12 VDC Capacity

M1 Support Forum 12 VDC Capacity

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  • #4547
    M1 Installer

    All the data bus modules (keypads, expansion I\O, etc.) use 12vdc power off the data bus, and the main board provides VAUX output power for devices like smoke alarms, as well as its own 12v digital outputs, etc. I’ve seen specs for fusing of different features, but I haven’t seen a spec. for the maximum output capacity as a whole, of the on-board 12v power supply. And what is the spec on maximum 12v draw per data bus? Output expanders have a potential of 330mA each, so two or three along a single bus is drawing a lot of DC power and I assume there’s a maximum capacity for the power delivery per bus line.

    #4548
    ELK Tech Support

    The M1 has 1 AMP of continuous Current available and during alarm 2.5 AMP with the additional current being drawn from the battery. The 1 AMP continuous is a combination of the +VKP, J16, +SAUX and +VAUX terminals. You can check the system current draw from a keypad Menu 8, 86-System Diagnostic, 2:Sys Volt/Curr. If the current during normal operation (not in alarm) is above 1 AMP you will need a secondary power supply.

    #4549
    M1 Installer

    Is that diagnostic information available remotely via RP2 or M1toGo, rather than having to be present at the local keypad?

    #4550
    ELK Tech Support

    Only available from keypad programming

    #4551
    M1 Installer

    Its possible I’m exceeding the capacity of the on-board 12v power. My calculated consumption is between 800mA to 1.3A (depending on number of active outputs). I might be right at the 1A limit during normal operation — I’ll have to check that out (P.S. I sent you the databus info via email). Would exceeding the capacity cause the symptom that I’m seeing? An I\O expander going “missing” on a data bus line? What’s odd is that its always the same expander every time. I would expect a power issue to be more systemic and cause random dropouts, if not across the board, then at least on the same databus branch.

    #4552
    M1 Installer

    Can I use the ELK-P1417 plug-in power supply to provide supplemental 12vdc power to the system? I have a 120vac UPS so my battery backup is external to the system, and I don’t need the charging board.

    #4553
    M1 Installer

    Was able to get to the system diagnostics on the keypad via your instructions, and it showed 0.420mA at 13.8V

    #4554
    ELK Tech Support

    As long as you do not need the battery back-up then the ELK P1417 will work. Please remember to have a Common DC Negative between the P1417 and a “NEG” on the M1

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