9Volt vs. AA Recheargeable Batteries
9Volt vs. AA Recheargeable Batteries
(OP)
Hello,
I'm not quite an electrical engineer (YET! ;) but I do some of this as a hobby as I get my degree. I have a question I need assistance with, hope you can help me.
At my job we are working with magnetometers that are powered by a pack of 7 AA batteries (Rechargeable) encapsulated in a pack that has a 9v type connection to the circuit board. One of those devices is connected to a simple 9V rechargeable battery instead of the pack.
The batteries are at terrible shape (due to neglect and bad maintainance of the devices, mostly) and we are about to change them all. As the only person that knows half a thing about electrical currents and circuits, the job of choosing the replacements fell on me.
My question is this: Which type of rechargeable battery is better? The 9v or a pack of 7 AA ? which would hold out longer, or which would survive longer? Is there really a difference?
I apologize if I don't supply information that is relevant, I don't know much about batteries. If you need more information, please ask. I also apologize if this is in the wrong forum. Again, I'm doing this as a Hobby, and try to learn in the process.
Thank you very much,
Moriel
I'm not quite an electrical engineer (YET! ;) but I do some of this as a hobby as I get my degree. I have a question I need assistance with, hope you can help me.
At my job we are working with magnetometers that are powered by a pack of 7 AA batteries (Rechargeable) encapsulated in a pack that has a 9v type connection to the circuit board. One of those devices is connected to a simple 9V rechargeable battery instead of the pack.
The batteries are at terrible shape (due to neglect and bad maintainance of the devices, mostly) and we are about to change them all. As the only person that knows half a thing about electrical currents and circuits, the job of choosing the replacements fell on me.
My question is this: Which type of rechargeable battery is better? The 9v or a pack of 7 AA ? which would hold out longer, or which would survive longer? Is there really a difference?
I apologize if I don't supply information that is relevant, I don't know much about batteries. If you need more information, please ask. I also apologize if this is in the wrong forum. Again, I'm doing this as a Hobby, and try to learn in the process.
Thank you very much,
Moriel





RE: 9Volt vs. AA Recheargeable Batteries
Assuming a constant energy density, would a larger volume produce more total energy?
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RE: 9Volt vs. AA Recheargeable Batteries
I usually go from 9V to a set of AA. Not AAA.
AA has come to be THE battery used in most applications. It is THE battery that has a good combination of volume, capacity, price and longevity.
I even choose cameras and similar things based on batteries. If not AA, then I evaluate AA battery devices first.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: 9Volt vs. AA Recheargeable Batteries
http://www.cadex.com/
You may be able to repair the batteries by a suitable charging method.
On the other hand, if the batteries are 5 years old you will get at least double the energy capacity by using new ones, simply because energy densities have improved dramatically in this period.
Comparing battery packs you need to compare run time, weight and cost. This will allow an informed decision.
RE: 9Volt vs. AA Recheargeable Batteries
Last time I was interested (at least a decade back, so treat with caution), PP3 sized NiCd were still mass plate technology, compared with AAA and bigger which had all moved on to a sintered construction.
The sintered technology tolerates much faster charging, and from what I can remember, had a better energy density.
A.
RE: 9Volt vs. AA Recheargeable Batteries
Go to http://energizer.com/default_refresh.asp and check out the 'learning center' and 'technical info' pages.
RE: 9Volt vs. AA Recheargeable Batteries
Mike Halloran
Pembroke Pines, FL, USA
RE: 9Volt vs. AA Recheargeable Batteries
RE: 9Volt vs. AA Recheargeable Batteries
Dan - Owner

http://www.Hi-TecDesigns.com
RE: 9Volt vs. AA Recheargeable Batteries
But, then again, the Urban Legend part of it is intriguing - anyone with first-hand information?
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: 9Volt vs. AA Recheargeable Batteries
Hmmm... Smells like an urban legend. Is there a reference anywhere?
9 volt batteries are still very commonly used in clock radios for back-up power.
RE: 9Volt vs. AA Recheargeable Batteries
Dan - Owner

http://www.Hi-TecDesigns.com
RE: 9Volt vs. AA Recheargeable Batteries
If there is a world-wide ban on designing 9-volt batteries into anything other than smoke detectors, then I didn't get the memo...
RE: 9Volt vs. AA Recheargeable Batteries
Dan - Owner

http://www.Hi-TecDesigns.com
RE: 9Volt vs. AA Recheargeable Batteries
RE: 9Volt vs. AA Recheargeable Batteries
RE: 9Volt vs. AA Recheargeable Batteries
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: 9Volt vs. AA Recheargeable Batteries
If you go the AA or AAA route, it is best to have all the same type cell and all the same age/usage pattern.
Get all new cells and once you've assembled them into a battery pack, keep them together. Don't mix old with new.
I'd avoid Nickel-Cadmium (NiCad) batteries. Cadmium is nasty stuff. Restricted in RoHS compliant countries. Go with nickel metal hydride (NiMH). They are less tolerant of over-charging than NiCad, but are environmentally much better. You need a charger specifically designed to handle NiMH. (It will also be able to charge NiCads if you must, but a NiCad charger can't necessarily charge NiMH safely, and may easily damage the battery or reduce their useful life.)
Also, dispose of your old batteries properly. Recycle them. Depending on where you are there may be businesses and organizations that will handle this. Nickel is a valuable commodity these days and quite recycleable. If you've got old NiCad batteries, cadmium is very bad for the environment. Don't just dump them in the trash.
RE: 9Volt vs. AA Recheargeable Batteries
It is much cheaper nowadays to build remotes that run on 2.8V than 9V (or whatever the '9V' batteries actually deliver at the end of life), so they use 2x1.5v batteries.
The world is always built the 'cheapest' way, when it comes to consumer products - therefore AA batteries replaced 9V units.
It has nothing to do with 'code' requirements - do you really think that Korean or Japanese electronic mfrs care what building codes are enacted in Wyoming or Pittsburg?
RE: 9Volt vs. AA Recheargeable Batteries
Dan - Owner

http://www.Hi-TecDesigns.com
RE: 9Volt vs. AA Recheargeable Batteries
The idea behind his statements was that the use of 9V batteries was discouraged (if not prohibited) in devices that would encourage the average Joe or his offspring from removing the batteries by making them useless in most consumer electronics. Granted, technical issues involving reduction in normal operating voltage may have helped.
RE: 9Volt vs. AA Recheargeable Batteries
Walkie talkies, DVMs, RC transmitters all used 9V batteries. The only reason that quad AAs are used is the poor current capacity of a 9V battery.
TTFN
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