Yet another diversion/hot water question

[Vern Faulkner]

Yes, I did a search....

So. I've got a standard hot water heater (ie: 240-volt appliance) but it's wired to plug into a relay-switched 120-volt outlet to draw power - albeit less (600W) - from a 4000watt inverter/charger when signalled to do so from a Classic 150 off the aux 2 output.
(I've got a thermosiphon off a wood stove producing all the winter hot water I could ever want, so this is strictly for hot water in summer.)

I've got Aux 2 to send 12v power to the relay. I've got all that figured out (the electrician did the work.)

Now comes my job: programming the thing to dump diversion power after my 25.6v, 200Ah LiFePO4 battery is charged.

I've got Absorb set to 29.0, which is a titch below the 29.2v upper end suggested by the battery manufacturer. I've got a sneak suspicion the Classic is reading voltage at just a bit low than actual, but my voltmeter doesn't have a range that gives me enough accuracy to confirm that suspicion.

The simplest way to accomplish what I want seems to be to set AUX 2 to come on when "float" is triggered.

From reading, I gather Waste Not Hi will trigger the signal when a voltage is within a defined range for the charging profile. I don't want that - I only want the Aux 2 to trigger when the battery is reasonably likely to be fully charged. This is where my brain is struggling ...

I'd welcome input from someone who has done the same or similar.

[ClassicCrazy]

Vern - What is your pv input voltage ?
You could consider sending that to the water heater coil bypassing the controller.
I did that by using my classic aux to turn on contactor for pv to my hawkes bay controller.

But I have also switched AC power from inverter using Classic Aux - but that was when I was using lead acid batteries . I used Waste Not on Aux 2 . That worked to pwm the extra power above absorb or float to the water heater element.
I don't think the pwm would work with lithium for Absorb since there is no extra power since all of it goes into the battery. Maybe for float stage ? Or just turn on the load using something in Aux that is not pwm driven .

You may have voltage discrepancy because of the voltage drop on the battery cables. You should check that voltage drop because it is important for the lithium charging and you can offset it in a Classic setting.  You would set that at the top of the charge . You do need a decent meter to read that, but they are very inexpensive these days . Look at Kaiweets HT 118 $27 which had lots of testing on youtube by skilled techs comparing to their good precision meters. Kaiweets also has some other meters that are pretty good.

If you get a Whizbang and shunt for your Classic you can then use SOC to turn your relay on and off. That ties up Aux 2 but you would still have Aux 1 to switch things ( but no pwm on aux one ) 

I have some videos on my youtube channel of my water heater setup . I show both my Waste Not PWM of 120v ac from inverter, and my direct PV to water heater.
https://youtu.be/s7trVpHLts4  protype video
https://youtu.be/bqJz1jQztuU  a more refined setup of above

In another video I show how I bypassed the power around the controller to resistance space heater.
https://youtu.be/1Vjfv_GMH94
Larry

[Vern Faulkner]

So, I do not want to divert directly from solar to the hot water heater - too many issues.
Using standard 120v to power the heater coils (albeit at 1/4 power) was the most effective solution.
Nothing is going from the battery to the tank directly. The system is set up to toggle a relay that will energize the 120v receptacle at the hot water tank.

Right now I have it toggled using Aux 1 to energize the relay, with the trigger being when the system hits float. I have absorb at 3 minutes because its LiFePO4.

I just want to know if there's a better logic for the Aux 1.