Understanding battery capacity: Ah is not A
I used battery holders for eight “C” alkaline cells on my robot after not finding a 12V, 1A battery.
My earliest electronics projects and my first robot were powered by regular alkaline batteries, and I didn’t think about current or the capacity of those batteries. The batteries were prominently labeled “1.5V”, and I was happy in my understanding that putting four in a battery holder got me to 6 volts; when the motors slowed down, it was time for new batteries. When I began designing my second robot, I found some 12V, 1A motors (what a “1-amp motor” might mean is a topic for another post) and promptly wasted many hours dragging parents and teachers to Radio Shack and car parts stores looking for a 12V, 1A battery. No one understood that the batteries were labeled with capacity, not current, and since the smallest 12V motorcycle and alarm system batteries in town were 3Ah or 4Ah, I went home empty handed. I ended up using alkalines. Apparently, once the battery capacity wasn’t in my face, I forgot about my concern that they would force too much current into my motors.
I made many common mistakes in going about my battery selection:
- Not understanding that my circuit would draw whatever current it wanted from the battery, as opposed to the battery forcing a given amount of current into the circuit.
- Thinking that my motors would draw a fixed amount of current.
- Confusing current and capacity.
- Ignoring the “h” in “Ah”
- Forgetting about a property, such as capacity, as soon as it wasn’t in my face.
The first two points are complex enough that further elaboration would merit their own posts; today I want to FOCUS on some technical details of battery capacity and current and touch on the sloppy attitude that leads to the last two mistakes.
A battery stores energy; the “capacity” is how much energy it can store. Energy is measured in joules, abbreviated J, but it can also be expressed in different units such as watt-hours, abbreviated Wh (for larger quantities, such as residential electricity use, kilowatt-hours (kWh) are used; a kWh is a thousand Wh). This is similar to the way area can be measured in acres or in square miles: there are units specifically for area, such as acres, but you can also arrive at a measure of area by multiplying length by length, to get mile-miles, or the less awkward square miles. (The hyphenation imposed by English grammar does not help matters since the hyphen looks like a minus sign when we are actually multiplying the units together.) Watts and watt-hours are generally good units for electronics since they are easily related to voltage and current and since typical batteries that you can hold in your hand will have a capacity of a few dozen watt-hours.
In the case of a typical battery, where we can assume a constant voltage, we can replace watts with volts multiplied by amps. A 12-volt, 1 amp-hour (abbreviated Ah) battery and a 6-volt, 2Ah battery each store 12Wh, but the voltage is usually a critical parameter for a battery, and once a voltage is selected, the capacity can be specified by the amp-hour rating. The value in using the amp-hour is that it makes explicit our multiplication of rate, the amp, and time, the hour: a battery rated for one amp-hour can provide a current of one amp for about one hour, two amps for about half an hour, or 0.1 amps for about ten hours. I say “about” because the exact capacity will depend on the current.
The current and capacity for a battery are like the speed and range of a car. If your car has a range of about 300 miles, you can go 30 miles an hour for ten hours, or 60 miles an hour for five hours. Your efficiency will get worse with speed, so by the time you go 60 miles per hour, you might run out of gas after only four hours, for a range of 240 miles. Going back to my battery search, looking for a 1-amp battery was like looking for a car with a speed of 60 miles: 60 miles isn’t even a speed, and even if I revised my search to a car that could go 60 miles per hour, it still wouldn’t be a useful specification to look for. Most batteries on the scale I was looking at can deliver one amp, just like most cars can go sixty miles per hour. The maximum available current, like the maximum speed of the car, might be a more reasonable specification to search for, though providing those kinds of specifications might make the respective manufacturers nervous.
It is reasonable, though, to consider the maximum current a battery can safely deliver. That value will depend on all kinds of things, including the chemistry of the battery, but the maximum discharge rate is almost always tied to the capacity. That means that given a particular technology, a battery with double the capacity can deliver double the maximum current. Batteries are often specified with a discharge rate in terms of C, where C is the capacity of the battery divided by hours. For example, for a 2Ah battery, C is 2A. If the battery has a maximum discharge rate of 10C, the maximum current is 20 amps. It’s good to keep in mind that a 10C discharge rate means a battery life of less than 1/10th of an hour, and with the loss of capacity that a high discharge rate generally causes, the battery life would be less than five minutes.
As I tried earlier to recall what happened with my failed battery search, I was struck by the extent to which I ignored the “h” in the “Ah” specification and the ease with which I forgot about my critical “1-amp battery” requirement when I returned to the alkaline batteries. Unfortunately, this kind of carelessness or sloppiness is common, especially for beginners who might already be overwhelmed by all the information they need to sort through and who have not yet had the experience of losing time and destroying hardware because of inattention to details. I do not have any particular solution to this problem beyond reminding you to pay attention and think about how things should work before just hooking things up. Be on the lookout for contradictions; seeing “Ah” where you expect “A” should definitely make you very uneasy and lead you to reevaluate your expectations.
I will wrap up this article with some example battery capacities.
- A typical alkaline or NiMH battery in the standard “AA” size has about 2000 to 3000 mAh (or 2 to 3 Ah). With a cell voltage of 1.2 V to 1.5V, this corresponds to 2 to 4 Wh per cell. When multiple cells are used in series, as with the use of a battery holder or most pre-made battery packs, the voltage goes up but the capacity in amp-hours stays the same: an 8-cell NiMH pack made of AA cells will have a 9.6 V nominal voltage and a 2500 mAh capacity. There can be quite a range in capacities depending on the quality of the batteries. For larger cells, such as C and D size, the capacity should go up approximately proportionally to volume, but some cheap units (they’re usually light) can have the same capacity as the smaller cells. Alkaline cells have a more pronounced drop in capacity as the current drawn out of them goes up, so for applications requiring several hundred mA or more current, NiMH cells of the same size could last significantly longer. For low-current applications that need to run for months, alkaline batteries can last much longer because NiMH cells can self-discharge in a few months.
- 9V alkaline batteries can be convenient for their high voltage in a small size, but the energy density (watt-hours per given volume or weight) is the same as other batteries with the same chemistry, which means the capacity in amp-hours is low. In approximately the same size as an AA cell, you get six times the voltage, so you also get about six times less in the Ah rating, or about 500 mAh. Given the high losses incurred from discharging in anything under a few hours, 9V batteries are impractical for most motors and therefore for most robots.
Coin or button cell batteries.
- Coin or button cell batteries vary in size and chemistry, but you can generally expect 1.5 to 3 volts with a few dozen to a few hundred mAh.
12V, 8Ah sealed lead-acid battery.
- Lead-acid batteries are popular for larger projects since they are usually the lowest-cost option and are widely available. Sealed lead-acid or gel-cell batteries are available in 6 V and 12 V versions (other multiples of 2 can be found), with the 12 V versions weighing about a pound per amp-hour. 12 V car batteries store a few dozen amp hours, and they weigh a few dozen pounds.
11.1V, 1800mAh Li-Po battery.
- Lithium-based rechargeable batteries have around double the energy density of alkaline and NiMH batteries by volume and even better improvements by weight. These newer batteries are far less standardized in terms of battery size and shape, but since they are usually intended for applications where capacity or maximum battery life are important, these batteries usually have their voltages and capacities prominently labeled.
Introduction to Jan’s blog
by Jan. 12 November 2010 My name is Jan Malášek, which is a Czech name, so the “J” is pronounced as an English “Y” (if you care, we can go over the last name in person, or.
Know your units
by Jan. 19 November 2010 How many volts of current are there in a bolt of lightning? That’s the kind of stupid question your local news anchor might ask while bantering.
2 Комментарии и мнения владельцев
Thanks for the article Jan!
It’s probably worth noting, particularly for lead-acid batteries, that the capacity is usually listed assuming that the battery will be discharged over a 20 hour period. If you’re using it in relatively high current applications (i.e. robotics or motors of any kind) then you can expect almost half of that. This is something that caught me out when I was looking at battery options.
Great comment; I’m sad that I neglected to mention that. Another variable to consider is how far the battery is allowed to discharge before being considered fully drained.
BU-303: Confusion with Voltages
A battery is an electrochemical device that produces a voltage potential when placing metals of different affinities into an acid solution (electrolyte). The open circuit voltage (OCV) that develops as part of an electrochemical reaction varies with the metals and electrolyte used.
Applying a charge or discharge places the battery into the closed circuit voltage (CCV) condition. Charging raises the voltage and discharging lowers it, simulating a rubber Band effect. The voltage behavior under a load and charge is governed by the current flow and the internal battery resistance. A low resistance produces low fluctuation under load or charge; a high resistance causes the voltage to swing excessively. Charging and discharging agitates the battery; full voltage stabilization takes up to 24 hours. Temperature also plays a role; a cold temperature lowers the voltage and heat raises it.
Manufacturers rate a battery by assigning a nominal voltage, and with a few exceptions, these voltages follow an agreed convention. Here are the nominal voltages of the most common batteries in brief.
The nominal voltage of lead acid is 2 volts per cell, however when measuring the open circuit voltage, the OCV of a charged and rested battery should be 2.1V/cell. Keeping lead acid much below 2.1V/cell will cause the buildup of sulfation. While on float charge, lead acid measures about 2.25V/cell, higher during normal charge.
In consumer applications, NiCd and NiMH are rated at 1.20V/cell; industrial, aviation and military batteries adhere to the original 1.25V. There is no difference between the 1.20V and 1.25V cell; the marking is simply preference.
The nominal voltage of lithium-ion is 3.60V/cell. Some cell manufacturers mark their Li-ion as 3.70V/cell or higher. This offers a marketing advantage because the higher voltage boosts the watt-hours on paper (voltage multiplied by current equals watts). The 3.70V/cell rating also creates unfamiliar references of 11.1V and 14.8V when connecting three and four cells in series rather than the more familiar 10.80V and 14.40V respectively. Equipment manufacturers adhere to the nominal cell voltage of 3.60V for most Li-ion systems as a power source.
How did this higher voltage creep in? The nominal voltage is a function of anode and cathode materials, as well as impedance. Voltage calculations include measuring the mid-way point from a full-charge of 4.20V/cell to the 3.0V/cell cutoff with a 0.5C load. For Li-cobalt the mid-way point is about 3.60V. The same scan done on Li-manganese with a lower internal resistance gives an average voltage of about 3.70V. It should be noted that the higher voltage is often set arbitrarily and does not affect the operation of portable devices or the setting of the chargers. But there are exceptions.
Some Li-ion batteries with LCO architecture feature a surface coating and electrolyte additives that increase the nominal cell voltage and permit higher charge voltages. To get the full capacity, the charge cut-off voltage for these batteries must be set accordingly. Figure 1 shows typical voltage settings.
|Nominal cell voltage
|Max charge voltage
|Classic nominal voltage of cobalt-based Li-ion battery
|Marketing advantage. Achieved by low internal resistance
|Surface coating and electrolyte additives. Charger must have correct full-charge voltage for added capacity
|Surface coating and electrolyte additives. Charger must have correct full-charge voltage for added capacity
Figure 1: Voltages of cobalt-based Li-ion batteries.End-of-charge voltage must be set correctly to achieve the capacity gain.
Battery users want to know if Li-ion cells with higher charge voltages compromise longevity and safety. There is limited information available but what is known is that, yes, these batteries have a shorter cycle life than a regular Li-ion; the calendar life can also be less. Since these batteries are mostly used in consumer products, the longevity can be harmonized with obsolescence, making a shorter battery life acceptable. The benefit is longer a runtime because of the gained Wh (Ah x V). All cells must meet regulatory standards and are safe.
The phosphate-based lithium-ion has a nominal cell voltage of 3.20V and 3.30V; lithium-titanate is 2.40V. This voltage difference makes these chemistries incompatible with regular Li-ion in terms of cell count and charging algorithm.
How To Test AA Battery Using A Voltmeter Multimeter
Electrical devices like toys, flashlights, and remotes generally feature AA batteries. When these devices stop working, their batteries are the usual suspects. To test them, you must know how to use a voltmeter, a multimeter, and other special devices.
Since most people are unfamiliar with this device, they opt for the fastest replacement method. This method involves replacing the existing battery with a new one to see if all functions will be restored.
If the new battery powers the device, it is assumed that the previous one is now bad or damaged. Using any metering device, on the other hand, can help you with all sorts of batteries, not just AA types.
This guide will teach you how to test AA batteries with a voltmeter, multimeter, and other alternative methods. You will also learn about the major principles guiding each technique.
What Should the Voltage Read on an AA Battery?
Before testing, knowing what a good or bad reading would look like in an AA battery is essential.
While manufacturers produce AA batteries with different ratings, most ratings usually sit between 1.25 and 1.5 volts. For a used battery, you should expect a lower reading.
How to Test AA Battery
There are various methods you can use to test AA batteries. Most of these procedures measure the electrical resistance of a battery in a state of rest.
Without further ado, let’s go through the various ways you can test an AA battery:
How to test an AA battery with a voltmeter
- Testing an AA battery with a voltmeter begins with setting the direct current voltage (DCV) to 20.
- Connect the red probe of the voltmeter to the battery’s positive terminal and jot down the reading. The reading here indicates how much charge is left on the battery.
- At this stage, if the reading is low or zero, such a battery is dead and should be replaced. This test must be performed more than once for an accurate reading of an alkaline AA battery.
- If the value is at 1.5 or very close, such a battery is still okay for use.
How to test an AA battery with a multimeter
The process is almost similar to a multimeter. The only difference is that it involves connecting two (red and black) probes to the battery terminals.
- It begins with adjusting the DCV setting on your meter to 2 or 20 volts.
- Connect the red probe to the battery’s positive terminal and the black probe to the battery’s negative terminal.
- Check the meter’s dashboard for readings that should appear in millivolts (mV).
- If there is no indication of power being generated by the battery or no reading, the battery is no longer functional and should be replaced.
Alternative ways of testing AA battery
If you do not have a voltmeter or multimeter, can you still test an AA battery? Yes, you can use any of these alternative methods:
Test the battery in a device
This is similar to the replacement method I discussed earlier. The only difference here is that you will insert the suspected battery in another device instead of replacing it with a new one in the same device.
If the battery you think is spoiled works in another device like a remote or video game controller, it means the battery is still functional. In other words, your troubleshooting efforts should be focused somewhere else.
Test the battery via a drop test
Drop tests work best for alkaline (non-rechargeable) AA batteries. This process involves dropping an AA battery’s bottom (usually the negative terminal) on a hard surface.
If the battery bounces lightly, there is a high chance it is still functional. However, if it bounces remarkably, such a battery is likely dead and should be replaced.
Does shaking an AA battery help?
Sometimes, when you shake a dead battery, it may become functional again.
However, this only works with AA batteries with liquid energy storage and will not always work.
What is the average life of a AA battery?
AA batteries can last up to 2 hours or more. Brands like Duracell can even go up to 10–20 hours with low-powered devices like flashlights.
Do unused AA batteries expire?
Unused AA batteries expire. To know their best if used by (BIUB), check the upper part of the battery.
It is safe to say there is more than one way to test AA batteries. For those with a voltmeter or multimeter, you can follow the processes above to know the amperage of AA batteries successfully. In this case, readings to expect may range from 1.25 to 1.5 volts or more.
You can opt for any alternative methods for those without a metering device. However, you should be aware that these methods are not error-proof and will not provide you with any readings.
I hope you found this guide helpful. A deteriorating battery warrant testing. Here is how to tell if a battery is damaged.
THE COMPLETE GUIDE TO AAA BATTERIES
AAA batteries are among the top 5 highly in-demand power cells. These 5 most wanted power solutions are AA, AAA, C, D, and 9V batteries as they are commonly used for domestic, industrial, and even general purpose. So, what is a Triple-A battery? How is it different from a Double-A battery or the other cells?
In this article, I am going to give you the compact yet complete guide to AAA batteries for all your battery requirements for various applications and devices for your home, office, business, or any industry and individual needs.
WHAT IS AN AAA BATTERY
AAA batteries are smaller than AA battery cells. A single cell has a dimension of 44.5 mm in length and 10.5 mm in diameter. Its weight, nominal voltage, and battery designations or technical names vary on the specific battery chemistry. These can be both disposable and rechargeable batteries. These can be used as a single cell or in multiple cells, depending on the particular battery requirement of your specific devices and applications.
AAA BATTERY TYPES
As already mentioned earlier, AAA power cells can be both rechargeable and disposable batteries. To determine whether your AAA batteries are rechargeable or disposable, you must check the battery chemistry as some are just designed to be disposable or primary in nature while others can have both variants. This is also true with the nominal voltage. For instance, Alkaline batteries have a nominal voltage of 1.5V. On the other hand, Nickel Metal Hydride (NiMH) cells have a nominal voltage of 1.2V while still others have 1.25V or 3.7V depending on certain chemistries.
Primary or disposable batteries are the ones that are disposed of after it has been used for a certain period as indicated by the manufacturer. It cannot be recharged using a charger. These are somewhat cheaper than rechargeable ones. However, the regular battery replacement and shelf life may affect the costs or your own budget. Batteries of such chemistry as Zinc-carbon and Lithium Iron Disulfide (Li-FeS2) are solely primary variants. Alkaline batteries have primary variants, too, while some are rechargeable ones.
Primary batteries are your on-the-go, ready-to-use batteries for your portable devices whether you are outdoors or just staying indoors. Some consumers do not have to worry about using disposable batteries as some highly authentic brands can last for up to 10 years or even more.
There are also some primary AAA batteries that are just intended for low drain devices so you should make sure that you use this type of battery for low drain devices only to maximise its full potential and power capabilities. On the other hand, there are also AAA cells that are professionally designed for powering high drain devices and applications (like digital cameras and cell phones) so you better make sure whether your device or certain application requires high drain or low drain power solutions for optimal functions.
This is the reason why Procell Alkaline AAA for low drain and general-purpose batteries exist. Its partner, the Procell INTENSE Power AAA batteries also exist for high drain (has high output voltage) professional devices. Other batteries used to power specific devices are the industrial batteries from such original brands as Energizer, Varta, Duracell, and many others.
ALKALINE AAA BATTERY FEATURES AND APPLICATIONS
Alkaline batteries derive energy from manganese dioxide and zinc metal reaction. These have longer shelf life and higher energy density compared to zinc carbon batteries.
Common applications include:
Alkaline AAA batteries are environment-friendly, mercury-free and the latest developments even design such batteries to be totally leak-free.
PRIMARY LITHIUM AAA BATTERIES : FEATURES AND APPLICATIONS
Here are some features of Lithium AAA batteries that you can compare or even contrast to the Alkaline variants.
CARBON ZINC AAA
A Carbon Zinc AAA batteries are used for general and heavy-duty purposes. However, this chemistry is the cheapest disposable type. This is only applicable for low drain devices such as clocks and remote controls.
RECHARGEABLE AAA BATTERY
AAA rechargeable batteries are the opposite of the primary ones. These do not just last for about 3-4 months of use that you can dispose after that given timeframe. These are capable to be recharged and have a slight difference in its physical appearance than the disposable cells. Most of these AAA rechargeable batteries are sold along with a suitable charger so consumers do not have to worry in finding a compatible charger. However, other rechargeable Triple A batteries are also sold without a charger, as what happens in those sold in glittering packs of 2, 4, or any other variant that you can usually find in most convenience stores. If this is the case, try to find a compatible AAA battery charger or even a charger that can charge both AA and AAA. In some cases, you can also find a universal charger. Just make sure this can work well on your specific battery type and device requirements.
Triple A rechargeable batteries are classified as rechargeable Alkaline, Li-ion, Nickel Metal Hydride (Ni MH), Nickel Zinc (Ni Zn), Nickel Cadmium (Ni Cad). Check their distinct features and some similarities for your specific battery requirements.
RECHARGEABLE ALKALINE AAA
The rechargeable Alkaline battery chemistry is usually called as the RAM or RAMs. This stands for Rechargeable Alkaline Manganese. RAMs are the only battery in the market that have both benefits of having higher voltage and long shelf life at the same time, in the same package. However, some drawbacks also exist. For instance, the battery capacity is reduced after every cycle. This same thing also happens with the voltage.
NICKEL METAL HYDRIDE (NiMH) AAA
This chemistry works well in high drain devices (e.g., flash units, handheld GPS devices, digital cameras). These cells are quite common too, so you will not have to waste your time and energy looking for these in further places. Its wider accessibility among others makes the NiMH batteries even more popular. The only drawback that most consumers see here is that its nominal voltage is 1.2V, which is a bit lower than other rechargeables.
NICKEL ZINC AAA
This chemistry was introduced in 2009 by PowerGenix as Nickel Metal Hydride (NiMH) alternative. It works well in rechargeable devices. Compared to NiMH, the Nickel Zinc chemistry lasts longer in high drain devices. Its higher voltage of 1.65V makes lighting even brighter. However, this battery chemistry is only available in AAA and AA battery sizes.
LITHIUM-ION AAA (10440)
This rechargeable battery works great in high drain devices. However, just make sure you do not put these cells in 1.5V devices as the voltage of a Lithium-ion cell is 3.7V. Doing so could fry your batteries. These also require a special charger. NiMH chargers should not be used here. For safety purposes, Lithium-ion AAA battery size has been technically named as “10440” to separate it from other AAA batteries since its nominal voltage is 3.7 volts. Some popular applications of the Lithium-ion battery packs are digital cameras and laptop computers.
NICKEL CADMIUM (NiCad)
Although Nickel Cadmium (NiCad) is obsolete, it is also a rechargeable battery that works with a high drain device. Being the oldest, it has the lowest capacity compared to any other rechargeable battery. It is also toxic, having high self-discharge, and low voltage.
FREQUENTLY ASKED QUESTIONS (FAQs)
I have gathered here a list of the frequently asked questions (FAQs) that could help you understand AAA even more and get the most benefits from this battery size for powering up all your compatible devices. You may also find terms here that may not be related to Triple-A cells but are associated with them.
How long does AAA rechargeable batteries last?
On average, rechargeable AAA batteries last for about 10 years. These batteries are pre-charged and ready to use when you bought them from stores and suppliers. It can hold its charge for a year while its shelf life is good for 10 years.
Can you mix different brands of batteries?
No. It is not advisable to mix different brands of batteries. This is for the fact that the voltage and battery chemistries vary across different brands and battery types. This can also lead to poor performance and battery leakage. To get the best results, it is highly recommended that you must replace your batteries with the same size, brand, voltage and chemistry for your device’s optimal function and the users’ overall safety.
How to obtain a better battery life?
Here are some tips to help you extend battery life. Try removing batteries from devices and appliances when not in use. If you have some gadgets that you do not use frequently, remove the batteries as soon as you have finished using them. To optimize the use of your batteries, store them in normal room temperature. Place some protective cover on both ends to prevent the terminals from getting into contact with other metallic objects.
Does it matter what type of battery I use in my device?
Yes, it does. It is always best to use the same type of battery, brand, chemistry, and voltage from your device’s manufacturer as much as possible. If in any case, this is not possible, try to get the best replacement batteries recommended by the manufacturer or direct supplier.
Why is changing all batteries in your device important?
Once you see that that there is a malfunction or the performance of your device is gradually degrading than it should do, it is high time to change all the batteries in your device at the same time. But why should you replace all the batteries together at the same time? This is for the fact that replacing one or two batteries only in that device will just drain the new ones. The partially used batteries will consume the energy stored in the newly replaced cells and this will still result in poor performance. It can also destroy your devices eventually.
Where to buy a Triple A battery?
Buy your AAA batteries here at HBPlus Battery Specialists and get more savings for unbeatable quality you can always trust. The Battery Specialists offer you a wide range of choices and world-class brands of Triple A batteries and other power solutions for all your specific requirements. Order from the comforts of your home as we offer faster shipping for orders within Australia, New Zealand, or even from any other country. Save more with bulk batteries and experience unbeatable quality and price than you could have ever imagined!
THE BOTTOM LINE
Triple A batteries are important for household use and other portable devices outdoors and other professional industries. Getting to know the various types and other battery information give the consumers the proper knowledge they need in getting the most of their devices. Buy batteries in bulk to enjoy all the benefits of having them ready whenever you need them anytime, anywhere. This is always hassle-free and even saves you more money or profits for your business. You not only save but you also get the privilege of having superior quality batteries for maximum performance. Understanding more about high drain (digital cameras) and low drain devices (clock) gives you the right kind of batteries to use for specific device. This optimizes battery performance, make tasks easier than ever, and gives you the best value for your money.
Having exceptionally reliable power solutions for your office, business, industry and even your household keep you stress-free, more efficient, and even more productive. Experience the power of the incredibly powerful brands that provide long-lasting power such as Procell INTENSE, Procell Alkaline, Duracell, Energizer, Varta, Eneloop, Eneloop Pro, Ansmann, Camelion, Panasonic, Fujitsu, and many more. Grab your favourite AAA batteries now!