My final post on ClassBForum.com regarding this matter, because:
I made the original source information available to you, referencing the attached post I made on the IRV2.COM site. I have neither a product, nor service to sell anyone. Not looking to build a social media platform that generates ‘clicks’.
The intention of my post is to share relevant information for boondockers (though, I won’t be told HOW to do that) for whom ‘AC on battery runtime’ is a valuable commodity.
Ultimately, whether the information is deemed useful or ignored, matters not to me. I am not here to proselytize or ‘twist anyone’s arm’.
Aspects of your tone/comments seem suggestive of one whom presumes the role of an authoritative ‘gate keeper’. Your inability to ‘make the math work’ is not my concern …and I feel no further obligation to offer insight.
Clearly, you are a skeptical ‘unbeliever’ …which is perfectly fine with me. Enjoy your RV and AC capability as it is. Place me on ‘ignore’ …or I can just delete the information I’ve attempted to share
Very few people could explain how pressing the keys on their keyboard ‘magically’ creates a screen icon …yet (to the consternation of technophobes) it works.
**Extracted from IRV2.COM**
Can off-grid AC runtime be measured in days ...or WEEKS?
(Yes)
The eventual 'mission requirement' I'd visualized for my CH Platinum 220TB, was to obtain robust boondocking capabilities ...primarily in spring/summer climates.
Incremental upgrades from multiple aftermarket sources/installers have allowed that objective to have finally been reached.
An effective independent energy producing/storing strategy can take on different forms/budgets.
Secondary alternator (underhood
generator)
Large solar array(s): Rooftop/portable
Expansive battery bank
I opted for the second & third methods, as the implementation of an aftermarket secondary alternator on Ford E-series gasoline platforms, remain somewhat of an 'esoteric mystery' ...that most RV service centers refuse to touch.
Not so regarding MB Sprinter vans ...and to a lesser degree; Ford Transit vans/cutaways.
Maximizing rooftop solar capture would require me to accept some aesthetic compromise, but the practical advantages gained, made it certainly worthwhile.
I'd taken numerous measurements & photos while standing atop a ladder, examining my rooftop area ...and considering various solar array designs.
After researching various brands/models/sizes, I felt the best approach for my goal was to tolerate some minor overhang, DO NOT avoid panel installation atop the fridge/freezer vent ...and mount a second array of smaller panels where the 200w panels won't fit (adjacent to AC unit)
A beneficial consequence of the minor panel overhang, is the added roof-shading effect created by shadows and the higher air gap existing between the panel arrays and the roof. (Similar to a 'double roof' or 'cool roof' energy efficient homebuilding designs that reduce radiant heat transfer)
The addition of the 6 solar panels and the Starlink Mini, drastically reduced the UNSHADED percentage of rooftop surface area ...allowing the AC unit to work less.
Efficient use of rooftop space, permitted installation of four 200w Renogy ShadowFlux 'anti-shading' N-type panels,
and two of Renogy's smaller 120w versions of the ShadowFlux model ...totalling 1040w.
Favorable initial data following the initial install (6 June, mid-day in Poncha Springs, CO with scattered clouds) yielded 848w from the 800w array, with a combined array total @ 60amps.
Subsequent daily energy tracking shows consistent averages of 900w + ...or 50 + amps over varied mid-afternoon sky conditions. Enough to provide a substantial 15 percent daily charge to the 1920a battery bank, without using a shore power connection, idling the engine or running the generator.
Current Victron MPPT solar controller technology, provides higher efficiency than the 2018 era Go Power PWM solar controller circuitry installed by CH.
Rooftop panel mounting method/hardware: Oversized adjustable bracketry with larger feet provide greater adhesion and distribute contact pressure over a larger area.
The solar panel fixture methods were unintentionally 'torture tested' when I'd soon encounter 45 MPH wind gusts in Casper, WY. (No creaks or leaks!)
3M VHB industrial grade double-faced adhesive tape applied to the substantial bracket feet, followed by screws and thoroughly covered by permabond caulk. (leak prevention strategy)
Adjustable brackets provide users with ease of access to underside of panels, cable connections and rooftop ...for inspection/cleaning while permitting owners to experiment with preferred angle orientation.
Each of the six 320ah Li Time LiFePO4 batteries replacing the six 100ah BB LiFePO4 batteries, contain 3x the energy density in a form factor just 2-3 inches larger, with just a modestly increased weight.
Li Time's 'Mini' series employ a safe industry-recognized positive/negative terminal design ...and are priced $200 less.
Their customer support & product warranty are an improvement, and the company's financial health and rapidly growing market share are confidence inspiring.
For approx $1200 less than what it cost for a 600ah battery bank, I was able to assemble a 1920ah bank, which occupies only slightly more systems space ...and eliminates justifiable safety concerns over the documented BB terminal design defects and subsequent arcing risks.
Yesterday, I snapped screen shots of the Victron BMV-712 showing that the incoming solar energy was offsetting the power usage of my Atmos AC (during it's compressor cycle) by two thirds ...reducing the energy consumption to just 25 amps.
Conversely, during the AC fan circulation cycle, I regained 40 - 50+ amps. The solar gain during this alternating dual-phase operation, had previously allowed my 600a battery bank to run the AC for 2+ continuous days.
Testing of the AC runtime on battery/solar array 22 - 28 July 2026 Fortson, GA. RV parking pad surrounded by tall pine trees, leaving a small unobstructed 'solar window'.
Cloudy skies, 85 degrees, 73 percent humidity.
Start time: 12:13 pm
Battery bank SOC = 100 percent.
Dreiha Atmos AC (Dehumidifier mode)
Temperature setpoint: 86 degrees.
86 degrees doesn't sound 'comfy' at first glance ...until ALL of the humidity is removed. Suddenly, it feels like a breezy 72 degrees!
The final battery bank system check occurred at 2:47 pm on 28 July = 11 percent. The battery bank signed-off the following day in the early morning hours of the 29th.
Observations/conclusions:
Daily on-battery AC energy expenditure averaged between 7 - 13 percent.
The test conditions coincidentally created an approximate worst case scenario, that significantly handicapped solar energy collection.
Trees! Lots of em:
The driveway and RV parking pad are closely encircled by (mostly) tall pine trees, which significantly reduce continuous sun exposure and effective energy harvesting angles.
I would never intentionally park in a heavily forested area with such a narrow 'clear sky window'.
Pine needles:
I didn't have the foresight to employ a ladder for visually inspecting the panels before/during testing ...to ensure their surfaces were clean and remained obstruction free.
However, several days after testing concluded, while on the second story of the house ...I noticed on the panels a substantial accumulation of pine needles.
Naturally, I cannot determine the quantity of needles present while testing commenced, but the shedding pattern of the pine trees observed around the driveway/parking pad perimeter strongly suggest there'd been enough needles present to challenge Renogy's vaunted 'ShadowFlux' feature.
Sloped driveway impact:
Because I hadn't pulled my rig up onto the leveling ramps that normally lie beneath it ...the panels were nowhere close to parallel with the ground/sky. Further aggravating the sub-optimal solar exposure conditions.
Given the restrictive 'solar-impaired' test location combined with two days of sporadic rain showers and moderate - high cloud cover during the trial, I'm convinced that my typical spring/summer boondocking conditions will easily provide a WEEK+ of continuous on-battery AC runtime.
