Technical Editor Margery Conner's PowerSource streams the latest developments in electronic power design and related technologies. Follow Margery on Twitter at: http://twitter.com/margeryc.
Advertisement
Profile
RSS Feed
-
Add this blog to your RSS newsreader!
Recent Posts
- Solar heat engine’s 20% efficiency may trump solar panel’s 15% for some apps
- Startup battery company Imara folds, sells equipment to Yardney
- Energizer battery charger opens backdoor on unwary owners
- 3D holographic prints can replace bulky physical models
- GaN community grows: ex-IR CEO launches GaN-based power transistors
- San Diego airport terminal lets waiting passengers plug in
- IR’s GaN platform: Is the long run of the silicon MOSFET ending?
- New MOSFETS target server power supply efficiency
- US manufacturing strong, so why the disastrous job losses?
- Panjiva finds, evaluates international suppliers based on shipping data
Recent Comments
- Dermologyscincare on Here’s a list of micro-inverter companies (and some proposed new installations)
- Chris P on Solar heat engine’s 20% efficiency may trump solar panel’s 15% for some apps
- Grant on Solar heat engine’s 20% efficiency may trump solar panel’s 15% for some apps
- kool on 3D holographic prints can replace bulky physical models
- kool on 3D holographic prints can replace bulky physical models
Most Commented On
- Utilities suffer from CFLs’ poor power factor (110)
- This was not the right application for a compact fluorescent light (101)
- Not so easy to run an LED ”bulb” off of a dimmer switch – but here’s how (77)
- Proposed ban by China of rare-earth metal exports would affect hybrid cars, CFLs (72)
- Why diesel is so expensive (58)
Archives
- March 2010
- February 2010
- January 2010
- December 2009
- November 2009
- October 2009
- September 2009
- August 2009
- July 2009
- June 2009
- May 2009
- April 2009
- March 2009
- February 2009
- January 2009
- December 2008
- November 2008
- October 2008
- September 2008
- August 2008
- July 2008
- June 2008
- May 2008
- April 2008
- March 2008
- February 2008
- January 2008
- December 2007
- November 2007
- October 2007
- September 2007
- August 2007
- July 2007
- June 2007
- May 2007
- April 2007
- March 2007
- February 2007
- January 2007
- October 2006
- September 2006
- August 2006
- July 2006
- June 2006
By Category
- AC-DC (2)
- Aerospace & Defense (8)
- Analog (2)
- Analog Circuit Design (1)
- Automotive (2)
- Automotive (33)
- Battery Power (47)
- Biometrics (1)
- Body Electronics (1)
- Business and Marketing (5)
- Capacitor (2)
- China (1)
- Communication functions (2)
- Communications & Networking (7)
- Company Types (1)
- Components, Hardware, Interconnect (90)
- Computers (2)
- Computers, boards, buses (2)
- Consumer Products (1)
- Convergence (1)
- DC-DC (1)
- Design Engineering (1)
- Digital ICs (1)
- Discrete Components, Active (2)
- Discrete Components, Passive (2)
- Displays & Indicators (5)
- Displays and indicators (40)
- DSP Engineering (1)
- EDA (1)
- Electromechanical & Mechanical (1)
- Electronic Accessories (2)
- Electronics Business (2)
- Electronics Components (12)
- Electronics Environmental Issues (2)
- Electronics Licensing & Technology Agreements (1)
- Electrostatic Discharge (ESD) (1)
- Embedded Systems (3)
- EMI (1)
- Enclosures (1)
- Environmental Compliance (1)
- Global Supply and Trade (2)
- Globalization (1)
- Government/regulation (3)
- HBLED (29)
- Heat Dissipation (1)
- Hybrid & Green Cars (1)
- Industrial-Embedded Computing (1)
- LED (42)
- Licensing & Technology Agreements (1)
- Low Power (1)
- Low-Power (2)
- Manufacturing Operations (2)
- Medical (1)
- Medical Electronics (5)
- Mergers and Acquisitions (1)
- Motors (1)
- OLED (4)
- Parts Databases (1)
- Passive components (2)
- Piezoelectric Crystal (4)
- Point-of-Load (1)
- Power components (4)
- Power Consumption (5)
- Power Dissipation (2)
- Power Management (1)
- Power Sources/Controllers (321)
- Power supplies (20)
- Power Supplies (76)
- Powertrain (1)
- Printed Circuit Boards (2)
- Research (1)
- Robotics (1)
- Sensors (12)
- Solar/Photovoltaics (22)
- Standby (1)
- Supply Types (1)
- System Engineering (1)
- Technical Standards (1)
- Transformer (1)
- Transistors (6)
- Venture Capital & IPOs (1)
- Wireless (1)
- Wireless Networks (1)
Power Management Articles
- Battery simulator has variable ESR response
- The Black and Decker GH1000 Type 2 string trimmer
- Editor’s welcome
- EDN on Power Technology: GaN-on-Silicon gains momentum, more...
- EDN on Power Technology: HB LED reliability and lifetime; EDN's Innovation Award finalists; More...
- More...
Blog
Tuesday, January 9, 2007
What's inside a 9V battery? More batteries! (…and why you never see a AAAA)
Jan 9 2007 8:32AM | Permalink |Comments (22) |
I came across a Gizmodo post with an eye-catching photo of a disemboweled 9V battery – apparently taken from the Axe Collector source post, "Why I Never Pay For "AAA" Batteries". Axe Collector has several photos of the innards of a 9V, which consist of six 1.5V cells that if you squint are about the same size as a AAA battery, and in a pinch could be used in its place.
Well. This is like getting permission to do something vaguely illicit – you mean you can tear apart a 9V battery and not be sprayed by flesh-eating acid, wait, alkaline? [Immediate disclaimer – I used a Duracell battery. No idea what's inside of the others, but hey, alkaline is alkaline.]
So I disemboweled a handy 9V battery to see what I could see. It came apart quite neatly, with the six 1.5V cells connected by bendy metal tabs, all in series, encased in a clear plastic wrapper.
How close are they to AAA batteries? As Axe Collector says, they're smaller, and he reckons they're actually AAAA size. I measured them at 0.303 in (diameter) by 1.592 in. (length). Trotting over to the virtual bookshelf and pulling down my copy of Wikipedia, it defines AAAA batteries as being 0.33 in (diameter) by 1.67 in (length)*. Not an exact match, but pretty close. Let's say that these are AAAA batteries.
I measured a stray AAA battery that was lying about (no doubt quivering when it saw what happened to the hapless 9V battery) and it came in at .400 in. (diameter) by 1.67 in. (length). As you can see from the photo, there's not much difference. But calculating out the volume, the AAA battery comes in at .21 cubic in vs. the AAAA's .11 cubic in: Almost double the volume -- thus the power -- for a fractional increase in length and diameter. It's easy to see why the AAAA battery was replaced by the AAA.
*Wikipedia gave the dimensions in mm: 8.3mm (diameter) by 42.5mm (length)
Related entries in: Power Sources/Controllers |
Reader Comments
at 1/10/2007 3:18:21 AM, roberto said:
i remember in the oldies '80 that the battery was made of a rectangular cell in series...
i also open a duracell 9v now and....is like the article...
bye- roberto radaelli italy
at 1/10/2007 11:50:57 AM, oldbatteryguy - Boston said:
If more designers of small devices knew what was really in a 9V, they'd use something else. There's really not much capacity available but these were handy when designing for a 5V project. But I was dismayed when I bought a noise cancelling aviation grade headset (I'm a private pilot) and found it was powered by a 9V! It ran through batteries like crazy. Regarding the quad-A, I think Energizer offers these for commercial sale.
at 1/12/2007 2:25:25 AM, Henrik Volkers said:
HINT: If you carefully open the 9V block at the bottom and push out the ingrediens, you get a metall shielded housing with the 9V clip for your own small projects. Directly clips on a new 9V block
at 1/16/2007 1:15:27 PM, Hans said:
Indeed in the 80's these batteries were a pack of rectangular cells... I remember making radio jammers with them, taking out half of the cells. This gave a 4.5V battery and half the space of the 9V pack left free to fit a 7413 IC with its output shortcircuited to its inputs. The IC oscillated at around 30 Mhz, tunable by squeezing the battery package a little bit. The 3rd harmonic jammed the radio of our janitor at school that time, he never suspected the battery next to his radio did this...
at 1/16/2007 1:41:28 PM, DayTimer said:
I've seen AAAA's in retail packaging at Menard's; 2fer ~$3; one of the few places that I found them. I use them in a Streamlight LED penlight. They were one of the 1st to do so, & they come in different colors, incl. UV, & w/ a goose neck. They're about the dia. of a #2 pencil in a HD Al housing, kind of a micro-MagLight.
at 2/7/2007 1:03:54 PM, Kevin said:
What is in the batteries?
at 2/7/2007 2:08:06 PM, mb said:
Radio Shack also sells AAAA batteries. They make a penlight that uses them.
A while back I took apart another manufacturers 9V battery (forgot which one, maybe Energizer?) and it had similar construction, except that the cells did not have metal tabs welded to them. The relied on pressure against the circuit paths on the endcaps to make the connection.
at 2/15/2007 11:01:24 AM, Dan said:
I remember disassembling a ray-o-vac carbon-zinc 9V battery in the 80's, and, like Roberto said, it was a stack of 6 rectangles. Then I opened a Duracell alkaline, and it looked just the picture above.
This discussion should remind us that the 9V is a true battery, while D, C, AA, AAA, etc. are all just cells.
at 6/1/2007 6:15:31 PM, batteryguy said:
There are still some 9 volt alkaline made of the stacked cell type. Gold peak makes them this way as does Rayovac for some but not all. Rayovac uses both types and actually the different designs have different discharge curves. For people who have a need to individual AAAA cells, mostly lazer pointers as far as I have seen, the AAAA in the 9 volts can be used in place of individual AAAA cells if you just put a sleeve on them after dissasembling them and they are much lower cost this way than purchased in 2 pack consumer version.
at 6/29/2007 8:37:47 AM, Andy I said:
I also remember disassembling (probably in the 60s or 70s)and finding six rectangular cells. Thinking about this a bit, I would think the rectangular cells should be more space-efficient (and therefore have more capacity) than cylindrical AAAA cells of the same chemistry. But I guess they changed over because it let them stop manufacturing the rectangular cells which probably weren't used anywhere else.
at 1/8/2008 4:51:24 PM, Jim said:
If you liked this demonstration, take a look at what's inside a 6V Lantern battery. It contains 32 size AA cells. At $5 to $6 for a Lantern battery, its a much better deal than 32 AA alkaline batteries.
at 1/8/2008 4:56:49 PM, Hal said:
"But calculating out the volume, the AAA battery comes in at .21 cubic in vs. the AAAA's .11 cubic in: Almost double the volume -- thus the power -- for a fractional increase in length and diameter. It's easy to see why the AAAA battery was replaced by the AAA."
Thinking of cost density instead, one wonders about C and AA sizes as well. For example, even though a D cell has more than twice the amp-hours of a C cell, the selling price is often the same or just slightly more. The difference in capacity between C and AA is even greater yet the price difference is much less. And AAAs are often the same price as AAs. I always cringe when a device runs on 4 AAs but a D would have fit and have a running cost about 1/3 as much.
at 1/8/2008 5:39:04 PM, Pat said:
I opened a 6V lantern battery that seemed to have a strange feel to its center of gravity. It was one third plastic spacer and two thirds D cells (four of them in series).
BTW EDN proofreaders, the noun form of alkaline is alkali.
at 1/8/2008 10:32:03 PM, pbarnrob said:
My wife found the same trick useful when her Wacom tablet's pen was AAAA-powered. Now they just put a PCB coil in the tablet and a solenoid in the pen for power; and people think _that's_ something new!
at 1/9/2008 4:21:22 AM, BigRed said:
I have been taking apart this type of 9V batteris and use 4 of them to replaced the expended one inside the J-pack 6V battery (for economical reasons). It should be awared that this type of cells can swell up or even explode when not bounded by the metal housing. I have the experience of having a couple of the loose cell sitting in the component drawer and exploded by themselves for no apparent reason - not being connected and no shorting. The force broke the plastic drawers!
at 12/3/2008 1:00:07 PM, Doug B. said:
Striclty speaking, the AAA battery has double the energy, not double the "power" of a AAAA battery. Both batteries could provide the same amount of power, however the AAAA would only provide it for about 1/2 as long.
at 1/14/2009 11:35:53 AM, TheMANwithNoName said:
Margery, I like the way you think -- wondering?...open it up and see what's inside.
Kevin and 4kevin, try google and wikipedia, lots of info there about what's inside a battery.
Doug B, check your definitions. 'Power' generally means watts. while energy is in units like watt-hours. If you look at the internal resistance or the discharge curve of the batteries you will find that the AAA does is in fact capable of producing both more instantaneous watts of output and also more watt-hours (more like watt-minutes. The power output is roughly proportional to the increase in surface area of the components, not to the volume, while the increased energy capacity is roughly proportional to the increase in volume when going from AAAA to AAA.
at 2/16/2009 6:36:15 AM, vman1019 said:
i took a 9v apart and one of the batteries exploded does that mean acid came out?
at 3/25/2009 9:20:50 AM, delswick said:
Has any one ever opened a 9v lithium?
at 6/12/2009 3:02:12 PM, zappy said:
Does anybody know which brand 9 Volt block battery currently (2009) contains six AAAA cells? All the ones I popped open contained stacked cells. Eeek!
at 2/24/2010 12:25:18 PM, lol said:
u are gay wt the fck r wrong with u
at 3/9/2010 12:43:41 PM, Jonathan said:
And this is the reason I read www.edn.com. Incrdible post.
Post a comment
ADVERTISEMENT
About Us | Contact Us | Free Email Newsletters | Free Magazine Subscription | Advertising | 
RSS
©1997-2010 Reed Business Information, a division of Reed Elsevier Inc. All rights reserved.
Use of this Web site is subject to its Terms of Use | Privacy Policy