What is the mandatory autonomy duration for a GMDSS reserve battery under SOLAS?

Under SOLAS Chapter IV Regulation 13.2, the reserve source of energy must supply the radio installation for at least 1 hour if the vessel is fitted with an emergency diesel generator (EDG) complying fully with SOLAS II-1/42 or 43. If no compliant emergency generator is fitted or connected to the GMDSS console, the battery must provide at least 6 hours of continuous autonomous operation.

How is the equivalent continuous discharge current calculated according to IMO COMSAR/Circ.32?

The calculation follows the IMO standard distress duty cycle formula: I_total = I_rx + 0.5 * I_tx + I_other, where I_rx represents the combined current consumption of all radio equipment in simultaneous receive mode, I_tx is the transmit current of the highest-rated transmitter (typically MF/HF at full RF output), and I_other accounts for continuous loads such as console emergency lighting, GNSS receivers, and navigational data interfaces.

What are the statutory pass/fail criteria for the GMDSS battery discharge test?

Classification societies and Port State Control enforce three concurrent requirements: 1) End-of-discharge terminal voltage under load must remain above 21.60 V for a 24V DC installation (1.80 V per 2V cell); 2) Delivered actual capacity must equal or exceed 80% of the rated/required capacity (SOH >= 80%); 3) Maximum voltage imbalance between individual monoblocks must not exceed 0.30 V.

How does the tool integrate actual delivered capacity during the discharge test?

The engine uses the trapezoidal numerical integration rule across test steps: C_actual = Σ [(I_k + I_k+1) / 2 * (t_k+1 - t_k) / 60] in Ampere-hours (Ah), ensuring authentic physical integration across varying discharge rates and terminal voltage decays.

How does the print engine guarantee an ad-free official survey report?

The application deploys extreme DOM isolation: upon clicking 'Print Protocol (PDF)', the script compiles the formal survey document into a dedicated static container (#gmdss-battery-print-area) while CSS media rules suppress WordPress headers, footers, theme widgets, and Google AdSense banners.

GMDSS Battery Capacity Test Calculator — SOLAS Reserve Energy Report

Saved

Import JSON

1. Ship Particulars & Reserve Battery Bank Specifications

Ship Particulars & GMDSS Reserve Battery Bank Technical Specifications

Ship Particulars & Survey Information (SOLAS Survey Record)

Ship Name *

IMO Number *

Call Sign

Flag State / Registry

Date of Survey / Test *

Port / Anchorage Location

Radio Surveyor / Company

Ship Radio Officer / Navigating Officer (GOC)

Reserve Battery Bank Technical Specifications

Manufacturer & Model *

Battery Chemistry *

Bank Configuration & System Voltage

Rated Capacity C10/C20 (Ah) *

Commissioning / Install Date *

Battery Service Life & Age Status

-- Specify commissioning date to evaluate age

Discharge Method Applied

2. Connected GMDSS Equipment Audit & IMO COMSAR/Circ.32 Current

SOLAS IV/13.2 Autonomy Requirement & Equivalent Discharge Current Formula

Statutory Autonomy Requirement (SOLAS IV/13.2):

1 Hour Autonomy

Emergency Generator complies with SOLAS II-1/42 or 43 Emergency generator supplies GMDSS radio installation

6 Hours Autonomy

No compliant Emergency Generator fitted for GMDSS No compliant emergency generator fitted to supply GMDSS equipment

Active	Connected GMDSS Radio Equipment	Rx Current (A)	Tx Current (A)	Continuous / Other (A)	Circ.32 Equivalent (A)
Sub-totals:		0.00 A	0.00 A	0.00 A	0.00 A

IMO COMSAR/Circ.32 Discharge Current Formula:

I_total = Σ I_rx + 0.5 × Σ I_tx + Σ I_other

I_total = 0.0 + (0.5 × 0.0) + 0.0 = 0.00 A

Equivalent Discharge Current (I_total) 0.00 A Equivalent continuous discharge rate

Required Capacity (C_required) 0.00 Ah Based on 1 Hour duty

Design Reserve Margin (Margin) 0.00x Compliant

3. Periodic Discharge Measurements Log & Vector Curve

Periodic Discharge Measurements & Interactive Vector Discharge Curve

Step	Time (min)	Total V (V)	Current (A)	Batt #1 V (V)	Batt #2 V (V)	ΔV (V)	Temp (°C)

Vector Discharge Profile (Terminal Voltage Under Load)

Actual Bank Voltage SOLAS Cut-off Limit: 21.6 V (1.80 V/cell) Degradation Zone (< 21.6 V)

4. Degradation Analysis & Statutory Compliance Verdict

Numerical Capacity Integration (Trapezoidal Rule), SOH Assessment & Statutory Verdict

Actual Delivered Capacity (C_actual) 0.00 Ah Integrated via Trapezoidal Rule

End-of-Discharge Voltage (End V) 0.00 V SOLAS threshold ≥ 21.60 V

Max Monoblock Imbalance (ΔV_max) 0.00 V Permissible delta ≤ 0.30 V

State of Health (SOH) 0.0 % Minimum statutory ≥ 80.0%

SOLAS Chapter IV Reg. 13 & IMO COMSAR/Circ.32 Compliance Checklist:

✓

End-of-Discharge Terminal Voltage ≥ 21.60 V (1.80 V/cell) --

✓

State of Health (SOH) ≥ 80.0% of Required Duty --

✓

Monoblock Voltage Symmetry ΔV ≤ 0.30 V --

GMDSS Radio Survey Hub SOLAS // CH.IV REG.13

Passage Planner Pro ↗ GMDSS Radio Suite ↗

GMDSS Reserve Source of Energy Capacity Testing: SOLAS IV/13 & IMO COMSAR/Circ.32

The annual verification of the GMDSS Reserve Source of Energy is a critical statutory checkpoint during annual Safety Radio Surveys by classification societies (DNV, LR, BV, ABS, ClassNK) and Port State Control (PSC) inspections. Governed by SOLAS Chapter IV Regulation 13, IMO Resolutions A.694(17), A.702(17), and circular IMO COMSAR/Circ.32, radio batteries must demonstrate verified operational endurance under distress duty conditions.

The GMDSS Reserve Battery Calculator & Capacity Test Pro automates connected load audits, determines statutory 1-hour or 6-hour minimum capacity demands, logs periodic discharge readings (via load bank or live equipment load), performs trapezoidal capacity integration, tracks monoblock symmetry, and renders an interactive discharge profile. An integrated print isolation engine formats an official A4 compliance certificate with zero advertising interference.

IMO Load Auditing

COMSAR/Circ.32 Current

Automated distress duty cycle computation via formula I_total = I_rx + 0.5·I_tx + I_other mapped against 1-hour or 6-hour SOLAS autonomy criteria.

Degradation Analysis

Trapezoidal Integration & SOH

Numerical Ah integration across elapsed test intervals, State of Health (SOH) evaluation, monoblock ΔV symmetry verification, and end-voltage monitoring.

Statutory Reporting

Official Survey Certificate

High-resolution vector SVG discharge profile, statutory Pass/Fail verdict seal, and extreme DOM isolation for clean A4 PDF survey record printing.

Frequently Asked Questions (GMDSS Battery Survey FAQ)

When is a vessel required to maintain 1 hour vs. 6 hours of GMDSS battery reserve?

Under SOLAS Chapter IV Regulation 13.2, a 1-hour reserve duration is permitted if the vessel is equipped with an emergency generator that fully complies with SOLAS Chapter II-1 Regulations 42 or 43 (automatic starting and automatic transfer to power the GMDSS console upon main power failure). If the vessel is not fitted with an emergency generator, or if the generator is not configured to supply the GMDSS console, the reserve battery bank must provide at least 6 hours of continuous autonomous radio operation.

What terminal voltage indicates a battery failure during the discharge test?

For a standard 24-volt lead-acid installation (AGM or GEL VRLA), the statutory cut-off voltage is 21.60 V DC (1.80 V per 2V cell). If the terminal voltage drops below 21.60 V under load before the required 1-hour or 6-hour period elapses, the battery fails the survey and must be replaced prior to departure.

Why is the monoblock voltage imbalance limit set to 0.30 V?

In a 24V series bank (e.g., two 12V monoblocks), a voltage disparity (ΔV = |V₁ - V₂|) exceeding 0.30 V points to severe cell degradation, internal short circuits, or heavy sulfation in one block. Even if the combined bank voltage temporarily measures above 21.60 V, the weaker monoblock will suffer polarity reversal under emergency loads, posing an immediate risk of radio console blackout.

What is the recommended service life for GMDSS reserve batteries?

Most classification societies and marine battery manufacturers recommend replacing VRLA (AGM/GEL) batteries every 3 to 5 years. Under IMO COMSAR/Circ.32, batteries exceeding 36 months (3 years) in service warrant heightened inspection, and ships' officers should perform internal discharge checks quarterly to detect accelerated capacity fade.

Can survey results be saved and exported for company records?

Yes. All vessel particulars, equipment load currents, and periodic discharge readings auto-save to browser LocalStorage. The "Export JSON" button generates an archival file for company safety records, while "Print Protocol (PDF)" renders a vector-accurate, ad-free A4 survey report ready for surveyor and Master signatures.

Regulations: SOLAS IV/13, IMO Res. A.694(17), A.702(17)

Test Method: IMO COMSAR/Circ.32 (Discharge Test & SOH ≥ 80%)

Survey: Annual Safety Radio Survey & PSC Ready