How To Choose the Best Car (AGM) Battery?

The Best AGM Battery For Your Car

Over the lifetime of your car, you will need to replace the battery once or twice because it gets old or wears out over time. A dead battery can be a real problem because it can happen at the most inopportune time.

Pay attention to matching amp-hours between vehicle and battery. New batteries might have slightly higher Ah values, this is completely normal, just don’t lower it. If the car battery has a high cold type current, it wins most tests.

For small and medium sized vehicles, we recommend using AGM batteries 40 – 70 Ah (12 V), 440 – 720 CCA.

Best Car Battery

Table of contents:

1. Varta Blue Dynamic Car Battery
2. Optima Batteries 35 RedTop Starting Battery
3. XS Power D3400 AGM High Output Battery
4. Delphi MaxStart AGM Premium Automotive Battery
5. ACDelco Professional AGM Automotive

Best 5 Car AGM Battery

Car AGM Battery Buying Guide

How to choose the right product from the car batteries comparison above

• Car batteries are used to start the vehicle and also feed the onboard electronics at low speeds. Starter batteries for motor vehicles are usually lead-acid accumulator cells connected in series, each with a nominal voltage of 2.12V.
• Automotive batteries can usually be replaced by the layman. When buying a new accumulator, pay particular attention to the capacity, dimensions and bottom terminal type so that the new starter battery fits your vehicle.
• The pole arrangement must also be correct so that the installation of the new battery does not become a crisis. Type “0” is the most common: here the terminals are located on the front edge of the battery – the positive terminal on the right, the negative terminal on the left.

What physical causes this, what you should look for when changing your car battery, which manufacturers and brands lead and what to consider when buying a new starter battery – we clarify all this in the buying guide to the car battery.

Best AGM Battery

What is the function of the starter battery?

The most important function of the car battery is to supply the starter motor with the required electrical voltage.

The car batteries of most brands have a voltage of 12 V and capacities of 36 or more ampere-hours (ah). For trucks, battery voltages of 24 V are standard.

In addition to supplying the electric starter for a short time during the starting process (currents of 100 to 1000 amperes are required here for a short time), the battery feeds the electrical consumers in the vehicle electrical system when the alternator is too slow or not running at all, i.e. when stopping or parking.

While driving, the vehicle battery is charged by the generator of the alternator.

The consumers are all the vehicle’s electronic equipment: radio, a navigation system, windshield wipers and heater, lighting, air conditioning, sunroof, heated seats, and the like. Since the electronic extras usually become more than the vehicle class increases, the larger or better equipped the car (or even motorcycle), the larger the capacity battery is recommended.

Are there different types of batteries for different types of vehicles?

The advent of ecologically relevant technologies such as automatic start-stop in more modern motor vehicles has also led to a certain pressure to innovate on the part of battery manufacturers.

The most important battery types at a glance:

Lead-acid batteries – the classic starter battery

The classic design of vehicle batteries is a series connection of several lead-acid accumulators, so-called wet cells.

Lead-acid batteries have electrodes made of lead and lead dioxide. Sulfuric acid acts as an electrolyte. The cells sit in acid-resistant housing. These automotive batteries are largely maintenance-free.

Advantages and disadvantages of the classic lead-acid battery as a starter battery:

Advantages

• Maintenance-free
• With branded products: long service life
• The Cheapest car battery type

Disadvantages

• Sensitive to cold: battery check before winter required
• Not suitable for vehicles with an automatic start-stop system

EFB batteries

EFB batteries are also lead plate acid batteries but optimized for use in vehicles with automatic start-stop systems.

Unlike conventional lead-acid batteries, the Enhanced Flooded Battery is equipped with a so-called polyester scrim. This is a special braid that sits on the battery’s positive electrode plate and holds the active material in place.

In addition to faster charging and discharging, the batteries also have a longer shelf life.

Advantages and disadvantages of the EFB car battery as a starter battery:

Advantages

• Lower internal resistance: This results in longer capacity even at  Standstill
• Safer: No acid leakage when tilting or in case of damage
• Longer service life than conventional lead-acid batteries
• Insensitive to cold: Starts even in the depths of winter
• More charging cycles: Suitable for vehicles with an automatic start-stop system
• Maintenance-free (e.g. due to automatic gas discharge)

Disadvantages

• Costly compared to conventional lead-acid batteries
• Not suitable for vehicles with recuperation technology

What is a start-stop system?

The start-stop system is an automatic system for reducing fuel consumption when the vehicle is stationary, for example at traffic lights: as soon as the car stops, the engine switches off automatically. If the foot is taken off the brake and the accelerator pedal is pressed, the engine starts again in automatic cars. In vehicles with manual transmission and automatic start-stop system, a gear must be engaged. In this case, the engine starts up again when the clutch is pressed.

AGM batteries

The abbreviation AGM stands for Absorbent Glass Mat. In this further development of the lead-acid battery, the electrolyte is bound in a glass fiber fleece.

The original motivation for the development was to find a way to make the wet cells used until now tillable and less susceptible to shocks or rocking, so that the batteries could be used on motorboats or yachts, for example.

But the result has other advantages:

AGM batteries are less sensitive to deep discharge than conventional starter batteries.

Likewise, their service life is longer and they are less sensitive to cold: cars with AGM batteries as starter batteries start better in the cold winter.

Advantages and disadvantages of AGM car battery as a starter battery:

Advantages

• Lower internal resistance: Thus longer capacity even at a standstill
• Safer: No acid leakage when tilting or in case of damage
• Longer service life than conventional lead-acid batteries
• Insensitive to cold: Starts even in the depths of winter
• More charging cycles: Suitable for vehicles with an automatic start-stop system
• Also, suitable for vehicles with recuperation technology
• Maintenance-free (e.g. due to automatic gas discharge)

Disadvantages

• Costly compared to conventional lead-acid batteries
• Susceptible to high temperatures: Usually not installed in the engine compartment

Capacity

The capacity describes the amount of electrical charge that a battery can store or deliver. It is specified in Ah (e.g. “starter battery 45 Ah”, “car battery 90 Ah”, etc.).

The higher the capacity, the more electrical consumers can be supplied. A table is provided below to illustrate the capacities required by vehicles.
Battery capacity

• Motor scooter from 30 cm³ 4 – 14 Ah (6 – 12 V)
• Motorcycle 6 – 19 Ah (6 – 12 V)
• Microcar 36 Ah (12 V)
• Compact class 28 – 50 Ah (12 V)
• Medium class cars 40 – 70 Ah (12 V)
• Vans 55 – 120 Ah (12 V)
• Truck (up to 7.5 t) 175 Ah (12 – 24 V)
• Truck (over 7.5 t) 225 Ah (24 V)

Attention: These are approximate values. Some experts advise choosing the next highest value when buying a car battery.

Since even small cars now come with many technical extras – heated seats and infotainment systems can already be found in this vehicle class – the energy yield must be treated inflationary: With a stronger battery.

CCA (Cold Cranking Amperes)

Sometimes called cold test current or CCA; it is the maximum current (A) that the battery can deliver at a temperature of -18°C for a duration of 30 seconds. According to the German industry standard DIN, the total voltage of a 12V car battery should still be 9V after 30 seconds. The cold start current of car starter batteries is usually between 200 and 850 A. Especially in winter, the strongest possible cold start current is useful. Most brand batteries deliver usable values here.

Pole type

The pole type is commonly designated 0 and 1. 0 means that the positive pole is located on the right. It can be recognized by a small plus symbol or a red cap. The negative pole (also called ground) is marked by a blue color or a minus symbol and is located on the left. In the car battery comparison, this was the most common pole type. In pole type 1, the positive and negative poles are swapped. You should pay attention to the polarity of the battery in your car so that no nasty surprises arise.

Dimensions and base strip types

You should also base the dimensions on the specifications provided by your old battery. The best car battery is of no use if it doesn’t fit the particular type of vehicle. When buying car accessories, you should also keep an eye on the base strip. This is marked with a number and a “B” on the car battery, e.g. “B18”. When buying online, you can usually just enter your vehicle and filter the search results for suitable results right away.

What should a layman or professional look out for when replacing the battery?

With most vehicle models, the layman can also replace the battery himself. However, this is not advisable if

• it is a leased vehicle or a car otherwise bound to an authorized workshop or
• the battery is no longer easily accessible in the engine compartment, as is the case with some newer vehicles, but is located under the rear seat, under the trunk or in other places that are difficult to access or require know-how and special tools. Here, car battery replacement could cause difficulties.

If the above indications do not apply, it is still necessary to observe a few small things:

The sequence of disconnecting and connecting the car battery:

• Always disconnect the negative terminal of the car battery first! This is usually black (sometimes blue) and marked with a “-“.
• The terminal can usually be loosened with an open-end wrench or a screwdriver and removed from the terminal cap.

Background: The negative pole of the vehicle electronics is connected to ground, i.e. the conductive metal parts of the engine and body. If the positive pole were unscrewed first, there would be a risk of triggering a short circuit by touching another metal part with the tool.

Both when jump starting and temporarily bridging the car battery when changing: Always connect positive terminal to positive terminal and negative to negative or ground!

Bypassing with infotainment systems

In more modern vehicles with infotainment systems or a modern retrofitted radio, etc., a longer interruption from the car battery can cause not only the time and date to be lost, but also other stored information such as favorite stations, playlists, Bluetooth connections, and so on.

You can help yourself with a simple trick: By connecting the new car battery to ground (negative pole to body) and positive pole by means of suitable cables (for example, jumper cables) before disconnecting the old battery, the power supply will not be interrupted.

As the batteries are automatically connected in parallel in this way, the voltage is not higher than usual (this could be dangerous for the on-board electronics and control unit).

In short: First connect the new battery, then disconnect the old car battery – this way radio code and stored stations are preserved.

Connecting the batteries in series would result in a higher voltage that can harm electrical equipment.

Important manufacturers and brands

Well known manufacturers sometimes hide from the masses not so well-known brand names. Varta is known to most for household batteries and accumulators. Therefore, it is actually not surprising if the manufacturer an exclusive car battery brand. In the following we list other important names:

• Varta
• ACDelco
• Optima
• Bosch
• ODYSSEY
• Delphi
• XS Power

Accessories for maintenance and care: What does “maintenance-free” mean here?

As the saying goes, “There’s always something”. And that’s exactly how it is. However, in order to face the empty starter battery with a prepared and thus raised head, the right accessories are needed, at least when the nice neighbor is not around at the moment:

• Car battery charger
• Pole grease
• Jumper cable

Frequently asked questions about car batteries

How long does a car battery last?

A reliable car battery test always shows that the batteries last 5-7 years even if the car is driven regularly. If the car is parked frequently, the life span can be shortened considerably, as crystals of lead sulfate then form and coalesce inside the battery.

To extend the life of the battery, you should avoid tilting positions (i.e. strong inclinations) and also pay attention to deep discharge.

When a car battery is completely dead, it can damage the life of the battery. Before winter, you should check the charge indicator and use a battery charger if necessary.

At what point is a car battery broken?

The car battery, the most important accessory of a passenger car, is broken when a voltage of 12 V can no longer be maintained and the amperage drops below the minimum specified value. As a rule, it happens every 4 years and the car eventually no longer starts. Initially, however, the capacity steadily decreases.

Which car battery do I need?

The car battery comparison has shown that you should base your choice of car battery on the performance specifications of your old battery. Either you read the data on the car battery directly or you look in the manual of your car. Everything you need should be noted there.

And how does it work on a motorcycle?

The same way. Make sure the ignition is off before you open the battery compartment. Usually, it can be found under the seat or one of the side covers. Unscrew the negative terminal of the motorcycle battery first, then the positive terminal. Then remove the battery. Usually, this is rated with a strap or an elbow.
Then connect the positive cable to the positive terminal of the new battery. After that, you can connect the negative terminal of the motorcycle battery. Make sure to lay the cables so that they are nowhere in the way or chafe.