Rivian reduced electrical wiring by 1.6 miles and 44 pounds
Rivian’s move to a zonal electrical architecture, consolidating many electronic control units (ECUs) and cutting about 1.6 miles and 44 pounds of wiring, is seen as a way to simplify cars, reduce cost, and lower copper use. Commenters weigh this against new failure modes and software complexity, since a single zonal ECU outage could disable multiple functions in one area of the vehicle, and they debate how much logic should live centrally versus at the edge. The thread also touches on why wired links remain preferred over wireless for critical systems, and how shifts to higher-voltage (e.g., 48V) and Ethernet-based systems might further reduce weight and complexity in future vehicles.
Wireless vs. Wired Communication
- Several commenters ask why not use Wi‑Fi / RF to cut more wiring.
- Most responses oppose this for critical systems: higher latency, greater susceptibility to interference and jamming, no shielding, and much larger attack surface.
- EMI in EVs is already problematic (e.g., AM radio issues); adding more RF for safety‑critical links is seen as risky.
- Wireless is already used in constrained niches (tire‑pressure sensors, some battery management inside packs), but commenters stress it’s for non‑critical or hard‑to‑wire cases.
- In home/hobby contexts, some embrace RF for convenience; others deliberately avoid Wi‑Fi for security and reliability, preferring wired or protocols like Zigbee/Z‑Wave.
Zonal ECU Architecture & Failure Modes
- Discussion compares domain‑based ECUs (per function) vs zonal (per physical area).
- Concern: a zonal ECU failure could knock out many unrelated functions in that zone (locks, windows, seats, fans).
- Others say Rivian keeps safety‑critical domains (drive, battery, access, autonomy, infotainment) on dedicated ECUs; zones handle “small but important” loads.
- Multiple comments note that distributed real‑time systems are hard: state management bugs already appear in existing cars.
- Some advocate “dumb” edge I/O with centralized logic to simplify reasoning; others point out this re‑introduces single points of failure and wiring.
ECU Count, Modularity, and Suppliers
- Many like the reduction from dozens/hundreds of ECUs; others note legacy designs allowed reusable modules across models and suppliers with different safety/reliability levels.
- Rivian’s approach is seen as enabled by strong in‑house software and modern heterogeneous processors, whereas traditional OEMs are constrained by tiered suppliers and organizational inertia.
Wiring Length, Copper, and System Voltage
- Back‑of‑the‑envelope math in the thread finds Rivian’s 1.6‑mile / 44‑lb copper reduction plausible.
- Commenters doubt the quoted 20% material and 15% carbon savings come from copper alone; broader simplification is implied.
- Several point to 48V low‑voltage systems (as in Tesla) as the next major step: same power with far lower current, thinner wires, and less copper.
- Others discuss safety limits around ~50–60 V DC, tradeoffs, and the complexity of multiple voltage rails.
Broader Themes and Comparisons
- References to Tesla’s past wiring‑reduction plans and Cybertruck architecture; curiosity about Tesla’s “unboxed” distributed ECUs vs Rivian’s more centralized zones.
- Some feel modern cars are over‑complex (hundreds of ECUs, massive compute for cameras/radars); others note regulations now require advanced driver‑assistance anyway.
- One commenter links wiring complexity to Conway’s law: harness layout mirrors organizational and supplier boundaries.