AC Relay controlled by DC voltage for Water Heater load dump

[EddieB]

Is anyone aware of a off the shelf product which will read the DC battery level and switch on an AC circuit when the DC voltage reaches a specified level? I am exploring using a AC water heater element as a load dump. I have considered DC but the distance from the battery to water heater would require a lot of 6 AWG wire for the wattage and distance I am looking at.

 

[Cheap 4-life]

Some charge controllers can trigger relays at set battery voltages

 

[RCinFLA]

Is anyone aware of a off the shelf product which will read the DC battery level and switch on an AC circuit when the DC voltage reaches a specified level? I am exploring using a AC water heater element as a load dump. I have considered DC but the distance from the battery to water heater would require a lot of 6 AWG wire for the wattage and distance I am looking at.

Many available. Just look for relay DC coil voltage you desire.

Similar to what is used for inverter pass-through relays.

One example:

 

[timselectric]

DC 6~80V Voltage Detection Charging Discharge Monitor Relay Switch Controller with Case LED Display https://a.co/d/76tJX3A

 

[Quattrohead]

Charge controllers, inverters and shunts often have this built into them.

 

[Hedges]

Depending on hysteresis or delay functions in the controller, every time large AC load of heater is connected to inverter, battery voltage will drop. That could cause rapid cycling.

 

[timselectric]

Definitely need a separate setting for on and off.
To minimize micro cycling.

 

[timselectric]

I ordered the one I linked. Because Andy used it.

 

[cyd]

You are better off monitoring PV voltage and battery current as well as battery voltage in order to decide whether to divert energy to the heater.

Also look at how to gradually ramp up the amount of energy diverted to the hot tank.

Slamming a relay on and off based on battery voltage does not take into account whether or not the sun is actually shining. A fully charged battery is unfortunately not a reliable indicator of sunshine.