The ProPower Onboard (PPoB) system is not a standalone generator bolted to the frame. It is a software-defined power export layer that draws from the same high-voltage (HV) bus that the motor-generator unit (MGU) uses for hybrid operation. Understanding this distinction is critical to evaluating the system's efficiency.
The MGU is the pivotal component. Because it is physically situated between the ICE crankshaft and the 10-speed transmission input shaft, it rotates at engine speed at all times the truck is in motion. This topology creates the efficiency argument at the heart of the in-motion generation claim.
The central premise is this: when the truck is moving, the mechanical energy required to spin the MGU rotor is already embedded in the drivetrain's friction budget. The bearing drag, windage, and rotor inertia of the MGU are paid for by the wheels turning, not by dedicated fuel combustion. Therefore, the incremental fuel cost to begin extracting electrical power from the MGU is limited to the thermodynamic conversion cost of combustion producing additional crankshaft torque — not the cost of spinning up a cold generator from a standing start.
This is subtly but importantly different from a conventional claim. A standalone generator at idle must consume fuel to: (a) overcome its own mechanical friction, (b) run through incomplete combustion at low load, and (c) manage thermal losses at a non-optimal RPM. The PowerBoost MGU in motion does none of these things — it is already thermally stabilized, mechanically spun to road speed, and operating in a regime where the ICE is in or near its BSFC-efficient cruise band.
To extract 5.8 kW from the MGU while moving, the ICE must produce approximately 6.9 kW of additional shaft torque (5.8 kW ÷ 83.9% chain efficiency). At 30% BTE, that requires about 23 kW of additional heat release, or ~0.68 gal/hr of incremental fuel. The rotor drag already paid by the drivetrain contributes an estimated 0.7 kW reduction, trimming the incremental figure to roughly 0.61–0.68 gal/hr — consistent with the speed-controlled regression from the telemetry.
Compare this to static generation (parked, ICE cycling at ~1,000 RPM): community-reported data and the physics of low-load ICE operation suggest 0.8–1.0 gal/hr for ~6 kW output. The implied brake thermal efficiency at that operating point is only 18–20%, versus 28–32% at cruise load. This is the fundamental efficiency advantage of in-motion generation — the ICE is running at a load point where it converts heat to shaft work far more effectively.
The 5.8 kW leaving the ProPower 240V outlet undergoes four conversion stages before resting as stored energy in the LightShip battery. Each stage introduces a measurable loss.
| Stage | Loss mechanism | Loss (W) | Loss (%) | Cumulative efficiency |
|---|---|---|---|---|
| NACS cable (~15 ft, 10 AWG equiv.) | I²R resistive heating at 24.2A | 23 W | 0.40% | 99.6% |
| NACS connector contacts | Contact resistance ~4 mΩ | 2 W | 0.04% | 99.5% |
| LightShip onboard charger (OBC) | AC-DC rectification, switching, magnetics | 464 W | 8.0% | 91.6% |
| LightShip battery cells | I²R cell resistance, coulombic loss | 107 W | 1.8% | 90.2% |
The LightShip onboard charger (AC→DC rectifier) consumes ~464 W converting the 240V AC from the ProPower outlet to the LightShip HV DC bus voltage. This is 8% of the input, or roughly 61% of all conversion losses in the chain. Cable and connector losses are essentially negligible at this current level. Battery coulombic efficiency at this very low C-rate (~0.075C into a 77 kWh pack) is excellent. Net delivery: 5.23 kW into the cells from 5.8 kW AC input — a 90.2% chain efficiency from outlet to stored energy.
Combining the in-motion generation efficiency with the AC-to-battery conversion chain gives the end-to-end efficiency of the V2V charging system.
The theoretical maximum: 30% × 83.9% × 90.2% = 22.7%. This means roughly 7.7 kWh of stored energy in the LightShip battery per gallon of gasoline consumed by the PowerBoost for generation purposes.
At ~7.7 kWh/gal stored into the LightShip battery, and gasoline at $3.50/gal, the effective cost of energy delivered to the LightShip is $0.45–0.49/kWh — approximately 2.7× the U.S. average residential electricity rate of ~$0.17/kWh. However, this is mobility-delivered energy with no charging infrastructure required, delivered at 62 mph. The correct comparison is not residential electricity but rather: (a) a campground hookup where available, or (b) the opportunity cost of a Supercharger stop adding significant time to the journey.
The round-trip logs provide an empirical ground truth against which to test the theoretical model.
| Metric | Theoretical (in-motion) | Outbound measured | Return measured | Δ vs theory |
|---|---|---|---|---|
| PP fuel rate allocated | ~0.68 gal/hr | 0.697 gal/hr | 0.753 gal/hr | +3% / +11% |
| Avg AC output | 5.80 kW (rated) | 5.363 kW | 5.795 kW | −7.5% / 0% |
| kWh AC per gallon (fuel→outlet) | 8.54 | 7.70 | 7.69 | −10% |
| Implied engine BTE | 28–30% | 27.0% | 27.0% | −3 pts |
| Full chain eff. (fuel→cells) | 22.7% | 22.6% | 22.6% | ≈match |
| kWh into LightShip per gallon | 7.72 | 7.08 (est.) | 7.08 (est.) | −8% |
The TrekDrive TurboAssist proposal states "5.8 kW at 0.5 GPH." If taken as the total allocated fuel rate, this implies 11.6 kWh/gal and 34% total efficiency — physically unreachable with a 30% BTE engine feeding an 83.9% chain. However, the claim becomes plausible if interpreted as the incremental fuel cost: the speed-controlled regression from the 55–65 mph band shows a delta of approximately 0.50–0.65 gal/hr when ProPower is active versus inactive at the same speed. This incremental figure isolates the generation cost from base cruise fuel, yielding 8.3–10.8 kWh/gal — much closer to 11.6 than the full-allocation number. The two methods are measuring different things, not contradicting each other.
The fact that both trips show nearly identical efficiency (7.69–7.70 kWh AC per gallon, 22.6% total) despite dramatically different operating conditions (descending vs. ascending, 65°F vs. 91°F) confirms the structural model is correct. The generation efficiency is determined primarily by the fixed chain losses (MGU→inverter at 83.9%) and the ICE BTE at cruise — both of which are relatively stable across the operating range seen in these trips. Grade and headwind change the base towing fuel but do not materially alter the incremental generation efficiency.
The 8% gap between theory (7.72 kWh/gal) and measurement (7.08 kWh/gal) is attributable to two factors. First, the fuel allocation method — the OBD-reported fuel rate during ProPower operation includes some base cruise fuel that the regression cannot fully separate. Second, the PMU occasionally throttled ProPower output during high-load grade events (observed at outbound minutes 263–286 and multiple return trip climbs), causing the average measured AC output to be slightly lower than 5.8 kW while the fuel rate remained elevated from the grade load.
| Mode | ICE operating point | BTE | Fuel rate (6 kW) | kWh/gal delivered | Best use case |
|---|---|---|---|---|---|
| In-motion | Cruise load, 1,400–1,800 RPM | 28–30% | 0.68–0.72 gal/hr | 7.7–8.3 | Highway towing, any distance |
| Static (engine warm) | ~1,000–1,200 RPM, cycling | 20–24% | 0.80–0.95 gal/hr | 6.3–7.5 | Campsite top-up, short sessions |
| Static (cold start) | <1,000 RPM, enrichment, cycling | 15–18% | 0.90–1.10 gal/hr | 5.4–6.7 | Avoid — worst efficiency |
The in-motion advantage is real and consistent — approximately 20–30% more stored energy per gallon versus parked operation. This is the payoff of the hybrid architecture: the ICE never operates at the low-efficiency idle cycling mode that a conventional generator must use when stationary. The MGU in motion is always at a thermally stable, mechanically efficient operating point.
Community-reported experience (F150gen14 forum) confirms 0.8–1.0 gal/hr for approximately 6 kW static output, with the ICE cycling on/off to maintain HV battery SOC. One reported observation: the ICE runs almost continuously at ~1,000 RPM when ProPower is at full load — the 1.5 kWh HV battery (with only ~600 Wh usable headroom) depletes within seconds at a 6+ kW extraction rate, so the engine cannot pulse-and-coast as it does under lighter loads. This is why static efficiency is limited: the engine is locked into a low-RPM, partial-load operating point with no ability to burst into a more efficient range.
The real-world implication: an overnight drive of 700+ miles would theoretically deliver a full charge to a depleted LightShip battery. For practical trip segments of 250–300 miles, the umbilical system delivers 17–22 kWh — enough to materially offset TrekDrive discharge during that leg or provide 1–2 days of campsite electrical autonomy. The round-trip telemetry confirmed 25.3 kWh outbound and 17.3 kWh return (reduced due to ProPower being off for the first 119 minutes of the return), for a combined 42.7 kWh delivered over 557.6 miles.
Forum posts from the LightShip owner note that early testing with the modified PowerBoost at sea level with no wind at 62 mph confirmed 17 MPG while the ProPower umbilical was connected. This is an important data point that deserves scrutiny against the round-trip record of 12.64 mpg combined.
17 MPG at 62 mph, sea level, no wind, with ProPower active is fully consistent with the model. The outbound trip — which was predominantly descending with no significant headwind — achieved 14.52 mpg. Remove the 5,100 ft descent gravity assist and replace it with level ground: the grade-climbing fuel that dominated the return trip (~6 extra gallons) disappears, and the system would approach or exceed 17 mpg on a flat sea-level highway. The round-trip composite of 12.64 mpg reflects the asymmetry of the route: the return trip ascended 5,100 ft in 91°F heat with a 7 mph headwind — conditions that have nothing to do with the V2V charging efficiency and everything to do with the gravitational and aerodynamic work of the specific route.
A simple estimate validates the 17 mpg figure. At 62 mph, sea level, with TrekDrive off, the aerodynamic and rolling resistance load of the F-150 + LightShip is roughly 40–50 hp. The EcoBoost at ~50 hp cruise burns approximately 2.5–3.2 gal/hr at 30% BTE. Add 0.68–0.70 gal/hr for ProPower at 5.8 kW: total ~3.2–3.9 gal/hr. At 62 mph: 62 ÷ 3.5 = 17.7 mpg. The claim is credible within the margin of real-world variation.
There are four reasons the measured telemetry shows 0.70 gal/hr rather than 0.50 gal/hr for the ProPower generation load, and understanding them is important for calibrating expectations.
| # | Factor | Effect on measured fuel rate |
|---|---|---|
| 1 | Allocation method vs. incremental method | The OBD-based fuel attribution (0.70 gal/hr) allocates total fuel consumed during ProPower-active periods. The incremental method (speed-controlled regression, 0.50–0.65 gal/hr) isolates only the additional fuel. Both are mathematically valid; the document's 0.5 gal/hr is likely the incremental figure. |
| 2 | PMU power throttling during climbs | During high-load grade events, the PMU limits ProPower output to protect HV battery SOC. Average measured output was 5.36 kW (outbound) rather than 5.8 kW, while fuel rate remained elevated from the grade load — dragging down the kWh/gal ratio. |
| 3 | High ambient temperature (return trip) | 91°F ambient triggers EcoBoost fuel enrichment above 86°F — an open-loop rich command that increases fuel consumption independent of load or ProPower. This adds ~5–8% to base fuel consumption on the return, inflating the denominator of the allocation. |
| 4 | Engine BTE at partial load | The measured implied BTE is 27.0% — slightly below the 30% modeled peak. At 1,400–1,800 RPM with moderate load, the actual EcoBoost BTE tends to 26–29% rather than the 30–32% achievable at optimal load. This ~3% BTE gap accounts for approximately 0.05 gal/hr of the discrepancy. |