Frequently Asked


All right, you’ve got questions. So let’s cut the chitchat and get right to it.

Charging Fitment Miscellaneous

Battery Product Information

What is the difference between REDTOP®, YELLOWTOP® and BLUETOP® batteries?

REDTOP: Use this for normal engine starting where an alternator immediately monitors the state of charge and provides energy to the battery whenever it is needed. This would describe most stock vehicles.


  • Automotive and RV underhood starting
  • Heavy equipment where starting is the primary function
  • Diesel-powered vehicles with original equipped Hi-Fi systems
  • Agricultural equipment, construction machinery
  • Generators
  • Emergency vehicles

YELLOWTOP: Use this when electrical loads are higher than average, or when the discharge cycle is more than typical engine starting, such as vehicles without alternators. This also includes vehicles with significant electrical loads that may exceed the average alternator output (for example, aftermarket audio systems, GPS, chargers, winches, snowplows, inverters). This can also include vehicles that have a lot of electronics from the factory, such as a minivan with power sliding doors and a DVD player, especially if the DVD player is used when the engine isn’t running.


  • Diesel-powered vehicles with aftermarket electronics
  • Car audio/video applications exceeding 250 watts over the OE system
  • Vehicles or heavy equipment with inverters (Caravans), hydraulics (construction vehicles), winches (4x4) or other consuming accessories
  • Electric vehicles

BLUETOP: The BLUETOP starting battery (dark gray case) is to be used when a dedicated starting battery is required; it should never be used for cycling duty. The dual-purpose BLUETOP (light gray case) can be used for both starting and deep cycling; it is a true deep-cycle battery with extremely high cranking power.


  • Trolling motors, marine applications with heavy electrical accessories and RVs should use a dual-purpose BLUETOP (which is both a starting and deep-cycle battery)
  • Use a BLUETOP starting battery for marine applications and RVs when the battery’s only function is engine starting


Note: The difference between BLUETOP and YELLOWTOP deep-cycle batteries is that BLUETOP batteries have both automotive (SAE) posts and threaded studs, while YELLOWTOPs (other than D31T) only have SAE terminals.

If you ever get confused on the colored tops, just remember: if it has a dark gray case, then it’s a starting battery; if it has a light gray case, then it’s a deep-cycle (dual-purpose) battery.

What does the OPTIMA® SPIRALCELL TECHNOLOGY® design do?

The OPTIMA® SPIRALCELL TECHNOLOGY® provides many features not available in ordinary batteries, such as:

  • More plate surface, closer plate spacing and the use of high-purity lead. RESULTING IN: Low internal resistance. This low resistance gives you more power in a smaller box, the ability to recharge much faster, and higher and cleaner voltage characteristics during discharge
  • Immobilized plates under compression (locked in place). RESULTING IN: Improved vibration resistance, no shedding of active paste material, reduced gradual loss of power and capacity as the battery ages. This gives you a battery that lasts longer and performs better throughout its life

Why does an OPTIMA® battery last longer than other batteries?

The main reasons the OPTIMA battery has a longer life are:

  • There is no shedding of active paste material
  • The SPIRALCELL TECHNOLOGY® immobilizes the plates, preventing the active paste from working loose, which can cause plate-to-plate shorting
  • It utilizes a high-purity lead grid
  • The grid material in OPTIMA batteries is more resistant to grid degradation – a type of internal corrosion that affects the plates inside a battery as it ages
  • The completely sealed design prevents loss of water which can lead to plate dry-out and failure

Why the low rate of self-discharge?

Mostly this is due to the purity of the lead in the OPTIMA® plates. Some of the alloys in conventional batteries are more prone to electron transfer, resulting in higher self-discharge than is found in an OPTIMA battery.

Why is OPTIMA® not as perishable as other batteries?

OPTIMA batteries have an increased ability to withstand the high demands being placed on batteries today, including high-heat situations, heavy electronic loads and increased vibration. The SPIRALCELL TECHNOLOGY® in an OPTIMA battery is what keeps it from shedding active material that gives a battery power. This technology also extends an OPTIMA battery’s cycling ability.

What is a gel battery? Is OPTIMA® a gel battery?

A gel battery design is typically a modification of the standard lead-acid automotive or marine battery. A gelling agent is added to the electrolyte to reduce movement inside the battery case. Many gel batteries also use one-way valves in place of open vents, which help the normal internal gasses to recombine back into water in the battery, reducing gassing. Generally, gel batteries are less tolerant of high heat and are charged at lower power than traditional or AGM batteries.  An OPTIMA battery is neither a gel battery nor regular flooded battery. OPTIMA® is a SPIRALCELL TECHNOLOGY® AGM battery.

Does an OPTIMA® battery ever gas?

When used with a properly regulated constant voltage charging system (such as an alternator), the OPTIMA will not emit hydrogen gas. However, gassing can occur when charging at excessive voltage levels or in extreme high-temperature conditions. In automotive applications, this typically will not happen if the alternator/regulator stays below 15 volts.


What does deep-cycle mean?

Deep-cycle means using the battery in an application that will typically discharge 60 to 70 percent or more of the battery capacity. A standard automotive battery is an SLI (starting, lighting, ignition) battery. Its plates are designed to deliver maximum power for a short duration. Starting a car typically discharges an SLI battery less than 5 percent. When an SLI battery is used in a deep-cycle application, or in a vehicle with heavy accessory loads, the battery life will be shortened proportionally to how deeply it is cycled on a regular basis.

When should I consider a deep-cycle battery?

Anytime you need the battery to supply all the operating power for a vehicle or other device. Additionally, deep-cycle batteries should be used in vehicles that have heavy accessory loads where the alternator cannot maintain the battery in a fully charged condition. Some examples include vehicles with powerful stereo systems, vehicles with increased electronics like GPS, game systems, DVD players and LCD screens or boats with onboard chargers, trolling motors, fish-finders, stereos, lights, etc.

What’s the difference between an OPTIMA® deep-cycle and a starter battery?

The OPTIMA deep-cycle battery utilizes a different chemistry. This chemistry change allows for a much longer life in cycling applications, with only a slight reduction in starting power.

When should I use a deep-cycle OPTIMA® battery as a starting battery?

Deep-cycle batteries are designed for applications that require deep, repetitive amperage drain like trolling motors, golf carts, and electric wheelchairs or RV house power sources. However, there are other applications called heavy-cycling or high-cycling, when a deep-cycle OPTIMA® battery can successfully replace a starting battery to provide longer life and better performance. In heavy-cycling or high-cycling applications, a vehicle will pull unusually high amperage levels from the starting battery due to extra accessories or limited alternator capacity. Public safety professionals such as police, fire and ambulance fleet managers often find that traditional starting batteries cannot provide adequate life and performance due to heavy cycling. Using an OPTIMA® deep-cycle battery in this type of application will result in longer life and better performance.

In any vehicle or equipment that will use the battery only for starting, lighting and ignition (SLI) requirements and has a properly working alternator, the OPTIMA® REDTOP® Starting Battery will perform extremely well, often providing up to two times longer life than conventional batteries. If the vehicle has few or no aftermarket accessories and uses a stock or upgraded alternator, the OPTIMA REDTOP Starting Battery is the appropriate choice.

Remember, it is possible to have a deeply discharged YELLOWTOP® that will not start the engine; the advantages of the YELLOWTOP are that it can accept a rapid recharge and it will recover from discharge many more times.

It is necessary to consider both the application and the charging system before deciding which OPTIMA battery is correct for you. For example, if you have a Ford Expedition with an aftermarket alarm system and you drive the vehicle every day, the OPTIMA REDTOP would be the correct choice since the amperage drain will be nominal and the battery would be recharged on a daily basis.

However, if you store the vehicle for long periods with the alarm system engaged without maintaining the battery, you should use an OPTIMA YELLOWTOP since the amperage drain over several weeks would damage a REDTOP and reduce its life.

How does a gel cell compare to your deep-cycle?

Most gel batteries have much higher internal resistance, meaning they will not be able to deliver and receive current as efficiently. This is especially apparent at higher amperage levels. For example, most gel batteries will not work successfully in engine-starting applications.

Does an OPTIMA® Deep-Cycle have a “memory?”

Lead-acid batteries do not suffer from memory effect. Many people think they have a memory because they experience a reduction in capacity or runtime as the battery ages. The active paste material in a lead-acid battery is a consumable item, similar to tread on a tire. Every time you cycle the battery, some of the paste is used up. As the battery ages, less of the active paste is available to charge and discharge, resulting in a reduced operating time. This situation can be more apparent in the case where a high-power or starting, lighting and ignition (SLI) battery is used in a deep-cycle application. The plates of an SLI battery are designed for high-current, short-duration discharges. Plates in deep-cycle batteries are better suited to repetitive deep-discharge applications.


Will the battery discharge if left sitting on concrete?

No, today's batteries use polypropylene plastic for the case material. They will not be affected. When possible, always store a battery in a cool, dry location.

What are storage recommendations for OPTIMA® batteries?

The most important consideration when storing any battery is to make sure the voltage never drops below 12.4 volts. We recommend using a type of "battery maintainer" – a device that will monitor your battery and keep it at full state of charge during storage.

There are two types of maintenance chargers:

  1. Preferred – Fully automatic multistage or multistep chargers, which monitor the battery and charge it as necessary. Multistage maintainers will charge at varying voltages and varying amperage (rarely exceeding 2-amps). Some of these multistep chargers are also capable of being regular battery chargers (seven amps or more).
  2. OK but not preferred – Traditional float chargers provide constant voltage with tapering amperage to the battery even when it is fully charged. For float charging, we recommend 1 amp max, 13.2-13.8 volts.

If it is not possible to use a maintenance charger, disconnect the battery from the vehicle during storage to prevent small electrical drains from discharging the battery. Always provide a full charge with a battery charger prior to storage, and then check the battery voltage every three to six months. Charge the battery if it falls below 12.4 volts.

Also, when possible, store your battery in a cool, dry location.


Why is my battery dead? (troubleshooting battery/electrical issues)

Fully charged, engine not running, starting batteries (all REDTOP® or BLUETOP® 34M) should measure about 12.6 volts to 12.8 volts. Deep-cycle batteries (all YELLOWTOP® and dual-purpose BLUETOP) should measure approximately 12.8 volts and 13.0 volts. Voltage measurements of the battery when the engine is running are the output of your alternator. This measurement should be about 13.3-15.0 volts, which may differ due to temperature. At average operating temperatures of 50° to 80°F, your alternator output voltage should be about 14 volts to 14.8 volts.

If you don’t have a multimeter, you can test the output of your alternator by starting the car and turning on the headlights. If they are dim, it indicates the lights are running off the battery and that little or no power is being produced by the alternator. If the lights get brighter as you rev the engine, it means the alternator is producing some current, but may not be producing enough at idle to keep the battery properly charged. If the lights have normal brightness and don't change intensity as the engine is revved, your charging system is probably functioning normally.

If this checks out, you should determine whether or not the battery is holding a charge, or if something on the vehicle is discharging the battery.

There are three likely scenarios to explain the problems you're having:

  1. A high parasitic draw (key-off load).This can quickly discharge a battery and decrease its service life. This may be caused by a trunk light, cigarette lighter, clock/radio, alarm system or any other electrical device. Current drain on the battery can be checked with an ammeter. With the ignition off, disconnect one of the battery cables. Connect one ammeter lead to the battery and the other to the cable. The normal current drain on most vehicles should be about 25 milliamps or less. If the key-off drain exceeds 100 milliamps, there's an electrical problem that requires further diagnosis. If you don’t want to take your car to a mechanic, the easiest way to isolate the problem is to pull one fuse at a time from the fuse panel until the ammeter reading drops.
  2. A problem with your battery is causing it to not hold a charge. To check this, remove the battery from the vehicle, charge it to the full voltage, wait 12 to 24 hours then measure its voltage. Another faster, but less preferable way to do this is to turn on the high-beam headlights for 15 seconds, turn them off, wait 5 to 10 minutes, then check the voltage. If you measure the voltage of the battery the next day, week or even a month later, the voltage should be close to the max voltages listed above. If the voltage holds when not installed in your vehicle but drops when it is in your vehicle, see #1 above.
  3. The battery was somehow discharged, and your maintenance charger is not able to properly charge your deeply discharged battery. Please see the directions for charging a deeply discharged battery.

Do I need a special charger for my OPTIMA® battery?

Under normal vehicle starting applications, most regular automatic lead-acid battery chargers will properly charge an OPTIMA battery. However, since OPTIMA batteries are frequently used in high-performance applications or nonstandard vehicle starting applications, there are certain instances that must be given special considerations.

An OPTIMA battery is an AGM battery, not a gel battery or regular flooded battery. A deeply discharged OPTIMA battery (less than 10.5 volts) will not test or recharge properly if treated as a gel battery or regular flooded battery. A handheld electronic battery tester will most likely provide inaccurate test results.

An OPTIMA battery has the benefit of very low internal resistance, which allows high-amperage output as well as efficient charge acceptance. This benefit also allows an OPTIMA battery to run longer than its specified ratings and run to a lower voltage than typical flooded batteries. All of this can lead to confusion when it comes to recharging a deeply discharged OPTIMA. Most basic battery chargers have a built-in function to prevent charging a battery with less than 10.5 volts. If your OPTIMA battery is discharged below that, the battery charger may not start up.

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. 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. It may be necessary to follow the instructions provided in Section #3.

For regular charging we recommend a maximum of 10-amps, 13.8-15.0 volts. For float charging, we recommend 1 amp maximum, 13.2-13.8 volts.

Under normal (engine-starting) conditions, an OPTIMA battery should never experience “at-rest” voltages below 10.5 volts. In these applications, most 12 volt chargers (old or new) or alternators will sufficiently recharge an OPTIMA battery with at least 10.5 volts. Typically, we only see issues with charging when it relates to stand-alone deep-cycling applications or severely discharged OPTIMA batteries.

How do I charge a deeply discharged battery?

charging_illustration.gifIf an OPTIMA battery is deeply discharged (below 10.5 volts), most basic chargers will not supply a charge. Also keep in mind that an OPTIMA battery will not recharge properly if treated as a regular flooded or gel battery. To charge the battery, you can wire a second fully charged automotive battery (12+volts) to the discharged AGM in parallel (+ to + and – to –). Then hook up the charger to the deeply discharged battery, setting the charger at 10 amps. Leave for two hours, monitoring frequently. During this process, if the discharged battery gets very hot or if it is venting (hissing sound from vents), then stop this process immediately. When the discharged battery reaches 10.5 volts or more, remove the standard battery and continue charging the AGM until fully charged.

For normal charging, a relatively low current, such as one or two amps, can work well, but when the battery has been deeply discharged, some sulfation of the battery plates may have occurred. If you charge at 10 amps, the higher current will help to break up this sulfation.

If you have an automatic charger, let it run until the charger indicates charging is complete. If you have a manual charger, you can get a rough estimate of the charging time in hours of a completely discharged battery (11.2 volts) by multiplying the capacity (amp hours or Ah) of the battery by 1.2. If your battery is not completely discharged, the time would be less.

In most cases these steps will recover an AGM battery. It’s OK for the AGM battery to get slightly warm during the charging process. If it’s hot to the touch, it means there’s a short and the process should be discontinued.

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.

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.


Why doesn’t my vehicle show up on the fitment guide?

Unfortunately, OPTIMA® does not offer an exact-fit replacement battery for every application. You can measure the dimensions of your existing stock battery to see if there’s an OPTIMA® battery that will work for your vehicle. Below is a link to the product specification page where you can find exact dimensions for all OPTIMA® batteries:

View our products spec pages to find the exact dimensions.

Alternately, you can check the Internet enthusiast forums for your vehicle to see how others have created custom fitments for their OPTIMA® batteries.

If you are using an OPTIMA® battery in a custom fitment application, it is important to consider the following:

  1. Hood clearance – There should be at least ¾-inch clearance between the top of the battery terminals and the underside of the hood.
  2. Trunk/interior mounting – If your battery is mounted inside the passenger compartment or trunk (common in many European makes), the battery must be vented to the outside of the vehicle. OPTIMA® group 27, 51, DS46B24R, 78, 34C and 31 batteries all have ports for connecting a vent hose.
  3. Side terminals – OPTIMA® 34/78, D34/78, 75/25 and D75/25 batteries have both top and side terminals. If you are using one of these batteries in a vehicle that uses the top terminals, it is important to ensure that the side terminals cannot come into contact with anything metallic (for example, the firewall or fender well), thereby causing a short. We suggest keeping the post protectors on the terminals you are not using. A winch should only be connected to the automotive posts.
  4. Battery modifications – Cutting, drilling, trimming or otherwise modifying your OPTIMA® battery may present a safety hazard and will void the warranty.
  5. Mounting – Your OPTIMA® battery must be securely mounted. The terminals are not intended to be used to secure the battery. Using the terminals in this way will damage the battery and void your warranty.

Do I need a 35 or a 75/25?

If you don't have aftermarket electrical accessories in your vehicle, we recommend the REDTOP® 35. If you do have aftermarket electrical accessories, such as an audio system with amps, we recommend YELLOWTOP® D35. Both of these are top-post-only batteries.

Please note we also make a group 75/25 battery (some retailers will label it 75/35 in their system). This battery has both top and side posts and probably will not work in your vehicle. The positive and negative posts are on the wrong side for your vehicle and your cables may not reach.


Can I hook up an OPTIMA® battery in parallel with my other battery?

No, when hooking batteries together in parallel, they should be of identical in age, size and type.

Can I use an isolator with an OPTIMA® battery?

Yes, most any type of battery separator or solenoid can be used with an OPTIMA battery. The important thing to remember is that the charging voltage must be within the limits suggested by OPTIMA batteries. If you are using an OPTIMA battery and a conventional battery, your system must charge each battery independently. Remember, some isolators cause a voltage drop, so make sure your charging voltage AT THE BATTERY is sufficient. Continued undercharging of a battery will lead to premature failure and a drop in capacity.

Who should I contact if I have questions about the product?

For technical or warranty support, please call OPTIMA® customer service at +44 (0) 1753 480 610 or via email at