12V Guru – Choosing The Right Lithium Battery Set Up For Your Caravan

12V Guru – Choosing The Right Lithium Battery Set Up For Your Caravan

Question to 12V Guru:

Good morning,

We have ordered a new caravan which will have 220 litre Compressor Fridge and it was suggested that in order to ensure we had an ample power supply, we have been advised that the following would be the way to go 2 x 135 AH deep cycle AGM batteries and 2 x 170 watt sola panels. 

As weight is a something I have to take into consideration (our GVM is 6000 KG),  I have been looking at Lithium Batteries and in doing so have found a large price range from $440.00 for a 135 AH battery to about $3000.00 for a 300 AH battery and many different makes and suppliers. Also I have had difficulty with some brands ascertaining what are the warranty terms and conditions. 

Could you please give me some advice on the value for money and quality on the many brands of batteries available? My thoughts are that 200 AH of lithium battery and 1 x 170 watt sola panel would do the same job as 2x AGM batteries and one sola panel.

Your advice regarding my questions would be greatly appreciated.

Regards Robert Cook

Choosing the right battery to power your adventures

12V Guru answers:

Hi Robert!

Thanks for your question and it’s very timely as it seems that Lithium in 12V is certainly the topic of the month and therefore a great time in which to be able to try and steer you in the right direction. So to attack your question in the reverse order I think it’s worthwhile to first address your query in regards to whether 200Ahr of Lithium is capable of doing the same job as two AGM batteries.

Understanding Your Lithium Battery

In short, NO! 

The storage capacity of Lithium far outweighs the storage capacity of AGM batteries in the short and long term. The Lithium will greatly outperform any AGM of the identical nominal capacity as it has the capacity to be discharged to a substantially lower depth of discharge i.e. 10% remaining instead of 50% remaining with a lead acid. Cycling of lead acid batteries on a regular basis to below this level is not recommended, as it will shorten the overall lifetime capacity of your battery. This is one of the major advantages that lithium has over older technologies such as lead acid as it means that you have effectively, almost double the available Ahr of power in a 100 Ahr direct comparison.

Also, because the voltage on a lithium battery does not drop off slowly during the discharge it means that you will be using less total Ahr of the battery capacity then what you would with a lead acid battery. For example, as a lead acid battery decreases incapacity the voltage starts to decrease immediately and more substantially than a lead acid battery. As a load such as lights or in this case a fridge requires a particular level of Watts to operate – the simple physics law of Watts (W) = Volts (V) x Amperage (A) applies. To maintain the Watts to keep your fridge operating when Volts decrease require more Amps, in turn depleting a lead acid battery faster.

Key Recommendations

In the latter part of your question, you have suggested to reduce to one solar panel. We wouldn’t recommend. Two solar panels will charge your lithium battery faster and as it can accept charge faster than a lead acid battery it is best to keep your batteries topped up as much as possible before the sunsets, shading or worse still for a couple of wet and dark gloomy days with little solar generation.

Regarding your consideration on what quality looks like? Unfortunately, it is a very difficult question to answer however I would certainly steer you in the direction of working with reputable brands that have been around for a substantial period and have demonstrated expertise in the caravan and outdoor space.

A good example of where hype and warranty have failed to deliver value to consumers is the sale of solar panels for residential rooftop installations.  In the last decade, Government incentives, discounts and 20-year warranties etc have enticed thousands of consumers to install solar PV systems. As rebates and discounts evaporated, solar panel manufacturers and installers disappeared faster than a coldie after setting up camp in 40C. There are currently numerous cases of dishonoured warranties due to failed or poor performing solar panels, and customers left stranded as their retailer has made their quick dollar and left town. If retailers need to discount a Lithium battery in the height of their market adoption to attract your purchase, then as per the old saying going “if it’s too good to be true, it’s too good to be true”.

We would suggest that spending between $900 to $1,500 for a Lithium battery 100Ahr from a reputable company should put you in good stead for purchasing a quality product. Our analysis and deep dive investigations of batteries has proven that the cheaper the battery the more likely they have sufficient substantial flaws in their design capacity or build quality which unfortunately means (for the consumer) that it could be a risky purchase.

So, in summary spend in the middle to upper end of the range, don’t buy super cheap and seek out a company that has experience and longevity in the caravan 12V space.

Safe travels,

12V Guru

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3 thoughts on “12V Guru – Choosing The Right Lithium Battery Set Up For Your Caravan”

  1. Hi,
    curious why charging is capped at 30A.?
    3 hours to charge 100 ah
    On road so running fridge at 17,5 a/hr so effective charging is only 12,5 a/hr you take 8 hours of recharging. On this basis, is there any way to recharge a 200 or 300 ah system?

  2. Hi,
    curious why charging is capped at 30A. (Lithium)
    3 hours to charge 100 ah
    On road so running fridge at 17,5 a/hr so effective charging is only 12,5 a/hr you take 8 hours of recharging. On this basis, is there any way to recharge a 200 or 300 ah system?
    Fridge is 3 way 420A / 24hr
    My daily usage is estimated at 68A without fridge, so looking at 300ah to enable free camping.
    May be size with an inverter, so I can use microwave for a few minutes a day. 🤔

  3. Make sure that an Lithium battery purchased includes an Integrated Battery Management system. Some cheaper ones possibly don’t. The battery management system will shutdown the battery under overload conditions thus preventing opportunity for thermal runaway issues. It will also shutdown to protect the battery in under-voltage conditions. Both very important points.

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