DieHard® CAR BATTERY REPLACEMENT. Agm car battery replacement


You may have gas in the tank but if your vehicle won’t start, you aren’t going anywhere. If you are ready for a car battery replacement, we have the information you need to navigate battery types, groups, and how to select the right battery for your vehicle.


When it comes to batteries, you have a lot of options. We take the guesswork out of car battery replacement, because our expert technicians will find the perfect battery for your vehicle, budget, and driving style. Here’s what you can expect out of a car battery replacement at Firestone Complete Auto Care:

  • System diagnostic: Inspection of key starting and charging system parts and functions that may include the battery, alternator, starter, and voltage level
  • Battery sizing: Review of car’s electrical system and current battery to find your vehicle’s recommended battery group size and type
  • Battery replacement: Installation of the best battery for your vehicle factoring in make, driving habits, climate, and performance
  • Fixed right: We get replacements done right the first time. If anything is installed improperly, we’ll fix it at no added cost to you during your warranty period.

Get free battery testing at any local Firestone Complete Auto Care location.



Suited vehicles: Side-post batteries are compatible with most General Motors vehicle makes.

Sizes: The most common side-post battery sizes are 70, 74, 75, and 78.


Suited vehicles: Standard top-post batteries are compatible with most American and Japanese makes and imports.

Sizes: The most common standard top-post battery sizes are 24, 24F, 25, 34, 35, 51, 51R, 52, 58, 58R, 59, and 65.


Suited vehicles: Recessed top-post batteries are compatible with most European makes like Volkswagen, Audi, Mercedes-Benz, and BMW.

Sizes: The most common recessed top-post battery sizes are 41, 42, 47, 48, and 49.

Guest Blog: How to service AGM batteries

As the AGM battery becomes more popular in vehicles, technicians must be aware of the differences in servicing this battery compared to the traditional lead-acid battery.

For many of you, the AGM battery is a familiar item. Perhaps you have a bass boat with an Odyssey battery powering your trolling motor or a vintage car equipped with an Optima battery. If this is the case, you likely know that these batteries require different equipment when servicing them (sometimes). But for most vehicle and equipment owners, the AGM battery brings more questions than answers and not everyone knows the meaning of AGM. So, we thought we’d take this opportunity to address some of the service implications of AGM batteries, which are becoming more and more prevalent in today’s vehicles.

What is an AGM battery?

First, let’s start by defining what an AGM battery is and why is it becoming increasingly popular in today’s vehicles. The AGM battery (meaning absorbent glass mat) is a modified version of the traditional lead-acid battery, with several construction changes to allow it to deliver improved performance in several areas. These construction changes include the use of thinner lead plates, allowing more plates to be packed into the same battery size, which results in greater power. The thinner lead plates can be used because each plate is wrapped in an absorbent fiberglass mat material, which provides structure to that thin plate, keeps the plates from touching, and creates a medium in which the battery’s electrolyte is suspended. This mat is what gives these batteries their name. Finally, because these batteries do not have liquid electrolyte, or are not “flooded”, they are completely sealed, as opposed to a traditional flooded acid battery with fill caps.

These construction changes result in a battery that is more powerful, more durable, longer-lasting, and better able to handle deeper discharging than a traditional lead-acid battery. This last feature is the reason they have become more popular – their ability to be more deeply discharged without harm has made the AGM battery the battery of choice for vehicles equipped with Stop-Start technology. This technology, as we have all come to experience, turns the engine off with each stop to reduce fuel consumption. Doing so places greater strain on the vehicle’s battery since the vehicle’s systems must remain powered during the stop, and results in the battery getting more heavily discharged more often than happens with traditional system designs. Due to this evolution in vehicle system design, the number of new vehicles manufactured using AGM batteries has increased significantly over the past ten years.

What does this mean for service?

Because the AGM battery features a different construction than traditional lead-acid batteries, there are service implications that result. One of the biggest questions we get from professionals and consumers alike is, “How do I know what type of battery it is?” This is a great question. The good news is that starting around 2010, the battery manufacturers and vehicle OEMs did a better job of labeling these batteries AGM. So, the first place we suggest you check is on the battery label itself. Since these batteries are considerably more expensive than standard lead-acid batteries, their AGM construction is usually highlighted. Second, check the battery model number. Often, it could have a suffix such as.AGM. Lastly, check your vehicle owner’s manual – if the vehicle is specified to have an AGM battery installed, it is often called out there. Also, for shops, check your shop information system. These usually do a good job of identifying the battery type specified for each vehicle.

So now you have identified that the vehicle in question does, in fact, contain an AGM battery. What does this mean for servicing it? Of course, that answer is, “It depends!” We’re not trying to make this harder than it has to be, but it really comes down to what type of service we are talking about, as you’ll see below.


When it comes to jump-starting a vehicle with an AGM battery, whether that vehicle is a more traditional design or is equipped with Stop-Start technology, you should proceed as usual. The jump-starting process is essentially augmenting the vehicle’s starting battery (which for some reason is not up to the task of starting the vehicle) with additional battery capacity. It is a DC-DC connection and the jump starter is roughly the same voltage as your vehicle’s starting battery. So, connect as you normally would, following the proper connection procedure, and attempt the jump start. When it comes to jump-starting AGM batteries, it is very straightforward (unlike other service applications).

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AGM batteries are much more sensitive than traditional lead-acid batteries when it comes to charging. This falls into two specific areas: the requirements of the overall charging approach/routine and sensitivity to voltage. Traditional lead-acid batteries are very forgiving and can take a multitude of charging approaches and keep on ticking. Not so with AGM batteries, which want a very specific approach and sequence when it comes to charging. They want a constant current bulk charging phase followed by a constant voltage absorption phase, just like what we deliver with our PRO-LOGIX charging approach. In addition, because they are sealed, they are very sensitive to voltage. For batteries, voltage equals pressure. Since the sealed AGM battery has no means to dissipate pressure, voltages must be precisely managed to avoid over pressuring the battery, which can result in degradation of the plates, which eventually will mean that they can no longer hold a charge. So, when charging an AGM battery, it is critical that you use a charger that is specifically designed for use on AGM batteries. This can mean that it is designated “safe” for AGM batteries or, better yet, has a specific charge setting for AGM batteries, as our PRO-LOGIX chargers do. The good news is that these chargers will charge your traditional lead-acid batteries better as well.


When it comes to testing, it is important to distinguish between digital testing and invasive testing. We’ll get invasive testing (testing with a traditional fixed load or variable load carbon pile tester) out of the way first. For invasive testing, like jump-starting, test the AGM battery as you would test a traditional flooded battery. We recommend using the BCI standard or the specific standard recommended by the equipment the battery is installed in. For digital testing, like charging, it is critical that you use a battery tester that has a specific testing routine for AGM batteries. Preferably, it should have testing routines for the different AGM batteries you will encounter. For instance, our SOLAR BA Series digital testers have specific testing routines for Flat Plate AGM batteries (shaped like a traditional battery) and Spiral Wound AGM batteries. This is because the different AGM constructions behave differently when tested, so, an accurate analysis requires that we have different testing routines for each AGM battery construction.

We get a lot of questions related to this topic and there are many trade publication articles related to it, which tells us that there remains a great deal of confusion when it comes to AGM batteries. We hope that this review of the service implications of AGM batteries helps to reduce some of the confusion and allows you to be more effective and confident when it comes to AGM service.

Information provided by Clore Automotive

Start-Stop AGM Battery Applications

AGM or Absorbent Glass Mat is an advanced lead-acid battery that provides superior power to support the higher electrical demands of today’s vehicles and start-stop applications.

AGM batteries are extremely resistant to vibration, are totally sealed, nonspillable and maintenance-free. AGM offers better cycling performance, minimal gassing and acid leakage when compared with conventional lead-acid batteries.

The end result of all of the features of AGM technology is superior life performance.

AGM Battery Applications

Start-Stop Vehicles, Large Audio Systems, Heated Seats and Other Electronic Accessories

If you’re looking to power a vehicle with numerous electronic features or plug-in accessories, you should consider a deep-cycle battery or a battery made with advanced technology like AGM.

AGM batteries are a great premium choice for high-end and advanced fuel-efficient vehicles with large power demands, and for people who seek greater reliability and longer life in auto batteries. Electronic features such as DVD players, GPS, heated seats and audio systems all add to the demands on a battery.

Start-Stop Vehicles

AGM batteries are also the preferred solution for start-stop vehicle technology, which rapidly gained popularity in Europe and entered the U.S. market in model-year 2013 vehicles.

Start-stop vehicle technology automatically shuts off the engine when your vehicle stops, such as at a traffic light or in stop-and-go traffic, and restarts it quickly and quietly when the clutch is engaged or the brake pedal is released. When the engine is off, the battery is the sole source of power to all the car’s electrical devices, such as air conditioning, the radio and the navigation system. And, in advanced start-stop systems with features like regenerative braking or passive boost, the battery is stressed even more.

In order to power electrical loads during engine-off periods and to support a high number of starts per trip, these vehicles need a battery that is more robust than the typical lead-acid battery. With superior cycling capability, charge acceptance and the ability to operate at a low state of charge, AGM is the technology of choice.

AGM Battery Construction

In AGM batteries, the positive and negative plates are separated by an absorbent glass mat that absorbs and holds the battery’s acid and prevents it from flowing freely inside the battery. The plates are tightly compressed into each cell and held under pressure in the plastic case. The internal compression limits the shedding of plate material caused by cycling and allows for significantly longer life. The element compression also lowers internal resistance and maximizes pulse power output. A rigid container maintains the necessary compression throughout the battery’s life.

The basic design also includes relief venting to release pressure from minor gassing that occurs during charging. The valves open at low pressure and close automatically to prevent air from leaking into the battery.

AGM Battery Benefits

If you have a vehicle which has the stop start feature then it is crucial you replace the battery with a specific AGM stop start car battery. These batteries are different than standard wet lead acid batteries which are fitted to vehicles without stop start functionality. Due to the greater demand on the battery caused by regular stop starting standard batteries will wear out very quickly as they are not designed to operate under those circumstances. AGM car batteries are and will last much longer than conventional wet lead acid batteries even if the lead acid battery is of premium quality and specification.

You can check if your vehicle has a Stop Start AGM battery fitted by looking in your owners manual or checking your existing battery. Your battery fitted should say AGM on the top or side specification label. Please contact us if you are unsure

Essential for Modern and Premium marque vehicles such as Mercedes, Land Rover, BMW, AUDI Porsche with high onboard power demands and stop start technology. AGM car batteries offer fantastic value for money and reliability; this is because they have low self discharge and more starting power than other car batteries with up to 50% more starting power. So when choosing an AGM car battery you can be assured of power, quality and reliability. It is essential you replace your existing AGM battery with the same type of AGM technology as your vehicle will have been designed to have one.

Instead of using normal lead acid constrcution they use a fibreglass type material that makes them spill proof, vibration resistant and holds the electrolyte in place. Our selection of AGM car batteries come mainly made by Bosch, offering you a wide choice of specifications and something for all budgets too.

AGM battery mainly uses its high performance combined with Auto Start-stop technology. However, even if the car does not have a start-stop system, the advantages of the AGM battery can be used: Auto Start-stop technology provides a greater power reserve, and traditional vehicles can also benefit from it, for example due to the longer battery life.

Advantages of Auto Start-stop technology

In addition to the advantages already mentioned, there are other reasons to upgrade to AGM batteries. It is recommended to replace the AGM battery in the following situations:

  • Large short trips of less than 10 kilometers or annual mileage of less than 10,000 kilometers do not allow the alternator to have enough time to fully charge the battery. Every time the battery is not charged to the full SOC (state of charge), the more difficult it is for the battery to start the vehicle next time.
  • If the vehicle is only used on a seasonal basis, the old traditional starter battery may discharge prematurely. This is especially true if there are unfavorable conditions in the storage location and the battery charger is not being used to keep it charged. AGM batteries can better withstand long downtime, because with Auto Start-stop technology, the electrolyte isolated in the diaphragm will not be stratified, thereby reducing sulfide. This means that AGM batteries are easier to charge than wet batteries after a long period of shutdown.
  • AGM batteries can also withstand extreme external temperatures and have high power reserves. The traditional starter battery’s response to extreme heat and cold causes a Rapid decrease in capacity and a faster discharge.
  • If the vehicle is equipped with a large number of non-standard electrical equipment, these equipment will increase the power consumption, for example: AGM battery is a complex audio system that can provide the necessary power for the vehicle that cannot be provided by traditional wet batteries.

AGM Batteries – The first choice for light commercial vehicles

In commercial use, vehicles are often used for multi-shift operations. AGM batteries can withstand higher loads during multi-shift operation better than ordinary starter batteries.

City trucks are usually also equipped with electric parts and special equipment. Due to the decomposition of active materials related to its capacity, conventional starter batteries quickly reach their limits and deteriorate. Due to the special design of the battery and the special mixture of active materials, AGM batteries can withstand more and deeper charging cycles than traditional batteries.

City trucks are usually also equipped with electric parts and special equipment. Due to the decomposition of active materials related to its capacity, conventional starter batteries quickly reach their limits and deteriorate. Due to the special design of the battery and the special mixture of active materials, AGM batteries can withstand more and deeper charging cycles than traditional batteries.

Automatic start-stop systems are more effective with an AGM battery

Vehicles that are equipped with a simple start-stop system and do not need to reclaim braking energy (recovery) are usually equipped with EFB batteries. However, even in this case, it is worthwhile to replace the AGM battery: Auto start-stop technology is reliable and trouble-free. Last but not least, the high load capacity of AGM batteries is impressive: During their entire service life, AGM batteries have better charge acceptance than EFB batteries.


AGM eliminates acid spilling in an accident because it is sealed. They can be installed at odd angles.

Have you noticed that more batteries are moving under the trunks and seats of some vehicles? If the battery is not under the hood, it is most likely an absorbent glass mat (AGM) or gel battery. Since AGM is sealed, it can avoid acid spills in accidents. They can be installed at strange angles.

These batteries are powerful due to their size and weight, which allows manufacturers to reduce the weight of the vehicle by several pounds. This is an important reason why they are increasingly appearing on new vehicles. In addition, these batteries have a larger backup capacity to support stop/start systems and flameout functions.

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Here are the four AGM myths that you may have heard.

1)You can use your regular battery charger on AGM or gel cell batteries.

Due to the difference in internal resistance, these batteries like to charge slowly.

Many AGM battery chargers have a microprocessor that collects information from the battery and adjusts the current and voltage accordingly. Some have different settings to charge flooded batteries or AGM batteries. Overcharging will kill these batteries. In addition, the alternator is not a charger. Do not rely on the alternator to complete the work of the charger. If the battery is discharged to the point where the vehicle cannot be started, please use the charger as soon as possible to ensure that the battery is fully charged.

2)AGMS and gel cells can be tested the same way as conventional batteries.

These types of batteries have lower internal resistance than flooded batteries. Older capacitor battery testers/analyzers may not be able to accurately read these batteries. Most new battery analyzers have a special mode of AGM/gel battery. Old-fashioned load testers may not provide conclusive results.

Using a multimeter to measure the state of charge is different from using a traditional flooded battery. After removing the surface charge, the voltage of an AGM with a 100% state of charge may be 13.0 volts. A battery filled with water may only have 12.6 volts.

3)AGM or GEL cell battery replacement is the same as flooded battery replacement.

Although the battery installation of the two battery types may be the same, some vehicles require additional steps to tell the vehicle that the battery has been replaced.

Newer GM vehicles have a battery sensor module on the negative battery cable. Ford has a battery monitoring system (BMS). Other manufacturers have similar systems. If the battery is replaced, these systems need to be recalibrated using the scanning tool. If the system is not recalibrated, the alternator may overcharge the new battery and cause the replaced battery to quickly fail.

Some vehicles can self-learn the battery by measuring the internal resistance of the battery. But usually the scanning tool can enforce the program, so you know there will be no problems battery.

4)You can’t upgrade a customer to an AGM battery if the vehicle originally came with a flooded battery.

You can install AGM batteries into flooded battery applications. AGM batteries will provide vehicles with greater cold start power and greater heat resistance and vibration resistance. However, you never want to downgrade a vehicle equipped with AGM batteries to flooded batteries.

AGM battery can be said to be a kind of storage battery manufactured for start-stop system. Different from ordinary lead-calcium batteries, the adsorption type glass fiber board of AGM battery can ensure that the electrolyte is absorbed around the plates, so that the battery has more powerful charging and discharging capacity, faster charging and discharging speed and longer long-term deep cycle life. Effectively reduce the hidden danger of power loss and provide strong support for the start-stop system. Of course, the AGN battery without hydrogen system can also be used as an ordinary battery, but this will shorten the life of the AGM battery.

Tag in this article:#AGM #Start-Stop #Starter Battery

Tips: more detail information, for start/stop car battery。

What Is Battery Registration For AGM Batteries?

If you own a continental car, you probably have heard that you need to do a battery registration upon replacement of a car battery. This applies to only a few car models from a few manufacturers like Audi, Volkswagen. But the golden question is, why it is required?

Battery Management System (BMS) Technology

We are all aware that modern cars are equipped with a lot of features and functions such as the start-stop function along with the seat heating, HUD, navigation system etc. All of these functions demand a significant amount of energy from the battery, thus the introduction of EFB and AGM type batteries.

But the advancement of technology does not stop there. Company manufacturers have come up with the Battery Management System (BMS) for modern cars. The main function of the BMS is for :

  • Battery Monitoring : Constantly monitor the battery’s state of charge (SOC) and state of health (SOH) during charging and discharging.
  • Battery Protection : Prevent irregular operations outside of it’s safe operating area.
  • Battery Optimization : Cell balancing to improve battery life and capacity, thus optimising driving range for HEV, PHEV and BEV cars.

In short, the BMS function is meant to ensure a longer lifespan of the battery.

Battery Energy Management (BEM) Code

With the introduction of the BMS technology, some manufacturers have decided to implement the Battery Energy Management (BEM) Code in their cars. The BEM code is an identification code for the battery, that is required to be ‘registered’ into the car’s BMS with a battery registration tool. It is also known as ‘Battery Registration’.

Why Do You Need To Do Battery Registration?

Battery registration is meant to ‘inform’ the car’s BMS that a new battery has been installed into the car. This will allow the car to adapt its charging and monitoring of the battery for the new battery.

As you know, old batteries would have degradation thus requires longer charging compared to a new battery. Registering the battery into the car would assist the BMS to adjust its charging system and cycle.

There are 2 types of BMS system, open and closed system. An open system does not require a BEM code to reprogram (registration) upon battery replacement. Therefore, the car could install any battery with the same specification. Manufacturers such as BMW, Mercedes operate on an open system.

A closed system however requires registration. BEM code, serial number and nominal capacity of the new battery would be ‘registered’ into the car system. Due to this, most independent battery shops are not able to do battery registration due to this restriction. Some manufacturer like Audi, Volkswagen uses a closed system for their BMS.

But worry not, if you are looking for a battery for your Audi/Volkswagen, CARPUT has the ability to perform a battery registration for your car if you purchase a battery with us. Free of charge! You only pay for the battery price and we will perform an on-site installation and battery registration without additional cost.

Can I Replace Battery Without Registration?

Some independent sellers may sell you at a cheaper price without offering battery registration. This may sounds like a good deal, but in the long run, it will cost you more. Some of the consequences of replacing a battery without registration includes :

  • May cause electrical problems to electrical components
  • Battery lifespan may decrease due to undercharging/overcharging
  • Worst case, damage to alternator and the electrical system

Certain electrical module may not work as usual, because the system may still think that you have a bad battery and trying to save it. Some of the common modules are power Windows, side mirrors, interior lights or even some modules to start the car.

In the end, you may have to drive to a service centre to perform the registration in order for everything to work as normal, which will be quite costly too.

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