Roadmap
A test programme is only as credible as its willingness to say which category a claim belongs in. This page is the register: everything this project has established, everything currently under test, and everything that remains a proposal with no measurement behind it.
The categories are not a ranking. A proposal is not a weak finding — it is a different kind of thing, and the failure mode this page exists to prevent is one quietly becoming the other.
V2V in-motion energy transfer works and has been quantified. 3,719 instrumented miles, 74.74 kWh delivered across seven independent legs, 7.70 kWh AC per gallon at the outlet, charging accounting for 3.8% of campaign fuel. Delivery held 5.69–6.06 kW across every leg and ambient condition — no output derate was observed anywhere.
The canopy-up aerodynamic penalty is measured at +251 N road load and −2.32 mpg at 62 mph, from a same-day, same-file comparison.
The hot-weather fuel cost is electrical, not combustion. On a 95°F leg the entire measurable thermal cost ran through the air-conditioning compressor; sustained enrichment did not occur. The pre-trip hypothesis was not supported and has been withdrawn.
Detail on V2V AC Energy Transfer and in the per-leg reports under Test Data.
Aerodynamic drag by speed-hold sweep. Two earlier methods failed for two different reasons, both now documented rather than repaired. A bidirectional speed ladder is the remaining path, and it is gated behind an expanded instrumentation set that yields an engine power estimate independent of fuel flow.
Trailer base-load characterisation. A direct measurement of what the trailer draws while charging, against ambient temperature — the open question described on Trailer Load & Thermal.
Parked inverter efficiency and accessory metering. A bench measurement to establish stationary transfer efficiency on this specific truck, replacing published third-party figures with measured ones.
Partial canopy lift. Whether an intermediate canopy position falls inside the tow vehicle’s wake shadow, which would make it aerodynamically close to free.
TrekDrive TurboAssist. The trailer already carries a motor on its own axle. The proposal is to have it contribute tractive effort during the moments the tow vehicle is working hardest — a grade, a merge, a headwind — so the engine does not have to.
What exists today is manual: a binary on/off driven by a hitch sensor. TurboAssist is the proposed automated, predictive version. It is not a product and this project has not measured it, because there is nothing yet to measure.
The evaluation is worth reading precisely because the current numbers are not flattering — see below.
TrekDrive TurboAssist — and why the honest number is not the headline one
A raw comparison of the trailer’s motor on versus off suggested a 47% reduction in fuel rate. That figure is wrong, and the reason it is wrong is instructive.
The trailer’s drive mode and the truck’s power export are mutually exclusive by interlock — running one necessarily switches off the other. So every measurement of the motor assisting is also a measurement of the inverter not exporting, and a naive comparison credits the entire difference to the motor.
Decomposed properly, the mechanical load transfer is 27.8%, not 47%. And once the trailer’s own battery consumption is priced at the measured recharge cost, the net was negative under every modelled battery-cost basis tested.
It does not mean the concept is dead. It means the value is not raw fuel saving, and any pitch built on that number is built on sand. Where the trailer is charged from a destination rather than from the tow vehicle, the sign of the net flips — so the case rests on battery-neutral operation and on thermal relief during high-load events, not on gallons.
It also means a trigger built on ambient temperature would miss the point: this project’s worst thermal event occurred at 78.8°F ambient, on a sustained climb at 7,500–8,200 ft. Any assist logic aimed at real thermal load needs an altitude or coolant-temperature term, not an ambient one.
Publishing an unflattering result on one’s own proposal is the point of keeping this register. The full evaluation — including the proposed driver-tunable operating modes and how the next campaign would test them — is on the TrekDrive TurboAssist page, where every figure is labelled modelled.
Open questions this project cannot currently answer
- Trailer-side instantaneous draw. No tow-vehicle channel observes it, so the trailer’s own energy accounting stays partly inferred. This is the single biggest gap in the measurement set.
- The thermal ceiling on the charging connector. One temperature-driven stop has been recorded in 6,000 miles. One event does not establish a threshold, and this project has stopped implying that it does.
- Whether the trailer’s charger engages from a 120 V source, and at what minimum current — which decides whether a tow vehicle without a 240 V outlet can recover a deeply discharged trailer at all.
- Stationary transfer efficiency on this truck. Currently carried from third-party published figures rather than measured here.
Kept visible rather than deleted, because a register that only accumulates is not a register.
Withdrawn: that reduced charging on hot legs demonstrated an equipment thermal limit. It was operator-commanded engine protection. The correlation was real; the causation was wrong.
Withdrawn: that the connected, low-rate transfer state represented standing overhead. It is energy reaching the trailer at house-load magnitude, and switching it off would move the same load onto the trailer’s pack.
Withdrawn: that a purpose-built generator would beat a parked tow vehicle on fuel per kilowatt-hour. Published figures do not support it; the reasoning assumed a continuous low-load operating mode the hybrid architecture does not use.
Withdrawn: a persistent fuel-trim asymmetry between banks, which did not survive being computed across all thirteen reduced segments.
Measured results live on V2V AC Energy Transfer and Test Data. The reasoning behind the whole programme is on The Honest Bridge.
If you have questions or comments, please visit the LightShip RV Owners Club on RVForums.com and post them to this topic. I monitor that site regularly and would enjoy your feedback.