More water heater related stuff....
I recently picked up a Xantrex Linkpro battery monitor from another member here (thanks SteveW!!).
I have been experimenting with using it to heat water in my 12V electric water heater with excess solar when the house batteries are charged by using the highly configurable low SOC/Low voltage alarm output on the Linkpro.
Member 1der and I have been playing around with this idea for awhile....at least since E350 posted some info from a guy named TechnoDave on the Midnite solar forum earlier in this thread.
1der has the Midnite Solar Kid controller which apparently does everything except slice bread, including using excess solar to power diversion loads like heat water....the kid has a handful of very configurable modes (well.....we'll see...) to do diversion loads and should provide hours of entertainment once 1der (Ray) gets his set up.
Since my controller is a bit more pedestrian (Samlex SCC-30 PWM unit), the Linkpro seemed like a nice addition to my setup...it does lots of things around monitoring battery health. For those wondering why I didn't just ditch the Samlex and buy a Kid.......I don't have the width to mount the kid in my panel and I like the Samlex...and it's paid for.....also for warm climate small systems the difference between PWM and MPPT is not much...
After mounting and wiring the shunt close to the house batteries, I had to fabricate another control panel to squeeze in the Linkpro.
...old panel on the left, newly fabricated panel on the right....those with a keen eye will notice a big round hole in the new panel...
...and the new panel bead blasted and installed......
To start, I configured the Linkpro low voltage alarm to be normally closed and to open when the battery voltage crops below 11.8V. This alarm output is wired in series with the switch the powers the water heater relay.
So, the use case is: If I want to turn on the water heater with the van parked, or keep hot water created while driving hot, I can turn on the water heater and leave the van without stressing about killing the house batteries, since now if they go below 11.8V the Linkpro will open shutting off the water heater relay.
When the sun is shining the solar system can pump amps into the batteries while the water heater is on.....that's the hope anyway.
The Linkpro has a few other settings for the low voltage alarm like also configuring it to activate at a low state-of-charge, and programmable deadband/hysterisis, on/off delays and seconds/minutes etc etc.
So we'll see what happens.....