How to choose the correct battery

Don’t let choosing the correct battery scare you. It’s really not that complicated!!
If you are unsure, please don’t hesitate to contact us at Battery HQ!!


  • Starting
  • Deep Cycle
  • Dual Purpose (starting and cyclic use)

First thing to determine is whether you need a starting battery, deep cycle battery or a combination.

Starting batteries deliver a large burst of power for a short time as needed for normal engine starting. The battery is then recharged by the alternator. Unlike a deep-cycle battery, starting batteries are not designed to withstand multiple discharge/recharge cycles, and draining it can significantly shorten its life. Starting batteries will generally have more CCA (Cold Cranking Amps) but less AH/RC (Amp Hours/Reserve Capacity).

Deep cycle batteries are designed to provide a steady amount of current over a long period of time. Deep cycle batteries can be repeatedly discharged and recharged without causing damage or shortening their life. They are well suited to powering numerous electronics and plug-in accessories, or other applications that place high demands on them such as marine. Deep cycle batteries will be the opposite to starting batteries and have less CCA but more AH/RC.

Dual purpose batteries are often found in some marine applications which require a combination of good CCA along with good AH/RC. (AC Delco HCM and SPN series)


  • Flooded lead acid
  • AGM (absorbed glass mat)
  • EFB (enhanced flooded battery)
  • Lithium

The way they are constructed, and the materials used determine the type of battery.

Flooded lead acid starting batteries are the most common. Most are Sealed Maintenance Free and common on most vehicles. These are great due to the lower manufacturing costs and the ability to handle the under-bonnet temperatures.

AGM and EFB are improvements in the construction to handle higher demands.

AGM and EFB starting batteries (AC Delco & Optima) can often be found in modern cars that have start/stop capabilities and in performance vehicles. This is a great upgrade from your flooded lead acid battery.

AGM deep cycle batteries (PowerSonic & Sentry) can often be found in caravans, boats and in the back of utes etc. They can handle more cycles and hold more Amp Hours. BUT, cannot handle under bonnet temperatures.

Lithium starting batteries are often found in performance vehicles and motorcycle applications, where small and light weight is necessary, but very high CCA are required.

Lithium deep cycle batteries are the ultimate package. They are light and compact yet hold a lot of AH and can be cycled a lot more than a flooded lead acid or AGM.



Most batteries are grouped by physical size. Automotive companies have designed their cars around fitting this size battery in a particular position. Make sure your new battery will fit according to the vehicle manufacturer’s specifications. In some cases, a bigger battery can be used if it fits without any interference. Please ensure the terminals have necessary bonnet clearance.


Make sure your new battery will be held down properly according to the vehicle manufacturer’s specifications. Some batteries will have a clamp over the top, and some will use a bottom hold down method.


Some European batteries (DIN) have recessed terminals which can allow a bigger capacity, with out taking up more area.


Some Japanese batteries (JIS) will have a smaller than standard post. Adaptors are available to make the battery’s post larger, but terminals would need replacing if standard posts are on battery and vehicle has small terminals.


Left, or right? Generally, this is referenced with the posts/terminals closest to you. In some cases, this won’t matter, but it is good practice to position the positive terminal to the centre and rear of the vehicle.



The current that a fully charged battery can deliver for 30 seconds and maintain a terminal voltage greater than or equal to 1.2v per cell (7.2v) at -18deg C.


The ability of a fully charged battery to deliver a specified quantity of electricity at a given rate over a period of time. (common AH rate is 20 hour)


Number of minutes a new, fully charged battery can be discharged at 25 amps and maintain a terminal voltage higher than 1.75v per cell (10.5v) at 27deg C.

It is important to choose a battery that meets the manufacturers requirements. In the past CCA has been the most important factor, but with electronic components and accessories increasing in modern cars, the reserve capacity is critical due to the parasitic drain of these when the engine isn’t running. Reserve capacity is also critical for vehicles that only do short trips, when the alternator doesn’t have time to replace the electrical energy used to start and run the vehicle.

If unsure, please contact Battery HQ for assistance with choosing the correct battery for the application. Please include as much information as possible.