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ELK M1G auxiliary power supply installation questions

TrojanHorse

Active Member
So I’ve been confused on the details of adding a supplementary power supply.  As I’ve been exploring this and searching the forums I think I found most of my answers, but I would greatly appreciate if the community can chime in and give me a sanity check.
 
I ran the ELK power consumption spreadsheet and it says that I’m over the 1 amp limit so I plan to add an additional power supply.  I’m surprised by this fact and didn’t expect it when I began since my install doesn’t seem that big (see list below), but regardless, I’ve ordered the ELK P212S and plan to install it in the enclosure.  This should give me some headroom as well as I continue to find new things I want to incorporate into my system.  In my case, the spreadsheet shows I’m drawing about 2.6 amps including the speaker and siren, and 1.6 excluding (and the keypad menu shows that standby is drawing about 0.5 amps). 
 
First, I’d appreciate help with sizing. Appendix F of the installation manual says that the 1 amp limit for the M1G is for +SAUX, +VAUX, +VKP AND J16. 
  • Can someone confirm if this means that if I run a speaker (ELK 73) on output 1 and a siren on output 2 (ELK 15) that the draw of those components does not count toward the 1 amp limit?  Page 7 of the manual and a response by Spanky in another thread suggests that’s the case.  (http://cocoontech.com/forums/topic/9373-confused-about-speakerssirens-and-ul-listed/). 
  • As an aside, is this in part the reason why the M1G kit came with a 45VA 16.5 VAC transformer (ELK TRG-1640) that can power ~2.7 amps?
 
Second, I have the following questions on the install:
  • I am going to add a battery to the P212S – can / should this be connected in parallel with the battery I already have for the M1G, or do I keep them separate (and deal with the different standby times)? 
  • I plan to shed almost everything to the P212S and use the M1G only for SAUX and siren / speaker outputs (edit: and M1RB) – does that make sense?
  • Back to my first comment on sizing, do people typically include the sirens and speakers in current draw / standby time calculations?
  • What battery size(s) would you recommend?  Elk’s power spreadsheet (including sirens) suggests the 12Ah battery for the entire system – am I correct to assume that the M1G or P212S can adequately charge that battery?
  • I plan to put this into the large enclosure with the M1G.  Is there a single transformer I could use or do I need to use 2?
  • What’s the best way to have the main power switch on the M1G control the P212S so that if I turn off/on the main power switch on M1G the P212S will do the same?  (not essential but might be nice)
 
Third (and maybe OT), this is going to force me to re-wire my enclosure, which I want to do the right way. 
  • Can someone please point me to a resource of “best practices” when wiring in an enclosure? 
  • I’ve seen pictures posted to FB by ELK and some posts here that give me guidance, but I’m wondering things like how long of a service loop to leave, the best way to manage the service loops, etc.  I’ve read the “wiring your new house” 101-103, which is helpful but doesn’t talk much about the enclosure itself.  I’ve also watched a structured wiring video from ELK on youtube that didn’t give me quite the detail I wanted.  I can start a new thread on this (and maybe post pictures) but was wondering if there’s a resource someone can point me to before I ask for specific suggestions on cleaning up my particular install. 
 
Thanks in advance guys.
 
ELK System components:
 
ELK M1G
M1XEP
M1RB
M1DBH
1 M1XRFTW wireless expander
3 of M1KP2 keypads
3 of Bosch BDL2-WP12G motion sensors
6 of COSMO2W (smoke / CO)
1 of COSMOD2W
Ipdatatell cell dialer
S73 speaker
S15 siren
Glass break detector
 

RAL

Senior Member
TrojanHorse said:
First, I’d appreciate help with sizing. Appendix F of the installation manual says that the 1 amp limit for the M1G is for +SAUX, +VAUX, +VKP AND J16. 

  • Can someone confirm if this means that if I run a speaker (ELK 73) on output 1 and a siren on output 2 (ELK 15) that the draw of those components does not count toward the 1 amp limit?  Page 7 of the manual and a response by Spanky in another thread suggests that’s the case.  (http://cocoontech.com/forums/topic/9373-confused-about-speakerssirens-and-ul-listed/). 
  • As an aside, is this in part the reason why the M1G kit came with a 45VA 16.5 VAC transformer (ELK TRG-1640) that can power ~2.7 amps?
 
Yes, the things you have connected to OUTPUT 1 and OUTPUT 2 don't count in the power calculation.
 
The M1 has a power supply that provides about 2.5 Amps.  1.0 Amps of that is available for powering the devices you have connected to SAUX, VAUX, VKP and J16.  The rest is used to power the M1 itself, charge the battery, and drive the speakers/sirens connected to OUTPUT 1 and OUTPUT 2.
 
 
TrojanHorse said:
Second, I have the following questions on the install:

  • I am going to add a battery to the P212S – can / should this be connected in parallel with the battery I already have for the M1G, or do I keep them separate (and deal with the different standby times)? 
  • I plan to shed almost everything to the P212S and use the M1G only for SAUX and siren / speaker outputs – does that make sense?
  • Back to my first comment on sizing, do people typically include the sirens and speakers in current draw / standby time calculations?
  • What battery size(s) would you recommend?  Elk’s power spreadsheet (including sirens) suggests the 12Ah battery for the entire system – am I correct to assume that the M1G or P212S can adequately charge that battery?
  • I plan to put this into the large enclosure with the M1G.  Is there a single transformer I could use or do I need to use 2?
  • What’s the best way to have the main power switch on the M1G control the P212S so that if I turn off/on the main power switch on M1G the P212S will do the same?  (not essential but might be nice)
 
The battery for the P212S must be separate and should NOT be connected in parallel to the battery for the M1.  The NEG terminals of the M1 and the P212S should be connected together, but the +12V terminals must be kept separate.   Do not connect a wire between +12V (e.g. +VKP, +SAUX, +VAUX or J16) on the M1 and +12V on the P212S.
 
You will need an additional TRG1640 (45VA) transformer for the P212S.   Or you could get a 100VA transformer and power both from the single transformer, but I don't believe you'll find a wall wart type that large.  These are usually open frame transformers.
 
You should choose battery sizes for the M1 and the P212S so that the P212S battery lasts longer than the M1's battery.  The sizes you need will depend on the load that each one is powering.  Since the P212S is probably going to have a larger load than the M1, it will need a larger battery than the M1.   If you have an 8 Ah battery on the M1, you may need 2x (or more) than that capacity on the P212S.  When you plan your power, think about the typical power draw as well as the max power conditions in alarm mode (e.g. the smokes draw very little until they detect smoke and sound an alarm).  Depending on which loads you put on which power supply, the max power draw numbers might make you think that the P212S should last longer than the M1, but in actual practice, it won't.
 
The M1 is spec'd for batteries up to 18 Ah.  The P212S is spec'd for 12 Ah. How much standby time you require depends on how long a power failure you want it to last through. For a residence, 4 hours minimum is required by UL.  But going with a larger battery that can last 12 to 24 hours isn't unreasonable.  Where I live, it's not unheard of to have a power failure of 24 hours.  
 
The M1 and the P212S will probably charge the battery at a rate of about 0.1 to 0.5 Amps per hour (I haven't made an actual measurement).  Larger batteries will take longer to recharge after a prolonged outage. According to ELK, you can put a battery larger than 12 Ah on the P212S.
 
The P212S has its own on/off power switch.  The P212S doesn't have a power control input that would allow the M1 to power it off.  You would need to use a double pole relay (or 2 single pole relays) to disconnect the AC power and battery connections if you wanted that sort of control.  Not sure I would go through the trouble if they are both located near each other.
 
I wouldn't try and power everything from the P212S.  Leave some devices powered from the M1.
 

TrojanHorse

Active Member
Thanks RAL!! I appreciate the prompt thorough response. That definitely points me in a great direction! (note, I revised my post to say I planned to keep the M1RB on the M1 - and will consider keeping other items there too)
 
Of interest:
 
Open frame transformers open up the issues with code compliance. You're not allowed to technically put them out in free air and have their primary side exposed, same with the HV splices.
 
Power calcs should always be a worst case (relays active, etc) value/scenario. There should also be a 25% cushion considered on top of the value calculated for headroom. All covered via applicable codes (UL is far more conservative).
 
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