Mike Swanson
aaf4172b3c
New projects from 2026-02-09 research session: Wrightstown Solar: - DIY 48V LiFePO4 battery storage (EVE C40 cells) - Victron MultiPlus II whole-house UPS design - BMS comparison (Victron CAN bus compatible) - EV salvage analysis (new cells won) - Full parts list and budget Wrightstown Smart Home: - Home Assistant Yellow setup (local voice, no cloud) - Local LLM server build guide (Ollama + RTX 4090) - Hybrid LLM bridge (LiteLLM + Claude API + Grok API) - Network security (VLAN architecture, PII sanitization) Machine: ACG-M-L5090 Timestamp: 2026-02-09 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
3.2 KiB
3.2 KiB
Wrightstown Solar - Session Log 2026-02-09
Session: Initial Research and Planning Machine: ACG-M-L5090
Work Completed
1. Cell Selection Research
- Researched EVE C40 (IFR40135) cylindrical LiFePO4 cells
- Specs: 3.2V, 20Ah, 64Wh per cell, 366g, 50-60A continuous discharge
- Selected for home solar battery pack build
2. Pack Design
- Determined 16S5P configuration for 5kWh packs (80 cells each)
- 48V nominal system, 51.2V actual
- Modular design: build in 5kWh increments up to 20kWh (4 packs)
- Chose 5kWh over 10kWh packs for: cost spreading, manageable builds, fault isolation, single-person liftable weight
3. Inverter Selection
- Existing solar: Fronius IG Plus (grid-tie only, no battery port)
- Selected Victron MultiPlus II 48/5000 for:
- <20ms transfer (UPS-grade seamless switchover)
- Physical relay disconnect (zero backfeed)
- Generator input support
- Creates micro-grid for Fronius to sync during outages
- Architecture: whole-house UPS with generator failover
4. Salvaged EV Battery Analysis
- Evaluated Tesla LFP, Chevy Bolt, Nissan Leaf salvage options
- Conclusion: New C40 cells are cheaper ($190-282/kWh vs $365-780/kWh for salvage)
- Salvage has hidden costs: voltage conversion, custom BMS, cooling, unknown SOH
- Most salvage is NMC chemistry (less safe than LFP for home use)
- Decision: Proceed with new EVE C40 cells
5. BMS Research (Victron CAN Bus Compatible)
- Comprehensive comparison of 8 BMS models
- Recommended: JK BMS B2A8S20P 150A ($80-150)
- 2A active balancing (critical for cylindrical cells)
- Victron integration via dbus-serialbattery driver + USB-UART cable
- Known gotcha: CAN pinout reversed (use USB-UART path instead)
- Alternatives: SEPLOS V4 (native CAN, $150-250), REC Q16 (plug & play, $559)
- Cerbo GX ($320-350) selected as GX device
6. Budget Estimates
- Phase 1 (5kWh + full Victron system): $2,175-2,945
- Full 20kWh system: $3,635-5,750
- Battery-only $/kWh: $86-153
Decisions Made
| Decision | Chosen | Over | Why |
|---|---|---|---|
| Cell type | EVE C40 (new) | Salvaged EV packs | Cost, safety, lifespan, simplicity |
| Pack size | 5kWh modules | 10kWh modules | Modular, manageable, fault isolation |
| Inverter | Victron MultiPlus II 48/5000 | Other options | UPS switchover, relay disconnect, generator support |
| BMS | JK BMS B2A8S20P 150A | REC, SEPLOS, Daly | Active balancing, price, community support |
| GX device | Cerbo GX | Raspberry Pi | Easier setup, native BMS-CAN port |
Files Created
projects/wrightstown-solar/PROJECT_INDEX.mdprojects/wrightstown-solar/documentation/system-design.mdprojects/wrightstown-solar/documentation/bms-comparison.mdprojects/wrightstown-solar/documentation/ev-salvage-analysis.mdprojects/wrightstown-solar/documentation/parts-list.mdprojects/wrightstown-solar/session-logs/2026-02-09-session.md(this file)
Next Steps
- Finalize BMS selection
- Source EVE C40 cells (Grade A, matched, with test data)
- Order Victron MultiPlus II + Cerbo GX
- Design physical cell holder / bus bar layout for 16S5P cylindrical pack
- Plan sub-panel / transfer switch wiring
- Build Pack 1, test for 1 month before expanding