Crankshaft to bed outlet: how ProPower Onboard actually makes its power
The whole chain, in one picture
Every watt this project has ever delivered into the LightShip's 77 kWh pack while towing has taken the same path. It starts as crankshaft torque, becomes three-phase AC inside the bellhousing, is rectified to roughly 300 volts DC, sits briefly on a shared bus, is inverted back to 240 V AC by a second and entirely separate inverter, leaves through a twist-lock receptacle in the bed, and finally passes through the trailer's onboard charger into the cells.
Eight conversions. Each one takes its cut. That is why the measured yield is what it is, and why no clever operating strategy is going to move it much.
The modular hybrid transmission
The F-150 PowerBoost uses a 10R80 ten-speed automatic with an extra module bolted to the front of the bellhousing. Ford calls the result the 10R80‑MHT — modular hybrid transmission. "Modular" is literal: the hybrid hardware is a bolt-on section forward of an otherwise conventional gearbox, and the transmission behind it shifts through all ten gears whether the power arriving is coming from the engine, the electric motor, or both.
The architecture debuted on the 2020 Explorer Hybrid behind a 3.3 L V6. The F-150 PowerBoost is the same modular concept behind the 3.5 L twin-turbo. The teardown unit photographed below is the Explorer variant — same family, and the reason every dimension-specific claim on this page is drawn from the service manual rather than from the bench.
The machine that does all the work
Inside the module is a single electric machine: a 24-slot stator with concentrated delta windings, and an 8-pole internal-permanent-magnet rotor. The rotor is not on a shaft of its own — it is welded directly to the outside of the torque converter. That construction is the key to the whole system's behaviour. Rotor and torque converter are one rotating assembly, permanently coupled to the transmission input.
The label on the teardown unit puts the machine at 35 kW / 47 hp. Supplier is Schaeffler. No torque figure is published.
ProPower's 7.2 kW rating is 21% of this machine's 35 kW capacity. The 5.8 kW this project actually draws while towing is about 17%. That fraction is not spent from some separate accessory budget — it comes off the same rotor that would otherwise be assisting the engine or capturing regen. Section 09 works through what that means for TurboAssist.
The engine disconnect clutch
The input shaft from the flywheel does not drive the rotor directly. Left alone the two free-spin relative to each other. What joins them is a wet multi-disc clutch pack — three fibre discs and four steel plates, applied by a hydraulic piston fed through the bellhousing. The steel plates spline to the input shaft; the fibre discs spline to the rotor. Apply the pack and the engine is mechanically joined to the electric machine and to the transmission. Release it and the engine is gone.
This is what makes the F-150 PowerBoost a P2 hybrid: the electric machine sits between a disengageable engine and the transmission input. The belt-driven starter-generator on the front of the engine is a separate P0 machine, used for warm restarts.
The transmission carries an electric oil pump in addition to the engine-driven mechanical one, so hydraulic pressure survives engine-off operation. An extra solenoid on that electric pump is what applies the disconnect clutch.
The obvious worry about a clutch that repeatedly reconnects a running engine is wear. The mitigation is that it is never asked to absorb much slip: the belt-driven starter-generator spins the engine up to match rotor speed first, and only then does the pack apply. Add a wet, ATF-lubricated design and the duty is mild. Field reports support this. It is still an operator-facing wear item worth knowing exists.
Four states, one of which pays for ProPower
The disconnect clutch gives the powertrain a small state machine. The factory service manual names four states; the structure is directly analogous to the State A / State B framing this project uses on the trailer side.
| State | Disconnect clutch | What happens | ProPower source |
|---|---|---|---|
| Electric drive | Disengaged | Engine off; motor alone drives the wheels | Pack only |
| Electric driven | Disengaged | Driveline inertia spins the motor as a generator — regen | Recovered energy |
| Hybrid drive | Engaged | Engine drives the wheels; torque above driver demand charges the pack through the motor; motor can also assist | Fuel |
| Engine start | Engaging | Motor torque splits between driveline and cranking | — |
Towing at highway speed, the truck lives almost entirely in hybrid drive. So the honest description of in-motion V2V charging is this: ProPower is a request for additional engine torque. The PCM meets a 5.8 kW electrical demand by asking the crankshaft for roughly 7 kW more mechanical power, and the fuel map does the rest.
The second row of that table is the interesting one. During regen the bus is being fed by recovered vehicle energy — routinely −10 to −14 kW on this rig, up to about −38 kW. A 5.8 kW ProPower draw taken during a descent is therefore partly or wholly not a fuel cost at all. Campaign 1 could not separate this: the 7.70 kWh/gal figure is a whole-campaign average that quietly includes whatever descent charging happened to occur.
It is now computable. The Campaign 2 stream carries DCACA high-voltage-side current, and the HV Battery Power channel was confirmed bus-terminal by the 2026-07-29 bench test. A descent-window energy balance — regen in, ProPower out, fuel rate throughout — would establish whether downhill charging is materially cheaper than the campaign average. If it is, that is a route-planning finding with a real number behind it, and it belongs in the pitch.
One bus, five branches
Everything electrical on this truck converges on a single high-voltage bus at roughly 300 volts DC. The battery, the traction inverter, the DC/DC converter, the air-conditioning compressor and the ProPower inverter all connect to it through a BECM-controlled junction box with precharge sequencing and continuous isolation monitoring against the chassis.
Two details in that junction box matter more than they look.
- The fusing is deliberately asymmetric. A 150 A high-current fuse protects the traction side. A separate 50 A fuse protects the DCDC and DCACA together. A ProPower fault cannot propagate into traction — the topology structurally prevents it.
- ProPower and the 12 V system share that 50 A. At ~300 V that branch is good for roughly 15 kW. ProPower at full 7.2 kW output draws about 26 A from the bus; the standing 12 V load measured on the bench was about 2 A. Comfortable headroom, but they are on the same fuse, and any future accessory hung off the DCDC eats into ProPower's margin rather than traction's.
The callout list on the facing page is worth reading as a bus map rather than a parts list. Paraphrased, with this project's terminology in brackets:
| # | Component | Where it sits | What it does |
|---|---|---|---|
| 1 | High-voltage battery | Under the vehicle, aft | Liquid-cooled lithium-ion pack; the storage every other branch draws from |
| 2 | High-voltage cabling | Underbody, battery to engine bay | The bus itself. Orange sheathing throughout |
| 3 | Inverter System Controller (ISC/SOBDMC) | Under hood, passenger side | Traction inverter — DC to three-phase AC for the drive motor |
| 4 | Hybrid unit / HV electric motor | Between engine and transmission | Motor, torque converter and disconnect clutch in one housing [sections 02–04] |
| 5 | Transmission | Alongside the engine | 10-speed carrying the hybrid drive unit and its integral disconnect |
| 6 | Gasoline engine | Engine bay | 3.5 L; conventional in arrangement |
| 7 | Electric A/C compressor | Forward of the engine | High-voltage device with its own orange cable — replaces the belt-driven compressor [ACCM] |
| 8 | DC/DC converter | Under hood, passenger side, below the ISC | Steps the bus down to 12 V for the low-voltage battery and accessories [DCDC] |
| 9 | On-Board Generator Inverter (OBGI) | Under the vehicle, on the passenger frame rail ahead of the HV battery | Bus DC to AC for the ProPower Onboard bed and cab outlets [DCACA] |
| 10 | 12 V battery | Under hood, passenger side | Conventional negative-ground 12 V source |
| 11 | 12 V auxiliary battery | Under the right-hand rear seat | Carries transient loads through a crank event while the main battery is isolated |
Callout 7 confirms the compressor is a high-voltage device. It is described as electric with its own orange high-voltage cable, replacing the belt-driven unit — independent corroboration of this project's July correction, which had previously and wrongly described the compressor as a 12 V load hanging off the DC/DC converter. It draws from the bus directly, which is why it showed up in the bench test's HV Battery Power reading.
Callout 9 locates the ProPower inverter. Ford's term here is On-Board Generator Inverter; the diagnostic literature this project works from calls the same module the DCACA. It is a physically separate unit from the traction inverter (callout 3) and sits in a different place entirely — underbody on the passenger frame rail, ahead of the pack, not under the hood. That is the architectural point section 07 makes, now visible in a drawing.
A long-standing open question about this bus was whether the scan-tool "HV Battery Power" channel reports total bus-terminal flow or only traction. A parked engine-off test settled it: against a quiet baseline of +0.80 kW, applying ~1.35 kW of ProPower load moved the channel to +2.09 kW, and adding the A/C compressor took it to +3.17 kW — with pack SOC falling 52.9% → 50.2% as the independent witness. The channel sees accessory load with no traction involvement. It is bus-terminal.
The +1.29 kW step against a 1.35 kW applied load establishes that the channel responds, not the converter's efficiency — the difference is inside the baseline uncertainty of the test.
The pack is a buffer, not a reservoir. Ford publishes about 1.5 kWh; this project's multi-year field observation puts the working SOC band at roughly 40–62%, with a floor never seen below ~28% and a rare ceiling near 72%. Taking the full observed 28–62% span as usable gives on the order of 0.5 kWh — about five minutes at a 5.8 kW ProPower draw with the engine off. In practice the engine fires long before that.
The 1.5 kWh figure is a published product spec, not drawn from the service-manual extracts used elsewhere on this page; nominal capacity is not the same as usable. Treat the five minutes as an order-of-magnitude, not a number.
The DCACA: a second, separate inverter
ProPower Onboard is not a tap off the traction inverter. It is its own module — the DCACA — taking high-voltage DC off the bus and producing 120 V and 240 V AC. It has its own control logic, its own protection setpoints, and its own thermal limit, and it is cooled by the electric-powertrain coolant loop rather than by engine coolant.
| Protection | Threshold | Behaviour |
|---|---|---|
| HV input undervoltage | below 168 V DC | DTC sets; keeps trying to operate |
| HV input overvoltage | above 330 V DC | standby until the condition clears |
| 12 V supply | below 9 V / above 16 V | will not operate |
| Overload | >130% of rated for 2 s | shuts down |
| Over-temperature | 199.3 °F (93 °C) internal | standby until the condition clears; auto-recovers |
| CAN loss | no PCM message for 5 s | AC output disabled |
| Rated output | 7,200 W, 120/240 V combined | — |
| Keyed-on baseline | 400 W | available with Ready light on, no enable needed |
Three separate thermal domains exist on this vehicle and are easy to conflate. Engine coolant runs a 189.9–217.4 °F thermostat range. The electric-powertrain loop that cools the DCACA is capped far lower, at 158 °F. And the DCACA's own internal module temperature has that independent 199.3 °F cutoff, which is not the same measurement as either coolant loop.
Across every leg and every ambient condition of a 3,719-mile campaign, the DCACA delivered 5.69–6.06 kW whenever it was running. Duty cycle varied enormously — battery-management cycling, deliberate operator reduction on hot climbs — but the rate never sagged. When this system runs, it runs at rate.
Campaign 1 produced exactly one confirmed temperature-driven charging stop, at the NACS receptacle on the Cortez → Durango leg, which resumed as ambient fell on the climb. The truck-side inverter's own cutoff sits 95–100 °F above where that dropout occurred, and the manual documents automatic recovery with no fixed lockout timer — yet charging did not resume for 30–45 minutes. The DCACA is therefore excluded with confidence; trailer-side EVSE, onboard-charger or battery-management logic remains the candidate. n = 1. The exclusion is sound. The lockout duration is not generalisable from one event, and this page does not pretend otherwise.
The bed panel, and the receptacle that sets the ceiling
The 7.2 kW configuration presents four 120 V / 20 A outlets in the bed plus one twist-lock NEMA L14-30R at 240 V / 30 A, with an additional 120 V outlet in the cab. The L14-30R is two 120 V legs of 30 A each; a 240 V load uses both.
That receptacle is where the NACS umbilical to the LightShip's AeroHub inlet begins, and it is also where an arithmetic constraint appears that is worth stating plainly.
240 V × 30 A = 7.2 kW. The truck's rated output and its bed receptacle's current limit are the same number — the inverter is rated exactly to what the plug can carry, with the overload trip sitting at 130% for two seconds above it. A factory Turbo Edition specified at 8 kW therefore cannot be fed by ProPower Onboard alone on this truck: 8 kW at 240 V is 33.3 A, past the receptacle rating and past the inverter's continuous rating.
This is not necessarily a conflict — an 8 kW onboard-charger rating on the trailer may simply describe its shore-power or DC capability, with truck charging expected to run below it. But the distinction needs to be explicit in the product literature, and this project's own figures should keep saying what they are: prototype data taken at 5.8 kW, not validation of an 8 kW rating.
The 5.8 kW this rig actually draws is set by the trailer's onboard charger, not by any truck-side limit. There is roughly 1.4 kW of unused headroom at the panel on every leg of every campaign so far.
What the chain costs
Eight conversions, each taking its cut. The measured result at the bed panel:
| Quantity | Value | Basis |
|---|---|---|
| AC energy per gallon, at the panel | 7.70 kWh/gal | measured, 557.6 mi instrumented round trip |
| In-motion fuel rate | 0.697–0.753 gal/hr | measured |
| AC output at the umbilical | 5.36–5.80 kW | measured |
| Delivering-state rate, Campaign 1 | 5.69–6.06 kW | measured, seven independent legs |
| Fuel → AC at the panel | ~22.7% | modeled: 7.70 ÷ gasoline LHV |
| Fuel → energy in the cells | ~20.5–20.9% | modeled: above × ~92% onboard charger |
| Net charge rate into the pack | 5.23–5.34 kW | modeled from measured AC output |
| Cost per kWh delivered | ~$0.49 | modeled at $3.50/gal |
| Campaign 1 total delivered | 74.74 kWh AC | measured, bulk-charge basis, 3,719 mi |
| Campaign 1 fuel attributable | 9.71 gal — 3.8% | measured ÷ 7.70 |
The V2V baseline document currently labels 22.7% as full-chain efficiency "fuel LHV → LightShip cells." The arithmetic does not support that label. 7.70 kWh/gal is measured AC at the bed panel, and dividing it by gasoline LHV gives the fuel‑to‑panel figure. Getting to the cells requires the onboard charger's ~92% on top, which lands around 20.5–20.9%.
A second item in the same table wants checking: the quoted "8.54 kWh/gal theoretical" divided into the measured 7.70 gives 90.2% — exactly the onboard-charger chain efficiency quoted two rows below it. That coincidence suggests the theoretical figure may have been back-derived from the measurement rather than computed independently. Neither item changes any measured value on this page; both should be resolved in the source document rather than carried forward.
Why this matters to TurboAssist
Section 03 flagged the number to read twice, and this is where it lands. ProPower and electric traction assist are the same 35 kW machine. The machine cannot motor and generate simultaneously. So during exactly the events TurboAssist exists to address — a sustained high-load climb where engine thermal margin is disappearing — a running ProPower load must come from the pack, and the pack holds about five minutes. In practice the engine carries it.
That is a truck-side argument for moving assist onto the trailer's own axle motor, and it is one the current pitch does not make. The trailer's TrekDrive motor is a genuinely independent power source; the truck's is not. Campaign 1 measured the mechanical load transfer at 27.8% once the ProPower contribution is properly decomposed out — not the 47% a raw State A / State B comparison suggests, because the interlock means every TrekDrive-on run is also a ProPower-off run.
The competing-resource argument above follows from the architecture and from the 35 kW rating. It has not been instrumented. A clean test would be a matched pair of high-load climbs with ProPower on and off, watching whether the motor's contribution to traction changes — now feasible with the Campaign 2 channel set. Until then it is an inference, and it is labelled as one.
What is documented, what is measured, what is open
- Documented. Bus topology, ~300 V nominal, asymmetric 150 A / 50 A fusing, precharge and isolation monitoring, the four-state drive machine, every DCACA protection setpoint, and the three thermal domains. All from the factory service manual, chapter-tagged for the 3.5 L PowerBoost.
- Third-party teardown. 35 kW / 47 hp rotor welded to the torque converter, 24-slot concentrated-winding stator, three-fibre / four-steel wet disconnect clutch, ATF stator cooling, electric oil pump holding pressure engine-off. Weber Auto bench unit is the Explorer variant of the same modular family.
- Measured here. 7.70 kWh AC per gallon at the panel. 5.69–6.06 kW delivering rate with no derate observed at any ambient. Three distinct converter states, including a connected load-support state at 0.938–0.951 kW. HV Battery Power confirmed bus-terminal. 74.74 kWh delivered over Campaign 1 at 3.8% of campaign fuel.
- Open. Whether descent charging is materially cheaper than the campaign average. Whether ProPower measurably displaces traction assist under load. Where the compressor's high-voltage draw is metered. Whether the trailer's 8 kW rating and the truck's 7.2 kW receptacle limit have been reconciled in the product specification.
Mass basis measured — CAT scale + verified payload, 15,320 lb / 6,949 kg.
Factory sources: 2023 F-150 Hybrid Service Manual, sections 414-03A (HV battery and cables), 414-05 (voltage converter/inverter), 303-01G (electric motor), 303-06D (starting system / BISG), 302-03B and 303-03G (electric powertrain cooling).
Teardown source: Weber Auto (Prof. John Kelly, Weber State University Automotive Technology) — Ford modular hybrid transmission 10R80-MHT, “Ford's F-150 PowerBoost's One-Motor Hybrid System” ↗. Images 01–09 are frames from that presentation, used with credit; module cutaway is a supplier general-arrangement render. Descriptions are paraphrased throughout.
Product configuration (outlet count, NEMA L14-30R, ~1.5 kWh pack) from Ford published material and independent press coverage, not from the service-manual extracts.
Measured values green, modeled amber, flags rust, observations neutral — modeled numbers are never presented as measurements.
System description · drafted 2026-08-07. Carries one correction against the V2V baseline document (section 09) and one open specification question (section 08).