Alarm system charge currents and backup batteries

[Justloadit]

My concern is the 7.2 amp charge current (max), most alarm systems are only 0.5 amps.

This simply means that you must not exceed 7Amps on your charger, the fact that the current charger is only 0.5Amps means that a flat battery will take 14 hours to charge fully.
If your charger was say 3.5Amps, then it would charge the battery in 2 hours.

Lithium is not like lead acid, where a slow charge over many hours to charge is the norm.

You can charge a Lithium battery at 50% capacity without any issue besides watching that the temperature remains below 40°C

[Justloadit]

My concern is the bulk and float voltage, most alarms and gates only offer 13.8 volts for charging. I am not too clued up on this, so someone like justloadit would be able to advise, the impact of not offering 14.4 VDC for charging. After a few days of stage 4 load shedding it could prove to be an issue.

If I understand how lithium works, it would take a couple more days than a lead acid to drop below 10,5 VDC and drop out the system.

Taken from the blue nova spec sheet

Bulk Voltage 14.4 VDC
Float Voltage 13.8 VDC
Discharge Voltage (min.) 11.6 V
Charge Current 7.2 A continuous

This specification is typical for a Lead Acid battery.
They have created a Lithium pack which will work to these specifications.

Typical Lead acid batteries, once the charger is removed, the voltage drops quite a bit, not so with Lithium.
Lead acid has a non linear discharge curve. where as Lithium is a linear discharge curve with a smaller voltage differential from fully charges to discharged.

[Justloadit]

The only way to find out is to run tests, maybe one day I will order one of these batteries and test them, but for now I can replace batteries for the next 10 years and not justify spending R1000 on a small battery. I am considering looking into a 100 amp/hr lithium battery replacement (10 times the capacity, not 10 times the price).

Yep at say R800 a year translates to R8K in the 10 years, versus once of R800 for Lithium for the same period.
Your choice

[Isetech]

Can you connect a smart charger directly to an alarm battery with the alarm charger at the same time?

[Justloadit]

Can you connect a smart charger directly to an alarm battery with the alarm charger at the same time?

It depends on what the alarm charger does. If I remember correctly they have a simple voltage regulator which runs at 13.8V,
The smart chargers like to disconnect the charger once the battery reaches 14.4V, and then waits for the voltage to drop to 12.8V to then go into trickle charge mode. With the 13.8V from the alrm charger, the smart charger will remain disconnected, and would require you to disconnect and reconnect for it to reset the cycle.

[Isetech]

It depends on what the alarm charger does. If I remember correctly they have a simple voltage regulator which runs at 13.8V,
The smart chargers like to disconnect the charger once the battery reaches 14.4V, and then waits for the voltage to drop to 12.8V to then go into trickle charge mode. With the 13.8V from the alrm charger, the smart charger will remain disconnected, and would require you to disconnect and reconnect for it to reset the cycle.

It seems the relay option is really the only way to backup the system.

The ideal way to do it:

Connect a relay to the 230 VAC supply, if the power drops the relay contact switches from open to closed and the charger switches off, when the power switches on the relay switches switches back to the open position and the charger will switch on and start charging the support battery while the alarm battery will charge using the panel charger.

It is also very important to remove all peripheral devices power from the alarm panel, we install a 18 amp/hr battery with a 6.4 amp charger. This is also a primitive way of doing it. I am busy trying to figure out an affordable lithium solution.

Paying R900 for a 8 amp/hr lithium battery is as bad as paying R20 000 for a Sunsynk inverter. People are pulling the ring out of it.

My thoughts are to do away with the old method of using a 7 amp/hr lead acid battery or gel and 18 amp/hr lead acid or gel battery with a bigger power supply, rather fit a smart charger with a bigger lithium battery, and at the same time replace the 7 amp/hr with a lithium replacement (it doesnt have to be a 7 amp/hr, it could be smaller , which will connect to the big lithium battery when there is a power failure. The little battery is just be to keep the system running because the alarm companies havent move forward with the new technology. If they dont want to outlay the funds to upgrade their old technology easy money boards , then they should consider fitting a sperate charger supplied as an extra and disconnect old charging method.

At the rate 7 amp/hr batteries are being dumped, they should be considered a health risk, considering the method used to empty the batteries. After this long power outage we are replacing batteries by the crate. I shouldnt complain it is the fastest easiest R800 you can make. I should have got a lad on a bike, dropped the price to R600 and had him spend his day just replacing 7 alarm and gate batteries.

[Isetech]

It depends on what the alarm charger does. If I remember correctly they have a simple voltage regulator which runs at 13.8V,
The smart chargers like to disconnect the charger once the battery reaches 14.4V, and then waits for the voltage to drop to 12.8V to then go into trickle charge mode. With the 13.8V from the alarm charger, the smart charger will remain disconnected, and would require you to disconnect and reconnect for it to reset the cycle.

The charger will switch off when the power goes off and restart/reset once the power is restored ?

Would the 13.8 VDC charger and battery current charge state conflict with each other?

There must be a simple solution.

The alarm systems are supplied using an 16 VAC transformer, fitted with a 13.8 VDC charger which I am assuming is used to power the board? When the power is lost the battery back feeds into the panel to keep it powered during outages.

The person who figures out a solution to this alarm/gate 7 amp/hr battery problem is going to make some good money. I dont believe the lithium 8 amp/hr replacement battery is the solution, maybe on the budget systems where there is no need for a ton peripheral devices to operate (those people dont wan to spend R900 on a battery either) I see AC/DC have them on special for R850 .00

[Justloadit]

The charger will switch off when the power goes off and restart/reset once the power is restored ?

Yes

Would the 13.8 VDC charger and battery current charge state conflict with each other?

It may, because when the charger powers up, it looks at the battery voltage to determine the state of charge. However if the battery is flat, the limited current from the 13.8V alarm charger will follow the battery voltage, so the smart charger will identify the flat battery.

There must be a simple solution.

The alarm systems are supplied using an 16 VAC transformer, fitted with a 13.8 VDC charger which I am assuming is used to power the board? When the power is lost the battery back feeds into the panel to keep it powered during outages.

Correct. If you do not want the alarm charger to charge your battery, insert a 10A diode in series with the battery and the alarm system. Connect the smart charger to the battery. Problem solved.

The person who figures out a solution to this alarm/gate 7 amp/hr battery problem is going to make some good money. I dont believe the lithium 8 amp/hr replacement battery is the solution, maybe on the budget systems where there is no need for a ton peripheral devices to operate (those people dont wan to spend R900 on a battery either) I see AC/DC have them on special for R850 .00

Any other kind of solution is going to cost more then the Blue Nova, even using the 18Amp battery, what is the cost? Also it will take twice as long to charge off the alarm so called charger, and frequent power fails will never get the battery to charge correctly. Adding the external smart charger is no cheap solution either.
choose your poison they all come at a cost.

[Isetech]

Yip anyway you look at it, it is going to cost a few bob. I think it is going to be better to find an around solution for load shedding to include the alarm, lights, CCTV, router etc.

[Dylboy]

I have done a separate battery on a victron charger which replaces the the 7AH on the gate motor. Its a D5 and i have to have the charge pin thing plugged in for it to work on mains, so to a degree as far as I can work out it parallel charges. However it has been quite a few months with plenty loadshedding and no loadshedding and all is well. The battery is a 100AH lead acid something

But for homes where I install backup inverters I get the alarm, gate and garage motors on the inverter where possible.

Sent from my SM-N960F using Tapatalk