Elk 1280 Battery Life?

[Linwood]

How long does a typical Elk 1280 battery last (useful life, not run time).
 
I have mine in a panel in an air conditioned environment, and while doing an AC reporting test, about 3 minutes into the test I got a low battery alarm.
 
It lasted the whole 20 minutes or so I had it unplugged, and it restored on the next battery test (which I think are only 30 minutes), but looking at the discharge rates I would have expected more like 12-15 hours before I got a low battery (I have about a .5A load).   Not minutes.
 
The battery is only 2 years old (at least from my purchase), it is a real Elk branded battery from Automated Outlet.
 
Is this kind of life typical? 
 
 

 

[RAL]

I think your expectation of 12-15 hours for a 8 Ah battery and a 0.5A load is about right.  At least for a new battery.
 
A battery should last 3-5 years, but a lot depends on how many charge/discharge cycles it has been through.  Also, if a "new" battery was sitting on the shelf a long time and was allowed to discharge significantly before it was put into service, that can reduce its useful life.   One thing to look at is the date code on the battery and compare that to when you put it into service.
 
Did you measure the actual battery voltage at the point where you got the low battery alarm?

 

[Linwood]

I didn't notice the low battery until after I had restored power, I was testing a bunch of conditions for how the CS would react, and at first thought the low battery was just the AC fail, then noticed it wasn't.
 
So I don't know the voltage for real, but the voltage now matches the voltage on the keypad, and is in line with it being on the charger, so I suspect it is the battery.
 
The date codes are DL110620 (the one that gave low battery) and DH111224 (on the P212S and OK so far) would appear to be june 20, 2011 and December 24, 2011?   They were both ordered in mid-January 2012 from Automated Outlet, so it appears one may have been sitting around for a while, but is 7 months a long time for battery shelf life? 
 
I need a bigger battery anyway, had hoped for 24 hours, so it's time.  Got to see if the 18ah will actually fit in the same cabinet though.  And now not that keen on buying an Elk battery, given this life.  

 

[RAL]

7 months of sitting on the shelf should be ok. If it's been sitting around more than a year, then I begin to question whether it is still ok.

 

[tmbrown97]

My original elk-branded battery got me ~3.5 years before it blew out (bulged out the sides and started leaking).  At the time Elk had no replacement batteries, so I grabbed an equivalent from Fry's that's been fine since - and they don't cost much.

 

[Linwood]

So I have a perhaps silly battery question.
 
I have an extra jet ski (i.e. motorcycle) battery lying around, brand new.  Long story, but got one I didn't need.
 
It's 12V, and about 3 times the weight of the Elk 1280 (13 pounds vs. 3.4).   I was thinking of rearranging my can a bit and using it, then I noticed it is only a 10AH battery.
 
Is that because weight is needed to provide the huge cranking amps?   Not exactly needed for the M1G.
 
So this huge thing is little more capacity (for alarm use)?
 
Or is capacity measured in some dramatically different way between them, and this really would last 3 times as long? 
 
I'm more of a digital guy, this chemistry analog world is a bit odd to me.

 

[RAL]

I guess I'm surprised that it is only 10 Ah.  Most of the batteries I have come across for this purpose are about twice that. 
 
A battery used for starting an engine, whether a jetski, motorcycle, ATV, etc needs to be able to deliver a lot of current (100s of amps) to crank the engine for a short period of time, while an alarm panel is happy with modest current but needs it over a long period of time.   This characteristic is the difference between a starter battery vs a deep cycle battery.
 
As a result, the starter batteries have more plates to be able to deliver the high current, and that results in a larger, heavier battery.

 

[Linwood]

As a result, the starter batteries have more plates to be able to deliver the high current, and that results in a larger, heavier battery.

 
Yeah, so I guess it isn't worth trying to repurpose that one (it's a bit of trouble to rearrange some card slots to make room, and no point for added capacity I guess).

 

[Linwood]

Well, that's a bit of a mystery.  I redid the test, longer, and it didn't fail.
 
I took voltage readings from both the battery terminals and also other points (SAUX and an open zone) as it was discharging.
 
Charging (presumably trickle) voltage was 13.78.
 
ABout 20 seconds after disconnect it was still at 13.23.
 
4 minutes:   12.70
13 minutes: 12.42
30 minutes: 12.48
60 minutes: 12.49
80 minutes: 12.45 
 
Those are battery voltages.  At the same time panel voltages at the SAUX and open zones were about the same as each other, and were always about 0.5v less. 
 
Panel measured voltages (ElkRP zone voltages, and Nav voltage) were close to this but a bit erratic, sometimes more, sometimes less. 
 
The manual says the low battery trouble hits at 11.2, that's a long way from where this is.  The battery in all both cases should have been freshly charged (i.e. no recent power outages).
 
So the battery at least on the surface appears good, and held up for a while.  I still need to re-evaluate if it's big enough, but I can't explain why I had a trouble indication.  Strange.  But nothing to do about it that I can see.