Projects Solar Power

Low Voltage Cut off using MAX8212

Using a MAX8212 to add a low voltage cut off on our off grid solar PV system

Since upgrading our solar charge controller to a MPPT model we lost the facility for the charge controller to shut down the inverter when the battery voltage dropped too low. This resulted in a few days when the battery voltage dropped to a very low level and risked damaging the batteries.

To solve this we made a low voltage cut-off circuit using a MAX8212  micropower voltage detector with a 60A rated mosfet to switch the inverter on and off when the battery voltage reaches a set level.

The PCB layout and schematic are available to download in Diptrace format.

Download PDF schematic.

The etched PCB with the tracks covered in a layer of solder.

Low Voltage Cut off pcb

Testing the circuit with a 21W 12V bulb

Low Voltage Cut off testing

The completed project in a Diecast box with heatsink fitted to the top.

Low Voltage Cut off in box

The values used on the circuit below give a turn off voltage of 12.4V and turn on again at 12.7V on the input side.

Low Voltage Cut off Circuit

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