This Fusion battery is claimed to be virtually a drop-in replacement for existing deep-cycle batteries but check your requirements first with the vendor. Pic: Fusion.
Asking are lithium-ion batteries worth their price depends mostly on how and where you intend to use them. Here is the case for and against them – and why.
Are Lithium-ion Batteries Worth Their Price? – traditional battery issues
Whether basic lead acid, gel cell or AGM, traditional lead-acid batteries are bulky and heavy. Most (12-volt) weigh 25-30 kg per 100 amp hour. This is not a major issue for home and property systems. It is, however for RVs
Deeply discharging them shortens their lives. Even doing so to 50% is too much. Most, in homes and properties, fully charge each day and discharge by only 20% or so. Reality is that a (say) such 1000 amp hour battery is realistically only 200 amp hours. Here again, not an issue for homes and properties, however very much so for most RVs.
Similar limitations occur when charging. AGM batteries have the least, but one of 100 amp hour is limited to a charge of about 25 amps. This is not a major issue for homes and properties. It can be, however, be for an RV. Some have an alternator able to supply 100 amps.
Traditional batteries are nominally cheaper. They cost about a third of the price of lithium-ion (of the same nominal capacity). But as the following shows, nominal capacity is just that.
Are Lithium-ion Batteries Worth Their Price?
There are various types of lithium-ion batteries. Those used for homes, properties and RVs are usually LiFePO4. All are about one-third of the bulk and weight of traditional batteries. Here, however, direct comparison ceases. LiFePO4s have far fewer limits on the depth of discharge. They can be routinely discharged to 20% remaining. Their makers claim they will do so for about 2000 such cycles. Limiting discharge to 30%-35% is claimed to considerably increase that.
Another LiFePO4 plus is that it outputs 13 volts-12.9 volts over most of its range. This is a big plus for voltage sensitive equipment – such as fridges.
A LiFePO4 costs three times the price. It has, however, at least three times more usable capacity.
Are Lithium-ion Batteries Worth Their Price? – energy and power
Energy is the ability to perform work. A battery’s amp hour capacity is a measure of that. Power, however, is a measure of how fast that energy can be released. Here, battery promotion can seriously mislead. Even a tiny (e.g 18 amp hour) LiFePO4 can provide huge amounts of its stored energy – as required.
In effect, a LiFePO4 can double as a starter battery and a deep cycle battery. In home and property systems, however, a LiFePO4’s power ability is unlikely to ever be used.
LiFePO4 promotion often exploits. It claims (rightly) that LiFePO4s have more power. Prospective buyers, however, may see this as more available energy. They have not to any appreciable extent.
Are Lithium-ion Batteries Worth Their Price? – charging and monitoring
LiFePO4 batteries need specialised charging. This is understood by home and property solar installers, but less generally otherwise. They must have individual cell monitoring. This is typically done via a specialised battery management system. They are still a specialist product. They specialised knowledge to install. A few are promoted as drop-in replacement products – but may now warn re their charging requirements.
Are Lithium-ion Batteries Worth Their Price? – it depends on that price
Battery prices vary considerably. As a general guide lead acid and AGM batteries’ is almost directly related to their weight. The more they weigh the greater their probable capacity. A few have complex and cost-adding Bluetooth cell monitoring. But unless a lot heavier life expectancy is much as other brands. Ultra-cheap ones will be light but have limited power. They may not be able to run an inverter. Their life too is short.
LiFePO4s cost a lot more upfront (as to do AGMs), but as they weight far less delivery is cheaper. Their cost per delivered amp hour, however, is likely to be lower than for other battery types.
Are Lithium-ion Batteries Worth Their Price? – summary
LiFePO4 is a good choice for those using deep-cycle batteries in home and property systems Also for smaller RVs where space and weight are at a premium. For many other purposes, however, AGM or lead crystal are good options.
This is a complex topic that can only be outlined in article form. Of our solar books, Solar Success covers it in detail (for home and property systems). Solar That Really Works! does likewise for boats, cabins and RVs. Caravan & Motorhome Electrics covers all aspects of designing, installing and using such systems.
All our books are now available in digital and print form. The digital versions can be bought and downloaded right now from this website. (Just Click on the title/s). Print versions are available through all bookshops in Australia and New Zealand or via email from booktopia.com.au