Help with M1/Altronix Batteries

[phareous]

I'm planning on buying/installing an Elk M1 system and for my aux power I've calculated I need 4.9 amps for the aux power. I'm looking at the AL600ULX but it appears the cabinet can only hold up to two 9A batteries. So this would die way before the M1 panel does (which would use about 1.4 on 8ah). I probably need closer to 25 or more AH batteries for the AL600.
 
I could hook up some smaller ones outside the cabinet in parallel or get a big one like ELK-12260 26Ah or equivalent, but I am wondering if there would be an issues with the AL600ULX charging these? It says maximum charge current is 0.7A

 

[phareous]

Also, which cables should I use for hooking between the batteries and between the battery and AL600? Any recommendations on where I could buy them?

 

[RAL]

If you need more battery capacity than you can fit in the AL600 cabinet, then yes, you'll need to move the batteries outboard.  You can buy separate cans as battery enclosures.  Altronix makes several models, such as the BC400, BC600, BC800.  Other manufacturers also make battery boxes.
 
The AL600 will be able to charge the larger batteries, but it will take correspondingly longer.  E.g. a 26 Ah battery will take 37+ hours to recharge from a deep discharge.
 
For cables to connect the batteries, I would make my own by crimping F2 or ring connectors (depending on the battery terminals) onto 14 AWG wires of the appropriate length.
 
I would also place an inline fuse at the battery end of the cable.

 

[phareous]

So what would I be trying to prevent by having the inline fuse? 

 

[42etus]

So what would I be trying to prevent by having the inline fuse? 

Fire trucks outside your door in the middle of the night. 

 

[dementeddigital]

Batteries can deliver enough current to melt wire insulation and start fires. 
 
This could happen if the wires (and their insulation) get pinched, abraded, cut, or pierced.  These things have a better chance of happening when the battery is located outside of the enclosure, since the wires are exposed, they are longer, and they run through the metal enclosure.  Keeping the fuse close to the battery protects more of the wire.

 

[johngalt]

Is it advisable to have an inline fuse for all batteries or only for those in an separate box from the controller?

I have one battery in my Elk can and two in the AL600. The wire leads are short but I still would prefer to avoid any risk of fire.

 

[RAL]

When the batteries are in the same enclosure as the alarm panel, the wire lengths are pretty short and the risks are small, especially when the battery is located immediately below the panel, so you usually don't see inline fuses there. 
 
Some folks install an inline fuse anyway, as an extra safety precaution. 

 

[mikefamig]

Thinking outside the box, for systems with very large loads why not use a high capacity deep cell marine battery with a battery tender attached to it.
 
Mike.

 

[Del91574]

Thinking outside the box, for systems with very large loads why not use a high capacity deep cell marine battery with a battery tender attached to it.
 
Mike.

Chargers will fight each other unless you separate them via relays. Conversely, a battery tender is not UL listed for alarm systems.
 
As far as FACP's and the large batteries attached.....which is also a design concern with a normal power supply and large enough battery, the connections are generally separated and physically protected via conduit or raceways and the length is limited. If you have cabling getting damaged in an install like that, you have bigger concerns than simply installing a fuse on the battery lead.
 
While batteries do posses a lot of potential energy if unfused, generally they'll blow up or boil off before the fire potential happens. This comes from seeing it happen firsthand in 20 years of the industry.

 

[phareous]

So I'm thinking of buying 18 gauge ATC-type holders and then putting in a 7.5 Amp blade fuse since they don't make 6 amp ones that I saw, and the 18 gauge wire should be able to handle a ton more amps anyway (20+ amps at this distance), and all I am doing is trying to prevent it from melting.

 

[Del91574]

18 AWG is too light. You're in the realm of at least 14 or 12.

 

[phareous]

Hmm all the charts I saw online for 12V DC seemed to suggest 18 AWG would be fine for 6 amp over short distances. I don't have any problem switching it to 14, just want to make sure I don't waste money
 
EDIT: I see the Altronix manual says use 14 AWG or bigger.