How to recharge Optima batteries with a battery charger

We offer a wide variety of options to charge your Optima AGM battery. We recommend CTek, Enerdrive, Victron and Battery Fighter Battery Chargers .

On this page you will find detailed information on the best practices to charge Optima batteries, including each of the specific types: YellowTop, BlueTop and RedTop.

Can you use a regular battery charger on an Optima battery?

Do not use Gel or Gel/AGM settings, as they will not fully charge an Optima battery and could damage it over time. However, even some AGM-compatible chargers will not recharge deeply discharged (less than 10.5 volts) Optima batteries. In those instances, it may be necessary to follow the parallel charging instructions.

Most high-quality, modern battery chargers now have built-in features to charge AGM batteries like Optima batteries. Some have specific AGM settings, which should be used to charge an Optima battery.

Can you trickle-charge an OPTIMA battery? And what type of charger can I use?

Yes, and you can use any charger on an Optima battery as long as the voltage is regulated properly. If your charger will remain on indefinitely, the voltage should be at 13.8 volts maximum with a one-amp maximum current. We would only recommend trickle charge for charge maintenance purposes only.

Will my high-output alternator damage the OPTIMA battery?

No, as long as the voltage is properly regulated. Because the Optima battery has a very low internal resistance, it will accept high current more efficiently than conventional batteries.

How to charge Optima AGM Batteries.

Optima YellowTop, BlueTop and RedTop charging Information. The following methods are recommended to ensure a long battery life. Always use a voltage-regulated charger, with voltage limits set as described below.

Optima YellowTop Battery Charging

Charging Optima YellowTop Batteries: D51, D51R, D35, D75/25, D34/R, D34/78 & D27M & MORE…

These batteries are dual-purpose. They are designed for engine start and cyclic applications and for use in vehicles with large accessory loads.
Recommended Charger CTEK MXS7.0 7 Amp Multi Stage Battery Charger
Alternator 13.65 – 15.0V, no amperage limit.
Battery Charger 13.8 – 15.0V, 10 amps max, for 6-12 hours.
Cyclic Applications 14.7V, no current limit as long as battery temperature remains below 51.7°C. When current falls below one amp, finish with 2 amp constant current for 1 hour.
Rapid Recharge Max 15.6V (regulated), no current limit as long as battery temperature remains below 51.7°C. Charge until current drops below 1 amp.
Float Charge 13.2 – 13.8V, 1 amp max current, time indefinite (at lower voltage).

 

Charging YellowTop Batteries: D31A & D31T

These batteries are dual-purpose. They are designed for engine start and cyclic applications and for use in vehicles with large accessory loads.
Recommended Charger Victron 10 Amp Battery Charger with Blue Smart  
Alternator 13.65 – 15.0V, no amperage limit.
Battery Charger 13.8 – 15.0V, 10 amps max, for 6-12 hours.
Cyclic Applications 14.7V, no current limit as long as battery temperature remains below 51.7°C. When current falls below 1 amp, finish with 3 amp constant current for 1 hour.
Rapid Recharge Max 15.6V (regulated), no current limit as long as battery temperature remains below 51.7°C. Charge until current drops below 1 amp.
Float Charge 13.2 – 13.8V, one amp max current, time indefinite (at lower voltage).

 

Optima RedTop Battery Charging

Charging Optima RedTop Batteries: 34, 35, 34/78, 25, 35, 75/25

These batteries are designed for engine starting applications. They are NOT recommended or warranted for use in deep-cycle applications.
Recommended Charger Thunder 8 Amp Battery Charger
Alternator 13.3 – 15.0V, no amperage limit.
Battery Charger 13.8 – 15.0V, 10 amps max, for 6 to 12 hours.
Rapid Recharge Max 15.6V (regulated), no current limit as long as battery temperature remains below 51.7°C. Charge until current drops below one amp.
Float Charge 13.2 – 13.8V, one amp max current, time indefinite (at lower voltage).

 

Charging Optima RedTop Batteries: 6V

These batteries are designed for engine starting applications. They are NOT recommended or warranted for use in deep-cycle applications.
Recommended Charger Battery Fighter 6V Charger
Alternator 6.65 – 7.5V, no amperage limit.
Battery Charger 6.9 – 7.5V, 10 amps max, for 6 to 12 hours.
Rapid Recharge Max 7.8V (regulated), no current limit as long as battery temperature remains below 51.7°C. Charge until current drops below one amp.
Float Charge 6.6 – 6.9V, one amp max current, time indefinite (at lower voltage).

 

Optima BlueTop Battery Charging

Charging Optima BlueTop Batteries: 34M

These batteries are designed for engine starting applications. They are NOT recommended or warranted for use in deep-cycle applications.
Recommended Charger Thunder 8 Amp Battery Charger
Alternator 13.3 – 15.0V, no amperage limit.
Battery Charger 13.8 – 15.0V, 10 amps max, for 6-12 hours.
Rapid Recharge Max 15.6V (regulated), no current limit as long as battery temperature remains below 51.7°C. Charge until current drops below 1 amp.
Float Charge 13.2 – 13.8V, 1 amp max current, time indefinite (at lower voltage).

 

Charging Optima BlueTop Batteries: D34M, D31M, D27M

These batteries are dual-purpose. They are designed for engine starting and deep cycling applications, as well as for use in boats with large accessory loads.
Recommended Charger Battery Fighter Multi Amp Multi Stage Battery Charger.

It’s like two chargers in one!

Alternator 13.65 – 15.0V, no amperage limit.
Battery Charger 13.8 – 15.0V, 10 amps max, for 6 to 12 hours.
Cyclic Applications 14.7V, no current limit as long as battery temperature remains below 51.7°C. When current falls below one amp, finish with two-amp constant current for one hour for D34M and three-amp constant current for one hour for D27M and D31M.
Rapid Recharge Max 15.6V (regulated), no current limit as long as battery temperature remains below 51.7°C. Charge until current drops below one amp.
Float Charge 13.2 – 13.8V, one amp max current, time indefinite (at lower voltage).

 

Safety information & precautions when charging Optima Batteries

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 reduction in capacity.

These guidelines are intended for typical consumer applications. For military, commercial applications or new equipment design, please contact Optima for additional technical information and assistance.

How to revive a deeply discharged Optima AGM Battery

In time, AGM batteries, including Optima batteries, may fail. Failures are often caused when a starting battery is used in a cycling application, for which a deep-cycle battery is the better choice.

If you have bad AGM battery, you attach it to your charger and the charger won’t even charge it. The assumption is that it must be a bad battery. However, in many cases, Optima batteries that are assumed to be bad may actually be perfectly fine, just deeply discharged.

The great thing about AGM batteries, including Optima RedTop and YellowTop batteries, is that they have very low internal resistance. This allows very high amperage output so that the battery can power your accessories longer and deeper than a traditional battery, but at the same time deeply discharging it.

An AGM battery with its low internal resistance may stump car guys because sometimes it doesn’t work like a traditional flooded lead-acid battery.

Here’s the problem: Most battery chargers have built-in safety features that may prevent chargers from recharging deeply discharged batteries. A traditional battery that’s at 10.5 volts or less is seen as defective, having either a short, a bad cell or some other defect. Most analog chargers are binary and are either on or off. If they don’t come on, it may be because the charger thinks the battery is “bad.” Turning on to charge a “bad” battery could create an unsafe scenario. But the fact is that the AGM battery may be just fine; it has simply slipped below the minimum voltage threshold of the charger to turn on, and the charger doesn’t know what to do with the battery, so it does nothing.

Here are three options for bringing that deeply discharged AGM battery back to peak operational performance.

Method 1: Use an AGM specific charger to recover an Optima battery

The best method for recharging a deeply discharged AGM battery is to purchase a modern charger that has kept up with battery technology. Many chargers now have AGM-specific settings and desulfation steps that help recondition and recover deeply discharged AGM batteries. These are becoming more common, and they work well for all lead-acid batteries. They have the additional capability of doubling as a battery “maintainer” for batteries in storage. Some come with additional ring terminals to permanently attach to your battery leads so you can charge the battery externally with an accessible charger or maintainer. This makes it easy to hook up when you store your car, truck, boat or RV.

The OPTIMA Chargers Digital 1200 12V Performance Battery Charger and Maintainer enhances the performance of OPTIMA and other AGM batteries, recovers deeply discharged batteries and extends battery life. The OPTIMA Chargers Digital 1200 12V Performance Battery Charger and Maintainer is optimized when used with high-performance AGM batteries, but has enhanced charging capabilities that can also be used with all traditional types of automotive batteries.

This is the preferred method of charging a deeply discharged battery.

Method 2: Use a traditional charger to recover deeply discharged battery.

This method uses your traditional charger the deeply discharged AGM battery via some manipulation.

Here’s what you need:
  • Battery charger (under 15 amps)
  • Jumper cables
  • A good battery, preferably above 12.2 volts. (either AGM or flooded battery)
  • The seemingly dead, deeply discharged AGM battery
  • A voltage meter
  • A watch or timer
Instructions:
  1. Hook up the good battery and deeply discharged AGM battery in parallel – positive to positive and negative to negative. Do not have the charger connected to the battery or turned on at this stage.
  2. Now, hook up the good battery to the charger. Turn on the charger. The charger will see the voltage of the good battery (hooked up in parallel), and start providing a charge.
  3. After the batteries have been hooked up for about an hour, check to see if the AGM battery is slightly warm or hot to the touch. Batteries naturally become warm during charging, but excessive heat may be an indication that there really is something wrong with the battery. Warning: Discontinue charging immediately if the battery is hot to the touch. Also discontinue the process if you hear the battery gassing (a hissing sound coming from the safety valves). If it’s hot or gassing, stop charging immediately!
  4. With your voltage meter, check back often to see if the AGM battery has charged to 10.5 volts or above. This generally takes less than two hours with a 10-amp charger. If it has, disconnect the charger from the wall outlet and remove the good battery from the charger. Now, connect only the deeply discharged AGM battery to the charger. Turn on the charger and continue until the AGM battery reaches a full charge, or until the automatic charger completes the charge process. In most cases, the AGM battery will be recovered.
Method 3: Take the battery to a professional

If you don’t own a battery charger, you don’t want to make the investment, or you’re not the do-it-yourself kind of person, this is the option for you.

Take the battery to a professional battery specialist who knows AGM technology. Most specialists are willing to provide “charge and check” procedures free or for a small fee. Auto parts stores are typically not capable of accurately determining an AGM battery’s condition and many use conductance testers that don’t provide correct readings. Battery specialists, such as the Battery Base, are experts who can help determine if your battery is recoverable or not.

What is multistage charging?

A multistage charger uses numerous fully automatic modes that follow a sequence through various stages.

There are a wide variety of battery charges out there with multiple stages available. Below is an example of a charger with 6 stages.

Below are the 6 stages of a 6 stage multistage charger for an Optima battery:

Stage 1: Analyze your battery’s condition, state of charge and quality of connections before charging.

Stage 2: Soft-ramp charging control for deeply discharged batteries when necessary.

Stage 3: Fast-charge bulk mode for moderately discharged batteries also known as normal battery charging.

Stage 4: Conditioning mode for conditioning your battery with a finish/complete charge.

Stage 5: Auto maintain, float mode for keeping your battery fully charged.

Stage 6: Automatic storage recondition mode – desulfates your battery when in storage and being maintained.

Some Multistage Chargers available from The Battery Base