Creating a low-cost EV charging station with Arduino

Original Article ↗ Hacker News Discussion ↗

Cost and “low-cost” claims

  • Several commenters question calling this “low-cost” when the J1772 cable alone is ~$140–150 and complete 16–32A chargers can be bought in that range.
  • Others argue that’s simply the real cost of quality copper cable; truly cheap units may be skimping on wire or build quality.
  • Aluminum conductors are mentioned but dismissed as unsuitable for flexible cables and tricky to use safely.

Safety, insurance, and legality

  • Strong concern that DIY EVSEs can cause fires, damage cars/homes, or injure people, with unclear insurance coverage.
  • Some clarify that in many US policies electrical fires are covered, but insurers will seek to recover from whoever did the work; unpermitted or non‑code work increases personal liability.
  • In some jurisdictions (e.g., cited Australian rules), most household electrical work is illegal for non‑licensed people and may void insurance.
  • Others highlight that licensed work can also be poor; competence and inspections matter more than the license alone.

What an EVSE actually does

  • Repeated clarification: for AC charging, the “charger” is in the car; the EVSE is a smart switch / extension cord that:
    • Advertises max current via J1772 pilot PWM.
    • Only energizes when plugged into a vehicle and shuts off on disconnect.
    • Provides ground‑fault (GFCI/RCD) and over‑current protection and opens a contactor/relay on faults.
  • Commenters stress these are non‑trivial safety functions; they are not “just a smart outlet.”

DIY design critiques

  • Specific concerns about the project: lack of visible thermal cutouts, marginal PCB layout/clearances, questionable isolation, and use of simple relays instead of heavier‑duty contactors.
  • One detailed post lists features of robust commercial EVSEs: current monitoring and cutoff, redundant relays, stuck‑relay detection, temperature sensing, coil power management, proper waterproofing, and conformal coating.
  • The RCBO with DC leakage detection is praised for safety but noted as expensive, eroding the “cheap” claim.

DIY vs commercial / open alternatives

  • Many argue the risk, permitting issues, and lack of UL listing make homebuilt EVSEs impractical for regular unattended use, despite the technical feasibility.
  • Others defend DIY under informed, code‑compliant conditions and recommend mature open-source platforms like OpenEVSE as safer starting points.
  • There is tension between enthusiasm for hacking and a strong “don’t DIY life‑safety systems” sentiment.