One of the most difficult decisions a family of limited means has to face when dealing with batteries is the decision to reduce a battery bank. When batteries begin to fail it forces owners to make difficult decisions, namely to cut out the bad batteries from the battery bank (and reducing bank capacity) or buying new batteries. While it is natural to resist taking the decision to remove bad batteries, it is vital that you do this earlier rather than later, the longer you keep even one bad battery in a battery bank, the more the harm will spread, – bad batteries make weak batteries worse and eventually you find yourself with several bad batteries and a next to worthless system.
Obviously in an ideal situation you buy new batteries, even fewer new batteries are better than a larger battery bank of weak batteries, but resist the urge to just replace one or two batteries with new batteries, as while this is an option the new batteries will have shorter lives and in the long run is generally counter-productive. The weaker batteries will “lean” on the new batteries and it will shorten the useful life of the good batteries.
Perhaps the most routine task servicing batteries is the most important, – the watering and testing of batteries is absolutely critical to long life and problem free service. It is imperative to monitor and maintain water levels; nearly as important is routinely testing batteries, watching for signs of poor performance. One bad battery can drag down entire battery bank, if ignored long enough a few bad batteries can leave you with a next to worthless system.
The first sign of a problem is typically the batteries not holding power like they use to, they cannot handle loads for very long and they quickly shed voltage at a certain point, – typically they hold a moderate load until a certain point and then the bottom falls out rapidly. Say your 24-volt system will hold well until sundown, and then remain stable until 23.4 volts, and then the bottom will fall out within 30 minutes; this is a sign one or more batteries are bad or underperforming, dragging your good batteries down. This pattern can be subtle at first, but over time it will worsen and become very noticeable, but it is better to catch this early as the harm can become cumulative.
The general outline of general service follows, it is very basic and takes only half an hour, but it must be done religiously once a month, possibly more often if your batteries are older or weak, some failing batteries will consume more water and even feel warm (a bad sign usually).
Living on your own terms can be both rewarding and challenging and this is never truer than when it comes to living with batteries. Taking the decision to live remotely, for whatever reason, whether due to the love of solitude or whether to escape the rules and regulation of society the same dependency for power is ever-present. Batteries and inverters are often the most practical means to achieving this goal of taking the best society offers without all the conformity that goes along with it.
A power system designed around batteries offers many advantages, for one if taken care of they can last for a decade or more, they are reliable under most conditions, in this age of high energy costs they can be economical over the long-term; lastly they provide a family with power in a wide array of options and most people can adapt to their use and maintenance with a minimal commitment of time. The only real disadvantages are the upfront cost and the fact you are the utility company, – there is no one to call when there is a power outage!
Here we will go over the basics, what you will have to deal with eventually if you buy and maintain your own battery bank. We will not pretend to know all there is about batteries and inverters, only our personal experience of actually living off-grid for over 15 years, – there are literally hundreds or thousands of websites dedicated to batteries, PV, wind and inverters, here we will only cover the raw basics drawn from actual trial and error.