Decided to test one of my AC180s on the house fridge, off grid. It has been tested briefly for the UPS function, but not battery capacity.
Items used;
Fridge -Mitsubishi Inverter 508lt, Top freezer Mod # MR-508EK-ST-A2, rated at 266W max.
Power station - AC180, 1800W inverter, 1152Wh battery, approx. 3 months old, fully charged.
Additional battery - Pylontech 100Ah LiFePO4, approx. 5 years old, (3 yrs in previous RV) fully charged.
240VAC power meter plugged into the AC180s 240VAC outlet.
Test 1 - AC180 only, powering fridge until display reads 50%.
Test 2 - Adding Pylontech 100Ah connected to AC180 DC input for the same time test 1 takes.
DC meter on the Pylontech will give total Wh capacity to compare with calculated capacity and AC180s screen input.
My reasons for limiting the tests. First, I do not want to run down the AC180 or Pylontech to flat. Second, I’m not getting out of bed in the wee hours to monitor and risk the fridge without power.
At the start of the test I noted the Volts and Watts on the AC180 display and the same per the power meter
Of note the initial wattage the fridge drew was a little over 100W, however this settled to a little over 50W and remained at this level each time I checked the meter/display. I believe this was due to the fridge having been opened by my wife several times shortly before connecting the AC180.
I then connected the 100Ah battery to the DC input of the AC180. The results and screenshots for this stage will be posted tomorrow as it will be approx midnight when the 2nd test is complete.
I’ll then tabulate the results and calculate an approx runtime for 100% capacity use from both the AC180 and 100Ah Li. Stay tuned…
(Yes it was 52% on the hour, so that is where I drew the line, lol.)
To explain methodology of the 2nd part of the test;
The AC180 was run to 52% SOC after 7 hours, then the 100Ah Lithium was added to supplement the capacity via its DC input. I decided to run this test until the 100Ah showed a usage of 50Ah (half its capacity). This took a further 6 hours to achieve.
I then assumed it will run for a further 6 hours until depleted. I note that as the load of the fridge was less than the charge from the 100Ah it returned the AC180 SOC to 61%, an increase of 9%. I then assumed during the second 50% of charge from the 100Ah it would also charge at a similar rate, which would return the AC180 to 70% SOC. I then extrapolated that given 42% gave 7 hrs, 70% would give a further 11.7 hours.
To be conservative, I called this 11 hours + the initial 7 hours + 12 hours from the 100Ah for a total of 30 hours.
Conclusion - up to 30 hours combining the AC180 and a 100Ah lithium.
Caution - These time were for my fridge in conditions noted. All voltages are AU 240VAC. Watts and Watt hours should be used to calculate capacities of battery and loads of appliances for your grid type.
Edit - Finger trouble, I typed 6 hours initial instead of 7, which altered the total to 30hrs runtime.
Constant checks showed the AC180 output voltage hovered at 232VAC.
At 50% SOC the Pylontech was at 12.99VDC.
After 13 hours the fridge used 510Wh = Avg 39W per hour or 71% on - 29% off. (Power Meter) I consider the cycle rate a little high, but due to the very low wattage used compared to its rating, very happy with the result.
Daily power use off the Bluetti = approx. 942Wh.
Also noted, the AC180 cooling fan came on when I connected the 100Ah battery, likely due to the combined inverter output and the DC conversion input.
