I haven’t found what you’re looking for. But lots of 48vdc voltage controlers with relay and then I’d get a 48-12v power supply for your 12v loads.
Not so elegant but functional Jay
On Jul 21, 2026, at 8:56 AM, David Quattro via RE-wrenches <[email protected]> wrote:
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, 2]
2. Wire the 12V Trigger Circuit [ 1] - 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]
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]
- 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.
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, 2] 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] 🔌 Recommended DIN Rail Components - 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, 2, 3]
- 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]
🛠️ DIN Rail Wiring Schematic Ensure your primary battery lines are fused appropriately near the terminal before feeding into this control circuit. - 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 Convertersimultaneously. [1, 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, 2]
- 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]
- Return Path: Connect the 12V (-) Output from the Mean Well converter directly to the Ground / Negative (-) coil inputs of your target 12V relays. [1]
⚙️ 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]
- 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, 2]
- Time Delay (⚡): Set to roughly 2 to 3 seconds. This stops surface charge fluctuations or solar charger ripples from causing false-trips. [1]
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? On Tue, Jul 21, 2026 at 6:36 AM Drake Chamberlin via RE-wrenches < [email protected]> 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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