Battery Basics

16 March 2020

Today, we are diving into unchartered blog waters. Batteries – a never before (or rarely) discussed topic on this blog. Not anymore!

So, let’s talk about these things.

Batteries are used to ensure that critical electrical equipment stays on – always.

You’re probably familiar with the battery in your cell phone – you know – the one that you’re obsessed with charging. Yes, that one. Or the batteries in your TV remote, so you’re never Netflix-less.

But batteries are in so many other places too, and you’re in luck because we are going to list them for you. Right now.

Where are batteries used?

Well, you’ll find batteries in…

  • Electric generating stations and substations for protection and control of switches and relays
  • Telecom systems to support phone service, especially emergency services
  • Computers – to back up data (especially financial information)
  • Industrial protection and control applications
  • Business information systems

Thanks to battery back-ups – in the event of a power outage – hospitals keep their doors open, your data isn’t lost forever, and emergency services can keep on running.

But how do batteries work?

Chemistry! My favorite.

Batteries store chemical energy and convert it to electrical energy. Inside a battery, chemicals cause electrons to flow from one electrode to another – creating an electric circuit. Inside the battery, you’ll find different electrodes and electrolytes – a medium for charged ions – swimming around. They’re not just going for a swim though; they’re producing different chemical reactions. How cool?

It’s these reactions that determine how a battery works, as well as the amount of energy it can store and the voltage it can provide.

Now, what kinds of batteries are there?

You’re just asking all of the right questions today, aren’t you? Well, you already know than a battery is an electrochemical cell (or series of cells) – per my previous explanation – that produces an electric current.

There are two basic types of batteries – primary and secondary - that can be expanded into many, many other categories of batteries.

Primary batteries are single-use, non-rechargeable batteries, like your classic AA or AAA household batteries. These are typically made from standard alkaline or lithium.

Secondary batteries, on the other hand, are rechargeable. On a small scale, you’ll find secondary batteries in smartphones, tablets, and cars, as well as on a larger scale in those industrial applications we were just talking about. These batteries are typically made of lead acid, nickel cadmium, or lithium ion.

Now that you’ve got that down, let’s break down secondary batteries even further. Don’t worry – we won’t get too into the chemistry. It gets complicated, but we’ll try to keep it simple by only talking about the most popular type – lead acid batteries.

Lead Acid Batteries

There are two kinds of lead acid batteries – flooded and sealed. Flooded batteries or Vented Lead Acid (VLA) lose water during the electrochemical reaction. Neat, right? Because of this, you have to add distilled water periodically – kind of like a plant. Typically, these batteries last about 20 years. Pretty nice life for a battery!

On the other hand, sealed or Valve Regulated Lead Acid (VRLA) batteries are sealed. You cannot add water, under any circumstance, since they’re sealed. Unfortunately, this shortens their life span, so these batteries only last about 5 to 8 years with proper maintenance.

Lead acid batteries can also be categorized by their application – cyclic, standby, or starting lighting and ignition batteries.

Cyclic batteries are typically used in the marine industry, as well as in forklifts and golf carts. Kind of a weird range of industries – if you ask me – but we’ll go with it. For these batteries, thick plates of lead antimony are used, which help the battery withstand the heating effects associated with constantly charging and discharging.

Standby batteries are designed to stay on float for a long time. Here’s some more information about float if you need it. They don’t handle the heat, since these are typically made from lead calcium or lead selenium.

Starting Lighting and Ignition batteries – or SLI for short – are your typical car battery. They’re designed to provide a great deal of current over a short period of time.  If you’re like me, you’ve experienced one (or more) car battery deaths. SLI batteries can’t be discharged deeply, so they have to be recharged immediately in that event.

What about battery failure? Why do batteries fail?

Well, we have a whole book that talks a whole lot about this, but for now – like everything else in this blog – let’s chat about the most common.

Positive Grid Corrosion is a common failure mode in VLA and VRLA batteries. When lead alloy turns to lead oxide, you’ll get positive grid corrosion. It’s like you just can’t escape the chemistry this week! While this can happen naturally, it can be accelerated through heating.

When lead acid batteries discharge, you may get plate sulfation. As the plates sulfate, the impedance – or internal resistance – increases. Fortunately, when the battery is recharged, this reverses itself. Unfortunately, if the batteries are not fully recharged, then the plates remain partially sulfated, and the longer they stay like that, the harder it is to recover the lost capacity.

Moving right along. Dry-out is another natural phenomenon for VRLA batteries. Since you can’t add water, it makes sense that a “dry-out” would occur. When excessive dry-out is not addressed, the batteries internal components can actually melt, which basically results in catastrophic failure. We call that thermal run-away – another common failure mode.

Almost done. We should also talk about shorts – hard and soft. Hard shorts are usually caused by paste lumps, which are a manufacturing defect. In these cases, your battery is probably going to fail really quickly. On the other hand, soft shorts happen when a battery is too deeply discharged, causing lead to dissolve in the electrolyte and get trapped in the separator – forming dendrites that short out on the plates. When your car battery dies, and you recharge it only to have it die again – this is exactly what’s happening!

Okay, you made it. Obviously, we didn’t hit every failure mode, or you’d be here for a while. If you’re interested in that, here’s your last reminder to download our Guide to Battery Testing, or maybe we’ll get into it more in our next blog. I guess you’ll have to wait and find out.

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