Dual batteries

[ctwilliams]

Due to my ordering mistake on my part, I have two of the Elk 12v 8amp hour batteries.

If I read the manual correctly, it looks like it can take up to a 16amp hour battery, so if I connect these two 8amp hour batteries in parallel, will that cause any problems for the Elk (m1)?

Thanks,

CT

 

[rfdesq]

Shouldn't be a problem. That's what I plan on doing.

 

[Digger]

Two 8 aH batteries in parallel are actually required for UL Residential fire requirements. I beleive that the M1 can actually handle up to 18 aH battery.

The more battery backup the better in my opinion.

 

[Spanky]

No problem with two 8AH batteries in parallel. Keep in mind that the more battery amp hour capacity is to be recharged, the longer it will take after a battery run down.


FYI:
When putting two batteries in parallel, should a cell in either battery ever short, it will bring down the other battery also. The M1's low voltage battery test will let you know it has a problem.

 

[cliffs]

It is never a good idea to put batteries in parallel, because if a couple of cells short in one battery it will overheat the shorted battery and could cause a fire. If you want to use more than one battery they should be isolated with diodes, this will prevent one from discharging the other and the fire potential.

Cliff s

 

[tuantu]

cliffs

i have the two batteries in parallel and i want to do what you suggest by adding diodes but don't know how. could you describe exactly where do you install this diodes in relation to the battery and M1 panel. Where can I get this diodes and part number. Radio Shack?

 

[ano]

It is never a good idea to put batteries in parallel, because if a couple of cells short in one battery it will overheat the shorted battery and could cause a fire.

While this comment may apply to some type batteries, sealed lead acid batteries are not one of them. Failure mode is almost always an open cell, not a shorted cell. HAI even makes a wiring harness for the sole purpose of wiring two batteries together and their panels are UL certified.

Just make sure the two batteries are the same age, and in the same state of charge before connecting them together.

 

[dublin00]

I beleive that the M1 can actually handle up to 18 aH battery.

Has anyone mounted an ELK 18 aH battery in the structured wiring panel (I have the 28" model)? I was just about to do that for my ELK Alarm, but the standard battery shelf isn't deep enough to hold the 18aH battery. Any ideas?

 

[rocco]

As far as I know, multiple batteries in the ELK cannot be isolated with diodes, since the same wiring is used to both charge and discharge the batteries.

 

[cliffs]

First: the battery is meant to buffer short power outages, not be used for long standby operation.

The simple answer is to use a larger battery. Sealed batteries are available to over 100 amp hours. They come in all sorts of sizes.

The M1G would probably maintain a battery of at least 25 amp hours. It would take some time to complete a complete charge, but the system normally is only providing a trickle charge to keep the battery fully charged.

If a longer standby time is desired in a remote location(summer cabin) a solar charger might be considered. The charger would need to have capacity of about 25% greater than the normal load.

Cliff s

 

[Digger]

In my opinion once you get to the point you need more than 16 aH for standby you should add a supplemental power supply with additional battery backup. This way you can recharge the batteries in a reasonable amount of time.

The other day some told me that if there is a power outage they would not worry about the alarm system past a few hours. But in a prolonged outage is when you really need the alarm especially for fire and CO etc. I feel. I think people are very careful with candles etc when the outage first occurs but after a few hours they get complacent. And how many people heat their house or apartment with the gas oven in the kitchen in a prolonged outage?

 

[bmil]

I just plug my M1 (and a small receiver for a wireless driveway sensor) into it's own APC 350VA UPS I got on sale for $20. I figured that it should be able to power the M1 for quite awhile considering what has to be a minuscule power draw compared to a PC. Then the M1's battery would take over...

 

[jlehnert]

First: the battery is meant to buffer short power outages, not be used for long standby operation.

Actually, as part of the UL process for fire/burg panels, it needs to be able to go for an extended amount of time, at least 24 hours.

IIRC, it's 24 hours with one 5 minute activation of the fire portion of the alarm. I'm sure there are some qualification there, as a sytem with 2 smokes will last longer than one with 20. I'm sure Spanky & Co. know the specifics.

 

[Digger]

The M1 has a max 500 ma standby and 1 A additional for alarm with 2 8 aH batteries for standby power if I remember correctly for Residential fire.

 

[Sandpiper]

An excerpt from the National Burglar and Fire Alarm Association (NBFAA) Installation standards:

Every alarm system must have standby power sufficient to operate the system in non-alarm status (without being the cause of alarm activation) for a minimum of four hours. Fire alarm systems shall have a minimum of 24 hours of standby power........

From the National Fire Alarm Code (NFPA 72):

Smoke and heat alarms shall be powered by one of the following means:
(1) A commercial light and power source along with a secondary battery source that is capable of operating the device for at least 24 hours in the normal condition followed by 4 minutes of alarm........