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>
7.5 KiB
7.5 KiB
Wrightstown Solar - BMS Comparison (Victron CAN Bus Compatible)
Created: 2026-02-09 System: 16S5P, EVE C40 20Ah, 48V, Victron MultiPlus II + Cerbo GX
Quick Comparison
| BMS | Price | Current | Balancing | Victron Method | Complexity |
|---|---|---|---|---|---|
| JK BMS B2A8S20P | $80-150 | 100-200A | 2A Active | dbus-serialbattery (USB) | Moderate |
| SEPLOS V3/V4 | $150-250 | 100-200A | Passive | Native CAN | Easy |
| Overkill Solar (JBD) | $280-320 | 100A | Passive | dbus-serialbattery (USB) | Moderate |
| 123SmartBMS Gen3 | $300-400 | Configurable | 1A Active | Native USB to Cerbo | Easy |
| REC BMS Q16 | $559 | Varies | 0.9A Passive | Native CAN (plug & play) | Easiest |
| Batrium WatchMon | $650-850 | High (shunt) | 28Ah/day | Native CAN | Complex |
| Daly Smart BMS | $80-150 | 100A/50A charge | 30mA Passive | dbus-serialbattery | Moderate |
| Orion BMS | $500+ | Configurable | Active options | Native CAN | Easy |
Recommended: JK BMS B2A8S20P (150A Version)
Why This BMS for EVE C40 Cylindrical Cells
- 2A active balancing -- Critical for cylindrical cells which have more cell-to-cell variation than prismatic. With 5P strings, mismatches multiply. Passive balancing at 30-200mA takes days; JK's 2A active balancing corrects in hours.
- 150A rating -- 16S5P is 100Ah, so 150A provides headroom for inrush and peak loads
- $80-150 -- Best value in the market
- Huge DIY community -- Every problem already solved on forums
Specs
- Current ratings: 100A, 150A, 200A options
- Balancing: 2A active (best in class at this price)
- Communication: Bluetooth, RS485, CAN, UART
- Monitoring: Real-time via smartphone app
- Temperature: Multiple sensor inputs
Victron Integration
JK BMS --[USB-UART cable ($15)]--> Cerbo GX
|
dbus-serialbattery
(free open-source driver)
|
DVCC enabled
|
Victron MultiPlus II
Required:
- USB-UART cable (~$15)
- dbus-serialbattery driver (free, install via SSH on Cerbo)
- DVCC enabled in Cerbo settings
[WARNING] Known Gotcha: Reversed CAN Pinout
JK BMS has CAN-H and CAN-L SWAPPED compared to Victron's RJ45 pinout. Solutions:
- Buy pre-made JK-to-Victron cable (AliExpress)
- Make your own cable and swap pins 7 & 8
- Use USB-UART connection instead (avoids CAN entirely -- recommended path)
Known Issues
- Firmware updates frequently with no changelog -- check forums before updating
- SOC can jump from 85% to 100% prematurely during fast charge
- Battery capacity/consumed Ah data may not transmit to Cerbo via some driver versions
- Inconsistent quality control between batches -- test thoroughly on arrival
Where to Buy
- AliExpress: $80-120 (multiple sellers)
- Amazon: $120-180 (JKBMS official store)
- EEL Battery, SeLian Energy (resellers)
Alternative: SEPLOS V3/V4 (Easiest Native CAN)
Why Consider
- Native Victron CAN protocol -- no drivers needed
- One CAN cable to Cerbo, auto-detects
- Multiple units can chain on one CAN link (good for expansion to 4 packs)
- $150-250 is reasonable mid-tier pricing
Drawbacks
- Passive balancing only (slower than JK's active)
- Less community documentation
- Setup can be tricky initially
Where to Buy
- Seplos.com (official)
- AliExpress, Alibaba
Premium Option: REC BMS Q16 (Zero Hassle)
Why Consider
- TRUE plug and play -- one CAN cable, auto-detected, DVCC works immediately
- Most reliable Victron integration available
- Professional-grade, excellent documentation
- SOC/SOH calculation, cell resistance measurement
Drawbacks
- $559 -- nearly 4x the JK price
- Passive balancing only (0.9A) -- slower for cylindrical cells
- No active balancing option
Where to Buy
- Off Grid and Marine Energy (OGM Energy): $559
- REC-BMS.com (official)
Budget Option: Daly Smart BMS [NOT RECOMMENDED]
Why to Avoid for This Build
- 100A discharge but only 50A charge -- will bottleneck solar charging
- 30mA passive balancing -- useless for large cells (would take 200+ hours)
- CAN speed mismatch: Daly defaults to 250kbit/s, Victron uses 500kbit/s
- Developers of dbus-serialbattery specifically do NOT recommend Daly for new builds
- Bad CAN communication implementation
Victron Side Configuration
Hardware Required
Cerbo GX ($320-350) -- Recommended
- Native BMS-CAN port (500kbit/s)
- 2x USB ports for dbus-serialbattery driver
- Built-in display, Ethernet, WiFi
- VRM remote monitoring portal
Budget Alternative: Venus OS on Raspberry Pi 4 (~$100)
- No native CAN bus -- needs USB CAN adapter ($20-40)
- More complex setup
- Works for USB-UART BMS connection (JK, Overkill)
CAN Cable Pinout (Cerbo GX BMS-CAN RJ45)
| Pin | Function |
|---|---|
| 3 | GND |
| 7 | CAN-H |
| 8 | CAN-L |
Only 3 wires needed. Always verify against your specific BMS datasheet.
Software Settings
- Update firmware on Cerbo GX, MultiPlus II, and any MPPTs to latest
- Battery Monitor: Set to BMS (not "Automatic")
- DVCC: Enable
- DVCC Sub-settings:
- Limit managed battery charge voltage: OFF (let BMS control via CVL)
- SVS (Shared voltage sense): ON
- SCS (Shared current sense): OFF
- STS (Shared temperature sense): Optional
- BMS-CAN speed: 500kbit/s (default, don't change)
dbus-serialbattery Driver (for JK/Overkill/Daly via USB)
- Install on Cerbo via SSH
- Edit
/data/etc/dbus-serialbattery/config.ini - Set BMS type and serial port
- Free, open source: https://github.com/Louisvdw/dbus-serialbattery
DVCC Explained
DVCC allows the BMS to send real-time limits to the Victron system:
- CVL (Charge Voltage Limit) -- max voltage the battery will accept
- CCL (Charge Current Limit) -- max charge current right now
- DCL (Discharge Current Limit) -- max discharge current right now
The Cerbo relays these to the MultiPlus and any solar chargers, preventing overcharge, over-discharge, and overcurrent dynamically.
Common Mistakes to Avoid
- CAN speed mismatch -- Victron is 500kbit/s, some BMS default to 250kbit/s
- JK pinout reversal -- CAN-H and CAN-L are swapped on JK BMS
- Enabling DVCC without setting battery monitor -- set monitor FIRST
- SVS with disconnect BMS -- if BMS disconnects on overvoltage, turn SVS OFF
- Multiple BMS on CAN -- only ONE BMS should control Victron via DVCC (use master/slave for multi-pack)
- Charging below 0C -- LFP cannot be charged below freezing; ensure BMS low-temp cutoff is configured
- Passive balancing on large cells -- 30mA on 20Ah cells takes forever; use active balancing