Calculate 12v Battery Expectancy

The system may have anti-tamper series resistors in the sensor contact loops and across the contacts - if the loop current is out of range it gives a tamper alarm.

The system in the factory here is like that, with each circuit drawing 1 or 2 mA-ish (contacts open/closed), and there are about 50 sensors! If you poke the right buttons on the control panel, you can get a numeric display of the current for each loop.

That's Quite Interesting ... fine for a factory with a mains supply of course.
Del

Don't know why they don't strobe or multiplex it - each sensor loop would only have to be on for say 1 msec/sec.^[1] But as you say, there's a nice comfy mains supply, so usually it's not a problem.

Having said that, the power was off here for most of 48hrs once after a catastrophic underground cable failure.

I agree that for a battery-run system, micro- rather than milliamps would be more realistic. A decent buck/boost power supply would be a good thing to have as well, so the system could run at say 9V from a nominal 12V battery and squeeze the last useful drops out.

[1] [Edit - er, um, is that what you meant by "... get the alarm to activate intermittently ..." ?]

Sir,

How to compare different UPS products in the market for choosing it technically ?

What questions should be asked for finding out which one is offering the best specifications ,and give better battery life and prolong working ?

It is said that if battery is not discharged regularly, the life reduces. What happens to the battery life if the power failure is not so frequent?

Is there a provision in the ups to discharge the battery to required extent after a pre-designed time to enhance the battery life.

What is trickle charging? Is there a possibility of overcharging? (If it is not designed properly.) How it will affect the battery life?

kiran nawathe

What is the impending failure voltage of device?

That is to say, at what voltage will the device cease to function. A device I sell operates stand alone on 4 'AA' cells. It will operate correctly until the voltage in the cells reaches 4.6VDC. At that time, the low battery alert routine begins.

[edit] I see Del's comment on complete drain. If the device is like most I have seen, when fault voltage is reached the device will shortly shut down. I agree with him, the actual time between battery replacement will be disappointing.

Don't start me on 'low battery alerts' that consume extra power and hasten the demise of the battery.
Out of interest, to get decent life out of an alkaline dry cell you have to run it down to 1v or below. I always use that as a catch question for the new guys to see what they know.
Q. 'How many volts do you get from a 9v battery'
A. Six is the smart answer (I've never heard it yet tho') I once had a firm of consultants design a unit for us on the assumption that you got 9v throughout it's life. (Ooooh can you imagine how I slapped those overpaid suckers down)
Oppologies if I'm preaching to the converted...it's a slow day here, I'd rather be home makin' bows.
Del

Sounds quite simple to me. Assuming your 90 Amp.Hr battery is quoted at the "10-hour discharge rate," then it would supply 9 Amps for 10 hours. Hence 200 mA for 450 hours. In practice it will probably be longer than this because the capacity will be somewhat higher due to the lower discharge rate. Let's guess at 480 hours - 20 days.

I take this opportunity to thank all for their input. This gives me a start point to see what can be done to improve upon the initial design. May need to look at a couple of batteries and a Solar Powered Panel to maintain at least some input back into the batteries. Anyone know anything about the size of Solar Panel I would require to maintain the batteries, based upon the 200 ma draw. ?

Anyone know anything about the size of Solar Panel I would require to maintain the batteries, based upon the 200 ma draw. ?
Arrrggghhh!
Reduce that damn 200mA draw first! And don't round it up to 200 mA, you surely don't expect the alarm to be going that much? If nobody responds to the alarm, there's not much point having it! (Someone will just come in and steal the batteries)
Google will get you loads of solar panels rated by current.... I know I've looked before. But again, if you reduce the current the panel will be cheaper too! Just google 12v 200ma solar panel.
Del

Thanks Del The Cat, I will look into that and take your advice re the AAARRRGH 200ma. Cheers

Answering your question John DG ( Scotland ) does that say it all or do you want me to be more specific. Not great Sun light if the truth be told. More of a Grey Light.

Long as you're south of the Arctic circle you should be OK - but you'll have to take the short Scots winter days (bugger-all sun and precious little light at a') into account.

How much sun you got?

if you are using a 90AH battery and consider worst case scenario of 200mA power consumption then it will give you 90/0.2 = 450 Hours of backup time. 450/24 = about 19 days.

There are proper battery testers availale from quite a few suppliers in the market that give you the battery status when connected to the battery in circuit. You could use this gadget to check the battery every 15 days or so.

Regards

Melwyn Sequeira

Why not using a battery system charged off the mains - using the batteries only in the event of a power cut?

I would be mostly using this system to operate in areas where there is no mains power supply, or Generator. Therefore it would be stand alone. In this case I want to be able to ensure that the operation of the system is not affected as its being used for Security of the area or cabin. The system should effectively be able to operate without a loss of power indefinitely. This is an upgrade of my initial question just taking it a step further with everyone involved in this discussions help.

design a system that checks the switches and anti tamper circuits every say 5 mins

then the only drain would be the main timer cicuit that switchs the checking ciruit on and off and the drain whilst checking is taking place, fit a solar panel to charge battery during dayselect solar panel to exceed the drain of monitoring circuit and charging thus during daylight no power is drained from battery, then only power drain would be in hours of darkness, this would limit the drain on the battery to the hours of darkness only

Hello peter.

A part of the trouble is, DTECT has not told us what is being monitored... is this a fire alarm panel? Intruder detection? Low volume of some liquid? Air/gas mixture? Rainfall? Temperature? All of these? A sample once every 5 minutes may never report an alarm condition, or may report alarm condition 4-1/2 minutes too late.

I will agree with you and others who have suggested solar maintenance. With the holes in the information, this (as well as suggestions to find a way to reduce consumption) seems the most reasonable way to manage the problem.

Hi Doorman its a Infra Red Perimeter Protection System which I have pulled all of the parts together and had special stands designed and manufactured to hold the detectors, lighting etc. The Sensors / Detectors are Solar Powered Battery Backed Up. Therefore the only draw on the Battery System I am trying to put together will be the actual GSM Autodialer Alarm Panel. The draw of 300ma is when the system is triggered, the auto dialler then starts its communication with my Monitoring Station, and also the on site Sounder.

Well, there we are.

The PIR detectors (an assumption of your system components) draw constantly, thus the 60ma standby draw... I doubt you can improve that current draw much. This is, actually, sort of low. This is the emitters/detectors, the monitor station, line loss...?

[edit] Thanks JohnDG. I misread his information. Oops!

Are there many LICs (Local Indigenous Critters) around to constantly trip the system?

Will the PV solar be protected enough, so an ambitious would-be intruder will have trouble disabling the device?

I read it that the PIR (or whatever) subsystem is independently powered, therefore no draw on the panel.

Hi Doorman

The system is not tripped by small animals or paper bags blowing around in the wind. It is situated behind the Perimeter Fencing and I always ask the Client to ensure that their Fencing is adequate to the task. They are billed for call outs to the location every time a Mobile Patrol has to attend so they generally work with me rather than against, it costs them money otherwise. Our response time is usually around 10 to 15 minutes so we are on site usually before anyone has got round to causing any real mischief as they are not aware that an alarm has even been triggered. If the sounder is on silent which is my preference. Does not use as much power and gives us the opportunity to catch the Intruder on Site.

Light barriers or PIR?

The Detectors are PIR and have up to 200m detection range

As has already been mentioned...

It isn't the alarm current draw that is going to be the killer - it will be the standby current. Keeping that as low as possible will be the ticket. If you have audible or visual alarm devices, find the lowest current draw devices you can as well, so as to minimize the alarm current draw. I would consider the 200 mA to be an extremely high average. Don't average, just estimate how long the alarm would potentially run for, and then deduct that from your 90AH. Then divide what is left by the .06. In fire alarm, we always add a safety factor. I would deduct 25% to ensure that you get there well before the battery gets so low it powers the unit down.

As for using various resistors and such, I don't think that will be an option. If it is a typical security panel, like ADEMCO or something, the resistors will need to be the proper value as the panel takes readings off each circuit for the purpose of supervision. Changing the values of the resistors will put the panel into trouble or alarm, depending on which way you go in the value.

Just an example of the calculation:

if your alarm is going to run for 10 hours (which is an absurdly long time) at 200 mA, that would be 2AH. that leaves you with 88AH. 88AH divided by 60 mA (.06) is 1466 hours minus 25% = 1100 hours = about 45 days.

Hope that helps you.

Hi TPIECORA

Yes that is helpful, and I appreciate your input. I have now enough information I believe to progress to the next stage which is the Solar Powered Stand alone System. The information I have received from everyone involved has been very helpful and I thank you all for your input. Should I require any further assistance in this matter I will come back to you as and when.

Thanks again Cheers DTECT

All I can Say is Listen to Del!

He helped me out on a battery operated wireless keypad I did. After about two years of these in the field. I would say that my actual battery life is within 5% of my calculations.

Del Rules and Dogs Drool! :) GA from me.

Bill12780