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Lithium Evolution by RV Travel Lifestyle Magazine

Monday, 14 May 2018

 

 

 

Lithium Evolution

 

Latest technology batteries are on the market; why we should upgrade; are lithium batteries compatible with our existing technology; what are the power comparisons. We asked Greg Mitchell from REDARC for his advice.

 

Batteries are one of the components in your RV or caravan’s setup that are a necessary evil. You need them – to start the vehicle and allow the electrical system to work effectively – so you can escape into remote bliss beyond the reaches of the mains-power grid, whilst maintaining essential comforts. But they take up large amounts of space that could be utilised in other ways, they weigh so much that structural strength of their mountings can be a problem, and in larger systems, they can even play havoc with the balance of the vehicle – especially in caravans.

In the last 10 years, lead-acid battery technology has come a long way, with improved designs having better tolerance of the harsh environments experienced in RVs, and greater ability to accept, store and deliver larger amounts of power in smaller packages. These batteries have tolerated our abuse – over vibrations, through the heat and cold, from full to flat and back again, more regularly and faster than is really best for them – but they have kept powering on and done the job.

It is, however, in our nature to improve on what we have and what we know, and when it comes to batteries for the RV market, there are a few manufacturers taking that next step. Lithium-battery technology has been around for a number of years already, in various different forms; most of your power tools and portable devices now use lithium batteries.

The type specifically being used in automotive and marine applications is known as Lithium Iron Phosphate (LiFePO4), or LFP. Automotive LFP batteries consist of (four) 3.2V cells connected together in series to make a 12V battery (or whatever battery voltage you need), then a number of these groups are paralleled together to give the required capacity. LFP batteries need to have inbuilt protection devices, or battery management systems (BMSs), to ensure that the internal cells aren’t subject to under or over voltage, imbalanced charge, or excessive charge or discharge currents. If this protection does not exist, the cells may fail and no longer be usable. Contrary to popular belief in New Zealand, LFP batteries with inbuilt protection and cell management are no more volatile than a lead-acid equivalent. A lot of people confuse Lithium Iron Phosphate batteries with Lithium Iron Cobalt, Lithium Polymer and many other Lithium-type batteries, which have a completely different chemical composition and can be volatile if not charged correctly.

The biggest advantage for those of us wanting a top-end auxiliary battery system is that an LFP battery can be one-third the weight and physical size of a lead-acid battery of comparable storage capacity; plus, their cycle life can be up to 10 times more cycles than a lead-acid battery. Another functional advantage is that they are capable of delivering more usable amp-hours, nearly double that of a lead-acid, by allowing deeper discharge at a usable voltage. In fact, the voltage curve of an LFP battery remains relatively flat in comparison to a lead-acid. A lead-acid battery’s voltage gradually falls from 12.6V at 100% charge, to around 12.2V at 50% charge, and 11.8V at 0% charge – or dead flat. An LFP, on the other hand, would remain close to 12.8V between 100% charge and as low as 20% charge; the voltage then tends to decrease rapidly below this level. This means that your loads run better – brighter lighting, more efficient cooling/heating, etc. throughout the operating range of the battery. Not only do they deliver power better, but they accept it better too. Lead-acid batteries are generally around 70% efficient when charging – meaning when you put 100Ah in, only 70Ah is actually stored as usable power. LFPs, on the other hand, are better than 90% efficient and can accept their maximum recharge current limit until nearly full, meaning faster recharge times. So what’s the catch? All these great advantages must come at some cost – and that they do: LFP batteries are much more expensive than lead-acid batteries. A top-quality AGM 100Ah battery would cost around $400, whereas an LFP 100Ah would be closer to $2000. Sounds like a big jump, but when you consider that it will take up one-third less space and weight, deliver nearly twice the usable amp-hours, last up to 10 times longer, and operate more efficiently throughout its life – it sounds like good value for money for high-demand auxiliary battery systems.

One thing that is no different between an LFP and a lead-acid battery is that you only get out what you put in, and so you need to charge them correctly to reap their full potential. The internal protection BMS plays a part in this with its cell balancing, but mostly it is about applying the correct voltage and current levels to the battery to bring it to full charge. You can’t charge an LFP battery from a standard lead-acid charge profile; not only will you not get the maximum run time of loads, but you will also severely shorten the life cycle of the battery. Thus it is vital that your charging system is matched to the LFP battery. If it’s not, you are buying false economy.

The good old lead-acid battery still has a home in many RV setups, particularly when LFP batteries may not fit the budget, but for those needing the next step up in auxiliary power storage, they are definitely worth a look. - For more information on REDARC Battery Chargers visit

 

To read the article in full please click here

 

This has been published with permission from RV Travel Lifestyle Magazine, you can visit their website here

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