Newer, more advanced battery analyzers like the Maha MH-C9000 test more than just the battery capacity. If a battery is unable to maintain a load the Maha MH-C9000 returns a result "HIGH" which stands for High Impedance.

What is high impedance? High impedance is another term for "high internal resistance". This means with age or poor maintenance, a rechargeable battery develops a high internal resistance causing the battery to collapse with heavy current demands. So, while the battery may show a 'full charge' on a volt meter and an acceptable capacity level on an analyzer, when put to the test the battery is not able to sustain the current draw for the application causing a low battery indicator. 

Are all rechargeable chemistries affected by high impedance? Yes, all rechargeable chemistries are affected by high impedance, but not in the same way. NiCad has the lowest starting internal resistance of common rechargeable chemistries, and after a hundred uses it may still maintain a low internal resistance. NiMH batteries start with a higher internal resistance and will develop higher resistance quicker than NiCad batteries, which is why most NiMH batteries have fewer charges available than a NiCad battery. Li-Ion batteries are between NiCad and NiMH, however due to the chemical construction of Li-Ion cells, cell oxidation causes irreversible high resistance with age.

Can high impedance be reversed? Once high impedance reaches a critical level in a rechargeable cell it is almost impossible to recover the cell to a highly useful state. Although with proper reconditioning, NiCad batteries (and in some cases Lead Acid batteries) may recover to a usable state for a brief period. NiCad batteries can be reconditioned with chargers designed to provide a reconditioning cycle.

Many battery packs are made up of individual battery cells. When batteries are purchased to be made into a pack it is a good idea to equalize the charge on the batteries before building the pack.

Equalizing the batteries is nothing more than ensuring the voltage on each cell is within a very close range at the same state of charge (i.e. fully charged).

If you do not equalize the batteries properly before building a pack, the charge and discharge cycles will be harder on some of the cells and will effectively shorten their life. Once a cell fails the entire pack will be weaker because of the one defunct cell.

There are a couple of ways to equalize a set of batteries:

• The first way is to connect the set that will go in the pack in a parallel configuration. Leave them in this state for at least 24 hours. The cells that have a higher charge will charge the ones with a lower charge and they will all equalize.
  


• The second way is to put them in a parallel configuration again, but charge them together at 1.4V, current limited to total capacity divided by 40 (e.g. 3000mAh/40 => 75mA current limit). This may be faster than equalizing via the previously mentioned parallel method and you will start with a charged set of cells when you make the pack. Be sure to have an accurate voltmeter to check the charge voltage.

With so many batteries available, it is often difficult to know how they should be properly disposed; can you toss it in the normal household garbage, or should it be taken to a hazardous waste location? 

Everyday batteries include:

Alkaline Batteries (flashlights, calculators, toys, smoke alarms, clocks, etc.) are classified as non-hazardous waste by the federal government. Most U.S. states, with the exception of California, can include with their normal household waste. California requires disposal of these batteries in accordance with the California Universal Waste Rules.

Button Batteries (watches, hearing aids, toys, greeting cards, remote controls, etc.) come in a variety of materials. They often contain mercury, silver, or lithium, and should be returned to the manufacturer when purchasing a new battery. Alkaline button batteries and zinc/air can be disposed of with normal household waste.

Li-Ion Batteries (laptops, camcorders, cell phones, etc.) are classified by the federal government as non-hazardous waste, however they can be recycled.

NiMH Batteries (power tools, camera, cell phones, computers, etc.) are rechargeable and can be recycled. NiMH are considered a non-hazardous waste in most U.S. States, with the exception of California. Check the California Universal Waste Rules.

NiCad Batteries (power tools, camera, cell phones, computers, etc.) are recyclable. NiCad is considered a hazardous waste by the U.S. government, and should be brought to a recycling facility.

Wet Cell Lead Acid Batteries, (automotives and tractors) also known as flooded batteries can be recycled at most retailers that sell lead-acid batteries.

AGM Lead Acid Batteries, (wheelchair, ATVs, home alarm, metal detectors, etc.) or Absorption Glass Mat Batteries can be reconditioned or recycled into new products. Collection services are available at most automotive stores, landfills, transfer stations, and service stations.

The Rechargeable Battery Recycling Corporation (RBRC), a nonprofit public service, targets four kinds of rechargeable batteries for recycling: nickel-cadmium (NiCad), nickel metal hydride (NiMH), lithium ion (Li-Ion), and small-sealed lead. Visit their website http://www.rbrc.org to find recycling locations near you.

The rule of thumb is that most rechargeable batteries are recyclable. Look for the RBRC logo or the standard recycling logo to know if your battery is recyclable. The US government states it is safe to dispose of alkaline and other non-rechargeable batteries with the household garbage. If you are concerned about the environmental effects, then it is time to switch to rechargeable batteries. Rechargeable batteries can be used over and over again, then recycled. You can learn more about battery disposal at the EPA website. Contact Zbattery.com at 1-800-624-8681 or sales@zbattery.com to learn what rechargeable battery options are ideal for your application.

The process shown here uses a lemon, copper in the form of a penny, and zinc in the form of a drywall anchor. Although neither of these metal items are pure copper and zinc they have enough copper and zinc on their surfaces to work, and they are readily available items anyone can find.

Simply insert the penny and drywall anchor into the lemon as shown. These become your positive and negative terminals.

When hooked to a volt meter, as shown, the cell measures 0.4V. What is happening is a chemical reaction at the copper along with a chemical reaction with the zinc in the lemon acid. So there are 2 reactions working together and each one is called a “half reaction”. Each set of metals in electrolyte (lemon juice in this example) is a single cell. As long as the lemon is in one piece, we have 1 battery cell.

Although the lemon battery shows voltage the current is far to low to support even the simplest current demands. To find out how to increase the current to be able to power for example a light bulb, or what chemical reactions are happening inside the cell, keep reading. If however, all you want to do is make a lemon cell, you can stop reading.

Here are the reactions in a lemon cell:
With the zinc: Zn → Zn2+ + 2 e-
At the copper: 2H++ 2e- → H2

What we want a battery to do is have electrons to flow through a wire from which we can utilize to power things. In each of the reactions in the lemon cell, the e-minus indicates electrons that are removed from the zinc to make a zinc ion and these electrons go over to the copper where they take hydrogen ions and make dihydrogen. All chemical cells work in a similar way. Other metals and electrolytes can be used, but one half of the half reactions will create an ion and the other half will reduce an ion. In our lemon cell these ions will be flowing through the electrolyte (the lemon's acid) while the electrons are flowing through the wire on our voltmeter. It happens spontaneously if the circuit is complete but the reaction stops almost completely when ions cannot be made because no electrons are flowing through the wire.

Thus, any chemical reaction creating an ion that can be coupled via ion transfer with another reaction that reduces an ion can create a battery cell. The potential difference in the ion creation/ion reduction determines the amount of power the cell will have. Dissimilar metals are ideal for this, and there are also some other non-metal materials that can do the same thing. That’s why there are a number of different kinds of battery cells. Each cell has different reactions which have different properties; so we can apply the right properties as required to get the job done.

You don’t see too many copper-zinc-lemon acid batteries in the world actually powering anything. So let’s look at our lemon cell again. What properties does it have that we would want to use it in our test? It’s got common materials that are easy to get and put together. That’s it. Well, actually that and it makes a lovely twist in an after-test refreshment (remove the metal parts for best results). But a lemon cell doesn’t deliver a lot of current, and the voltage is rather low compared to other battery cells even when it is at its maximum possible voltage. In fact, if you look around the internet you’ll find a number of people that made lemon cells with voltages higher than 0.4V. Many of them got 0.8V or higher. Looking at the possible differences in these tests can give us more insight into the world of batteries. So what are they doing that we aren’t?

Maybe they use bigger lemons? No, that's not the reason, and I’ll explain why. We can determine just how high the voltage in a lemon can get. We can even determine the theoretical voltage of any cell by looking at the half reactions and the differences in their potentials. Chemists have made tables with values for different metals and materials. Looking at the tables we can theoretically make a battery cell up to about 6V using different materials. And the highest theoretical voltage for a cell using water based electrolyte is a little over 2V. The theoretical max is about 1.1V for a lemon cell. So that’s the highest possible voltage you’ll see in a lemon cell and factors that affect the voltage will be the purity of the materials, both metals and electrolyte, and placement (construction). Maximizing the reaction is the key to the highest possible voltage. Maximizing the reaction is what the other lemon battery experimenters were doing to get a higher voltage. What we could do to get better voltage is to wait for the materials to settle in and have the greatest surface area available in the reaction, use more pure metals, or perhaps break up the inside of the lemon to get the electrolyte to flow better (or maybe some lemons are better than others).

So doesn’t lemon size matter? If we had a lemon as big as a truck and sheets of pure copper and zinc the size of picture windows, wouldn’t the voltage be even a little higher? Nope; the best you’ll see is still 1.1V. But aren’t there batteries, like powertool batteries or car batteries that are higher than 6V? There are. That’s the difference between a battery and a cell. If cells are attached to each other in series, their voltages add together. Put those in-series cells together in one container and you have a battery. So if we get 100 lemons and 100 pennies and 100 drywall anchors we could put each cell together in a row, each with ones drywall anchor hooked to the next one’s penny until they are all hooked together, except the first one’s penny and the last one’s drywall anchor. If we check the voltage of this chain at that first penny and last anchor, we could theoretically have 100 x 1.1V, or 110V! Wow, that’s like house plug voltage! Couldn’t that be dangerous? No, not really. Hooking all those lemon cells together adds voltage, but not current. And the current delivered by a lemon battery is tiny, as will be shown in a moment.

There is another way to hook the cells together; in parallel. When we put our 100 cells in a row, but this time hook all the pennies together and all the drywall anchors together the voltage would stay at 1.1V. So what good did all that slicing and poking do if all we get is the same voltage we started with? We got capacity. It’s just a little harder to see. If we ran our lemon cell down, using a device that ran on less than a volt, and measured how much energy we got out of it before it went dead, we could call it “1 lemon worth of energy”. Our 100-lemon battery hooked in parallel would also run that 1 volt device, but now we can run it 100 times as long (all things being equal) extracting all 100 lemons worth of energy. This is, in effect, making a bigger single cell. That truck size lemon may have had only 1V too, but it would run for a very, very long time. But there is something else putting together those lemons in parallel would do for us. Let’s look at an example to demonstrate the power of a parallel connection. Can our lemon battery light a 1V light bulb? A bulb for a Mag Solitaire flashlight (it runs on 1 AAA battery) will glow with 1V, and even a little less. However, even if we get the full 1.1V out of our lemon battery, it won’t do anything at all to Solitaire bulb. The reason is that the battery is pushing enough voltage through the bulb, but the bulb is trying to get more amperage from the battery than it can supply. Another way to say it is “the big hose is full of water, but the water just isn’t moving”. However, with enough lemons in parallel, or with that truck sized lemon, we’ll have no trouble getting that flashlight bulb to light. It’s just a matter of getting enough reaction going to supply the electron needs of a lit bulb.

By: Cori Hatheway

Valve Regulated Lead Acid (VRLA) Batteries are low maintenance sealed lead-acid batteries. They limit inflow and outflow of gas to the cell – thus the term “valve regulated”. VRLA batteries are unique due to the fact that they contain a “starved” electrolyte (acid), which is absorbed or immobilized in a separator.

Electrolytes are commonly absorbed or immobilized in two ways:

Absorbed electrolyte: a highly porous mat made from microglass fibers is partially filled with electrolyte, acting as a separator. Also called AGM for Absorbed Glass Mat.

Gelled electrolyte: Fumed silica is hardened into a gel that free-floats in its container. During charges, the gel dries more creating cracks and fissures develop between the positive and negative. Often referred to as Gel Cell.

Advantages:

·         Maintenance-free

·         Moderate Life

·         High-rate capacity

·         High charge efficiency

·         No “memory effect”

·         State of charge can be determined by measuring voltage

·         Relatively low cost

·         Available in a variety of sizes and voltages from single cell units (2V) to 48V or higher

Disadvantages

·         Cannot be stored in discharged condition

·         Relatively low-energy density

·         Lower cycle than NiCad batteries

·         Thermal runaway can occur with incorrect charging or improper thermal management

·         More sensitive to temperatures than conventional lead-acid batteries

According to BatteryUniversity.com, “heat reduces the life of VRLA. Most batteries are enclosed in spaces without proper ventilation or cooling. Every 8°C (15°F) rise in temperature cuts the battery life in half. A VRLA battery, which would last for 10 years at 25°C (77°F), will only be good for 5 years if operated at 33°C (95°F). Once damaged by heat, no remedy exists to improve capacity.”

Simple Guidelines

·         Always store in a charged condition. Never allow the open cell voltage to drop below 2.10V. Apply a topping charge every six months or when recommended.

·         Avoid repeated deep discharges. Charge more often.

·         Prevent sulfation and grid corrosion by choosing the correct charge and float voltages. If possible, allow a fully saturated charge of 14h.

·         To reverse sulfation, raise the charge voltage above 2.4V per cell for a few hours.

·         Avoid operating lead-acid at elevated ambient temperatures.

VRLA Uses:

·         Fork Lifts

·         Uninterruptible Power Supplies

·         Emergency Lighting

·         Wheelchairs

·         Telecom Back-Up Power Supplies

·         Lawn and Garden Tools

·         Engine Starters

Proper care and maintenance will prolong the life of any product, including your rechargeable batteries. With appropriate care and use, you should expect 2-7 years from most rechargeable batteries. Rechargeable cordless phone batteries can last 1-2 years with the right use and care.

To get the most life out of your rechargeable batteries follow these 10 simple rules:

·         Never overheat or incinerate your batteries. Batteries that are exposed to extreme heat or fire can explode. Locations that are too warm will reduce a battery's life. Store all batteries in a cool, dry place. Many still store batteries in the refrigerator thinking that it extends the life; although the refrigerator is cool, it is not an optimum location due to moisture.

·         New rechargeable batteries come in a discharged state and must be charged prior to use. Both new batteries, and batteries which have not been used for a long period of time, should be conditioned 3-4 times before they can achieve maximum capacity.

·         Avoid dropping or damaging the battery case to avoid exposure of corrosive contents.

·         Don’t short the connection. Keep batteries neatly organized, and do not let the ends touch. A short-circuit can cause severe damage to the battery, or even cause it to explode.

·         Do not mix and match batteries. Always use the same chemistry, capacity, and brand. Never mix rechargeable and non-rechargeable batteries.

·         Batteries that are not in use for a month or longer, should be removed from chargers and stored in a cool, dry place.

·         Due to engineering improvements over the years, "memory effect" now rarely occurs. When memory effect does occur it is primarily in NiCad batteries. NiMH batteries are rarely affected, and Li-Ion batteries are NEVER affected.

·         Select a charger that prevents overcharging and is designed specifically for your battery's chemistry.

·         Do not carry NiMH rechargeable batteries loosely in your pocket. Coins or other items could cause them to short, causing severe burns and fire.

·         Properly recycle used rechargeable batteries. Go to www.rbrc.org for your recycling location.