed the Radio Shack battery last night, now, about 12 hours later, the "low battery" warning light is STILL flashing.

Does this seem right?

How long should it take a new battery to charge as to "stop" the low battery warning light?

Thank you.

No, that doesn't seem right to me. Are you sure the 'wall wort' is OK? Will the alarm function without the battery? Will the battery run the alarm? How old was the old one? You may have a different problem.....

Doug Owen

Yes, the alarm functions fine WITHOUT the back-up battery.

The old battery was from 1997, so it seems reasonable to need a new one.

I guess I will just wait and see if the new Radio Shack battery charges up.

What's a "wall wort"?

Thank you.

Why did you need to replace it ?

With Lead acid paste batteries they are usually good for a lot longer than the 4 or 5 years recommended with the alarms. I have seen lead acid batteries 10+ years old in fire alarms and still running ok, as long as they are kept topped up on a tickle charge and not run down too far.

Maybe there is a fault on the charging circuit in the alarm ?

Borrow a Multimeter, and measure the battery voltage when it is disconnected. Your 12 volt battery should give about 13.8 volts. Typically, if it is more than about 14 volts your charger may be cooking it ny overcharging, if it is below about 13.5 volts then you may not be fully charging it.

Hope this is of some help.

what is the brand of your alarm panel.we service DSC alarms panels.our panels will clear the low batt trouble when it does a check every 12 minutes of the battery, some panels must have a installers code entered in to clear a lo battery trouble..thanks KEN TYE /WINCHESTER SECURITY

Maybe a reset will do? Have you read the instructions manual? Why not give your alarm installers a call?

Vince.

Thanks for the info.

What I did was to detach the new back-up battery, and turn off the circuit breaker to the alarm system.

After I reset the circuit breaker, I reattached the new battery, and guess what?

No more flashing "low battery" light!

Everything appears to be working fine, and again, thank you for your ideas!

Just in case this isn't clear yet, the Ah rating indicates the capacity of the battery. eg, 5Ah indicates that the battery can provide 5A current at the rated voltage (12V in this case) for 5 hours, roughly speaking.

So if you have a mains failure, or a burglar cuts power to your alarm system, your alarm system can be powered for an additional 25% longer with the 5Ah battery compared to the 4Ah battery before your alarm system becomes ineffective.

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Just in case this isn't clear yet, the Ah rating indicates the capacity of the battery. eg, 5Ah indicates that the battery can provide 5A current at the rated voltage (12V in this case) for 5 hours, roughly speaking.


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I don't think that's quite right. The Ah rating is the product of time and current. So 5Ah means 5A for 1 hour, or 1A for 5 hours. Of course, this is only a rough guide as the higher the current draw, the greater the effects of internal resistance, which means that your battery may not actually provide power for as long as it was rated.

Steelwolf, you are completely right. 5Ah does mean 5A for 1 hour, etc. I think it was a bit late when I wrote that. /ubbthreads/images/graemlins/smile.gif