What You Didn't Know About Batteries

At the heart of many renewable energy systems, there lies a battery of one sort or another but when we focus on whether we’re using photovoltaic or wind power to generate our electricity, we often tend to forget this simple fact.

We shouldn’t. The right battery can make the difference between a successful installation and an expensive flop – so if you’re thinking about generating your own power, there’s never been a more important time to get a better understanding of them. To start you off, here’s a few things that you probably didn’t know about batteries.


Deep Cycle Batteries Rule the Roost

There are lots of different makes and sizes of lead-acid batteries available, but for the alternative energy enthusiast, the most important thing to look out for is whether they’re ‘deep cycle’ or ‘shallow cycle’.

Car batteries are the shallow cycle kind and they’re perfect for providing a high current for a short period of time, but then they’ll need recharging. They’re very intolerant of being heavily discharged – starting a car seldom uses more than five per cent of their capacity – which means they make a poor choice if you’re relying on batteries to provide you with power on the days when the sun doesn’t shine or the wind doesn’t blow .

Deep cycle batteries, on the other hand, are far better suited to renewable applications since they are designed to be discharged more completely – by as much as 80 per cent – and deliver their current over a much longer period.

The Lead Acid Battery is Older Than You Might Think

It can trace its ancestry back to the mid-1800s, when Gaston Planté began experimenting with the familiar lead and sulphuric acid components to produce a way to store electrical energy. He first demonstrated his new invention to the French Academy of Sciences in 1860 and the first major development – using lead paste rather than Planté’s solid plate – took place some 20 years later. His idea has continued to be modified and improved upon ever since.

There’s No Quicker Way to Kill a Battery Than Leaving It for Dead

If you discharge a lead acid battery and then let it lie around ‘dead’ for any more than a few days, it will start to deteriorate – and the longer you leave it un-charged, the more serious the damage becomes. Chemical changes take place during the discharge cycle that alters the plates and if you leave it too long, those changes cannot be reversed – which normally happens as part of the recharging process.

If you need to store a battery and leave it unused for a time, always store it charged to avoid these problems, but remember a charged battery will gradually lose its charge over time – so check it periodically and be prepared to recharge it as necessary.

Temperature Makes a Difference

Remember all those urban myths about keeping torch batteries in the fridge to make them last longer? Well, when it comes to lead acid batteries, temperature really can make a difference – as a general rule, a battery will tolerate a deeper discharge in warmer conditions, while it will be able to accept more of a charge when it’s cold.

It’s part of the reason why the practical performance of any battery is so difficult to predict with absolute accuracy. Many factors, including its age, how many discharge/recharge cycles it’s already had, the current being applied to, or withdrawn from it – and of course the temperature – all interact to influence its behaviour.

Almost all off-grid electrical systems use lead acid batteries – and given their low initial cost, relatively modest maintenance demands, proven reliability and ready availability, it’s not hard to see why. With such a vital role to play, the more you know about the batteries you use, the better!