Best Car Batteries: A Guide to Buying a Car Battery in New Zealand

Lead-acid batteries, also known as SLI due to its purpose of providing power to Starting, Lighting and Ignition systems, are the most common type of battery. Internally, they consist of several positive and negative plates and a liquid solution called electrolyte that usually contains lead, sulfuric acid and water. What set this type of battery apart from the rest is their low manufacturing cost, and their ability to deliver short, quick bursts of energy.

Due to its working principle, this type of battery is better suited for old-style cars, that does not have too many electric accessories. It is important to notice that you can find in stores a special type of SLI battery called calcium battery, which is a lead-acid battery with no antimony in its grids. Calcium batteries offer better resistance to vibration, heat, and generally speaking offer better power output than their antimony based counterparts.
 
Lead-Acid Batteries Highlights 

• They are the most common type of battery.
• They are cheap.
• SLI batteries are good for “standard” vehicles that do not require continuous power from the battery, but quick bursts such as those needed during engine start.

 
Lead-Acid Batteries - What We Like:

• Economic. The technology behind modern SLI batteries has been around for more than 50 years. That makes these batteries cheap to manufacture and hence they are the most affordable type of battery you can find
• Widely available. Since this type of battery is (still) the standard in many applications, you can purchase it almost everywhere. This is an advantage in case you have an emergency far from home and need a battery to get your car running.
• Come in different sizes and capacities. It is almost certain that you can find an SLI car battery in any size, post configuration, and capacity you may need. Bear this in mind, since if you have a restoration project, or a custom application, this type of battery might be ideal to get the most out of your available space.

 
Lead-Acid Batteries - What We Dislike: 

• Require maintenance. Depending on their manufacturing process, some SLI batteries might require periodic maintenance that consists of completing the electrolyte solution in case of need.
• Leak prone. Since these types of batteries are flooded with acid, they can only be used in the position indicated by the manufacturer. They cannot be flipped or tipped as this would almost immediately lead to an acid spill.
• Not compatible with newer cars. This type of battery does not meet the specifications required by newer cars. In other words, most SLI batteries are focused on vehicles and applications from 5 years ago.

As their name implies, Enhanced Flooded Batteries (EFB) are optimized versions of the SLI batteries. This type of battery features additional insulation material between the inner plates, giving them an extended life cycle and more than double the partial and deep discharge performance compared to conventional batteries.

​Due to these enhancements, EFB batteries are often used as replacements for conventional SLI batteries. Some Deep Cycle Batteries use this technology since is relatively cheap and provide a decent number of charging cycles. The performance of EFB batteries also made them perfect for entry-level start-stop systems included in some newer cars.
 
Enhanced Flooded Batteries Highlights 

• Offer about 2x times the partial and deep discharge performance of SLI batteries
• They are still relatively cheap in comparison with other modern batteries
• Can be used in various car applications, including recent vehicles using entry-level start-stop systems

 
Enhanced Flooded Batteries, What We Like 

• Affordable. Although EFB batteries are more expensive than conventional SLI batteries, they are still way more affordable than other technologies used in newer cars.
• Better value than SLI batteries. Their increased performance and relatively reasonable price make EFB batteries a good option for many applications that consume more power from the battery.
• Come in different sizes and capacities. Similar to SLI batteries, EFB batteries are available in many sizes and capacities.

 
Enhanced Flooded Batteries, What We Dislike 

• May require maintenance. While most EFB batteries are “maintenance-free” we strongly suggest double-checking this aspect before purchasing the battery.
• Not compatible with high-performance applications. Although EFB batteries perform noticeably better than their SLI siblings, they still lack the required level of deep discharge performance and capacity of newer Gel and AGM batteries used in much newer cars.

AGM batteries have many advantages in comparison to “wet cell batteries”. First of all, since their electrolyte is bound to a special glass fibre separator they can be positioned in any direction without risk of leakage. Secondly, AGM batteries have a higher output which makes them perfect for more recent cars that have all kind of electric accessories, computers, and modules. In addition to these benefits, can withstand up to three times more charging cycles than a conventional SLI battery. 
 
Absorption Glass Mat (AGM) Batteries Highlights 

• AGM batteries offer higher output than EFB and SLI batteries.
• They ideal for cars with high power demands (such as automatic start-stop systems).
• Due to its construction, AGM batteries are maintenance-free.

 
Absorption Glass Mat (AGM) Batteries, What We Like 

• Highest power output. AGM batteries can be used in almost all type of vehicles, regardless of the number of accessories, electronic systems or total power consumption. They offer the highest specific power of any other type of battery.
• Great flexibility. AGM batteries can be positioned vertically, horizontally, or diagonally, without any risk of leaks. Depending on your application this can be a huge benefit. For example, in custom off-road applications you can position the battery (or batteries) attached to the sides of the trunk compartment if you need to.
• Excellent partial and deep discharge performance. Due to its design, AGM batteries are exceptional for off-road, and RVs applications that require a reliable power source to feed lighting systems, sound systems, infotainment systems, and more.
• Vibration resistance. AGM batteries are not affected by vibration, making them perfect for demanding off-road applications.

 
Absorption Glass Mat (AGM) Batteries, What We Dislike 

• Expensive. With the exception of Lithion-Ion batteries, this is the most expensive battery type of all.
• Sensitive to heat. One big disadvantage of AGM batteries is their low resistance to heat. For this reason, most manufacturers locate AGM batteries outside the engine compartment, usually in the trunk or bellow passenger seats.
• Deep discharge. Although AGM batteries offer better resistance to deep discharging than EFB and SLI batteries, they still fall behind Gel batteries.
• Cycle life. Arguably one of the most significant drawbacks of AGM batteries had to do with their expected lifecycle. They last more than EFB batteries by several orders of magnitude, however, Gel batteries typical outperform them by a factor of two.

Gel cell batteries are a special type of VRLA battery that basically differs from their AGM cousins in the material used for the electrolyte. In the case of Gel batteries, they use a silica-based electrolyte instead of fibreglass. This alone provides significant improvements in areas as average life expectancy, resistance to deep discharging, risk of thermal runaway, and cost. Due to their nature, this type of batteries is used for deep-cycle applications such as marine applications, small electric vehicles, off-road applications (ATVs), and more.
 
Gel Cell Batteries Highlights 

• They are expensive but more affordable than AGM batteries
• Perfect for deep-cycle applications
• They have an incredible life expectancy

 
Gel Cell Batteries, What We Like 

• Deep-cycle ready. Depending on your application, replacing your actual battery with a gel battery might be an excellent idea. For instance, if you love exploring remote places in New Zealand you might want to have a deep-cycle battery to power your lights and accessories during the night knowing that you will not harm batteries internals doing so.
• Reliable. Gel batteries are among the most reliable type of battery you can purchase. They share most features of AGM batteries and then enhance some of them even further.
• Faster charge. Gel batteries can be charged up to 5 times faster than conventional batteries using lead-acid technology.

 
Gel Cell Batteries, What We Dislike 

• Expensive. While gel batteries might cost you less than AGM batteries they are still quite expensive when compared with SLI type
• Heat sensitive. Although they can withstand heat better than AGM batteries, it is recommended to keep them in areas where temperatures do not exceed 49°C.