Optima BTDC-5.5 Blue Top · Marine battery 75Ah 975A AGM

Marine battery Optima BTDC-5.5 Blue Top 75Ah 975A 12V

The Optima BTDC-5.5 with spiral-cell AGM technology is a marine battery with 75 Ah and 975 A of cold cranking current (EN) for motor and sailing boats, both for engine starting and onboard services. Measuring 325 × 158 × 218 mm, it is the direct replacement for boats fitted from the factory with a 75 Ah battery of this format.

• Sealed: no spills or gases in the locker.
• Resistant to humidity and salt air.
• Spiral AGM construction, sealed and mountable in any position.
• Ready for starting outboard and inboard engines.

What the Optima BTDC-5.5 is for

The Optima BTDC-5.5 is designed for motor and sailing boats, both for engine starting and onboard services. If it is your starter battery, run the services from a separate battery; if it is a service battery, avoid routinely discharging it beyond 50%. Check that it matches your current battery in dimensions, terminals and hold-down: this reference has a weight of 27.90 kg and 1 & 21 terminals.

Will it fit your current battery tray?

In terms of format, the Optima BTDC-5.5 measures 325 × 158 × 218 mm (length × width × height) and weighs 27.90 kg. It uses 1 & 21 terminals, the system that anchors and connects it in the vehicle. Before replacing it, measure your current battery tray: if all three dimensions and the terminal positions match, the swap is direct and needs no adapters.

The Optima BTDC-5.5: Blue Top range and spiral-cell AGM technology

Within the Optima catalogue, the Blue Top series groups the references designed for this use. The BTDC-5.5 is the 75 Ah model of that family, with the same performance as its siblings in other sizes.

Spiral AGM construction winds the plates into cylindrical pure-lead cells: maximum active surface, extreme vibration resistance and cranking current far above a battery of the same size.

Optima: the maker behind the BTDC-5.5

Optima makes spiral-cell (SpiralCell) AGM batteries with pure lead: maximum vibration resistance, very powerful cranking and a durability recognised in 4x4, motorsport, marine and car audio. We guarantee that every Optima arrives new, charged and with the manufacturer's full warranty.

Official warranty

The Optima BTDC-5.5 comes with the manufacturer's official warranty against manufacturing defects. Deep discharge from winter lay-up without charging is not covered.

Usage and maintenance tips

Protect the terminals with dielectric grease and check the fixing: vibration and swell loosen connections. Charge with a voltage-controlled AGM charger; a fully discharged pure-lead battery may need a specific charger to recover.

Shipping, delivery and returns

Order before 6:00 pm with stock available and it leaves today: mainland Spain and Portugal receive it in 1 to 2 working days, the islands and the rest of the EU in 1 to 5 days. You have 14 days to return it if it has not been installed, with free collection on the mainland, and shipment tracking by email.