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SPF 3000TL LVM 24-P power saving mode - test results

gelmjw

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The Growatt is V 3.0. It was delivered in mid June 2021 from vendor watts24/7.

This morning I decided to try out the power saving mode by setting program 4 to SEN. I need this to work because I have discovered that the inverter requires a 3A charge rate to break even and hold the battery Volts steady. That is somewhere between 75 and 85 Watts! I have a 200Ah bank consisting of 4 x 100Ah AGM in 2s2P and a 410W panel. My Growatt is installed in my tow vehicle and I plug my 30A travel trailer into the Growatt.

Other key settings: 01: SOL, 05: AGM, 14: OSO. There are no 120V input connections for this test.

Test 1. find the cut-in and cut-out Watts.
I tested with two 120V lamps and three incandescent bulbs; 40, 60, 100W. The power saving cut-out at 140 Watts. Cut-in is somewhere between 100 and 140W, therefore, 'pretty low' is under 140W. It works.

Test 2. Run the 11,000BTU roof air in the travel trailer and observe if it cycles on and off correctly.
The A/c runs betwwn 900 and 1050W and has a Micro-Air soft-start. As of this writing, the A/C has cycled 8 times. The dashboard is showing Solar: 277W, Charging: 273W, and Consumption Power: 0W/0VA. The trailer is cooled as expected. It works.
 
Part II.

Test 3. Is there a separate cut-in/cut-out for non-resistive loads?
This morning I tested the inverter/charger(I/C) in the trailer and it would not start with power save on. It has a 12V, 50A charger which could pull 1000W on startup on a low battery. With the battery at 12.5V resting, I expected at least 500W to start.

I turned the I/C off and turned the A/C fan on knowing it was around 300W. It ran. Next, I used my 3-speed carpet dry fan. On high it started and ran at 127W. I switched to med and it ran at 109W. It would not run on low at 99W. Now we have a new operating range for power saving mode between 99 and 109 Watts.

I believe the reason the I/C would not run is that it has a 15 second incoming AC validation and the pulse from the Growatt is too short. And before someone says it, this was a test and no, I am not planning to run the I/C input from the Growatt output.
 
so you saying the growatt shuts down and back on fine with the A/C unit but not the battery charger?

I mean a RV A/C unit is pretty dumb load - while charger has a bunch of controls and even if it's only taking a few seconds - a charger ramps up.
While the A/C, Coffeemaker or even a Microwave is just throwing a relay and is adding a bunch of resistance to a circuit.

For fun you can measure how much resistance you got between the two AC prongs of the charger - vs your Fan. (turn the power off and disconnect - obvious)
 
so you saying the growatt shuts down and back on fine with the A/C unit but not the battery charger?

I mean a RV A/C unit is pretty dumb load - while charger has a bunch of controls and even if it's only taking a few seconds - a charger ramps up.
While the A/C, Coffeemaker or even a Microwave is just throwing a relay and is adding a bunch of resistance to a circuit.

For fun you can measure how much resistance you got between the two AC prongs of the charger - vs your Fan. (turn the power off and disconnect - obvious)
No. The Growatt does not shut down but works exactly as it should when transitioning in and out of power saving mode.

The I/C has a 15 second pause while it validates the quality of the Growatt's 120VAC. On power saving mode the Growat emits a brief pulse to see if anything wants to use 120VAC. The I/C alone apparently does not draw enough Watts during the pulse to cause the Growatt to make the transition. Both devices are operation correctly.
 
The I/C has a 15 second pause while it validates the quality of the Growatt's 120VAC. On power saving mode the Growat emits a brief pulse to see if anything wants to use 120VAC. The I/C alone apparently does not draw enough Watts during the pulse to cause the Growatt to make the transition. Both devices are operation correctly.
what about standby devices, like the clock on the Microwave? Will this be on in Power saving mode?

Have you tried something like laptop power supply?
Light bulbs have pretty high resistance when they are cold and reduce that resistance when they heating up. A motor (fan or compressor) has similar resistance all the time.

From an electrotechnical perspective I'm trying to understand what the Growatt can do to determine that a load is connected.
It could just run a small DC or AC current - to see how much comes back, usually in measuring applications we talk like 20mA
If nothing comes back - it stays in savings mode - as soon as something comes back it transitions out of savings.

for example:
So the growatt is in PowerSavings (PS) - your A/C relay in the thermostat clicks on - the winding in the compressor/fan will allow to complete the circuit and of the measuring current is going back to the growatt. - It's starts the inverter part - and the A/C springs to live.

Is this how it happens?
 
1. what about standby devices, like the clock on the Microwave? Will this be on in Power saving mode?

2. Have you tried something like laptop power supply?
Light bulbs have pretty high resistance when they are cold and reduce that resistance when they heating up. A motor (fan or compressor) has similar resistance all the time.

3. From an electrotechnical perspective I'm trying to understand what the Growatt can do to determine that a load is connected.
It could just run a small DC or AC current - to see how much comes back, usually in measuring applications we talk like 20mA
If nothing comes back - it stays in savings mode - as soon as something comes back it transitions out of savings.

4. for example:
So the growatt is in PowerSavings (PS) - your A/C relay in the thermostat clicks on - the winding in the compressor/fan will allow to complete the circuit and of the measuring current is going back to the growatt. - It's starts the inverter part - and the A/C springs to live.

Is this how it happens?
I prepared a reply earlier but it seems to be missing. I'll try again, but this time I will retain a copy.

1. The entire microwave(MW) is off, not just the clock. When the GW pulses, the MW beeps. The MW cannot make the power Saving Mode(PSM) switch off because the MW draws less that something between 99 and 109 Watts. To silence the annoying beep, I switch off the circuit breaker to the MW.

2. The laptop power supply uses less that 99W and cannot keep the PSM off. I don't believe resistance of a draw has anything to do with PSM.

3. I have no idea what you are talking about coming back.

4. I don't understand the concept of a device's draw going back to the source.

All I know is my tests show that the cut in and cut out of PSM happens somewhere between 99 and 109 Watts draw.
 
3. I have no idea what you are talking about coming back.

4. I don't understand the concept of a device's draw going back to the source.
sorry, I got a German electro engineering background and for some people what I'm talking about sounds rather gibberish.

I'm tried to describe something very complex with simple terms in my non-native language and apparently fail utterly while doing that.


Lets try that again.

There are very few ways in electro technology to measure, Voltage and current.

I just learned from you that the growatt pulses - so during that time it's sending out voltage and current - if nothing is connected to it - open circuit - it is not flowing from hot to neutral and so it is not receiving a signal at that pin.

As soon as you connect a device - with low enough resistance, it completes the circuit (hot- fan-motor- neutral) and the inverter can measure at the neutral input, that it has voltage or current.


Power supplies are switching these days - they have a very high resistance internally, If you would try and old school transformer power supply (power brick) - that might work with a lower wattage.
 
I just realized in #4, you said "your A/C relay in the thermostat clicks on". Actually my thermostat is battery powered and does not need to wait for the very brief pulse to engage the relay. Then, when the pulse happens, both motors in the A/C will draw no less than 300W without delay.
 
How many watts does the growatt use in power saving mode? I will also need to avoid the vampire drain.

Turning the inverter off with the switch seems like another option.
 
How many watts does the growatt use in power saving mode? I will also need to avoid the vampire drain.

Turning the inverter off with the switch seems like another option.
Good question. AFAIK, there is no published spec.

I do have my GW available for a test. I will leave my system on power save for a few days with only solar for a charging source, and no AC or DC draws. Perhaps the logs will reveal daily solar charge Whs into the battery.

Would that be the answer?
 
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Good question. AFAIK, there is no published spec.

I do have my GW available for a test. I will leave my system on power save for a few days with only solar for a charging source, and no AC or DC draws. Perhaps the logs will reveal daily solar charge Whs into the battery.

Would that be the answer?
anybody figure out the power consumption in standby mode?
 
anybody figure out the power consumption in standby mode?
Not exactly, however here is a graph depicting the last 6 days in KWhs without power saving mode(PSM).

There are no AC draws for the last three days.

The red line shows 1KWh because I add a 1 to any GW measured KWhs to account for a DC feeezer for drawing directly from the battery. IOW, 1 + 0 = 1.

The solar showing is 1.6KWhs for the last three days. This indicates a battery full condition on the new LIFEPO batteries.

For sure, the PSM cannot exceed 1.6KWhs, or 66Whs/hour. With the nearly record low ambient temperatures in Tucson, I estimate only around .6KWhs draw/day which is below the specs for the DC freezer.

That leave 1000Wh/24h which is 42W average. Therefore PSM-on must be lower than 42W.

gwpowerconsumption.png

I do not use PSM-on.
 
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