[RE-wrenches] Relay Drivers

Tue Jul 21 07:54:06 PDT 2026

Hi Drake,   I’ve been wanting something just like what you described.  AI
generated answers for me. Sorry if the font turns out weird but here it is:
      Step-by-Step Implementation
1. Configure the Voltage Monitor

   - Connect the voltage sensing inputs of your monitoring relay directly
   to the battery bank.
   - Set the function mode to *Overvoltage (OV)* or *Window Mode*.
   - Adjust the trip threshold to *53.5V*.
   - Set the *hysteresis (differential)* to a lower value (e.g., 51V) to
   prevent the relay from rapidly clicking on and off as the battery voltage
   naturally dips under the new load. [1
   <https://www.anernstore.com/blogs/off-grid-solar-solutions/guide-wiring-home-battery-storage?srsltid=AfmBOooQHwiFg7_J6zbdtMhqiXP9S9XEbgPrgudvTjcLTqQTj-x9YD-k>
   , 2
   <https://www.reddit.com/r/ebikes/comments/9d194n/what_is_the_low_voltage_cut_off_for_a_48v_battery/>
   ]

2. Wire the 12V Trigger Circuit [1
<https://forums.raspberrypi.com/viewtopic.php?t=259524>]

   - Connect the input of your *48V to 12V Buck Converter* to the battery.
   - Take the positive (+) 12V output from the converter and wire it
to the *Common
   (COM)* terminal of the monitoring relay's internal switch.
   - Wire the *Normally Open (NO)* terminal of the monitoring relay to the
   positive (+) coil terminal of your 12V relays.
   - Connect the negative (-) output of the buck converter directly to the
   negative (-) coil terminal of your 12V relays. [1
   <https://www.support.getzooz.com/kb/article/782-how-to-use-the-zen17-universal-relay-with-low-voltage-lighting/>
   ]

------------------------------
Component Checklist

   - *DC Voltage Monitor:* Look for a "48V DC Overvoltage Relay" with
   adjustable digital thresholds. Industrial options from brands like
   Macromatic or Phoenix Contact offer highly reliable rail-mounted units. [
   1
   <https://www.ato.com/dc-voltage-monitoring-relay?srsltid=AfmBOoqXnG_9VgHkqEI-PYDyL4lt5kN7vx-9sk5-Ix_1gU_aWgX5Eepc>
   ]
   - *Buck Converter:* Ensure the converter can handle an input up to *60V
   DC*, as a 48V battery bank will frequently exceed 54V during a full
   charge.
   - *Flyback Diode:* If you are chaining multiple 12V electromechanical
   relays together, place a 1N4007 Diode backward across the 12V relay
   coils to absorb inductive voltage spikes when they turn off.

To help narrow down the exact parts, what is the *total current (Amps or
Watts)* that your 12V relays will be switching on the load side? Also, are
you looking for a *plug-and-play DIN rail module* or a *DIY electronic
circuit board*?
I need DIN rail mounted components.
5 sites
To set up your 48V battery monitoring system on a standard *35mm DIN rail*,
you will need three core modular components: the digital monitor, an
isolated DC-DC power supply, and your 12V terminal relays. [1
<https://www.amazon.com/Adjustable-Voltage-Under-Voltage-Protector-Protective/dp/B0CMHQS24R>
, 2
<https://www.google.com/search?q=product&prds=pvt:hg,productid:1066366044745123193&ibp=oshop>
]
Because a 48V battery bank routinely climbs past 54V during high-stage
charging, all selected equipment is chosen to withstand continuous exposure
to higher high-end voltages. [1
<https://www.google.com/search?q=product&prds=pvt:hg,productid:1066366044745123193&ibp=oshop>
]
🔌 Recommended DIN Rail Components
[image: Voltage Monitoring Relay For Single Phase Systems With Adjustable
Over Voltage And Under Voltage Protection, 35mm DIN Rail Mount, DC 48V,
Indicator Li]
Voltage Monitoring Relay For Single Phase Systems With Adjustable Over
Voltage And Under Voltage Protection, 35mm DIN Rail Mount, DC 48V,
Indicator Li
$88.88
VXB.com Bearings
<https://www.google.com/search?ibp=oshop&prds=pvt:hg,pvo:29,imageDocid:7982363793066485891,headlineOfferDocid:1066366044745123193,productDocid:1066366044745123193&q=product&sa=X&ved=2ahUKEwidy8u4_eOVAxWZiCsGHWsuL4sQgLcPegYIAQgSEAM>

   - Features a wide input tolerance tracking overvoltage up to 68V.
   - Displays two dry-contact output channels (Normally Open/Normally
   Closed) rated for up to 6A to route your control signals safely.
   - Offers an adjustable time-delay function (0.1 to 15 seconds) to filter
   out transient voltage noise when high-surge loads kick on. [1
   <https://www.atorelays.com/dc-voltage-monitoring-relay.html>, 2
   <https://www.google.com/search?q=product&prds=pvt:hg,productid:1066366044745123193&ibp=oshop>
   , 3
   <https://www.amazon.com/Adjustable-Voltage-Under-Voltage-Protector-Protective/dp/B0CMHQS24R>
   ]

------------------------------
[image: Original MEAN WELL DDR Series 120W DIN Rail DC-DC Converter]
Original MEAN WELL DDR Series 120W DIN Rail DC-DC Converter
$82.56
RS - America& more
5.0
(2)
<https://www.google.com/search?ibp=oshop&prds=pvt:hg,pvo:29,imageDocid:5227688873399897076,gpcid:6422150473890717293,headlineOfferDocid:3929688011153459758,catalogid:11263001259817818262,productDocid:8247089737262540885,rds:PC_12493216142987996125%7CPROD_PC_12493216142987996125&q=product&sa=X&ved=2ahUKEwidy8u4_eOVAxWZiCsGHWsuL4sQgLcPegYIAQgSEBQ>

   - Accepts a highly flexible direct-current input from 33.6V to 67.2V DC,
   which perfectly encompasses your 53.5V activation threshold.
   - Drops the high-voltage battery power down to a stable, isolated 12V DC
   output up to 10 Amps (120 Watts total) to energize multiple relay coils at
   once.
   - Clips cleanly to your standard industrial rack alongside your
   automation blocks. [1
   <https://www.amazon.com/Original-Converter-33-6-67-2V-meanwell-Supply/dp/B097H4LHLJ>
   ]

------------------------------
🛠️ DIN Rail Wiring Schematic
Ensure your primary battery lines are fused appropriately near the terminal
before feeding into this control circuit.

   1. *Sensing & Supply Input:* Connect your Battery (+) and Battery (-)
   lines into the top power input terminals of the *ATO DVRD Monitor* and
   the input terminals of the *MEAN WELL DDR Converter*simultaneously. [1
   <https://www.amazon.com/Original-Converter-33-6-67-2V-meanwell-Supply/dp/B097H4LHLJ>
   , 2
   <https://www.amazon.com/Adjustable-Voltage-Under-Voltage-Protector-Protective/dp/B0CMHQS24R>
   ]
   2. *The 12V Loop:* Take the 12V (+) Output from your Mean Well converter and
   land it directly into the *Common (COM)* terminal of the ATO monitoring
   relay. [1
   <https://www.amazon.com/Original-Converter-33-6-67-2V-meanwell-Supply/dp/B097H4LHLJ>
   , 2
   <https://www.google.com/search?q=product&prds=pvt:hg,productid:1066366044745123193&ibp=oshop>
   ]
   3. *Trigger Output:* Wire a conductor from the *Normally Open (NO)* terminal
   of the ATO monitoring relay out to the Positive (+) coil inputs of your
   target 12V DIN rail relays. [1
   <https://www.google.com/search?q=product&prds=pvt:hg,productid:1066366044745123193&ibp=oshop>
   ]
   4. *Return Path:* Connect the 12V (-) Output from the Mean Well
converter directly
   to the Ground / Negative (-) coil inputs of your target 12V relays. [1
   <https://www.amazon.com/Original-Converter-33-6-67-2V-meanwell-Supply/dp/B097H4LHLJ>
   ]

------------------------------
⚙️ Setting Your Calibration Thresholds
Once powered up, use the adjustment dials or digital buttons on the front
face of the monitor to dial in the logic:

   - *Overvoltage (OV) Dial:* Turn this exactly to *53.5V*. When the
   battery hits this marker, the relay will click shut and send the 12V path
   to your slaves. [1
   <https://www.amazon.com/Adjustable-Voltage-Under-Voltage-Protector-Protective/dp/B0CMHQS24R>
   ]
   - *Hysteresis / Undervoltage Dial:* Set this parameter to roughly *5%
   below peak (approx. 50.8V to 51V)*. This ensures that if the newly
   engaged 12V load causes the battery to momentarily sag slightly under
   53.5V, the relay will not violently turn off and chatter. [1
   <https://www.atorelays.com/dc-voltage-monitoring-relay.html>, 2
   <https://www.google.com/search?q=product&prds=pvt:hg,productid:13784061694332394313&ibp=oshop>
   ]
   - *Time Delay (⚡):* Set to roughly *2 to 3 seconds*. This stops surface
   charge fluctuations or solar charger ripples from causing false-trips. [1
   <https://www.google.com/search?q=product&prds=pvt:hg,productid:1066366044745123193&ibp=oshop>
   ]

Would you like some recommendations for *slim, high-density 12V DIN rail
terminal relays* to finish off the load side, or do you already have those
on hand?

*David Quattro*
President

On Tue, Jul 21, 2026 at 6:36 AM Drake Chamberlin via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Hello,
>
> The Morningstar relay driver is a great device. It can measure 48VDC
> nominal and operate relays based on the measured voltage. The problem is
> that, if it is measuring 48VDC nominal, it outputs the same.
>
> Is there anything besides a charge controller that can measure 48 VDC
> nominal and put out a small 12VDC current? The 12VDC output of an Outback
> or Midnite charge control is perfect.
>
> If a relay driver, with several channels, could do this, it would be a
> very useful device. Does anything like this exist?
>
> Thanks,
>
> Drake
>
>
> *Drake Chamberlin*
>
> *Athens Electric LLC*
>
> *Ohio Electrical Contractor’s License 44810*
>
> *NABCEP Certified PV Installation Professional*
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