All About Batteries

This should be split into 3 articles, part 1, 2, and 3

Written by Zachary Mettin

What is a battery?

A battery is a container consisting of one or more cells in which chemical energy is converted into electricity to be used as a source of power. Portability and storage are the two main benefits of a battery. We use batteries in almost everything electric, that doesn’t have a cord plugged into it.

What that means for the vast majority any time you want something untethered from a cord It’s going to be powered by some sort of “battery.” Whether it be an alkaline battery like AAA size batteries in your TV remote or your AA batteries in your children’s toys there is something providing power to whatever object in question. Why we use these sources of power there instead of what we call Alternating current (or AC power) is something we will get into here.

But before we delve into that we should go over some specifics here. A battery by the definition provided above is a container that produced power by a chemical reaction. In most cases this is done by what is called an Alkaline battery. (AAA, AA, C, and D size batteries.) This is done by a principal called Voltaic action. Or Anode and Cathode. In the case of Alkaline batteries this reaction happens all the time via Zinc, and Manganese dioxide. Zinc being the Anode and Manganese being the Cathode providing you power at around 1.200 Volts DC.

That sounds like a lot is going on. So, we will get into that aspect of it here a little better.

An anode is an Electrode that positive current flows into from the outside. A Cathode is an electrode that has current flow from itself to the outside. In a chemically speaking sense an Anode will oxidize and a cathode will reduce. Lowering the reaction as time goes on. (less power being produced) In the case of an AA battery that can take anywhere from a couple hours inside a flashlight to years inside a remote control for your TV.

This is strictly only applying to non-rechargeable batteries in this example.

Now why are some rechargeable and some are not?

In a short answer because chemically it is impossible to refill the standard batteries most use for day to day life. However there are batteries you can buy that are the same size and voltage that are rechargeable in the same way larger batteries are.
They accomplish this by using a chemistry that can effectively be reversed. By way of providing an opposite electrical potential with a charger. Causing the chemical reaction to go backwards. IE almost as good as new.

There are plenty of batteries that are rechargeable by design. Your Car battery for instance. As you drive your cars alternator is generating enough power for your lights, stereo, AC, and enough extra energy to top off your car’s battery so when you go to turn the key later your car will start.
This kind of battery is called an SLI but we won’t get into that here.

How do batteries work?

To answer that question fully, I’ll have to go into some other details. First and foremost, what an Anode and a Cathode are. I touched on it earlier. One is where positive electrons flow from to the other causing oxidation by reaction to charge and discharge. This happens by a reaction through what is typically called an Electrolytic solution. In most batteries’ cases bigger than an Alkaline this is done by Acid.

In a non-galvanic battery, it helps to have a visual aid

                                                       visual aidvisual aid

In this example it shows the flow of ions in charge and discharge. Using this example, you can sort of see what is going on inside the cell. I say the word cell because depending on the use and size a battery can be a bunch of batteries thrown together to make a bigger battery and then each individual ‘battery’ becomes a ‘jar’ and each jar as a bunch of ‘cells’ What that means is its broken down into components, so we can troubleshoot issues later on.

Real life example: If you go into a mechanic shop because your car is starting harder in the fall your guy or girl might throw a battery tester on there and it will spit out either “good” or “bad” depending on the type of tester being used. What this kind of tester is looking at is related to how a battery generates its power. In this case with Lead, and Acid producing a chemical reaction to generate the power needed to start your car.
This reaction happens inside individual cells inside the battery. Because if you had just One anode and one cathode you wouldn’t produce much “power.” So, inside your battery in the vehicle is a container that holds 6 ‘cells’ with an anode and a cathode inside each cell. Which in turn produces a voltage.

This voltage is in relation to each other. In the case of a car battery anyway.
The components of a battery are as follows. * Anode, Cathode, Electrolyte/ solution, Cells (containment,) and terminals. 

Terminals are depicted here

Batteries provide DC:

DC stands for Direct current which differentiates from your power in your house. The power in your house is called AC voltage or Alternating current.

In the photo above is an example of the waveform of the different sources of power you use daily. DC is the red line. And AC is the squiggly bit that goes above and below the grey line. That grey line is you ZERO point. In this picture it shows you how DC power is above zero and always will be above ZERO. How it does this is by constantly supplying electrons regardless of state. You cannot turn a battery off. This makes working with them extremely difficult. If you are working in your house and you need to turn off whatever it is, you are working on you can either flip the breaker or the light switch. In the case of a battery you cannot just simply flip a switch to turn the reaction off. It’s always happening. You can drain the battery down and then your risk is slightly lower. But it’s always supplying electrons and the second you close that circuit or (path) it will release its energy until it cannot do so anymore. Usually this happens in the form of an arc.  You ever try to jump someone’s car and it sparks a bit? Yeah. That’s because of the difference in potential between both batteries in question.

A battery can always supply Direct current by design. They are by their nature always on. If Edison had his way many years ago your house would be powered by DC power. But that’s neither here nor there.

Types of batteries
There are a few common types of batteries. We touched on Alkaline, and briefly on SLI.

Here is a list of common types you come across in your day to day life: Alkaline (tv remote, smoke alarms, children’s toys,) SLI (starting lighting and ignition, car battery,) Coin cell (your watch, alarm clock etc…) Then you have some others. Lithium Polymer (cell phone battery,) Galvanic cells (hearing aid batteries,) and Lithium Ion batteries (tool batteries, laptops, and some medical tools.)

These are the most common you will see or use every day.

Now why are these used?

In a short answer each one is used out of convenience. Alkaline batteries are cheap and easy to produce, and they have been around for about 60 years or so. They are so common that pretty much everything in your house has them in them. Whether for sole power use or back up in the event of power loss. Your thermostat? Has a battery in it just in case you lose power, Smoke alarm? Same thing. They are good in storage for up to 10 years and can supply power in almost every climate/ temperature.

Why would you use alkaline when you can just use a rechargeable battery?

Good question: There isn’t really an easy answer for that one for most uses. Your yard lights that charge during the day and run during the night have rechargeable batteries in them for use during the night to light your path home. Why wouldn’t you use that same technology in your tv remote? Well you can. You can go to your local misc store and buy a 4 pack of rechargeable AA’s. But then you need a charger… now you must charge them for 8 hours before you put them in your remote. Now after about 6 months you have to take them out, and charge them again… you see where this is going? Not every application makes sense to have a rechargeable small form factor battery inside it.

This is where we get into the different kinds of batteries and their uses.

Types of Cells

We can start here with the most common type of cell in the world. That’s Lead acid battery.
A lead acid battery come in a few forms. 

There is

flooded: where the battery has free flowing acid across the anodes and cathodes inside the container. (These can be maintained with water or adding electrolyte.) 

Sealed: where the battery is completely sealed from external elements with a vent for charge and discharge cycles.

GEL: which uses a gelled acid solution in between the plates (anode and cathode) usually referred to as Gel cell battery. (these are usually a bit more specialized.)

AGM:  AGM stands for Absorbent glass mat. Meaning inside the battery there is these fiberglass quilted material that has an Acid solution impregnated in it. These also usually have a higher Lead content producing a higher surface area and thus increasing the amperes a battery can discharge in a given cycle.
STORAGE: Storage batteries aren’t much different than flooded in concept. But they usually have less Volts per cell and more amperes due to more surface area and total volume of electrolyte. 

Almost all of these use a standard of acid solution of Sulfuric acid. Which is then diluted in ‘water’ water being a generic term used for either distilled water or Deionized water. 

As Batteries use acid and the water as a catalyst for their chemical reaction. They do this by having the anode drawing in the acid, causing the bonds of oxygen and hydrogen to breakdown. This releases the hydrogen into the container and venting into the area they are in. And moving over to the reduction side IE Cathode. This moves Electrons from the Cathode to the anode. (I know bear with me here) This causes the anode to oxidize. Now this is just one cycle. On discharge. On charge this happens in reverse. But with a production of way more hydrogen gas. As it is causing the cathode to be “re-plated” with lead. This is called Electrolysis. And as this happens often. The water eventually either evaporates off or is “cooked” off by charge/ discharge cycles and needs to be replaced. Because Acid doesn’t evaporate or break down in the same way water does. The acid does not ever leave this cycle like water does.

That is your typical lead acid battery.

the same thing happens in the other ones as well just in a different fashion. In a sealed battery this happens and is vented through slots and once all the water is gone the battery’s internals do what is called sulfation(since you can’t add water to prevent this). Your SLI battery can do it. In fact, any lead acid battery can. Sulfuric acid is the culprit here.
what that means is that crystals are produced on the anode during discharge and block the passage of anions/ electrons in the backwards direction. Effectively cutting off part of the lead plates and lowering the capacity of the battery’s total available power. (this seems off topic but here is where its relevant.)  

There are other battery cell types that don’t do this. At least in the same way. Those are Lithium ion/ Lithium polymer. These types of batteries are in your phone for this reason. They can be charged and discharged frequently with minimal wear and tear on your battery. (it will still deteriorate over time, but not as dramatically.)

What makes these different is the chemical reaction they use to provide you power, and how they implemented it. These batteries are being used in place of Lead acid because of their Shelf life, power per weight, and their penchant for voltage abuse. (yes, they are also dangerous.) Most lithium poly cells won’t just explode like a galaxy note 7 but sometimes they do get unbalanced and one cell inside the pack will soak up more power than the rest of them. (read poof…) But the relevant bit is that cell types haven’t really changed much. At least in any dramatic way other than Lithium cells being used more commonly in day to day. You can even go to the store and buy lithium AA’s, and AAA’s / 9volts.

Specific gravity

The specific gravity in batteries is used more often in storage batteries for battery back ups in large scale facilities. It is a measurement of how much “not water” is in the cell. Because water is a value of 1.00 anything above a value of 1.00 (1.180 for an example) means there is something else inside the solution. What would that be? depends. In this case usually its an acid of some sort. If your value on certain batteries is beneath the specifications of the manufacturer that means your acid levels are dropping somewhere which can lead to other issues down the line. 

how you measure specific gravity can vary. Some testers use light, some use a granulated cylinder with a bobber, and some use a measure against mercury. How these things determine how much “not water” is in the solution isn’t going to be discussed here. But your specific gravity on a storage battery should almost always be somewhere around 1.250.  higher means more acid than water and lower means more water than acid.

how do battery chargers actually charge a storage type battery?

A battery charger can be as complex or simple as you are willing to go. Some you can set up and walk away like a battery tender which will go from a peak charge until about 80% of total voltage is reached, and then step down to a lower supplied current/ voltage (called float charge/ trickle charge.) or as simple as a tombstone style charger that will just throw a ton of amps at a battery and continue to do so until you turn it off. If you forget to turn such a thing off it can and will cook all the water out of the battery (lead acid in this case,) and cause a failure.

It does this by chopping up an AC signal and turning it  into a DC signal. 

Example you have a charger for your cars SLI battery and it plugs into a standard outlet. 120 volts AC. there is a rectifier inside there along with a small chip (usually) that will tell the charger Ok the battery is at 11.4 volts DC we need 5amps at 14.5 volts DC for a safe charge over X amount of time. The rectifiers job is to turn AC voltage and turn it into DC voltage and then supply it to the battery in question. This can be done either fast or slow and the computer/ chip gets in the middle and will usually pulse this in order to supply the correct power to the battery. The feedback loop from the chip/ computer will eventually say ok the battery at 12.5 volts let’s slow this down and adjust accordingly in order to keep not only the charger safe, but the battery, and your outlet as well.

How they charge is back to the chemical reaction example above. There are tons of different chargers. Ones for your car, your rechargeable AA’s, your cell phone, and your laptop to name a few. These are are doing essentially the same thing. Turning an AC signal into a DC signal and applying it to whatever it’s designed for.
You wouldn’t want to use your laptop charger for your phone or your phone for car.

Which brings us to the next topic in this one. Sizing a charger to your needs. Not every charger is designed for your needs. Your phone charger cannot charge your  car. Your cell phone charger is designed to put out 5.4 volts DC at such a small amount of amps in comparison to what’s needed for your car. As most car batteries run at 12.5 volts DC and your phone charger is designed to output 5.4 volts DC it would only charge your car battery up to 5.4 volts. But your cars battery wouldn’t ever be that low to begin with. (bad example but you get the point.)

So size your volts to the battery in question and make sure to verify that the requirements are met or exceeded by the charger.

So how do chargers charge the most common large cell storage batteries?

Most cases it’s done by large UPS equipment. Which is an all in one really expensive charger/ fancy light switch.

It stands for Uninterruptible power source. It takes Utility power from either an outlet in your house (battery backup for your computer APC is a brand to name one) and sends it to a bank of batteries to use in the event of power loss. It does this with software and hardware that senses loss of utility, and mechanically moves a switch from utility to battery and back again once utility power is sensed as being back. Its primary purpose is equalizing the cells in the array/ bank and transferring to and from Battery to utility in the event of primary power loss.

It charges the bank, on a constant current/ constant voltage like the one for your car but instead of 120 volts AC to  12.5 volts DC and 5 amps. Its taking usually 480 volts AC and going to 480 volts DC at crazy levels of amps. hundreds of them. As it’s designed to be one of the more efficient means of supplying alternative power to equipment.

Common equipment layout would be similar to this.  Utility power> Utility board> transformer>UPS module / UPM> Battery bank BIS  >  Batteries

This allows administrative controls as well as redundancy in equipment to prevent failure either mechanical or electrical. It also allows for a safer way to work on these systems as you can remove pieces of the equipment from the electrical path lowering chances for other pieces of equipment to lose power. Remember UPS’s are used for back up so redundancy is key here.

These are how it does this. (simple) There is a rectifier that turns AC into DC and supplies it to the batteries for charge. In the event of power loss it will then turn into an inverter and supply battery power in an AC waveform to a transformer that then feeds a panel that in turn supplies power to equipment. This is done in hundreths of a second.

there are a few types. stand by system, Online UPS, line interactive system, . There are some combinations of these in a packaged unit.

So in a typical UPS circuit for a facility of some size there would be an INPUT> Battery charger>control circuit>alarm circuit> Battery > Inverter> automatic transfer switch> Spike surge filter> OUTPUT.

the differences between these 3 types is Standby is just a fancy expensive light switch. It can be any size from small in your house powering your desktop / monitor or as large as a small bus in size powering a facility.

Line interactive is usually the most used in Hospitals and Data centers. It can sense when there are dips up or down in the utility power supplied and push it across the battery bank to filter them out. We call a system that doesn’t have this dirty power. (more on that later.) 

An online system is always ON. It moves power across itself and will usually go from AC to DC and then have a separate circuit doing a DC to DC conversion. I haven’t come across many of these personally.

A line interactive is usually quiet large and the capacity is usually higher than an Online systems run time. That also depends on the amount of batteries and their capacity in the array/bank.

There will be other articles where just these are addressed respectively.


As said earlier there is no way to turn the battery off. There are ways to mitigate your exposure to risk. Such as only connecting them up in chunks. But there is no sure fire way to take away all risk. In the example of lead acid batteries. You have not only exposure to higher lead levels than the average person, but also arc flash risks, shock risks, heavy,  and acid risks.

Mitigation for these are as follows.

ACID : Wear your eye protection, Nitrile gloves (latex will get eaten,) and always have some sort of spill containment/ neutralization on site. 

As acids are acids, you can neutralize them with Baking soda (creates gasses.) Ammonia (also creates gasses) or specifically created “pillows” that do no create gasses as they just absorb the acid solution and contain it inside the vessel.
You can neutralize spills by spreading baking soda or ammonia over the spill and then mopping it up with a mop and bucket/ diluting it enough to go down a drain. Or with pillows, applying the pillow to the spill and repeat as necessary.

Acid won’t eat your skin or melt you. However It will ruin your clothes, make you itch, and if it finds a cut it will make you yip a bit as it will instantly dry out your wound. Prolonged exposure to your skin however will start to damage your dermis.

ARC FLASH : this is a tricky topic as there is almost always going to be some flash when you are strapping up things. Especially if the difference in voltages is apparent, or if you get your polarities incorrect.

But you can mitigate some by knowing your voltage differences and or charging batteries/ using batteries in the same charge state. 

also connecting them up in order. first out last in. is an example of this. 

Lead Levels : Wear your gloves. in the case of lead acid storage batteries. There is no sure fire way to get rid of heavy metals once inside your system. Just wear your gloves, wash your hands thoroughly, and dont touch your mouth or nose.

Shock risk: Don’t touch anything else other than what you are sure isn’t a path to ground. That battery you are touching can and will hurt you. Not an alkaline battery. But anything larger than a car battery, can and will.

Heavy:  Storage batteries are heavy. Its lead. Even small ones can weigh 55lbs. Might not seem like a whole lot but if you move 55lbs wrong you will hurt yourself. And most storage batteries in use on larger UPS equipment isnt no 55lbs. Use mechanical advantage, lift with your legs, watch your fingers & toes, and most importantly don’t force the damn things.

Shorting out terminals: What happens when you connect positive to negative on a battery? well… You ever put a paper clip across a AA battery? you know how it gets real hot really fast? Alright. You ever jump your car? you ever wonder how much potential energy is inside that thing?

There is a rating on your car battery called cranking amps. Some cars need less, some need more. Usually the larger the battery the more amps it can put out. What happens when you connect these leads together is it completes the circuit for the battery and lets the ions freely flow. Only its going to keep flowing back to itself. This reaction keeps going and going. Faster and faster. As this happens things heat up. This can be called Thermal run away.
This is bad. It will keep doing this until something fails. Usually the thing connecting the terminals. Thus ending the connection. But sometimes it goes on for too long, and its failed internally now. This will continue to not only heat up, but also arc. As this reaction happens it creates hydrogen gas. In a critical failure of a system there is enough hydrogen gas to cause an explosion as its not only making gas but also heat.

None of that is a good thing. Not only can you weld your favorite ratchet to a battery but you can also end up with no eyebrows. YIKES.


there is a lot of debate on how to store your batteries. or where they are housed. My experience is with

large form factor storage batteries/flooded: These guys like to sit on steel racking, on float charge, and in a 67 degree F room. They like this because it gives them the most energy capacity, longevity, and thalmic stability.

That also depends greatly on the specifications of whom ever designed and made them.

Alkaline : these guys like a drawer and will stay good for up to about 10 years or so. 

AGM/GEL/Sealed: These guys all like to be charged once in a blue moon while being kept off the cold ground. Any other surface is fine. so long as it’s not below 55f.

Lithium: These guys like to be stored at half charge state and will sit there happily for months on end without any real issue. (there is some debate on this.)

Most of this is still being debated to this day.


SERIES & Parallel (Stacking batteries)

Example of series & parallel batteries. In diagram form.

In a series battery circuit you will “double” your voltage and half your amp output. In a parallel circuit you will keep the same voltage and double your overall capacity. (usually.) You can combine circuit types and get the best of both worlds but usually at a cost. IE Monetary cost as well as over all space.

The example above gives you nice easy numbers to work with for the sake of simplicity.

Your golf carts use a similar set up as to the bottom right of this diagram example.

AC/DC Power circuits: 

There are a few areas that will use both power sources inside the same equipment. Emergency lights is one of these. 

Whether it is the bug eyed kind like so


Both use the same principal.

They get power from a panel. Sometimes 277 volts AC other times 120 volts ac and will use that power to either stay on in the case of the tube lamp fixture or in the even of power loss use sealed batteries to stay on for a minimum time of X amount. Whether that is 5 minutes or 30. It does this with a control circuit which has two inputs on the board and “two” outputs. One input is AC voltage and the other is DC power input. The result is the same. The lights stay on. Or in the case of the bugeye emergency light it only turns on when there is no AC power.

The components inside will be something similar to Control board, Rectifier,  and battery in either emergency lights case. With the added component in the tube lamps case being a ballast.

In a more detailed explanation: 

Emergency lights are required to meet certain criteria and maintain it for their duration of service.
This means the lamps inside them are low power use, their batteries are constant charge rated, and service/ test intervals are regular. Guys/gals in the field know that this isnt always the case. So we have to familiarize ourselves with their form and function. Not every emergency light will look exactly like depicted here, and they certainly will not always be wired up the same way with the same source voltage or batteries inside them. 

But commonly they will always be wired up to AC voltage, and will always have a battery backup inside or close by. Battery backup voltage can vary wildly. As inside the control circuit that tells the lamps I lost power there is also a step down/ buck boost transformer. This will either step up or step down DC voltage supplying power to the lamps. Which can be any number of types/ voltages/ wattages. 

But also inside that circuit there is timer switches, test button circuit, and an alert circuit. Usually all this is contained on one board, but not holden to. 

So in a brief description you will have INPUT>Control circuit> Charger> Battery> Lamps/output

on that control circuit you will have alarm/ alerts, input sensing, and output control. I know this sounds like I am repeating myself but bare with me a moment longer.

The way this equipment uses ac/dc at the same time is on the wrap around / pass through which is contained on the board. This allows for it to always be available for light. Lets the unit self test,  diagnose itself, and also in some cases send out alerts to a control box somewhere inside the building. 

NEC ARTICLES : 700 – 706

This is where you can find CODE for everything from 

Storage batteries, Generator sets, UPS, Separate service, Fuel Cell, and Individual equipment.

This includes not only Solar cells, but Engine generators, and combined ATS systems (automatic transfer switches) As well as where your disconnect should be in relation to the equipment.

Here is where things get a little tricky though. There is also the IEEE standard, Uptime standards, and Emergency system standards. Not to mention manufacturer specifications.

The NEC or National Electric Code is missing a lot of information pertaining to these as there is a lot of finer details that go into these things. It tells you what should be there, and references other articles but is otherwise missing a lot of the finer details like what size Lugs should be used, as well as tables for sizing. Because most systems are designed to SPEC so a lot of these systems are completely custom from the ground up. Sure the basic equipment doesn’t change a whole lot, but the size, scope, and application varies wildly. So take that with a grain of salt. 

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