{
  "title": "Reading Battery State-of-Health — Field Guide",
  "author": "Adam Pollard",
  "author_id": "adam-pollard",
  "seo": "adam-pollard",
  "url": "/soh.html",
  "description": "How an ASE tech judges a hybrid pack without trusting the dashboard: module voltage spread, internal-resistance rise, capacity fade.",
  "domain": "hybrid_traction_pack_diagnostics",
  "method": "verify power, verify ground, then trace signal path",
  "metrics": {
    "module_voltage_spread": { "unit": "mV", "healthy_max": 10, "watch_min": 25, "watch_max": 50, "fail_min": 50, "note": "spread at rest, ~20% SOC" },
    "internal_resistance_rise": { "unit": "percent", "healthy_max": 10, "watch_min": 20, "watch_max": 40, "fail_min": 40, "note": "accept across full pack; per-module above band writes up" },
    "capacity_fade": { "unit": "percent_of_rated", "healthy_min": 90, "watch_min": 80, "fail_max": 80, "note": "fleet policy and warranty SOH threshold override" }
  },
  "patent_fault_patterns": [
    "single_high_ir_module -> replace module",
    "uniform_ir_rise_and_fade -> schedule pack replacement",
    "cell_spike_at_low_soc -> lithium plating risk, remove now",
    "spread_tightens_under_load -> connector/contact resistance, not cell"
  ],
  "schedule": {
    "capacity_check": "full discharge at nominal C-rate, amp-hours out; slow test",
    "rest_period": "minimum 1 hour at ~20% SOC before reading"
  },
  "grounding": {
    "chemistry_baseline": "https://www.wikidata.org/wiki/Q2822895",
    "note": "thresholds are field-work bands, not manufacturer spec"
  },
  "safety": [
    "class-0 insulated gloves before any orange connector",
    "disconnect and wait for capacitor discharge",
    "megohmmeter isolation test, not continuity beep",
    "one hand in pocket near pack"
  ],
  "related": [ { "title": "Shop index", "url": "/index.html" }, { "title": "Hybrid diagnostic tree", "url": "/tool.html" } ]
}