While at Donner Lake today…
I decided to do some raw meter testing, AFTER an initial camper cooldown from 84d/f to 77d/f…Start of 1300 test, outside temp was at 90d/f, and end of test 1500 outside temp was at 88d/f…(FWIW, I took a nap in between these hours…).
Equipment:
Two 200a/hrs LFP (actual load tested at 215a/hr per).
2000w ProSine PSW, pass-thru inverter-charger.
Victron SOC meter with bluetooth.
660w solar (serial add-ons…).
System is 12v, 0004 cables 6’ roundtrip…
Coleman Mach 1 P.S. 11kbtu air conditioner (w/Easy-Start)
Single full wall slide-out, 10’ Eagle Cap Truck Camper.
Duty cycle (after initial cooldown period) was approx 5 min ON, 5 min OFF (fan continuous run on low). Readings were via Victron BMV-12 SOC meter:
1300 (compressor ON, fan low)….Note, upon edit, to clarify (say upon test start) the -57amp figure (below) represents the difference between the amount being harvested vs air conditioner consumption, which is why the negative value referred to as the deficit…
*************
Starting SOC: 85.5% (approx 340a/hr of remaining capacity at start).
Amps (e.g. deficit after harvest amount): -57amps (dc)
LFP Voltage: 13.05v
**********
1500 (compressor ON, fan low)
Duty cycle had now increased to approx 8.5 min ON, 6.5 min OFF (fan continuous).
SOC: 72% (approx. 288a/hrs remaining capacity).
Amps (e.g. deficit after harvest amount): -54.5amps (dc)
LFP Voltage: 12.97
***********
Using a separate hall effect meter at the inverter’s 120v output (compressor ON, fan low):
Amps (ac): 8.5
Pf: 0.97
Hz: 60
Watts: 972
Voltage: 116
************
BTW, between compressor ON-OFF cycling, I used the Keurig one time at about 125 amps (dc), for an additional 2 a/hrs of battery consumption - Brewing completed before next compressor run call!!
************
FWIW (since writing the above summary - compressor ON, fan low), here’s two more unplanned readings at 1600, and 1700…Temps are now starting to drop off a bit….I’m expecting temps to be pleasant again starting at around 1800-1830 as sun angle drops off…(Cools off rather nicely here in the evenings :)
1600:
SOC: 64% (approx. 256a/hrs remaining capacity).
Amps: -63 (dc)…Some dang tree shading now over a couple of PV panels…
LFP Voltage: 12.94
1700:
SOC: 55% (approx. 220a/hrs remaining capacity).
Amps: -73 (dc)…Heavier shading
LFP Voltage: 12.90
Compressor duty cycle (at 1700 was 5 min ON, 6.5 min OFF…).
*****************
We maintained a comfortable 77d/f t-stat setting the whole time (still ongoing…). The main variable was the eventual tree shading of the panels, but still lots of battery reserve and will likely be at 90’ish % charge (this, my ‘normal full’ by say noonish - except for periodic cell-balancing…
Most importantly (non-intuitively so!), note that in this example, harvesting at a rate of 1 to 1 ratio with power consumption is not necessary…Having a deep enough reserve is what’s needed, aided by Lithium’s relatively flat discharge plateau…
Quite naturally, various equipment, camper size and user experience will vary…Though understandably not for everyone, yet at least this provides an example of what might be achievable - haven’t started the Honda 2200 in nearly a year…
***************
Oops, and this one final 1800 result for an even more comprehensive trend-line:
Compressor duty cycle (at 1800) was 3.5min ON, 9 min OFF…
Now starting to cool off nicely!
SOC: 45% (180a/hrs remaining capacity)
Amps: -76.4 (dc) still heavy shading….
LFP Voltage: 12.90
Total run time (including initial 100% duty cycle cooldown), 5hrs 25min…
Hope some find this example interesting …
3 tons