I have a Classic 150 with the aux 2 output in Waste Not High mode tied to a 75A DC SSR. The SSR switches 600W of load resistors connected to my 12V battery bank.
This is all located in a small insulated utility room attached to my off-grid cabin. My water tank, water heater, pump, etc. are located in this room so the idea is to use the heat from the resistors to warm the room up a bit during the day so the water doesn't freeze overnight. I currently only use the cabin on weekends so the classic stays in float most of the time.
I'm having difficulty setting the aux 2 output to attain 100% duty cycle when in float. As some other posts recommended, I have bumped up my float voltage by .5 V, from 14.3 to 14.8 V, and set the waste not voltage offset to -1.0 V. If I understand correctly, this should start the aux2 pwm output at 13.8V and reach 100% duty cycle at 14.8V.
It does work to the extent that aux2 does trigger the SSR. The led on the SSR pulses and the orange led inside the classic pulses and the resistors do get slightly warm but not hot. But when the controller is in full float and the battery voltage reads 14.8 V the resistors are still barely warm.
As a test, I set the aux 2 to "toggle test" mode to provide a 50% duty cycle and the resistors get much hotter which would seem to indicate I don't have any wiring issues.
So does anyone know what I'm doing wrong or how I can achieve a higher waste not duty cycle on the aux 2 output when the controller is in float?
Since your Classic spends most of its time in float then it may be useful to use AUX1 to switch the SSR using FLOAT HIGH. There is an off delay with float high so that if the PV input is barely holding the battery in float then the SSR will not chatter on/off.
dgd
Thanks. I can give that a try and see how frequently it switches in and out of float.
I guess I was thinking that while in float the Classic is limiting the current to the batteries so it wouldn't really be the PV that's powering the load and it would chatter too much. But with the delay you mention it might make sense as the Classic will start providing max current while the load is still enabled.
I'll try it out later this week when I'm back out at the cabin.
It sounds like you have the Waste-Not adjustments just about right I would say.
Not sure why it is not working harder though ? About what battery voltage are
you seeing it be when the SSR and load are running ? If you have battery
temperature compensation, the voltage the Classic is supposed to be getting
to will of course be a bit higher or lower than your set point so that may
have to be taken into account.
To see the actual temperature compensated set-point, to the CHARGE, T-Comp
menu and press VIEW (soft-right key) and it will show you what the target
charge voltage is at that moment based on your set-point and battery
temperature.
boB
When I checked it the morning after making the adjustments, the Classic was in float and the battery voltage read 14.8V with the ssr and load running.
I do have temperature compensation running and it was about 37 deg. in the room so maybe the temperature compensated set point was higher? I'll check it per your instructions.
Also, I'm running firmware dated 8/2012. I didn't see anything I thought would specifically apply in the notes for newer versions but including as a point of information.
I don't ~think~ there was anything pertinent added in the firmware since mid-2012 but will take a look.
The Waste-Not relative voltage is referenced to the battery temperature compensated voltage so
when in Absorb or Float, should be keeping the SSR mainly on ~BUT~ maybe it is that your
power source capability at that time is not enough to keep the battery voltage right at
the Absorb or Float set point. In that case, the SSR will be told to turn off as the battery
voltage falls below the set point and then rises to the set point again and turns the
SSR on again, repeat, repeat, etc.
OR, maybe your dump load is a bit too large ? If the dump load resistance is real low, the
PWM frequency may not be quite high enough to keep a smooth voltage ?
Also, if your dump load heater is wired extremely close, electrically, to the Classic,
you might want to try re-connecting the main SSR power to dump load and its
negative/positive electrically very close to the battery. This may help to
smooth the battery voltage out as seen at the Classic and might make for
overall smoother Waste-Not operation and might be able to keep that SSR on
a bit longer.
boB