Electrical

House Bank

LiFePO₄ across 10 × 12V WattCycle 100Ah bluetooth (internal BMS) batteries. 9 are in the main house bank, one is dedicated to the Electroscan macerator ("electropooper").

Three different capacity numbers are all valid for different things:

• House bank nominal: ~10.8 kWh (9 × 100Ah × 12V)

• Total system nominal: ~12 kWh (includes the 10th battery dedicated to the Electroscan)

• Actual realized: ~11.5 kWh per BMSes when fully charged — not all batteries reach a true 100Ah. This is the right figure for power-budget math (see Jimmy-Shower).

• Main house bank is in starboard salon (relocated from lazarette — see Interior for rationale & layout)

• Main house battery box is King StarBoard

Engine Electrical

A single AGM starter battery in a battery box under the center of the port quarterberth:

• Interstate 27M-XHD, 100Ah, MCA 1000 / CCA 800 — replaced 02/2026
• Big red battery kill switch on the bulkhead next to the battery
• Wired to this battery: starter and bilge pumps only
• Balmar 120A alternator with MC-612 external regulator (still installed). The oversized alternator/regulator are pointless feeding a single AGM. The right thing to do is reset the Balmar regulator and add a Victron DC-DC charger to feed the house bank.

Grounding

• House bank DC- and AC ground both bond at the engine block via the main earth ground in front of the companionway.
• Engine ground bonded to the engine block via heavy cable.

Charging & Inverter

• Victron MultiPlus 3000W inverter/charger (replaced earlier MultiPlus during refit; original MultiPlus was installed 2019)
• Solar: ~1 kW total
  • 4 × ExpertPower 100W rigid — davit-mounted (Kato SailDavits, 1" cross tubes; see Hull-Deck)
  • 2 × Tatoodaa 300W flexible — bimini-mounted
• 4 × Victron MPPT solar charge controllers
  • 2 × MPPT 100/30
  • 1 × MPPT 100/50
  • 1 × MPPT 75/15
  • Davit panels, bimini panels — extend wiring done 2026-04
  • MPPT → Cerbo via VE.Direct just doesn't work. Tried this to death, using a Duppa Quadport hub as well as building VE.Direct cables from UTP 22AWG Cat8 + JST connectors. None of the MPPTs lit up an RX or TX light 😢. Current plan is to extend another TP-Link Bluetooth adapter via USB-over-UTP with a powered extender, and use passive BLE Instant Readout into HA.

    Update 2026-04: Genuine Victron VE.Direct-to-USB cables (ASS030530000) into the Cerbo's USB ports — also did not work. The Cerbo's three native VE.Direct JST ports show no continuity to device ground when unloaded; the Duppa Quadport hub did not enumerate per-port ttyUSB instances reliably under Venus OS. Confirmed dead end. Path forward: BLE Instant Readout via TP-Link UB500 dongles, with one extended via USB-over-IP / Cat7 to the closet near the MPPTs.

• MPPT charge controller settings (lithium):
  • Load output: Always On (BMS handles disconnect)
  • Absorption duration: Dynamic (fixed is a lead-acid concept)
  • Tail current: 2% of bank capacity
  • Max charge current: ceiling at MPPT rated max (~60A); panels are the practical limiter
  • Absorption voltage: 14.2V
• Shore power: 110V via MultiPlus. The internal shore power cable is 10/3 with an extra join at the front of the lazarette shelf that's not loved.
  • TODO: replace with a solid cable
• TODO: AC wiring diagram
• Wind: Air 30 wired through a 300A SmartShunt (in supplier mode). Earlier diagnosis of mechanical failure was overaggressive — the Air 30 was being overpowered by winds >30 kt. At lower wind speeds it continues to work as expected. For future replacement reference, three options identified:
  • Primus Wind Power Air 40 — direct replacement, same mount (Primus bought the Air line). Caveat: not marine-rated.
  • Rutland (Marlec) 1200 / 914i — purpose-built marine, widely serviced.
  • Superwind 350 — premium marine, feathering blades (no clutch).

Both wind gen and solar feed to a single large bus in the starboard lazarette, which feeds a 1/0 cable back to the DC main punchdown behind the breaker panels.

Monitoring

• Victron SmartShunt 300A on the DC main only. This is a problem because it misses all MultiPlus traffic. A 1K shunt is on order to replace the 300A and be routed upstream to capture 100% of traffic.

  • The Cerbo is supposed to aggregate MultiPlus VE.Bus current with SmartShunt data via DVCC, but in practice this does not work — which is what makes the upstream 1K shunt urgent.

• SmartShunt LiFePO4 calibration for the WattCycle batteries (charge voltage 14.6V, no float spec):

  • Charged voltage threshold: 14.4V
  • Tail current: 2% of capacity (~18A on the 900Ah bank)
  • Peukert exponent: 1.05
  • Charge efficiency factor: 99%
  • MultiPlus float voltage (since not specified by battery): 13.5V

  These resolved the SOC-stuck-at-99% behavior.

• Cerbo GX central monitor. Feeds shunt + MultiPlus data to HA via MQTT. Still can't see MPPTs over VE.Direct (see above).

Per-circuit monitoring (planned)

Plan in progress for individual circuit consumption monitoring:

• ACS758 / ACS770 hall-effect sensors (50A or 100A variants) — most Defiant circuits are 15–30A
• Read via ADS1115 → ESP32-C3 SuperMini → ESPHome → HA
• Same architecture as fuel sender / water flow infra

See Home-Assistant for full HA infrastructure.

DC Distribution

• Main earth ground in front of companionway. Big bastard.
• Bus bars are in salon under starboard settee
• 3 cluster bus bars + 1 system bus bar, all 400A rated (Blue Sea / Victron)
• 4/0 from MultiPlus → bus bar
• 4/0 from main DC negative bus → engine block (~10–20 ft run)
• 1/0 from solar/wind feed bus in starboard lazarette → DC main punchdown
• 1/0 from bus bar → 12V panel
• TODO: full distribution diagram, fuse list

AC Distribution

MultiPlus was moved to below the nav desk (you can't miss it, it's a fucking mailbox). Outlets are metal boxes and brittle, need to be replaced.