Are Lithium Batteries A Good Value for Money?
Choosing the most cost-effective batteries for a new caravan.
Question: Good morning, we have ordered a new caravan which will have 220L Compressor Fridge. It was suggested that, in order to ensure we had an ample power supply, we have 2 x 135Ah deep cycle AGM batteries and 2 x 170W solar panels.
As weight is a something I have to take into consideration (our GVM is 6000kg), I have been looking at Lithium Batteries and in doing so have found a large price range from $440 for a 135Ah battery to about $3000 for a 300Ah 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? (from Robert Cook)
Answer: Thanks for your question and it is certainly 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 address query in regard to asking is 200Ah of Lithium capable of doing the same job as two AGM batteries.
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 per cent remaining instead of 50 per cent 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 lithium has over older technologies such as lead acid as it means that you have available effectively, almost double the available amp hours of power in a 100Ah direct comparison.
Also, because the voltage on a lithium battery does not drop off slowly during the discharge, it means you will be using less total amp hours 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 the fridge operating, if the Volts decreases than you will need more Amps, therefore depleting a lead acid battery faster meaning you will need a higher amount of amps to keep the fridge operating.
In latter part of your question is you, have suggested to reduce to one solar panel. We wouldn't recommend this as 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 a couple of wet and dark gloomy days with little solar generation.
Regarding your consideration of what does quality look 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 has 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 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 ‘ithium battery in the height of their market adoption to attract your purchase, then, as the old saying goes, ‘if it sounds too good to be true, it probably is.’
We would suggest that spending between $900–1500 for a Lithium battery 100Ah 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 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.