In terms of battery life, and assuming the same brand of Alkaline battery, is it more efficient to use a 9V battery or 2 AAA cells with something like the TL496 converter pictured here. http://www.electroschematics.com/6788/3v-to-9v-dc-converter/ If not, what is the approximate difference either way? The circuit involved is a test audio oscillator. Would be nice if they made more handheld cases to fit 4 x AAA's. Kevin Grant
9V Battery or 2 x AAA with 9V Converter
Started by ●May 12, 2014
Reply by ●May 12, 20142014-05-12
On Tue, 13 May 2014 07:22:35 +1000, kgrant wrote:> In terms of battery life, and assuming the same brand of Alkaline > battery, is it more efficient to use a 9V battery or 2 AAA cells with > something like the TL496 converter pictured here. > > http://www.electroschematics.com/6788/3v-to-9v-dc-converter/ > > If not, what is the approximate difference either way? > > The circuit involved is a test audio oscillator. > > Would be nice if they made more handheld cases to fit 4 x AAA's. > > Kevin GrantWhy not two AA cells? That's closer to the size of a 9V battery. Check the data sheet for the TL496 -- dry cell batteries are useful down to about 0.9V per cell; you really want something that will function down that far, or at least down to 1V/cell. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com
Reply by ●May 12, 20142014-05-12
On 5/12/2014 4:22 PM, kgrant@protec.com wrote:> > > In terms of battery life, and assuming the same brand of Alkaline > battery, is it more efficient to use a 9V battery or 2 AAA cells with > something like the TL496 converter pictured here. > > http://www.electroschematics.com/6788/3v-to-9v-dc-converter/ > > If not, what is the approximate difference either way? > > The circuit involved is a test audio oscillator. > > Would be nice if they made more handheld cases to fit 4 x AAA's. > > Kevin Grant >I don't think you mean efficient, I think you want to know which will last longer. From this page, ( I guess that,s what you said)> http://www.batterysavers.com/Compare-Batteries.htmlI see an alkaline AAA has a 1000mAh capacity and a 9v has 500mAh capacity. I would think, (that means you must verify) because of the voltage differences the equivalent of the 9 volt at 3 volts is 1500mAh minus the efficiency of the converter. I think the 9V would last a bit longer, not sure it is worth the extra circuitry though. Mikek --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com
Reply by ●May 12, 20142014-05-12
On Monday, May 12, 2014 10:22:35 PM UTC+1, kgr...@protec.com wrote:> In terms of battery life, and assuming the same brand of Alkaline > battery, is it more efficient to use a 9V battery or 2 AAA cells with > something like the TL496 converter pictured here. > http://www.electroschematics.com/6788/3v-to-9v-dc-converter/ > If not, what is the approximate difference either way? > The circuit involved is a test audio oscillator. > Would be nice if they made more handheld cases to fit 4 x AAA's. > Kevin GrantThe convertor is only 80 or 90% efficient, so clearly the 9v is more effici= ent - but I think thats not what you meant. If you mean cost efficient, 9v = batteries are terrible compared to 1.5vs. Only you can price your circuit, = your batteries, and know your use thus calculate the Total Cost of Ownershi= p for each option.=20 I always avoid 9v except when they have a big advantage, since they're far = worse value. NT
Reply by ●May 13, 20142014-05-13
On a sunny day (Tue, 13 May 2014 07:22:35 +1000) it happened kgrant@protec.com wrote in <2ee2n9l13jh3tek7p8sl55d4ei2185mvs1@4ax.com>:> > >In terms of battery life, and assuming the same brand of Alkaline >battery, is it more efficient to use a 9V battery or 2 AAA cells with >something like the TL496 converter pictured here. > >http://www.electroschematics.com/6788/3v-to-9v-dc-converter/ > >If not, what is the approximate difference either way? > >The circuit involved is a test audio oscillator. > >Would be nice if they made more handheld cases to fit 4 x AAA's.Design your circuit for 3.7 V LiPo. Use a voltage converter if you have to. Use a USB charger chip and micro USB connector for charging. This is perhaps more expensive (a little) in the short run, but saves batteries and environment. I think this is the current trend. A 1Ah Lipo with build in protection is almost the same price as a 9V block these days. Peak current capability is also higher, charge retainment is good. And Lipo needs less space, less weight than 4 AAA. Saves the battery connector pack, the need to have a housing with a battery lid or compartment, and prevents leakage etc, people putting them in the wrong way around, etc etc. And if the Lipo goes bad after some years .. sell them a new device (Apple?). Or solder in a new one...
Reply by ●May 13, 20142014-05-13
Never use AAA cells. You get twice the capacity in a AA cell at about a third the cost. I know people who use the type of battery in the remote to pick between brands of TVs. I try to run make everything I own AA cell compatible. No matter where you go, you can find chickens, 7.62 ammo, and AA cells.
Reply by ●May 13, 20142014-05-13
On 13/05/2014 08:27, miso wrote:> Never use AAA cells. You get twice the capacity in a AA cell at about a > third the cost.The most annoying things are low current devices that will only run on two AAA cells and will not work with NiMH rechargables at all. My phones LED display when the phone is off hook for instance.> > I know people who use the type of battery in the remote to pick between > brands of TVs. I try to run make everything I own AA cell compatible. > > No matter where you go, you can find chickens, 7.62 ammo, and AA cells.Only in the USA and some third world countries. AA cells are the only one of those three commonly stocked in Europe. -- Regards, Martin Brown
Reply by ●May 13, 20142014-05-13
On Tue, 13 May 2014 05:41:23 GMT, Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:>Design your circuit for 3.7 V LiPo. >Use a voltage converter if you have to. >Use a USB charger chip and micro USB connector for charging. >This is perhaps more expensive (a little) in the short run, >Have you ever seen this offered as a cost-effecive integrated, drop-in package, e.g. with the battery, charger, converter, and connectors? If not, looks like a good opportunity for someone. Kevin Grant
Reply by ●May 13, 20142014-05-13
On 5/13/2014 12:54 AM, kgrant@protec.com wrote:> On Tue, 13 May 2014 05:41:23 GMT, Jan Panteltje > <pNaonStpealmtje@yahoo.com> wrote: > > >> Design your circuit for 3.7 V LiPo. >> Use a voltage converter if you have to. >> Use a USB charger chip and micro USB connector for charging. >> This is perhaps more expensive (a little) in the short run, >> > > Have you ever seen this offered as a cost-effecive integrated, drop-in > package, e.g. with the battery, charger, converter, and connectors? > > If not, looks like a good opportunity for someone. > > Kevin Grant >If you're building one, these guys have some interesting modules. http://www.fasttech.com/products/1005/10002934/1219203-dc-dc-3v-to-5-9v-1a-boost-diy-mobile-phone-power-s
Reply by ●May 13, 20142014-05-13
On Tue, 13 May 2014 07:22:35 +1000, kgrant@protec.com wrote:> > >In terms of battery life, and assuming the same brand of Alkaline >battery, is it more efficient to use a 9V battery or 2 AAA cells with >something like the TL496 converter pictured here. > >http://www.electroschematics.com/6788/3v-to-9v-dc-converter/ > >If not, what is the approximate difference either way? > >The circuit involved is a test audio oscillator. > >Would be nice if they made more handheld cases to fit 4 x AAA's. > >Kevin Grant--- According to this chart from: http://www.techlib.com/reference/batteries.html Battery Type Capacity (mAh) Typical Drain (mA) --------------------------------------------------- D 12000 200 6 Volt Lantern 11000 300 C 6000 100 AA 2000 50 AAA 1000 10 N 650 10 9 Volt 500 15 the AAA cell has a capacity of 1000mAH with a 10mA drain, and the 9V battery has a capacity of 500mAH with a 15mA drain. Neglecting the TL496 for a moment, and assuming a 15mA load on the 9V battery, it'll last for 500mAH/15mA, or roughly 33 hours. During that time, the load will be dissipating 9V * 15mA, or about 135 milliwatts. Two AAAs in series will supply 3V and, if the converter were perfect, they'd have to supply 135mW into the converter for it to get 135mW out to the load. Since I = P/E, then, the AAA's would have to supply 135mW/3V = 45mA into the perfect converter. The AAAs have a capacity of 1000mAH so, with a 45mA drain, they'd last for 1000mAH/45mA, or about 22 hours. Unfortunately, the 1000mAH capacity is for a load current of 10mA, so the 45mA load would shorten the battery life even more. Then, on top of it all, the converter isn't perfect, so its less than 100% efficiency will also take its toll on the 3V battery's life. Just for grins, if we say that the converter is running 80% efficient with a 135mW load on its output, then its input will need about 169 milliwatts to do the conversion and, for a 3 volt battery, that comes to about 56mA. According to the constant current curves at: http://ww2.duracell.com/media/en-US/pdf/gtcl/Product_Data_Sheet/NA_DATASHEETS/MN2400_US_CT.pdf a 50mA load will get you about 21 hours to 1V cutoff, so I suspect 56 mA would get you about 10% less than that, or about 19 hours. John Fields.
