Battery and Charger Alternatives?

[Photon]

Has anyone used an automotive type battery with their security system?

I expect to order an Elk M1G later this month, and I can see that as I expand to phase 2 or 3, I will need an additional power supply. I have the 30+ Amp Hour AGM battery from my Miata sitting in the basement connected to an Accumate smart charger for the winter months. I've used the Accumate on this original battery for seven years, and the battery continues to provide strong performance the rest of the year in the Miata. That is roughly twice the longevity of the ordinary batteries in my other cars.

Is there any reason not to use this battery and charger combination for expansion boards, PIRs, Glass Breaks, strobes, and sirens? I don't need to preserve a UL-approved configuration for my Elk application. I already have the intelligent charger that has proven its ability to be kind to AGM batteries. I can try it with my existing battery until the Wisconsin road salt season ends and it goes back into the Miata. If successful, I can buy an additional AGM battery for the security system. $90 for a 30-Amp Hour AGM battery that I can expect to last eight years or longer is cheaper than buying 7AH sealed batteries over that time.

I'm just asking in case I've overlooked the obvious or if anyone has tried this and had a meltdown.

My charger: http://www.accumate.com/612/
Another similar intelligent charger: http://batterytender.com/default.php?cPath=11_2

 

[CollinR]

I'm not going to say it cannot be done but automotive batteries are designed for a very high load for a short duration (starting/cranking), you want the inverse a low draw for a long duration. Possibly look at Marine deep cycle batteries but still there are some inherent flaws in this.


On top of all this these batteries can dump hundreds of amps into the system, something to be careful of for sure.

 

[upstatemike]

I'm not going to say it cannot be done but automotive batteries are designed for a very high load for a short duration (starting/cranking), you want the inverse a low draw for a long duration. Possibly look at Marine deep cycle batteries but still there are some inherent flaws in this.


On top of all this these batteries can dump hundreds of amps into the system, something to be careful of for sure.

Use deep cycle/marine rather than automotive. The deep cycle ones are made for this type of application. I used to use these on my old phone system. It stayed up for the first 3 days of a week long power outage a few years back.

 

[CollinR]

I'm pretty sure the batteries in alarms will fail open and automotive/marine units have the capacity to fail in a short. So although marine batteries will do the job there may be other concerns.

 

[Digger]

If I remember correctly Costco has a deep cycle 85aH battery for about $90.

 

[Photon]

Thanks for your replys. I had considered a deep cycle battery, but I thought there is no need since we rarely have power outages here. In my view, the battery is there mostly to keep the system running if a bad guy kills our power some time before attempted entry. An automotive battery can take care of that situation, especially since it has to take care of that problem only once. On the other hand, if I buy a battery just for this system rather than using my slightly used Miata battery for the Elk's accessories and buying the replacement battery for the car, I will look into a deep cycle battery.

I'm not sure about failure modes, but I will connect an in-line fuse holder at the battery's positive terminal before the cable to the loads. I suppose I'd use a fuse rated about 150-200% the maximum expected draw. I'll look into something like the ELK-PD9HC downstream from that to protect individual loads because it is self-resetting.

Another suggestion I got from an engineer at my office is to place the battery in a marine battery box to protect the battery from any falling conductive objects and to protect the surrounding area from acid if the battery pops. He agrees that the AGM battery design does not usually vent hydrogen, but he said if the battery overcharges or if it does short, it might crack the case. I've seen advertisements where they drill holes in the case of an AGM battery. It doesn't leak any liquid, and it continues to function. On the other hand, a marine battery box is inexpensive, and it would neaten things up.

{Edited for clarity.}

 

[rfdesq]

In my view, the battery is there mostly to keep the system running if a bad guy kills our power some time before attempted entry.

Don't forget that if you have the M1 set up properly it will dial the Central Station and alert you to a power failure well before your battery runs out.

 

[Photon]

In my view, the battery is there mostly to keep the system running if a bad guy kills our power some time before attempted entry.

Don't forget that if you have the M1 set up properly it will dial the Central Station and alert you to a power failure well before your battery runs out.

I see the Sys Rpt Code Option SR11 can also be set to report "if the battery drops below 11.2 volts." (Page 45) I assume the M1 monitors only the battery that it, the main control, is powered by, correct? If so, then I am on my own to check up on batteries at remote panels, or even another battery powering accessories at the main panel area.

 

[CollinR]

I suggest you research more, some of the issues are complicated and could result in a total failure and possibly damage to equipment.

What happens if the battery shorts?
How will you disable the charging circuit in the M1G? I dunno about the first cycle will fix that without letting the smoke out.
How will you prevent the new charging circuit current from passing into the control?
How would you know if the battery were to fail open or become disconnected?

 

[Photon]

1. What happens if the battery shorts? I expect it would blow the fuse I attach to the B+ terminal as mentioned above, and I expect the charger to disconnect. If it shorts internally, I would expect a big, hot mess. That is what I expect of the battery and charger sitting on my workbench right now, as it has been for the past few months. I would expect the same from an Elk-brand battery if it shorts internally. The Accumate charger is UL approved for continuous duty, and it has served me well through many winters. I am not worried about it.

2. How will you disable the charging circuit in the M1G? I dunno about the first cycle will fix that without letting the smoke out. I was not clear that this would be an additional power supply I would connect to power additions beyond the basic M1's capacity. I would not change the battery or charging circuit on the basic control, and it would power only the basic control and a few Elk additional components such as keypads connected to it.

3. How will you prevent the new charging circuit current from passing into the control? I expect to use it only for some expansion boards, PIRs, glass breaks, strobes, and sirens. No current to the control's power supply, except that I understand the battery grounds of all supplies should be tied together. I'm still looking for a reference in the Elk documentation for that, though.

4. How would you know if the battery were to fail open or become disconnected? I don't know. Nor do I know how any additional genuine Elk power supplies and batteries would be monitored. I assume I would not know until my next system test after the failure. I would probably end up with a relay or opto-isolator between the battery of this additional power supply reporting to a zone input on the Elk-M1 control and some rule to tell me of a zero-volt condition. As the zone inputs are essentially volt meters, I might eventually get fancy and report a fault at some higher voltage such as 11.2 VDC as the main unit does.

Collin, I appreciate your thoughtful examination of my topic. I intend for my answers to your questions to be just that: answers. I hope you do not take them to be arguments. There is so much I have to learn about this system, and security systems in general. I appreciate those of you with actual experience taking the time to share your wealth of knowledge.

 

[rfdesq]

I mentioned that the M1 will alert you to a power failure. Based on your current demands and the size of your battery backup, you should be able to calculate how many hours of backup time you have.

 

[SethP]

Standard automotive or "starting" batteries are not designed to be constantly topped off by a charger. Especially if it's not used much, it will get destroyed in this environment. I would not suggest you use this kind of battery.

I took an old Belkin UPS, removed the dead internal battery, and hooked it up to an old car battery I had. It was backing up my cable modem/router/hub and a few other low-power items, and I estimate would have run for days. After a few months of nothing -- just sitting there operating on utility power, the battery completely died. Not even 5 seconds of backup time.

I replaced it with a deep cycle battery just recently, so it's too soon to tell, but my research says it should work quite fine.

Your AGM battery is likely designed for this kind of use as well.

I mentioned that the M1 will alert you to a power failure. Based on your current demands and the size of your battery backup, you should be able to calculate how many hours of backup time you have.

 

[AceCannon]

Photon,

So what did you decide to do? I found some large AGM batteries and high quality UPS's locally on Craigslist for very cheap, so I've been pondering similar questions. (See thread with details, pics here on AVSForum)

These UPS's have battery chargers in them, too... But I dunno exactly how to implement these with the M1G.

 

[Photon]

This Elk project went on hold for a couple months while I finished finding the software CDs for the new Dell I bought for my better half. I had to tear into dozens of cartons in various stages of unpackedness from the move into the new house. When I finally found them, I then discovered virtually nothing she uses wants to play well with Windows Vista. I suspected if I ordered the Elk toy first, then it would be months before I got the PC to the point where she could use it.

At this point I have the ElkM1G, three keypads, relay board, data bus hub, a pair of input expanders, Ethernet board, and a wireless receiver with a few fobs working together and not drawing as much power as I expected. I'm just beginning to add switches for the doors and windows, and I just received some more glass breaks and PIRs. I'll have to figure out what to do about power after I get everything up and running to see how much it demands. It will have to do without the Miata AGM battery since we are having having some top-down weather in Wisconsin, and I'm taking the Miata out of storage this weekend.

So to finally to answer your direct question, I got a slightly used 7AH alarm battery today, and it will meet my smart charger as soon as the miata battery comes off. If they get along, I'll probably put the pair in the garage attic where I have a sub-panel about 75 feet from the rest of the security system components. I also picked up a couple 10A relays with coils that draw only 30mA @ 12 VDC so I can handle higher current loads like sirens, strobes, and other lights without using the 16AWG pair I ran from the main alarm location. Rats, I forgot to pick up a fuse holder. I'm monitoring temps up there with a recording thermometer, and if it gets much over 120* F I'll relocate the battery, charger, wireless receiver, and one input expander to somewhere cooler. Or I'll run some flexible duct with a fan in one end from the eves to the can. Maybe even knit a fiberglass insulation sweater for the can. More likely I'll be out in the drop top with the wind in what little hair I have left and no thoughts of computers or security devices for the next few months.

Nice find on the UPSs and AGM batteries. A time-proven and UL-approved solution.