Water tank heating

[konstantin.vyaznikov@xplo]

Hi. I searched high and low, but cannot figure out how to heat water tank with excessive current from solar/alternator when my two batteries are charged. I think to switch current to 12v heating element when state of charge is 100% and turn it back to battery charge when SOC is let's say 90%. I do not want to use voltage level, because I am not sure when charger will be at 'float' state. I think I can deduct SOC from battery monitor using microcontroller which can operate relay to switch current direction back and forth.

Please advise what charger can I use where I can control charge direction - battery or heating element. In other words I saw chargers which have 'Load' and 'Battery' outputs. I want to switch between them at will, i.e. measuring SOC and turn on 'load' or 'battery'.

Thanks!

 

[dingbat]

I think to switch current to 12v heating element when state of charge is 100% and turn it back to battery charge when SOC is let's say 90%. I do not want to use voltage level, because I am not sure when charger will be at 'float' state. I think I can deduct SOC from battery monitor using microcontroller which can operate relay to switch current direction back and forth.

Please advise what charger can I use where I can control charge direction - battery or heating element. In other words I saw chargers which have 'Load' and 'Battery' outputs. I want to switch between them at will, i.e. measuring SOC and turn on 'load' or 'battery'.

Thanks!

How would one calculate State of charge w/o considering voltage?

This is the one I use to charge my two batteries with a common source

https://www.bluesea.com/products/7610/SI-ACR_Automatic_Charging_Relay_-_12_24V_DC_120A

 

[cyclops222]

State of Charge is normally a voltage level.

 

[Chris1956]

What is the difference between the average solar power output in watts, and the power consumption of the water heater?

If they are close, you can work something out. if the heater takes several times the average solar panel output, it will be hard to do.