2015 Tesla Model S 85D Battery Pack Repair Log
VIN: 5YJSA1H25FF091116 | Central data site: 85Dlog.5udyk.com
Current Status (Oct 24, 2026): Pack dropped and opened. Water previously confirmed in pyro fuse cavity. Module 9 (bunkhouse, with Module 8) showed heavy terminal corrosion and initially failed TBMM due to detached sense wires. After riveting the green, brown, and orange sense wires, Module 9 now PASSES cleanly at 5 mV imbalance. Other tested modules (12, 14, 15) also PASS. Priority remaining: Modules 6/7/8 and full sense-wire / BMB inspection.
Module 9 – TBMM Results
Physical: Significant rust/corrosion on several cell terminals and busbar areas. Sensor wires initially detached on green, brown, and orange (others attached).
| Test | Before (detached wires) | After (wires fixed) |
|---|
| Module voltage | 22.53 V | 22.53 V |
| High / Low cell | 3.847 V / 3.664 V | 3.756 V / 3.751 V |
| Imbalance | 182–183 mV (FAIL) | 5 mV (PASS) |
| Temps | 14.8 °C / 14.7 °C | 15.2 °C / 15.1 °C |
| Variance | Hi=42 mV, 6 cells >5 mV | Max 1 mV, 0 cells >5 mV |
| Result | Thumbs-down | Thumbs-up |
Sense-wire repair (riveting method) resolved the false high imbalance. Terminal corrosion does not appear to affect cell voltage balance on out-of-pack TBMM.
Other Module TBMM Results (summary)
- Module 12: PASS 4 mV (after bottom orange sense wire riveted)
- Module 14: PASS 3–4 mV
- Module 15: PASS 3–4 mV (22.50 V, cells 3.747–3.751 V)
- Module 16: Initially FAIL 146 mV (detached orange/green); repaired
Timeline
- Oct 24, 2026: Module 9 sense wires (green, brown, orange) riveted. Post-repair TBMM PASS at 5 mV imbalance (was 183 mV FAIL).
- Oct 23, 2026: Module 9 visual inspection – significant rust/corrosion on cell terminals and busbar areas. Sensor wires and TBMM not yet checked at that time.
- Oct 21, 2026: Module 12 bottom orange sense wire riveted. Post-repair TBMM PASS 4 mV.
- Earlier: Pack dropped, opened, water found in pyro fuse cavity. Pre-pull SMT data logged (pack ~361 V, CAC 208–211 Ah).
To-Do / Next Steps
- Complete sense-wire and TBMM checks on remaining modules (especially 6, 7, 8).
- Inspect Module 8 (paired with 9 in bunkhouse).
- Decide path: continue repair vs. 14-module conversion (remove 8/9) vs. full pack replacement for long-term.
- Document BMB connector and pyro fuse status.
Notes
Sense Wire Repair Guide (riveting method) previously added. Photos of Module 9 corrosion and TBMM screens available in project records. Total invested ~$7,300. Estimated remaining repair costs low if only connectors/sense wires; full pack replacement higher but lower risk for multi-year ownership.
EV School | Last updated: 2026-10-24