Boat Battery Sizer & Load Calculator

Generation vs Consumption vs Net

Cumulative Consumption Over Trip

Stacked Contributors (≥10% by default)

Trip Net vs Usable Bank

SOC Over Trip

User Manual

This tab explains each field, the core math, and how to interpret results.

1) System & Sizing Settings

• System voltage — Your DC bus nominal voltage (12/24/48 V). Affects Amp-hour conversions (Wh ÷ V = Ah) and alternator/charger energy.
• Battery chemistry — Sets default usable DoD: LFP ≈ 88%, AGM ≈ 50%, Gel ≈ 55%.
• Usable DoD (%) — Portion of the bank you plan to use before recharge.
• Reserve margin (%) — Extra headroom added to trip energy (weather, unexpected loads).
• Trip length (days) — Multiplies “per-day” loads.
• Capacity derate (%) — Reduces nameplate capacity to model cold/aging.
• Inverter efficiency (%) — Used to inflate AC loads back to DC side.
• Inverter standby (W) — “On but idle” draw; uses max AC hours per mode (Anchor/Underway).

2) Loads Table (Per-Day Inputs)

• Name / Category — Any label; category is for grouping.
• Type — DC or AC via inverter.
• Entry — Enter power/current as Watts or Amps.
• W/A — The numeric value (e.g., 60 W or 2 A).
• Hours @ Anchor / Underway — Hours the device runs in each mode.
• Duty % — Percent on-time within those hours (e.g., a fridge might cycle 35%).
• Qty — Number of identical devices.

3) Generation & Charging

• Solar — Panel W × Panels × Sun Hours × (1 − Derate%) × Controller Eff%.
• Wind — Rated W × Capacity Factor% × Hours.
• Alternator — DC Amps × System V × Hours.
• AC Charger — DC Amps × V × Hours × Eff%.

4) Calculations

• Row energy (DC)
  • If entry = W: Wh = Watts × Hours × Duty × Qty
  • If entry = A: Wh = Amps × System V × Hours × Duty × Qty
• Row energy (AC via inverter)
  • If entry = W: Wh = Watts × Hours × Duty × Qty ÷ InverterEff
  • If entry = A: Wh = Amps × 120 V × Hours × Duty × Qty ÷ InverterEff
• Inverter standby Wh/day — StandbyW × (max AC hours @ Anchor + max AC hours Underway)
• Total Loads (per day) — Sum of all rows + inverter standby.
• Total Generation (per day) — Sum of all sources (at system V).
• Net (per day) — Generation − Loads (positive = surplus).
• Trip energy — Loads/day × Trip days.
• Battery sizing
  • Trip Ah = Trip Wh ÷ V
  • Usable required Ah = Trip Ah × (1 + Reserve%)
  • Nameplate Ah = Usable Ah ÷ DoD, then adjust for Derate if set.
  • Suggested layout ≈ number of 100 Ah modules @ system V.

5) KPIs & Units

• Use the Ah/Wh toggle to switch units (defaults to Ah). KPIs and Reports follow your selection.
• Net card colors: green = surplus, yellow = small deficit, red = larger deficit.

6) Reports

• Bar Chart — Generation (positive), Consumption (shown as negative), and Net per day.
• Line Chart — Cumulative consumption over the trip.
• Both charts react to the Ah/Wh toggle.

7) Save / Load / Export / Print

• Save — Stores your scenario in browser storage.
• Load — Restores the saved scenario.
• Export CSV — Exports load rows and summary KPIs.
• Print Report — Prints a clean report view of the current state.

8) Defaults & Autosave

• On first run (or after Reset), a sensible set of example loads & solar generation is added.
• Autosave runs in the background so you don’t lose work; Reset clears autosave.

9) Tips

• Convert incandescent/halogen to LED to shrink nightly loads.
• Mind inverter standby; switch off when not needed.
• For AC devices, consider using actual measured watts (Kill-A-Watt / spec sheet).