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Which auxiliary battery do I need?

Which auxiliary battery do I need?

The honest answer to this question is often how deep is your wallet or how much do you want to spend?

We could spin various combinations but when it comes to batteries, budget is usually the tipping point when choosing your next auxiliary battery. With that being said, there are many varieties out in the market, in different sizes, weights, and chemistry types which will have some degree of influence in which battery you end up choosing for your next super tourer.

Let’s take a closer look.


Standard Lead Acid


Your standard lead acid battery is going to be the kindest on your pocket, however, it is going to require some regular maintenance with the topping up of electrolytes using distilled water. They are suitable for various vehicle applications and can be used either as a starting battery or a deep cycle battery.

Although not the lightest in weight, they are suitable for engine bay mounting if you don’t have space in your vehicle to install an auxiliary battery. A great all-rounder, they are a good option if you’re just starting out in the 12V space.


deep cycle installation




Coming at the same price point as a lead acid battery, the benefit a calcium battery is that they are maintenance-free as they come sealed, and are also readily available. They can also be mounted in the engine bay and used for starting or deep cycle applications.

They so have some advantages over lead acid batteries including improved resistance to corrosion, no excessive gassing, less water usage, and lower-self discharge. In addition they have a better tolerance to higher temperatures, environmental conditions, and vibration.


Gel/AGM batteries


Gel/AGM batteries are a little more expensive than lead acid and calcium batteries but are still reasonably priced. Some AGM and Gel batteries are not recommended for engine bay mounting as they can’t handle the heat which can be detrimental to battery life. They can however tolerate deeper cycling than other constructions without dramatically shortening their life.

Both AGM and Gel batteries have a very similar reaction when charging, which is why they have the same charge profile, although it is still not recommended to discharge below 50% in order to best extend battery life. Although maintenance free, AGM and Gel cell batteries do require precise charging and therefore require a charger designed for these battery types.


dual cab battery setup


Lead Crystal


New to the market, lead crystal batteries are more expensive than AGM/Gel batteries but do provide greater advantages, requiring 30% of the total Amp Hour rating in charge current to achieve 100% sttate of charge, and can sustain and recover from deep discharge better than the other battery types.

They’re also built tough and robust, can sustain and recover from heavy discharge, and are able to accept higher charge currents which allow the batteries to recover faster.




When it comes to auxiliary batteries, lithium batteries (LiFePO4) are the latest and greatest due to the various qualities and abilities they have over the other battery types. But those qualities come at a price. Lithium batteries are considerably lighter than other battery types - often up to 1/3 of the weight - are smaller, and can maintain a higher output voltage during the discharge cycle.

Whilst most other batteries recommend discharging of no more than 50%, lithium batteries, can handle up to 80% discharge and have considerably more usable power than all other battery types of the same amp hour rating. In addition, as lithium batteries can handle a higher charge current, recharge times are greatly reduced when compared to other battery chemistries.

Because of their unique chemistry type, these batteries do require a specific charging profile to ensure you are using them to their full potential. More power, better performance and a third of the weight, it’s easy to see why lithium batteries are so expensive, but they are sure to transform your rig into a super 12-volt charging beast.


Finding the right battery charging solution


No matter which battery you decide to go with, it’s important you have the right battery charger for your needs. Our range of dual battery chargers, including our new 50-amp BCDC, work with all battery types and are proven to ensure 100% charge. 

Ready for your next adventure? Check out the new REDARC BCDC1250D now or find out which products are perfect for your travel needs with our dual battery selector tool


Looking to start your 4x4, camper trailer or caravan upgrade but not sure what products will allow you to travel the way you want? Take the REDARC Hilux product tour or check out our dual battery selector tool to find out what products are best for your power management and towing needs.


Hinterlasse einen Kommentar
13.11.2018 02:29
18.12.2018 11:21
Good clear article, however, regarding the discharge of Lithium batteries, should the discharge percentage be 80% instead of the 20% quoted?
20.12.2018 13:38
Hi Paul,

Thank you for pointing out the miscommunication in the article, this has been edited to reflect your feedback. Thank you again.
22.08.2019 18:04
Is a lithium battery also suitable, to use as a starting battery in the extremely rare case you end up with a dead battery or is it purely for auxiliary

23.08.2019 08:43
Hi T.J,

Lithium batteries do not have a cold cranking amp rating. They are not recommended for jump starting. You can always confirm this with the battery manufacturer, as there is always new Lithium technology coming out.