The following charging methods are recommended to insure a long battery life - always use a voltage-regulated charger, with voltage limits set as described below.

YellowTop Type: D51 & D51R - D35 - D75/25 - D34 - D34/78
These batteries are dual-purpose. They are designed for engine start and cyclic applications and for use in vehicles with large accessory loads.

Recommended charging information:

• 13.65 to 15.0 volts, no amperage limit.

• 13.8 to 15.0 volts, 10 amps maximum, 6-12 hours approximate.

• 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.

• Maximum voltage 15.6 volts (regulated), no current limit as long as battery temperature remains below 125°F (51.7°C). Charge until current drops below 1 amp.

• 13.2 to 13.8 volts, 1 amp maximum current, time indefinite (at lower voltage).

• Always wear safety glasses when working with batteries.
• Always use a voltage regulated battery charger with limits set to the above ratings. Overcharging can cause the safety valves to open and battery gasses to escape, resulting in premature failure. These gasses are flammable! You cannot replace water in sealed batteries that have been overcharged. Any battery that becomes very hot or makes a hissing sound while recharging should be disconnected immediately.
• Failure to fully charge a battery can result in poor performance and a reduction in capacity.

The OPTIMA battery is truly maintenance free. When charged properly you will not have to worry about leaking, corrosion, or gassing. Periodically inspect your battery terminal connections to ensure they are clean, snug, and protected from the elements.

Open circuit voltage (OCV) and storage:

OCV: 34 / 34R / 34/78 / 6V / 34M / 75/35 >12.8 volts
(for a fully charged battery)

D34 / D34/78 / D6V / D34M >13.0 volts
(for a fully charged battery)

Battery Storage

Because of the high purity lead grid in the OPTIMA battery, it has a self-discharge rate much lower than conventional flat-plate batteries. This means the OPTIMA can sit for longer periods retaining enough charge to start your vehicle. Depending on storage temperature, the OPTIMA can usually sit for 8 to 12 months and start most vehicles.

When possible, store your battery in a cool, dry location. Check the battery voltage every 6 months and charge if it falls below 12.6 volts.

Remember, newer vehicles with on-board electronics such as computers, LCD screens, game systems, GPS units, clocks, etc., require battery power to retain system memory while the vehicle is parked. If the vehicle is to be stored for long periods you should use a maintenance charger to compensate for this drain. This charger should be voltage regulated between 13.2 - 13.8 volts, 1 amp maximum. On older vehicles, without electronics, disconnect the battery cables when the vehicle is not being used for extended periods.