OKi – Casa Azul

Overnight Anchor — Energy Management

General · 003-Knowledge-ANC-overnight-anchor-energy

Root Cause

At anchor overnight, shore power is disconnected and solar stops at sunset. On ALUNA (72kWh @ 24V), the battery bank is the only reserve for 10-12 hours. Air conditioning is the dominant overnight load at 1.5-3kW per unit. Without active load management, a generator backup plan, and a pre-sunset charging strategy, the service bank can reach critical SoC before sunrise. Repeated overnight depletion events accelerate battery degradation and create vessel safety risk.

Symptoms

Shore power disconnected at anchorBattery discharging with no charging source activeSolar at zero from sunset to sunriseAC units running overnight on battery onlyGenerator not available or not armedSoC dropping faster than expected overnightWater heater drawing power overnightDischarge rate above 4% per hourTime to critical under 4 hours overnight

Conditions

VesselState.LocationContext = anchor
VesselState.MovementState = stationary
AC.Shore = False
Solar.Power = 0
Derived.EnergyMode = DISCHARGING
Generator.Running = false
Battery.SoC < 70 and decreasing
time between 19:00 and 07:00
Energy.TimeToCriticalHours < 6

Solution

1. Before sunset: charge to 95-100% SoC while solar is active. 2. Assess AC plan: one unit maximum overnight — pre-cool cabins before sunset to reduce run time after midnight. 3. Arm generator auto-start at 40% SoC if AC runs overnight. 4. Disable water heater overnight — heat water during solar peak hours only. 5. Switch off all non-essential 230V loads: coffee machine, shore-linked chargers, entertainment systems. 6. Set OKi overnight watch with alert at 40% SoC. 7. At 40% alert: shed non-essential loads immediately. 8. At 25%: start generator or prepare Torqeedo passage to nearest marina. 9. At 10%: emergency protocol — contact WMC, consider EPIRB if no charging source available.

Actions

Confirm anchor is intentional — rule out shore power fault
Verify solar is producing before sunset — check MPPT state
Assess overnight AC load plan — one unit maximum recommended
Confirm generator availability and arm auto-start at 40% SoC
Disable water heater overnight — schedule during solar peak only
Switch off all non-essential 230V inverter loads
Set OKi overnight watch alert threshold at 40% SoC
At 40% SoC overnight: shed non-essential loads — recalculate reserve
At 25% SoC overnight: start generator or prepare Torqeedo passage to marina
At 10% SoC: emergency protocol — contact WMC via mobile and Tailscale
Morning: charge to 90%+ before next sunset — resolve any faults in daylight
Log overnight minimum SoC to care system for post-anchor review