Lithium Ion versus lead acid batteries – here’s what you need to know

Until recently the majority of homes with energy storage used lead-acid batteries, particularly those that were entirely off-grid, but in the past few years an increasing number of companies are offering home energy storage systems using lithium ion batteries. The question is which is really better?

Li-ion batteries do not contain hazardous materials where lead-acid batteries contain lead which is toxic to the environment. They also contain sulphuric acid which is extremely corrosive! Both battery types are recyclable although at present it’s much easier to recycle lead acid than li-ion batteries. Lithium-ion batteries require less energy to keep them charged than lead acid batteries. Lead acid batteries also self-discharge at a higher rate than Lithium-ion.  These efficiency gains, however, are offset by the need for Li-ion to have a battery management system (BMS) to protect against short circuits and overcharging.  This control and monitoring system uses power so the total operating losses are very similar between the two technologies.

Given the similar efficiencies one needs look to other factors.

Lead acid is the most mature energy storage technology. Lead-acid batteries have been used to provide back-up for solar homes since at least the 1970s. Lithium ion is a rapidly developing technology.

Initial capital cost for lead-acid batteries is lower than lithium ion batteries, which tends to make them more attractive for homeowners. The down side is the cycle life of a lead-acid battery is much lower than that of lithium ion. Some last as long as 1,000 cycles while others will only last for 200 charge and discharge cycles. Lithium ion batteries will typically cycle between 1,000 and 4,000 cycles and some of the latest technology up to a massive 10 000 cycles. Most lead acid batteries will not  last more than five years and sometimes substantially less. Over the lifetime of a solar array, a homeowner will have to replace lead-acid batteries numerous times.

Discharging lead acid batteries too deeply also significantly reduces their life expectancy so a bigger capacity battery is required than the actual useable energy it can provide.  Lead acid batteries therefore require a lot more space than lithium ion batteries do. Lead acid batteries may produce hydrogen gas so need a well-ventilated situation. Lithium ion batteries are lighter, far more compact (easier to accommodate) and generally aesthetically more acceptable than lead acid batteries.

Lithium ion batteries are quickly becoming the battery of choice for many applications, from cordless power tools to laptops and vehicles. They’re pre-packaged into solar batteries for homes. The primary reason lithium ion is not selected is cost. However, the new cost of a Lithium ion battery system keeps coming down and has already reached a point where the total cost over the lifetime of the system is much less due to their longer cycle life and no maintenance costs.

If you are serious about getting off the grid and taking back control of your electricity costs and supply, contact One Energy at gogreen@oneenergy.co.za with your contact details and area – we’ll schedule an obligation-free consultation to provide you with a thorough overview of the steps you can take to get off the grid, step-by-step.