GMDSS Reserve Battery Tool Radio Load, Capacity, Charger & Emergency Endurance

SOLAS IV/13 • 1 h / 6 h Reserve • Radio Load • C1 / C6 Capacity • 40% Life-Cycle Allowance • Charger 10 h Recovery • Voltage Drop • Emergency Endurance

GMDSS Reserve Battery Tool Radio Load, Capacity, Charger & Emergency Endurance

Size and screen the GMDSS reserve battery from the actual radio load instead of relying only on nameplate amp-hours. Simple mode converts receive/transmit duty into reserve current, applies the 1-hour or 6-hour SOLAS basis, rapid-discharge capacity effects, battery condition and charger recovery. Advanced builds a full reserve-bus load register, handles simultaneous versus alternative radio paths, checks current-condition endurance, life-cycle sizing, charger recovery, peak-current cable voltage drop and multiple reserve scenarios.

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Need individual radios, duplicated/alternative paths and voltage-drop checks? Click Advanced above.Simple uses the SOLAS/IMO reserve-load concept with a user-entered transmit duty factor and a 40% life-cycle sizing allowance.

Reserve1 h or 6 h endurance

CapacityUsable vs nameplate Ah

Recovery10 h charger screen

Reserve Load & Battery

Adequate SOLAS emergency radio supply?“Adequate” means the applicable emergency source can operate radiocommunications for the required 18 h cargo / 36 h passenger period.

Reserve bus nominal voltageV DC.

Total receive / standby currentA for radios/inputs that remain connected.

Total transmit currentA maximum transmit-current basis.

Transmit duty factor% of transmit current added to receive current. 50% is the IMO general reserve-load formula.

Additional emergency loadsA, e.g. required emergency light / navigation-data inputs.

Installed battery rated capacityAh at the selected nameplate rating basis.

Battery rating basis

Combined present-condition factor% remaining after state-of-charge, ageing and temperature effects.

Automatic charger rated currentA available for battery recharge.

SOLAS Reserve Duration & Battery Bank

Ship type

Emergency radio-supply enduranceh available from the ship’s emergency source to radiocommunications.

Reserve bus nominal voltageV DC.

Installed bank nameplate capacityAh.

Battery rating basis

Custom rapid-discharge usable factor% of nameplate capacity available at the required discharge period when custom is selected.

Initial state of charge%.

Capacity / ageing factor% of new-battery capacity retained.

Temperature capacity factor% from manufacturer data / engineering basis.

Life-cycle sizing allowance% added to the bare minimum calculated capacity.

Months since capacity testIMO guidance: capacity check interval should not exceed 12 months.

Reserve-Bus Radio / Essential Load Register

Average reserve current per row = quantity × (receive/standby current + transmit duty factor × transmit current). “Alternative” rows with the same group are treated as mutually exclusive and only the largest group load is counted. Use “Simultaneous” for loads connected at the same time. The default 50% transmit factor follows the IMO general reserve-load formula; change it only where the applicable equipment/flag calculation basis supports another duty factor.

Use	Load type	Qty	Rx / standby A	Tx max A	Tx duty %	Demand mode	Alt group

Automatic Charger & DC Distribution

Charger rated currentA.

Charging efficiency / net acceptance% used for recharge-time screen.

Charger directly supplies GMDSS loads while charging?

Required maximum recharge timeh; IMO guidance uses 10 h.

One-way battery cable lengthm for voltage-drop formula.

Copper conductor cross-sectionmm².

Minimum acceptable equipment voltageV, user/manufacturer limit.

Survey / Installation Checks

All required reserve loads includedBasic/duplicated radios, required nav inputs and emergency light are represented. Simultaneous / alternative architecture verifiedBattery calculation reflects which radio paths can operate together. C1 / C6 capacity data verifiedManufacturer discharge-rate and temperature data are available. Capacity test currentBattery capacity has been checked within the applicable annual interval. Automatic charger / alarms verifiedCharging, bridge indication and failure alarms are operational. Cabling / fusing verifiedPeak-current voltage drop and battery-circuit protection are acceptable. Battery location / ventilation verifiedTemperature, ventilation, access and manufacturer installation requirements are met. Controlled-discharge procedure availableIsolation of mains/emergency supply and charger is documented for capacity testing.

Engineering / regulatory limitation: this tool screens a GMDSS reserve-battery installation from entered electrical data. Actual compliance depends on the ship’s SOLAS applicability, flag-State interpretation, approved equipment, manufacturer C1/C6 performance, battery chemistry, temperature, battery condition, charger configuration and verified radio load. Use approved battery-capacity calculations and survey documentation as controlling.

Regulatory basis: IMO COMSAR.1/Circ.32/Rev.2 guidance for SOLAS IV/13 uses a reserve-radio load of ½ transmit current + receive current + additional loads, requires at least 1 h reserve when the ship has an adequate emergency radio supply and 6 h otherwise, recommends an extra 40% capacity to maintain the requirement through the battery life cycle, gives approximate rapid-discharge factors for C20 lead-acid and C10 non-lead batteries, and calls for a charger capable of restoring the completely discharged battery to the minimum required capacity within 10 h.

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