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Security system batteries during power outages
AC5ZO's comment about 6 volt golf cart batteries in another thread got me to thinking about our security system batteries. I'm hoping that somebody with home power systems or savvy radio operator (hint hint AC5ZO) can help me out here.
It seems that some (*&^%() thief in our area has found that rural homes are often easy picking for burglary. We haven't been broken into, probably because I am here most all the time since I work at home, but the guy down the road was hit a week ago.
To compound the problem we have fairly frequent power outages, and Murphy's law dictates that the outages occur when we're on vacation. We were gone for 10 days last Christmas, and we had a 5-day outage during that our trip.
We have a backup generator that we can run for a few hours each day to keep the food frozen. I am building a system to be able to dial-in to the house and start and stop the generator over the telephone and through our security system.
The problem is that for outages longer than around 12 hours our security system batteries die. Propane is too expensive to run the generator 24 hours a day just to supply the 1.5 amps that the security system needs.
I want to hook up two or three Optima deep cycle batteries (minimal outgassing) to power the security system. The problem is that these batteries will be on their own charger and I don't want the voltage from this charger to backfeed the security panel. So I need to hook up a diode of some sort to keep that from happening, and I want to get it hooked up without damaging the security panel, batteries, or battery charger in the process.
Any ideas? Does anyone here know of an off-the-shelf solution that I can use for this?
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Security system batteries during power outages
We can discuss this here, or you may email me at
ac5zo(at)yahoo.com
I do not know what you mean exactly about the battery charger backfeeding the security panel.
Most security panels have a small gelcell that can keep it powered for four or five hours. It has its own onboard charger that powers the security system when the AC line is working properly.
What I expect that you want to do is to have the Optima batteries being charged with their own charger and then connect the batteries to the security system. If that is the case, then you may use a diode from the optima batteries to the gelcell. If you lose AC power, both the charger for the optima batteries and the charger in the security system will go down at the same time. The gelcell in the security system will supply power for the alarm system until its voltage get 0.6 volts lower than the optima batteries and then power will be delivered from the optima batteries through the same circuit that pulls power from the gelcell.
When the AC power comes back on, both chargers will start to operate, but the security system charger will only charge the gelcell and not the optima batteries because of the diode. The optima batteries will charge with their own charger.
Sometimes the 0.6 VDC drop cannot be tolerated. If that is the case, you can put a 115VAC relay that is always powered on by the AC line. If the power fails, the relay relaxes and closes the NC contacts connecting the optima batteries to the gelcell. When the power comes back on, the relay will pull in and separate the optima batteries from the alarm power circuit.
For figuring the AH capacity of the battery, just multiply the amperage draw times the amount of time that you want standby power. This works for really light loads on batteries where you are expecting 100+ hours of power. So, if you want 100 hours of standby, you will need about 150 AH worth of the Optima batteries wired in parallel.
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Security system batteries during power outages
Thanks very much for the info. You nailed what I want to do with the batteries, but there are some niggling details I don't understand. I'll take you up on your offer and contact you via email.
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Security system batteries during power outages
I'd like to publicly thank AC5ZO for helping me out with my battery dilema. He has been generous with his time and answered all my questions thoroughly.
TractorPoint folks are the BEST!
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Security system batteries during power outages
You might look inside the main panel of your system. I recently discovered that I have gel cel backup batteries with a built in charger. I say discovered because the alarm would not stop beeping. I took the panel apart and found theese batteries that look like a motorcycle battery, only smaller. It was a bugger finding replacements.
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Security system batteries during power outages
Yes, the panel has two 12V 7AH gel cell batteries wired in parallel. During an outage they only last 12 hours or so, and therein lies the problem. I'd like at least a week of backup power.
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Security system batteries during power outages
I have worked on a number of security systems and they all used fairly standard gelcell batteries. The brand is not very important but the voltage is. Most are 12 VDC.
Get a battery that will fit and has at least the same AmpHour capacity as the previous battery. A small increase in AH capacity will not hurt if the battery will fit. Going much over the original AH capacity might strain the internal charging circuits.
If your system has a lead acid gelcell, stay with lead acid technology including gelcells, or non-vented, or starved electrolyte. Brand does not matter.
There could be some systems out there that use NiCads and you must stick with them. You can substitute NiMH if you cannot find NiCads, but do not substitute gelcells.
KW has gelcells in his alarm panel, but he wants to have backup power for many days rather than a few hours.
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Security system batteries during power outages
kschumm, Do you have a generator or back up power ? As long as there is power to the circuit the system should charge. A few years ago I picked up a larger Generac for about $1300 that will power 90% of my home at one time.Its about 13 hp. I had the generc circuit board and plugs installed so it can be plugged in the garage. The Generac switch/circuit panel is by the main breaker. The boxes were about $500 and another $500 for an electrician but I made some very long runs to have everything exactly where I wanted. The Honda generators of similar size are about 1k more but a lot quieter.
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Security system batteries during power outages
I was thinking that a solar panel as back up and battery maintainer might be preferable to a standard charger as it would provide some power when the house current is off.
Most of the commercial standby power systems are still vented lead acid, but I agree most of the valve regulated Lead acid batteries are better for this applications. The best for deep discharge are the flat plate AGM batteries as the plates are thicker and they have greater pressure on the plates to hold the oxides on the plates. Deka makes them among others. The Optima are essentually the same construction except they apply greater pressure and the plates are thinner as they are rolled.
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Security system batteries during power outages
A number of folks who are building hunting cabins near our camp are useing a battery powered system by Onan. They use perhaps 12 of the optima batteries. The Generator comes on automatically when the batteries are low to charge them. Two camps down they buitl about 1200 sq' and this system powers the entire camp.
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