Battery, Optima blue D34M

Deep cycle, sealed lead acid, 12v battery
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High power, dual purpose engine start and deep cycle, sealed lead acid battery, 12 volts. These batteries are dual purpose. They are designed for engine starting and deep cycling applications and for use in boats with large accessory loads.



  • Length: Standard - 10”; Metric - 254 mm
  • Width: Standard - 6.875”; Metric - 174.6 mm
  • Height: Standard - 7.813”; Metric - 198.4 mm (height at the top of the terminals)
  • Weight: Standard - 43.5 lb.; Metric - 19.8 kg
  • Terminal Configuration: SAE / BCI automotive and threaded stainless steel stud 5/16 – 18 UNC.



Performance Data:

  • Open Circuit Voltage (fully charged): 13.1 volts
  • Internal Resistance (fully charged): 0.0028 ohms
  • Capacity: 55 Ah (C/20)
  • Reserve Capacity: BCI: 120 minutes (25 amp discharge, 80°F (26.7°C), to 10.5 volts cut-off)




  • CCA (BCI 0°F): 750 amps
  • MCA (BCI 32°F): 870 amps



Recommended Charging:
All limits must be strictly adhered to.

The following charging methods are recommended to ensure a long battery life - always use a voltage regulated charger with voltage limits set as described below.) These batteries are designed for starting and deep cycling applications and for use in boats with large accessory loads.

  • Alternator: 13.65 to 15.0 volts, no amperage limit.
  • Battery charger: 13.8 to 15.0 volts, 10 amps maximum, 6-12 hours approximate.
  • Cyclic Applications: 14.7 volts, no current limit as long as battery temperature remains below 125°F (51.7°C). When current falls below 1 amp, finish with 2 amp constant current for 1 hour for D34M and 3 amp constant current for 1 hour for D31M.
  • Rapid Recharge: Maximum voltage 15.6 volts (regulated).
  • Maximum current: No limit as long as temperature
  • Maximum recharge time: Charge until current drops below 1 amp.
  • Float charge: 13.2 to 13.8 volts, 1 amp maximum current, time indefinite (at lower voltage).

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