Elk power consumption

mikefamig said:
I had to do a little reading but I think that I understand what you were saying about the RIB. You are saying to get a backup ps/battery for the 212 ps and have it switch based on the 212 supervisory zone, yes?
 
Mike.
No.
 
The 212 would have a small battery to satisfy it's charging circuit and self test functions. You would have a larger battery running on a more robust power supply/charger. The RIB would be DPDT and also have an AC trigger connection. No AC would cause the RIB to change state, disconnecting the 212's battery as well as the larger battery charger and connect the larger battery to the 212's battery leads.
 
I've thought about a similar arrangement using a second battery and a relay.  But do you really want to switch over to the second battery on the loss of AC?  That would mean that the 212's battery is never really being used.  My thought was to switch batteries when the 212's battery reached the low voltage cutoff point and it could no longer power its load.
 
One concern I had with using a DPDT relay was whether the M1 would notice the momentary loss of power to the 212s and whether that would cause any problems on the databus during the switch over.
 
While I pause to say this and I am going to strictly state to NOT do what I am putting out there, it is possible:
 
The battery on the 212 is unnecessary in the situation I put out above with the RIB relay. Completely redundant and not worth any standby time, the only reason why it's being installed is to keep the 212 happy for it's dynamic battery test and low battery annunciation. You could dummy out the power supply with a 12VDC output from the second power supply to make the 212 believe there is a battery attached....it's how we used to do it during my tenure at Notifier with our test panels, dummy the power so the charger believes there's a battery present and then the panel is happy, but it's a practice I would not perform in the field.
 
You would NOT however use the 212S with a battery and have a second battery take over on a LB condition....way too easy to end up having multiple devices connected or have in-between states if a battery was right at the cutoff voltage. By using a RIB to supervise the presence of AC (IE: on the LV transformer leg or even 120V feed to the supplies) it's an absolute cutoff when there's no AC present to ensure the respective supply and battery are connected/disconnected to the power supply so there's no possible way that a push-pull can exist or have both batteries connected to the supply.
 
The main issue with the M1 is the bus starts becoming unreliable far before a LBC starts on the 212S. All the M1 devices start getting funky just below 12V, far above a normal LBC of 10.5V. I doubt the M1 would even see the change, as many other panel manufacturers have white pages describing the same connection for their panels and batteries larger than their maximum charging size, and this was for entire systems and not just peripherals.
 
As I've mentioned before, while the 212 is a nice little unit, it's not designed to charge large batteries for long standby times, it's the wrong product for that application.
 
DELInstallations said:
As I've mentioned before, while the 212 is a nice little unit, it's not designed to charge large batteries for long standby times, it's the wrong product for that application.
 
The RIB sounds like a solid solution but I'm looking to keep things as simple as possible for myself. The more components you add to a system the more complexity, maintenance and points of failure you are adding. I plan to live with the short standby limitation of the p212s. I'm pretty comfortable with 4 hours or so of standby. This aint Fort Knox and I can only remember a few times in my life that we've had extended power outages.  I'm also pretty much convinced to not use the twa, it is a power hog and without it I can more than double my standby time to over ten hours using the batteries that I have.
 
DEInstallation - I'd be interested to know who makes the proper sort of power supply in the 2amp range that will sustain a larger battery?
 
Mike.
 
BTW guys - my system is still running great with no errant chimes and zero data bus errors since I removed the m1xrftw wireless. That piece is in a box in a big brown truck on it's way to North Carolina as we speak.
 
Mike.
 
DELInstallations said:
Receiver is going to India (look at the component silkscreens).
 
http://www.altronix.com/products/product.php?name=SMP3PMCTX
 
Max charge rate of .5A. 0V loss on DC, LB and AC supervision and 2.5A output. While not "green" because it's not a switching supply, it's a pretty robust unit. We've got thousands of Altronix units and boards out there.
Good to know. What is the maximum battery capacity? I can't find it in the specs.
 
Mike.
 
DELInstallations said:
Receiver is going to India (look at the component silkscreens).
 
http://www.altronix.com/products/product.php?name=SMP3PMCTX
 
Max charge rate of .5A. 0V loss on DC, LB and AC supervision and 2.5A output. While not "green" because it's not a switching supply, it's a pretty robust unit. We've got thousands of Altronix units and boards out there.
 
 
I did a little reading and found that the maximum charge rate on the Altronix SMP3PMCTX power supply is 0.5 amps. I understand that charge rates are generally stated in relation to discharge rates of the particular battery in question. So my question becomes - what is the minimum, optimal and maximum charge rate of an Elk lead acid battery?
 
Using my 18ah battery as an example:
 
I have learned that my 18ah Elk battery has a discharge rate of 10.8ah (making 1C charge rate = 10.8 amps).
The Altronix SMP3PMCTXhas a max charge rate of 0.5 amps (C rate = 0.5a/18ah = 0.027C)
 
That comes out to a very slow charge rate. Will that maintain  an 18ah battery? Or in other words, what is the maximum battery capacity that the charger will maintain?
 
I could not find any information on the p212s charging rate.
 
Mike.
 
Charging a SLA battery too quickly is the thing you want to avoid.  Doing so will shorten the life of the battery.  A charge rate of no greater than C/10 is a good rule of thumb. 
 
If the charger delivers 0.5A, then 0.5A x 10 gives you 5.0A, and 5Ah would be the minimum size battery you would want to connect to the charger.  But since C/10 is just a rule of thumb, it would probably work reasonably well with a 4.0Ah battery as well, charging it at a rate of C/8, though it might shorten the life of the battery a bit.
 
In terms of the largest battery a charger can handle, it needs to deliver a current that is sufficient to overcome the self-discharge losses and actually cause the battery to charge.  A few milliamps is usually all it takes to keep a battery topped up.   So 0.5A is enough to charge an 18Ah battery, although it could take over a day to do so (e.g. 36+ hours).
 
[Edit:] The PowerSonic technical manual says that under no circumstances should you exceed a charge rate of .30C,  or C/3.33.  That doesn't mean that charging at that rate is a good idea, but rather you will do significant damage to the battery if you exceed it.  It's always a good idea to leave a healthy margin.
 
RAL said:
Charging a SLA battery too quickly is the thing you want to avoid.  Doing so will shorten the life of the battery.  A charge rate of no greater than C/10 is a good rule of thumb. 
 
If the charger delivers 0.5A, then 0.5A x 10 gives you 5.0A, and 5Ah would be the minimum size battery you would want to connect to the charger.  But since C/10 is just a rule of thumb, it would probably work reasonably well with a 4.0Ah battery as well, charging it at a rate of C/8, though it might shorten the life of the battery a bit.
 
In terms of the largest battery a charger can handle, it needs to deliver a current that is sufficient to overcome the self-discharge losses and actually cause the battery to charge.  A few milliamps is usually all it takes to keep a battery topped up.   So 0.5A is enough to charge an 18Ah battery, although it could take over a day to do so (e.g. 36+ hours).
 
[Edit:] The PowerSonic technical manual says that under no circumstances should you exceed a charge rate of .30C,  or C/3.33.  That doesn't mean that charging at that rate is a good idea, but rather you will do significant damage to the battery if you exceed it.  It's always a good idea to leave a healthy margin.
 
RAL
 
Why does Elk put a maximum battery size of 12ah on the p212s power supply? What harm could there be in using an 18ah battery with it to extend stanby time?
 
Mike.
 
mikefamig said:
Why does Elk put a maximum battery size of 12ah on the p212s power supply? What harm could there be in using an 18ah battery with it to extend stanby time?
 
In theory, there is no harm connecting too large a battery if the charger is properly designed.   A battery charger must limit the current to the battery during charging to avoid charging it too quickly.   Since there is no way for a charger to automatically determine the capacity of the battery, it makes sense for a manufacturer to specify a minimum battery capacity, or at least specify the charging current, and then let the user figure out what the smallest battery should be.
 
For the maximum size, the practical consideration becomes the time needed to fully charge the battery.  Some users may want the battery to be charged in 6-12 hours, while others might accept longer charge times.
 
With the P212S, I don't know why Elk specifies 12Ah as the maximum.  It could be that they simply didn't test it with anything larger and don't want to go out on a limb.  Or perhaps there are some marginal components that have a problem if the charging time is too long.  But that shouldn't be so in a proper power supply design.
 
[Edit:]  One other reason for the 12Ah maximum could be that the charger assumes a maximum charge time based on the specified capacity and will report a battery problem if it takes too long to charge.   A simple, dumb charger wouldn't have this problem.
 
It surprises me that they don't specify the charging current that the supply delivers to the battery.
 
The batteries have a max charging current allowed.  Someone could connect a 4 ah battery to the PS so that is the max charging current that it can provide for safety reasons.  A 12 or 18 hour battery would take a while to charge at that rate and I "think" they specify the 12 ah as that is the max battery size they can charge in 48 hours.  The 48 hours comes from the NFPA as the longest refresh time that they permit for a Fire Alarm System. 
 
Its basically a balancing act.  I personally have two 26 ah batteries on my system and a supplemental charger.  Not perfect but it works for me.  The relay while a good idea introduces another possible point of failure.  But in reality..... it should work fine if done correctly.  Many mfg's of alarm equipment still use a relay to switch in their secondary batteries. 
 
The industry evolves all of the time.  15 years ago it was not accepted to use the internet to report alarms.  Now its becoming the preferred method because its found to exceed the old POTS lines in some aspects (not all).  The NFPA is actually increasing the supervision requirements on POTS lines maybe in part because they realize that they are not the best tech out there anymore for the application.  The industry is slowly moving to lithium batteries with smaller size and greater capacity just as systems are becoming more efficient then ever and requiring less and less standby power.  Wireless once frowned upon for short range devices is more popular then ever it seems.  Whole systems are being spec'd to be wireless now. 
 
RAL said:
In theory, there is no harm connecting too large a battery if the charger is properly designed.   A battery charger must limit the current to the battery during charging to avoid charging it too quickly.   Since there is no way for a charger to automatically determine the capacity of the battery, it makes sense for a manufacturer to specify a minimum battery capacity, or at least specify the charging current, and then let the user figure out what the smallest battery should be.
 
For the maximum size, the practical consideration becomes the time needed to fully charge the battery.  Some users may want the battery to be charged in 6-12 hours, while others might accept longer charge times.
 
With the P212S, I don't know why Elk specifies 12Ah as the maximum.  It could be that they simply didn't test it with anything larger and don't want to go out on a limb.  Or perhaps there are some marginal components that have a problem if the charging time is too long.  But that shouldn't be so in a proper power supply design.
 
[Edit:]  One other reason for the 12Ah maximum could be that the charger assumes a maximum charge time based on the specified capacity and will report a battery problem if it takes too long to charge.   A simple, dumb charger wouldn't have this problem.
 
It surprises me that they don't specify the charging current that the supply delivers to the battery.
 
This is how I have always understood the behavior of batteries and charger rates. The reason I ask this question is that my first p212s failed and it was suggested to me that having a larger 18ah battery attached to it could have caused the failure. This made no sense to me until I considered that Elk's smart charger may not have been smart enough to deal with the larger battery and self destructed.
 
Here is what the p212s manual says about the battery:
 
Innovative EBT - Elk Battery Technology circuit provides
maximum battery life
        -  Controlled  charge  ramp  and  maintenance  algorithm
        - Low Battery cut-off protects battery from deep discharge
 
It's that controlled charge ramp algorithm that concerns me. When I replaced the failed p212s I put the specified 12ah battery on it but I'd prefer the 18ah. I just don't want to risk trashing another power supply. I'm thinking that the only way to find out is to try it.
 
Mike.
 
Digger said:
The batteries have a max charging current allowed.  Someone could connect a 4 ah battery to the PS so that is the max charging current that it can provide for safety reasons.  A 12 or 18 hour battery would take a while to charge at that rate and I "think" they specify the 12 ah as that is the max battery size they can charge in 48 hours.  The 48 hours comes from the NFPA as the longest refresh time that they permit for a Fire Alarm System. 
 
I didn't know that NFPA requirement and it could explain the Elk spec in itself.


 
 
mikefamig said:
Innovative EBT - Elk Battery Technology circuit provides
maximum battery life
        -  Controlled  charge  ramp  and  maintenance  algorithm
        - Low Battery cut-off protects battery from deep discharge
 
It's that controlled charge ramp algorithm that concerns me. When I replaced the failed p212s I put the specified 12ah battery on it but I'd prefer the 18ah. I just don't want to risk trashing another power supply. I'm thinking that the only way to find out is to try it.
 
From the symptoms you described previously about your problem with the P212S and the 18Ah battery, I strongly suspect that the P212S was bad right out of the box.  I don't think that the battery caused the failure, although we have no way to know for sure.
 
Elk's description of the charge ramping doesn't tell us much.  It's normal for the current to ramp down as a SLA battery charges.  Some chargers actually ramp the current up a bit at first, until certain conditions are detected, then ramp it down.   Either way, the charging circuit has to limit the current so that it does not exceed the maximum permissible rate.   Larger batteries can handle larger currents, so in general, that should not cause a problem.  Using too small a battery is the condition that would worry me.
 
It would be nice if Elk would provide an explanation as to why they set the maximum battery size at 12Ah.  Digger may be on the right track that it has to do with charging time and the NFPA requirements.
 
But lacking any further information, I would be hesitant to exceed the maximum spec.  Elk had some reason for setting it, and without knowing the reasons, it's hard to say whether there would be any risk of damaging another P212S or the battery if you exceed it.   Theory says it should be ok, but I'd still hesitate to do it without knowing more.
 
One of the things I would like to do one of these days is to monitor the voltage and current to the battery on a P212S and see how it varies with battery size. 
 
Back
Top