OPTIMA BlueTop BT DC-4.2 12V 55Ah 765A L+

• Brand: OPTIMA
• Series: BlueTop
• Model: BT DC-4.2
• Type: Dual purpose
• Voltage: 12 V
• Capacity: 55 Ah
• Cold cranking (CCA): 765 A
• Polarity: L+
• Terminals: Standard terminal + threaded
• Dimensions (L×W×H): 254 × 175 × 200 mm
• Weight: 20.3 kg
• Maintenance-free
• Intended use: Marine and recreation

About this battery
OPTIMA BlueTop is the marine / RV version, adding threaded marine terminals alongside the standard posts. Depending on model it works as a starting battery (like RedTop) or a dual-purpose deep-cycle battery (like YellowTop) — suited to boats, trolling motors and campers. Its AGM SpiralCell construction makes it maintenance-free, spill-proof and vibration-resistant.

Key terms

• CCA (Cold Cranking Amps) — cold-start power; higher means a stronger start in the cold
• Ah — capacity / energy reserve
• L+ / R+ — terminal polarity (which side the positive post is on); important for correct fitment