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Battery choice: 9V vs 6 AAs

Started by Adam Funk May 5, 2015
I'm fixing a kid's toy that was damaged by corrosion (stored with the
batteries).  The only damaged part was the battery compartment, so I
opened it up, clipped off the internal wires to that bit, soldered
extensions on them & ran those through holes in the case, in order to
put an external 6 AA holder on.  As it turns out, the 6 AA battery
holder I bought clips onto a 9 V battery attachment, which I had in
stock.  As I was putting this together, I realized that 6 AAs in
series make about 9 V, so I'm wondering why a toy would run on 6 AAs
when 1 9V would be smaller & easier?



(Yes, I know it should be "cells" rather than "batteries".)

Thanks.

-- 
Specifications are for the weak & timid!
          --- Klingon Programmer's Guide
On 5/5/2015 7:41 AM, Adam Funk wrote:
> I'm fixing a kid's toy that was damaged by corrosion (stored with the > batteries). The only damaged part was the battery compartment, so I > opened it up, clipped off the internal wires to that bit, soldered > extensions on them & ran those through holes in the case, in order to > put an external 6 AA holder on. As it turns out, the 6 AA battery > holder I bought clips onto a 9 V battery attachment, which I had in > stock. As I was putting this together, I realized that 6 AAs in > series make about 9 V, so I'm wondering why a toy would run on 6 AAs > when 1 9V would be smaller & easier? > > > > (Yes, I know it should be "cells" rather than "batteries".) > > Thanks. >
Look up the amount of current the AAs can supply vs. the 9 volt.
On Tue, 05 May 2015 12:41:25 +0100, Adam Funk <a24061@ducksburg.com>
wrote:

>I'm fixing a kid's toy that was damaged by corrosion (stored with the >batteries). The only damaged part was the battery compartment, so I >opened it up, clipped off the internal wires to that bit, soldered >extensions on them & ran those through holes in the case, in order to >put an external 6 AA holder on. As it turns out, the 6 AA battery >holder I bought clips onto a 9 V battery attachment, which I had in >stock. As I was putting this together, I realized that 6 AAs in >series make about 9 V, so I'm wondering why a toy would run on 6 AAs >when 1 9V would be smaller & easier? > > > >(Yes, I know it should be "cells" rather than "batteries".) > >Thanks.
--- The capacity of the AAs is much greater than the capacity of the 9V. John Fields
On 5/5/2015 9:10 AM, John Fields wrote:
> On Tue, 05 May 2015 12:41:25 +0100, Adam Funk <a24061@ducksburg.com> > wrote: > >> I'm fixing a kid's toy that was damaged by corrosion (stored with the >> batteries). The only damaged part was the battery compartment, so I >> opened it up, clipped off the internal wires to that bit, soldered >> extensions on them & ran those through holes in the case, in order to >> put an external 6 AA holder on. As it turns out, the 6 AA battery >> holder I bought clips onto a 9 V battery attachment, which I had in >> stock. As I was putting this together, I realized that 6 AAs in >> series make about 9 V, so I'm wondering why a toy would run on 6 AAs >> when 1 9V would be smaller & easier? >> >> >> >> (Yes, I know it should be "cells" rather than "batteries".) >> >> Thanks. > > --- > The capacity of the AAs is much greater than the capacity of the 9V. > > John Fields >
As well as being way cheaper per amp-hour. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
On Tue, 5 May 2015, Adam Funk wrote:

> I'm fixing a kid's toy that was damaged by corrosion (stored with the > batteries). The only damaged part was the battery compartment, so I > opened it up, clipped off the internal wires to that bit, soldered > extensions on them & ran those through holes in the case, in order to > put an external 6 AA holder on. As it turns out, the 6 AA battery > holder I bought clips onto a 9 V battery attachment, which I had in > stock. As I was putting this together, I realized that 6 AAs in > series make about 9 V, so I'm wondering why a toy would run on 6 AAs > when 1 9V would be smaller & easier? > > > > (Yes, I know it should be "cells" rather than "batteries".) > > Thanks. >
It's simpler, change one battery rather than six. It's generally cheaper, or rather, the outlay at a given time is less with a 9v battery, though of course you probably buy batteries more often. Less space is required, which might be a factor. Take one of the old 27MHz license free walkie talkies, that all ran off 9v. If they'd used 6 AA batteries, They'd either have to make the case longer or wider to fit those extra batteries, and even if the per unit cost is tiny, it adds up over the production run. Likewise the 9v battery needs just the connector, while AA need a battery holder. There were 9v batteries before transistor radios, though bigger units if I get the picture properly. Then transistor radios came along, and they added the 9v battery. For lots of things, it's not optimum, but it's cheaper. You can buy little caps that fit onto 9v batteries to add a switch and an LED bulb, nice little flashlights. 9v is overkill, but you need more than one 1.5V battery to light the LED, so the 9v battery is simpler and cheaper. Michael
>"As well as being way cheaper per amp-hour. "
HAHA. Got these elcheapo meters from Harbor Freight. At one time they were on sale for like $3.99. I looked at a nine volt battery in the store and it was $4.99. Actually if you can grab their coupons, they actually give these meters away for free sometimes. Meter = free. Battery = ridiculous.
Adam Funk <a24061@ducksburg.com> wrote:
> As I was putting this together, I realized that 6 AAs in series make > about 9 V, so I'm wondering why a toy would run on 6 AAs when 1 9V > would be smaller & easier?
As has been mentioned, 6 AA cells have a lot more capacity than one 9 V battery. To put some numbers on it: http://ww2.duracell.com/media/en-US/pdf/gtcl/Product_Data_Sheet/NA_DATASHEETS/MN1500_US_CT.pdf http://ww2.duracell.com/media/en-US/pdf/gtcl/Product_Data_Sheet/NA_DATASHEETS/MN1604_6LF22_US_CT.pdf Look at the first graph in both data sheets. At a constant 10 mA load, the 9 V will last about 60 hours, while the stack of AAs will last about 320 hours; the AAs last 5.3x as long. In the second graph, at a constant 100 mA, the 9 V is good for 3 hours, while the AAs are good for about 27 hours; the AAs last 9x as long. You do pay for it in weight and size; the 9 V battery is 45 g and about 22.8 cm^3, and the 6 AAs will be about 144 g and about 50.4 cm^3. Looking at pricing, Wal-Mart sells a two-pack of Rayovac 9 V batteries for $5.47, or $2.735 each. They sell a 4-pack of Rayovac AAs for $2.97 ($0.743 each) or an 8-pack for $4.97 ($0.621 each). This makes a string of 6 AAs cost something around $3.73 to $4.46; more expensive than the 9 V battery, but also better performance. Matt Roberds
On 2015-05-05, mroberds@att.net wrote:

> Adam Funk <a24061@ducksburg.com> wrote: >> As I was putting this together, I realized that 6 AAs in series make >> about 9 V, so I'm wondering why a toy would run on 6 AAs when 1 9V >> would be smaller & easier? > > As has been mentioned, 6 AA cells have a lot more capacity than one 9 V > battery. To put some numbers on it: > > http://ww2.duracell.com/media/en-US/pdf/gtcl/Product_Data_Sheet/NA_DATASHEETS/MN1500_US_CT.pdf > > http://ww2.duracell.com/media/en-US/pdf/gtcl/Product_Data_Sheet/NA_DATASHEETS/MN1604_6LF22_US_CT.pdf > > Look at the first graph in both data sheets. At a constant 10 mA load, > the 9 V will last about 60 hours, while the stack of AAs will last about > 320 hours; the AAs last 5.3x as long. In the second graph, at a > constant 100 mA, the 9 V is good for 3 hours, while the AAs are good for > about 27 hours; the AAs last 9x as long. > > You do pay for it in weight and size; the 9 V battery is 45 g and about > 22.8 cm^3, and the 6 AAs will be about 144 g and about 50.4 cm^3.
Yes,that makes sense. And the weight is clearly related to the energy, related to the amount of "stuff" in an alkaline cell.
> Looking at pricing, Wal-Mart sells a two-pack of Rayovac 9 V batteries > for $5.47, or $2.735 each. They sell a 4-pack of Rayovac AAs for $2.97 > ($0.743 each) or an 8-pack for $4.97 ($0.621 each). This makes a string > of 6 AAs cost something around $3.73 to $4.46; more expensive than the > 9 V battery, but also better performance.
Interesting. Thanks (& to everyone else) for the information. -- Classical Greek lent itself to the promulgation of a rich culture, indeed, to Western civilization. Computer languages bring us doorbells that chime with thirty-two tunes, alt.sex.bestiality, and Tetris clones. (Stoll 1995)
On Tue, 05 May 2015 19:06:59 +0000, mroberds wrote:

> Adam Funk <a24061@ducksburg.com> wrote: >> As I was putting this together, I realized that 6 AAs in series make >> about 9 V, so I'm wondering why a toy would run on 6 AAs when 1 9V >> would be smaller & easier? > > As has been mentioned, 6 AA cells have a lot more capacity than one 9 V > battery. To put some numbers on it: > > http://ww2.duracell.com/media/en-US/pdf/gtcl/Product_Data_Sheet/
NA_DATASHEETS/MN1500_US_CT.pdf
> > http://ww2.duracell.com/media/en-US/pdf/gtcl/Product_Data_Sheet/
NA_DATASHEETS/MN1604_6LF22_US_CT.pdf
> > Look at the first graph in both data sheets. At a constant 10 mA load, > the 9 V will last about 60 hours, while the stack of AAs will last about > 320 hours; the AAs last 5.3x as long. In the second graph, at a > constant 100 mA, the 9 V is good for 3 hours, while the AAs are good for > about 27 hours; the AAs last 9x as long. > > You do pay for it in weight and size; the 9 V battery is 45 g and about > 22.8 cm^3, and the 6 AAs will be about 144 g and about 50.4 cm^3.
Do the math, and you see that the capacity/weight tradeoff is better for AA than 9V, too. I realize that you'd need to redo the computations with constant power rather than constant current, but I suspect the AA cells will still come out ahead most of the time. For a new-equipment design, I'd lean toward a pair of AA cells and a boost regulator, unless there's some really compelling reason not to. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com
On 5/5/2015 4:37 PM, Tim Wescott wrote:
> On Tue, 05 May 2015 19:06:59 +0000, mroberds wrote: > >> Adam Funk <a24061@ducksburg.com> wrote: >>> As I was putting this together, I realized that 6 AAs in series make >>> about 9 V, so I'm wondering why a toy would run on 6 AAs when 1 9V >>> would be smaller & easier? >> >> As has been mentioned, 6 AA cells have a lot more capacity than one 9 V >> battery. To put some numbers on it: >> >> http://ww2.duracell.com/media/en-US/pdf/gtcl/Product_Data_Sheet/ > NA_DATASHEETS/MN1500_US_CT.pdf >> >> http://ww2.duracell.com/media/en-US/pdf/gtcl/Product_Data_Sheet/ > NA_DATASHEETS/MN1604_6LF22_US_CT.pdf >> >> Look at the first graph in both data sheets. At a constant 10 mA load, >> the 9 V will last about 60 hours, while the stack of AAs will last about >> 320 hours; the AAs last 5.3x as long. In the second graph, at a >> constant 100 mA, the 9 V is good for 3 hours, while the AAs are good for >> about 27 hours; the AAs last 9x as long. >> >> You do pay for it in weight and size; the 9 V battery is 45 g and about >> 22.8 cm^3, and the 6 AAs will be about 144 g and about 50.4 cm^3. >
> For a new-equipment design, I'd lean toward a pair of AA cells and a boost > regulator, unless there's some really compelling reason not to. >
Like if the toy has a motor?