Software-Defined AI Roadster Engineering Hub
Comprehensive technical forensic audit, electrical schematics, and modernization roadmap for the converted 1970s MG Midget roadster. Transitioning from raw analog series DC control and unmonitored lithium modules to a deterministic dual-tier AI-Defined Vehicle (AIDC).
CRITICAL FORENSIC AUDIT DIRECTIVE: DO NOT CHARGE THE VEHICLE
High-resolution visual inspection confirms that the traction battery consists of three Chevrolet Volt (Gen 1, LG Chem / GM OEM) Lithium-Ion LMO/NMC modules. The OEM GM Battery Interface Control Modules (BICMs) have been removed, and the cell tap ports are covered in duct tape with zero BMS monitoring or overvoltage shutoff. Plugging in the Elcon onboard charger without cell-level balance and voltage isolation risks unbalanced cell overcharge, internal venting, and violent thermal runaway.
Immediate Triage Required: 1) Quarantine charging operations; 2) Insulate dangling 12V wire ends above Blue Sea fuse block; 3) Replace temporary yellow ratchet strap with rigid containment enclosure.
Newest Engineering Recommendations & Action Items
Synthesized findings from 24 detailed vehicle forensic photographs, bench tests, chassis clearance audits, and drivetrain verification.
Traction Battery: Longitudinal Trough Retention & Active BMS
Newest Photographic Discovery
Bird's-eye photo (trunk_three_modules_inline_overhead.jpg) reveals all 3 Chevy Volt modules are arranged in a single longitudinal line (in-line front-to-back) inside the trunk's center trough, held only by gray plastic banding and zip-ties. The 96V bulk charger is hard-mounted behind the right rear quarter panel.
Newest Engineering Directive
- Fabricate In-Line Trough Enclosure: Build a 72" × 7.0" × 11.0" welded 6061-T6 aluminum tray bolted directly through the chassis trough with 4x Grade 8 M10 bolts and 3" steel spreader plates.
- BMS Pigtail Harness: Tap the 16-pin OEM headers on each module using our newly published pinout guide (BMS_PINOUT_GUIDE.md).
- Charger Cutoff Interlock: Wire the BMS Charge-Disable relay to open the AC input or 12V enable pin of the 96V Elcon charger on the right wing.
Drivetrain: High-Voltage Motor Lug Insulation & Steering Column Gap
Newest Photographic Discovery
Overhead driver bay inspection (pedal_box_master_cylinder_bay.jpg) confirms the uninsulated 2/0 copper cable lug on the motor case is separated from the rotating steel intermediate steering shaft by only 1.5 inches. Under hard left cornering or frame torque, this presents an arc flash risk.
Newest Engineering Directive
- Heat-Shrink Motor Lug: Slide the red terminal boot back into position and heat-shrink with heavy-wall, adhesive-lined polyolefin tubing.
- Cable Clamp Anchor: Install an insulated, rubber-lined P-clamp anchoring the 2/0 welding cable firmly to the motor cradle to enforce a permanent 3.0"+ clearance from the steering shaft.
- Pass-Through Grommet: Install rubber edge grommets where the split-loom conduit passes through the wheel well sheet metal.
Vehicle Controls: Tailshaft Rev-Limiter & Electronic Throttle
Newest Photographic Discovery
Close-up photos (curtis_and_rack_front_iso.jpg) confirm a brass optical tachometer pickup is already installed on the motor tailshaft! Meanwhile, the driver pedal box retains its original Lockheed dual master cylinder and brake pedal bracket.
Newest Engineering Directive
- Flash Implemented VCU Code: Flash the newly generated VcuMain.ino firmware to a Teensy 4.1 microcontroller.
- Connect Tachometer to Pin 4: Wire the brass tailshaft sensor to VCU Pin 4 to activate the 4,500 RPM runaway rev-limiter.
- Brake Switch Cutoff: Tap a microswitch into the brake pedal arm and connect to VCU Pin 2 for instant sub-10ms throttle cutoff.
- Install Smiths Stealth Display: Fit the Waveshare 3.4" round display running Smiths Gauge Live inside the original speedometer chrome bezel.
What You Have vs. What Needs to Be Fixed
A comprehensive engineering audit mapping your verified as-built components against mandatory safety repairs, mechanical fabrication, and modern AI upgrades.
1. Motor & Controller Drivetrain
SOLID HARDWARE
What You Have:
• Curtis PMC 1231C-8601 (Verified Serial 9007-706356): 96V–144V DC, 500A peak armature current rating.
• Advanced D.C. Motors FB1-4001A: 20–30 kW series DC motor coupled to the 4-speed manual gearbox.
• Tailshaft Optical Tachometer: Brass-mounted proximity pickup already fitted to the motor rear shaft.
1. Uninsulated 2/0 Motor Cable Lug: Slipped silicone boot leaves live 144V copper exposed next to the steering column. Fix: Install dual-wall adhesive heat shrink and silicone terminal boots.
2. Potbox Throttle Linkage: Mechanical throttle rod to 0–5kΩ Curtis potbox lacks redundant return springs. Fix: Install dual return springs or electronic Hall pedal.
2. High-Voltage Battery Pack
CRITICAL SAFETY RISK
What You Have:
• 3x Chevy Volt Gen 1 Modules: OEM GM / LG Chem 16S LMO/NMC lithium modules (~7.8 kWh total, 48S nominal ~116V–175V DC).
• NEMA Trunk Disconnect Box: Manual service disconnect (MSD) switch with external "OFF / ON" toggle lever.
• Intact 16-Pin Tap Headers: Direct physical pin access to every individual internal series cell pair.
1. ZERO Battery Management System (BMS): OEM BICM modules were discarded and tap sockets taped with silver duct tape. Fix: Install an Orion BMS 2 or Dilithium BMS wiring harness directly into the 16-pin headers.
2. Plastic Banding & Zip-Tie Retention: 120+ lbs of lithium is secured only with commercial packaging straps. Fix: Fabricate a welded 1" steel/aluminum retaining cage bolted to chassis floor.
3. Exposed M6 Stud Terminals: Live module terminals lack protective rubber caps. Fix: Install snap-on polycarbonate terminal covers.
3. 12V Auxiliary & Charging Systems
REMEDIATION NEEDED
What You Have:
• Blue Sea ST-Blade 12-Circuit Fuse Block with ground return busbar.
• Duralast AGM Auxiliary Battery: 12V 18Ah battery powering instrumentation and relays.
• Elcon HF/PFC 2kW Charger & EverStart 3A trickle charger in rear trunk well.
• Albright SW180 Contactor & Dale RH-50 Pre-charge in front junction box.
1. Hood Hinge Scissor Pinch Hazard: Loose unbundled 12V wires run directly below the heavy steel bonnet hinge. Fix: Bundle into heat-resistant braided loom and secure with cushioned P-clamps.
2. Charger Has No BMS Cutoff: Charger currently bulk-charges the pack with no individual cell overvoltage trip. Fix: Wire charger enable wire through BMS high-voltage cutoff relay.
3. Missing DC-DC Converter: 12V battery relies on plug-in trickle charger. Fix: Install isolated Mean Well 300W DC-DC converter powered off 116V traction bus.
Implemented Firmware, Blueprints & Web Dashboards
Production-grade software, electrical pinout guides, and metal fabrication CAD specifications ready for deployment.
Teensy 4.1 VCU Safety Firmware
Complete 100 Hz deterministic vehicle control firmware. Features dual-Hall pedal plausibility checks, tailshaft tachometer interrupt rev-limiter (4,500 RPM hard cutoff), MCP41HV51 SPI digital potentiometer drive for the Curtis 1231C, and Orion BMS 2 CAN bus telemetry.
Smiths 800×800 Stealth Gauge UI
Custom circular gauge dashboard built for the Waveshare 3.4" Round IPS display. Designed to slip seamlessly behind the original Smiths chrome bezel, rendering real-time animated speed, motor RPM, pack voltage, current, and BMS health.
20G Battery Cage Blueprint
Dimensional metal fabrication blueprints for welding a 1" 6061-T6 aluminum angle cage with Grade 8 M10 through-bolts and 3" steel backing plates to safely trap the 125 lb Volt pack against 20G crash loads.
Chevy Volt 16S BMS Tap Pinout
Pin-by-pin electrical map of the OEM 16-pin recessed connector socket. Details wire colors, sequential voltages ($C_0$ to $C_{16}$), and interlock circuit diagrams for tripping the Elcon 2kW charger and Albright main contactor.
Ride Height, Suspension Dynamics & Common Questions
Rigorous engineering calculations, weight transfer analysis, battery chemistry pinouts, and drive-by-wire solutions.
Vehicle Weight Distribution & Ride Height Impact Analysis
Converting a 1,800 lb 1970s MG Midget to electric fundamentally shifts the sprung mass distribution. Removing the cast-iron 1275cc/1500cc engine, radiator, exhaust header, starter, and cast exhaust sheds approximately ~270 to 300 lbs directly off the front axle. Meanwhile, installing the Advanced D.C. Motors FB1-4001A adds back ~115 lbs (yielding a net front weight reduction of ~155 lbs). In the rear, removing the fuel tank and exhaust sheds ~45 lbs, while placing the 3x Chevy Volt modules and dual chargers adds approximately ~145 lbs.
Front Suspension & Ride Height
- Factory Setup: Independent coil springs with Armstrong lever-arm upper shock dampers.
- Behavior: With ~155 lbs net shed from the nose, the front end will rise by approximately 0.75" to 1.25" over factory ride height.
- Handling Consequence: Increases positive camber and toe-in; causes vague on-center steering and high-speed float.
- Recommended Correction: Install slightly lowered 350 lb/in competition front coil springs or mild lowering spacers to restore factory static height.
Rear Suspension & Leaf Spring Sag
- Factory Setup: Live rear axle located by semi-elliptic leaf springs and Armstrong lever shocks.
- Behavior: Adding ~100 lbs net cantilevered behind the rear axle causes the original leaf springs to sag by 0.5" to 1.0".
- Crucial Warning: In an MG Midget, leaf springs act as structural locating links. Sagging induces axle roll steer.
- Recommended Correction: Re-arch leaf springs or add a composite helper leaf; rebuild lever shocks with heavier 30W hydraulic oil or install tube shock conversion.
Optimized Corner Weighting
- Stock Weight Distribution: ~54% Front / 46% Rear.
- EV Conversion Target: 49% Front / 51% Rear (near-perfect sports car balance).
- Center of Gravity (CG): The Volt modules sit below the rear deck line, substantially lowering overall vehicle CG.
- Result: Reduced body roll in cornering, enhanced rear traction, and crisper turn-in once ride heights are leveled.
Q1: What are the exact voltage parameters of these Chevy Volt modules?
Each module is an OEM LG Chem 16S NMC pouch cell cassette. Three modules in series equal 48S:
- Max Bulk Charge: 48 × 4.15V = 199.2V (or 196.8V for extended life).
- Nominal Pack Voltage: 48 × 3.65V = 175.2V.
- Discharge Floor: 48 × 3.20V = 153.6V.
- Usable Energy: ~45 Ah × 175V ≈ 7.8 kWh (~35–45 miles range).
Q2: Can the Curtis PMC 1231C-8601 be controlled digitally by an AI VCU?
Yes! The Curtis 1231C accepts an analog 0–5kΩ potentiometer input. In our implemented architecture, a dual-Hall electronic throttle pedal connects to the Teensy 4.1 VCU, which verifies pedal agreement and drives an isolated MCP41HV51 digital potentiometer to feed the exact 0–5kΩ command with instantaneous brake cutoffs.
Q3: Why is Series DC Motor Overspeed dangerous, and how does the tailshaft sensor help?
Series wound DC motors accelerate exponentially without load (rotational runaway). Above 5,500 RPM, centrifugal force slings copper windings out of their slots. The implemented Teensy VCU connects directly to the brass tailshaft optical sensor to enforce a hard 4,500 RPM software rev-limit.
Q4: Do the Chevy Volt modules require active liquid cooling in this roadster?
For typical weekend street cruising (25A–40A average, <1.0C rate), passive ambient air cooling with a 12V 120mm exhaust blower expelling trunk air through the lower valance is fully adequate when monitored by BMS thermistors.
Briefing Presentation Decks
Comprehensive widescreen PowerPoint briefings prepared for engineering review and project stakeholders.
As-Built Systems Engineering Audit & Technical Diagrams
Rigorous deep dive into the current vehicle state: chassis packaging blueprints, high-voltage single-line schematics, mechanical drivetrain coupling cross-sections, Chevy Volt module pinouts, pre-charge RC inrush physics, and a full engineering FMEA matrix.
- Focus As-Built Hardware, Schematics & Physics
- Battery Identified Chevy Volt (LG Chem / GM OEM)
- Diagrams Included 8 Full Vector Schematics
- Risk Analysis Quantitative FMEA (RPN Scoring)
AI-Defined EV Modernization & Strategic Roadmap
Executive strategy and options analysis detailing the transition to an AI-Defined EV (AIDC): Teensy 4.1 real-time safety VCU, Raspberry Pi 5 + Hailo-8 NPU (26 TOPS), stealth circular Smiths digital cluster, vision ADAS, predictive range neural net, and itemized $2,314.50 BOM.
- Focus Software-Defined EV, Options & Procurement
- Options Evaluated Baseline ($1.4k) vs AI ($2.4k) vs AC ($9k)
- Edge AI Host Raspberry Pi 5 + Hailo-8 (26 TOPS)
- Total Hardware BOM $2,314.50 Turnkey Stack
Technical Schematics & Blueprints
Vector-rendered diagrams detailing the spatial, mechanical, electrical, and control loops of the vehicle.
Chassis Packaging & Spatial Blueprint
Top-down engineering layout of the MG Midget (80.0" wheelbase, 46.0" track). Highlights motor tunnel positioning, firewall electronics shelf, cockpit instruments, and rear boot battery bay with 52/48 weight distribution.
High-Voltage Traction Single-Line Diagram (SLD)
Complete DC power flow schematic: 3x Chevy Volt modules in series (48S total, ~96V-116V nominal) → Bussmann ANN-300A fuse → Albright SW180 contactor w/ Dale RH-50 pre-charge → Curtis 1221B controller → ADC series motor.
Powertrain Mechanical Coupling & Drivetrain
Exploded cross-section: ADC FB1-4001A 1.125" keyed shaft → taper-lock flywheel hub → 0.5" CNC 6061-T6 aluminum adapter plate → 6.5" sprung clutch disc & diaphragm pressure plate → British Leyland 4-speed manual gearbox → 3.90:1 rear axle.
Chevy Volt (LG Chem) 16S Module Architecture & Pinout
Inspection of the amber translucent plastic cell cassettes, aluminum cooling fin plates, and unmonitored voltage tap terminals. Highlights severe unbalanced cell overcharge hazard during charging without an active BMS.
12V Auxiliary Power Distribution & Fuse Block
Duralast ETX18L AGM battery (18 Ah, 340 CCA) connected to Blue Sea Systems 5025 12-circuit ST-Blade fuse block. Details active circuits (10A ignition/contactor, 5A gauges, 15A lighting, 20A DC-DC) and dangling bare wire hazard.
Pre-Charge RC Dynamics & Contactor Inrush Suppression
Mathematical modeling of Curtis 1,500 µF capacitor pre-charging via Dale RH-50 (750Ω 50W) power resistor. Demonstrates RC time constant (τ = 1.125s) and suppression of catastrophic 2,000A+ inrush down to 0.128A.
Cockpit Controls & Driver Interaction Loop
Bowden cable pedal actuation pulling under-hood Curtis PB-6 style 0–5kΩ potbox, Smiths 100mm mechanical speedometer cable drive, and 3-digit LED voltmeter sense loop. Documents severe driver information gaps (no SoC %, no kW draw).
Charging Subsystem & Auxiliary Power Flow
AC grid feed into Elcon/TC 1.5–2.0 kW high-frequency traction charger and EverStart 3A trickle maintainer. Highlights total absence of BMS charge cutoff interlock and why charging in the current state poses a severe fire hazard.
Hardware Specifications & Modernization BOM
Itemized technical register of installed as-built components and the proposed AI upgrade bill of materials.
1. As-Built Component Specification Registry
| Subsystem | Manufacturer & Model | Electrical / Mechanical Specs | Physical Location | Status & Integrity |
|---|---|---|---|---|
| Traction Motor | Advanced D.C. Motors (FB1-4001A / L91) | Series DC, 20–30 kW, 4000 RPM Max, -CW / -N Lugs | Transmission Tunnel | OPERATIONAL |
| Motor Controller | Curtis PMC (1221B / 1231C) | 96V–120V / 400A–500A Peak Armature, 0–5kΩ Input | Front Firewall Shelf | OPERATIONAL |
| Traction Battery | General Motors / LG Chem (Chevy Volt Gen 1) | 3x 16S LMO/NMC Modules (~16 kWh, 48S, ~96V-116V) | Rear Luggage Boot Floor | CRITICAL: NO BMS |
| Main Contactor | Albright International (SW180 / SW200) | 200A Cont / 1000A Inrush, 12V DC Coil, Blowouts | Front HV Junction Box | OPERATIONAL |
| Traction Fuse | Cooper Bussmann (ANN-300 / 400) | Fast-Acting Limiter Fuse, 80V–125V DC, 300A–400A | Front HV Junction Box | OPERATIONAL |
| Pre-Charge Resistor | Dale / Vishay (RH-50 / RH-100) | 750Ω 50W Wirewound Aluminum + 12V SPDT Relay | Front HV Junction Box | OPERATIONAL |
| 12V Aux Battery | Duralast AGM (ETX18L PowerSports) | 12V DC, 18 Ah Capacity, 340 Cold Cranking Amps | Front Passenger Shelf | OPERATIONAL |
| 12V Fuse Block | Blue Sea Systems (ST-Blade 5025/5026) | 12-Circuit Blade Block w/ Negative Ground Busbar | Front Passenger Fender | BARE WIRE HAZARD |
| Onboard Charger | Elcon / TC Charger (HF/PFC 1.5kW–2kW) | 120/240V AC Input, 116V DC Bulk Output | Rear Trunk Well | NO BMS INTERLOCK |
2. AI-Defined EV Modernization Bill of Materials ($2,314.50 Turnkey)
| Part / Component | Manufacturer & Model | Function & Integration | Documentation | Unit Cost |
|---|---|---|---|---|
| Battery Management System | Orion BMS 2 or Dilithium BMS | Active 48S cell balancing, CAN telemetry, contactor cutoffs | Manual | $890.00 |
| CAN Current Shunt | Isabellenhütte IVT-S-1000-U3-CAN | High-precision ±1000A galvanic isolated current & Ah count | Data Sheet | $384.00 |
| Isolated DC-DC Converter | Mean Well RSD-300D-12 | 96V traction bus to regulated 12V 25A auxiliary power | Specs | $145.00 |
| Real-Time VCU Controller | PJRC Teensy 4.1 + Dual CAN-FD | Deterministic ARM Cortex-M7 safety VCU & drive-by-wire | Pinout | $44.50 |
| Edge AI Compute Host | Raspberry Pi 5 (8GB LPDDR4X) | Quad-core host for Linux OS, telematics, and display server | Specs | $80.00 |
| Edge AI NPU Accelerator | Hailo Technologies Hailo-8 M.2 | 26 TOPS neural accelerator for YOLOv8s vision ADAS (3W) | Architecture | $70.00 |
| Vintage Digital Gauge | Waveshare 3.4" Round IPS (800x800) | Stealth circular cluster embedded behind Smiths chrome bezel | Wiki | $81.00 |
| Electronic Throttle Pedal | Curtis PMC FP-6 Dual-Hall | Redundant dual-sensor drive-by-wire accelerator pedal | Spec Sheet | $135.00 |
| Vision ADAS Sensor | Raspberry Pi / Sony Camera 3 Wide | 120° FOV Sony IMX708 sensor mounted behind rearview mirror | Data Sheet | $35.00 |
| Enclosure & Safety Interlocks | Custom 5052 AL Box / TE / Blue Sea | Sealed aluminum battery box, vent tube, cockpit E-Stop, wire | Fab Spec | $450.00 |
| TOTAL MODERNIZATION HARDWARE INVESTMENT | $2,314.50 | |||
As-Built Vehicle Photographs
High-resolution photographic evidence captured from the engine bay, high-voltage junction, cockpit, and battery bay.
Failure Modes & Effects Analysis (FMEA)
Quantitative risk scoring (Severity × Occurrence × Detection = Risk Priority Number) for the as-built vehicle.
| Failure Mode | Root Cause & Failure Mechanism | Sev (1-10) | Occ (1-10) | Det (1-10) | RPN | Mandatory Engineering Remediation |
|---|---|---|---|---|---|---|
| Battery Thermal Runaway / Fire | Overcharging unmonitored NMC cells; no BMS cell cutoff during charging | 10 | 8 | 9 | 720 | Install Orion BMS 2 or Dilithium BMS; plug in Chevy Volt harness; interlock charger shutoff. |
| 12V Electrical Fire / Short | Bare uninsulated wire ends hanging near Blue Sea fuse block (Quadrant 1) | 7 | 7 | 5 | 245 | Inspect, terminate, or heat-shrink loose conductors; install protective fuse block cover. |
| Contactor Welding on Inrush | Pre-charge relay failure or resistor open-circuit; inrush > 2,000A | 8 | 5 | 6 | 240 | Verify Dale RH-50 resistance; implement automated pre-charge voltage check via Teensy VCU. |
| Motor Commutator Arcing | Excessive sustained current draw with no brush thermal telemetry | 6 | 6 | 8 | 288 | Install NTC temperature sensor on motor brush ring; implement VCU current derating. |
| Battery Pack Ejection / Rupture | Rear-end collision fails single yellow steel ratchet strap | 8 | 6 | 4 | 192 | Fabricate bolted 5052 aluminum containment box with structural floor mount & vent tube. |