Optima BTDC-5.5 · Marine battery 12V 75Ah 975A AGM
Specifications
| Brand | OPTIMA |
|---|---|
| Part number | BTDC-5.5 |
| Voltage (V) | 12 |
| Capacity (C20) | 75Ah (c20) |
| Capacity (C5) | 68Ah (c5) |
| Cold cranking amps (EN) | 975A |
| Technology | AGM ESPIRAL |
| Length | 325.00 mm |
| Width | 158.00 mm |
€263.70
VAT included
5,0/5★★★★★1 reviewsVerified purchases
- ★★★★★José Luis G.:
Está batería la monte para reemplazar a otra igual y mismas características ya agotada su vida útil que fue espectacular.
Reviews originally written in Spanish
See all 1 reviewsOptima BTDC-5.5 12V 75Ah 975A is a marine battery, vibration- and deep-discharge resistant, suitable both for outboard engine starting and for onboard auxiliary services (navigation lights, GPS, sonar, fridge). Sealed and maintenance-free.
Why this marine battery?
- Marine designbuilt for boat swell and vibration
- Dual functionstarts the engine and powers onboard services
- Sealed and safemaintenance-free even when the boat rolls
Voltage
12 V
Capacity
75 Ah
Cold cranking
975 A
Dimensions
325×165×238 mm
Technology
AGM ESPIRAL
Weight
27,9 kg
Model
OPTIMA BLUE TOP
Marine battery Optima BTDC-5.5 Blue Top 75Ah 975A 12V
12VVoltage
75AhCapacity
975ACold cranking
27.90kgWeight
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 24-48 working hours, the islands and the rest of the EU in 3 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.
BCOM-OPTIMA-BTDC-5.5
Data sheet
- Brand
- OPTIMA
- Reference
- BTDC-5.5
- Model
- OPTIMA BLUE TOP
- Voltage (V)
- 12
- Length
- 325.00 mm
- Width
- 158.00 mm
- Height
- 218.00 mm
- Weight
- 27.9 Kgs
- Technology
- AGM ESPIRAL
- EAN
- 4016987113592
- Terminal layout
- 8
- Terminal type
- 1 & 21
- Cold cranking amps (EN)
- 975A
- Capacity (C20)
- 75Ah (c20)
- Capacity (C5)
- 68Ah (c5)
- ETN
- 8521880008882
Specific References
- EAN13
- 4016987113592
- MPN
- BTDC-5.5
Machinery that uses the OPTIMA BTDC-5.5
5,0/5
Verified purchasesLatest verified reviews
Reviews originally written in Spanish
★★★★★José Luis G.Verified purchase
09/10/2026Producto de alta calidad y rendimiento
Está batería la monte para reemplazar a otra igual y mismas características ya agotada su vida útil que fue espectacular.
Codes and references Optima BTDC-5.5
| Brand | Optima · see all Optima batteries |
|---|---|
| Manufacturer range | OPTIMA BLUE TOP |
| Manufacturer part number (MPN) | BTDC-5.5 |
| Also known as | BTDC5.5 · BTDC 5.5 · 852188000 |
| ETN code | 8521880008882 (short form 852 188 000) |
| EAN-13 barcode | 4016987113592 |
| Dimensions (length × width × height) | 325 × 165 × 238 mm (325x165x238) |
Recommended accessories
Compatible vehicles
The Optima BTDC-5.5 fits 2 vehicles. Most searched below:
How to change the battery
Guide to replace a marine battery (cranking or house) in 20-30 minutes. Moisture and vibration in marine environments require reinforced hold-downs and sealed copper terminals.
Step 1. Prepare the vehicle
Park on a flat surface, switch off the engine and remove the key. Make sure all lights and electrical accessories are off. Wait 1-2 minutes before starting.
Step 2. Locate the battery compartment
Usually under the passenger bench, engine room or a dedicated ventilated compartment. Verify the compartment is dry and well ventilated before opening.
Step 3. Disconnect the negative (−) terminal
Use the 10 mm wrench to loosen the negative cable nut (black, marked −) and remove the cable from the post. Move it aside so it cannot touch any bodywork.
Step 4. Disconnect the positive (+) terminal
Repeat with the positive cable (red, marked +). Important: never let a terminal touch metal of the car while the other is still connected.
Step 5. Remove the old battery
Marine batteries are heavy (15-50 kg). If it has rope handles, use them; otherwise have a carry strap ready. Secure the new one with metal hold-downs (not plastic) to resist sea-state vibration.
Step 6. Install the new battery
Place the battery in the same orientation as the old one (positive terminal on the same side). Tighten the hold-down clamp firmly.
Step 7. Connect the cables
Connect the positive (+) terminal first, then the negative (−). Tighten the nuts with the wrench until each terminal does not move. Apply anti-spark grease if you have any.
Step 8. Verify circuit + water protection
Apply dielectric grease on terminals to prevent salt-air corrosion. Check the engine charging circuit delivers 13.8-14.4 V at 2,000 rpm.
Frequently asked questions
Is the BTDC-5.5 model AGM? What does this technology offer?
Yes. The BTDC-5.5 from Optima uses AGM (Absorbent Glass Mat) technology: a sealed lead-acid battery where the electrolyte is absorbed in a glass-fibre mat. It withstands more charge/discharge cycles than a conventional one, handles heat better and is the required technology for boats with advanced Start-Stop and regenerative braking. Expected lifespan: 5-8 years under normal conditions.
How is the Optima BTDC-5.5 battery installed in the vehicle?
In most boats it fits in 15-30 minutes with a 10 mm wrench; if the battery is under the seat or in the boot the time can double. See the step-by-step guide on this page. Quick summary: 1) switch off the engine and remove the key; 2) locate the original battery (engine bay, boot or under seat); 3) disconnect the negative (−) terminal first, then the positive (+); 4) loosen the hold-down clamp and remove the old battery; 5) fit the new one in the same orientation — match the polarity shown on the product sheet; 6) connect the positive (+) first, then the negative (−). On boats with Start-Stop or BMS, register the battery via OBD so the alternator applies the correct charging profile.
How many years does this battery last?
Expected lifespan of the Optima BTDC-5.5 is 5 to 8 years in mild-climate boat use with Start-Stop. In cold regions it drops slightly due to cold-start stress; in very hot regions it also drops because of electrolyte evaporation. To extend its life: avoid deep discharges (headlights on with engine off), have the alternator checked yearly, and keep the battery clean and properly secured.
What are the dimensions of the Optima BTDC-5.5 battery?
Dimensions (length × width × height) are 325×165×238 mm — also written as 325x165x238 mm — following the European DIN standard. Always measure the space in your boat before buying: even one extra millimetre can prevent the hold-down clamp from closing. The height shown includes the terminals.
What ETN and EAN codes does the Optima BTDC-5.5 battery have?
The manufacturer reference (MPN) is BTDC-5.5 and its ETN code is 8521880008882 (short form 852 188 000), the European identifier used in spare-part catalogues. The EAN-13 barcode is 4016987113592. It belongs to the OPTIMA BLUE TOP range. Any of these codes identifies exactly this battery when requesting quotes or comparing prices.
Will the Optima BTDC-5.5 battery fit my boat?
Three options to confirm: 1) enter your number plate in the finder (DGT/DVLA/KBA auto-detect your model and engine); 2) check the "Compatible vehicles" tab on this page, where we list every vehicle verified by our technical team; 3) if you cannot find your model, message us on WhatsApp with brand, model, engine and year — we reply during business hours (Mon–Fri 10:00–13:30 and 16:40–18:00 (Spanish time, CET)). The BTDC-5.5 fits 2 verified vehicle versions in our database.
What are the equivalents of the BTDC-5.5 model?
Directly interchangeable batteries (same dimensions, same polarity, same Ah and CCA) are the OEM equivalents from leading brands: Bosch, Tudor, Exide and, depending on the model, Banner or Yuasa. Exact equivalence depends on technology — an EFB cannot be replaced with a conventional battery in Start-Stop boats. See the "Equivalents" section to view recommended options at the same performance level.
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