eli5: Why do seemingly all battery powered electronics need at least 2 batteries?
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Your typical alkaline battery, whether it’s AA or C or D, has a nominal voltage of 1.5V — that is, it can exert 1.5 “units” of “electrical pressure” on a circuit it’s installed into.
That’s not a super useful amount of voltage, but 3V is — and by placing two batteries in series, you end up at 3V because you add the voltages together.
The voltage put out by a battery is determined largely by the materials used. While you can increase the available current by making it bigger (or ganging up a bunch of smaller ones in parallel), the voltage is somewhat fixed.
The standard batteries used for many years had a natural voltage of about 1.5V. But for the transistors of the time, that voltage was not optimal.
There’s a hack for that. If you “stack” two batteries in series, then their voltages add up. Two 1.5V batteries will output 3V. If you stack four of them you get 6V. Which was pretty useful when the “standard” for many transistors and integrated circuits was 5V.
A lot of things have changed since those days, of course. Different battery materials are in widespread use, and integrated circuit technology has changed such that 5V is not only undesirable, it’s not acceptable.
As transistors were made smaller and smaller (“shrunk”), it became necessary to reduce their supply voltages. This has gone through many phases, from 5V -> 3.6V -> 3V etc. etc. A lot of integrated circuits now are very happy to run on 1V or so. If a gizmo uses only such ICs, it can use a single battery.
But there are at least a couple of reasons to use higher voltages. One is that there are still some old technology devices around that run on a 3V standard, or use signaling busses between them that use a >1V standard. There are also some components, such as certain displays, that work on higher voltages.
It is possible to boost voltages, but a better strategy is often to use a power source that provides the highest voltage needed. For the lower voltage devices, it’s relatively easy/cheap to drop the voltage down.
So you use two batteries in series and that provides a nominal voltage of 3V (actually less pretty quickly). For things that don’t need that, you reduce the voltage.
Your typical alkaline battery, whether it’s AA or C or D, has a nominal voltage of 1.5V — that is, it can exert 1.5 “units” of “electrical pressure” on a circuit it’s installed into.
That’s not a super useful amount of voltage, but 3V is — and by placing two batteries in series, you end up at 3V because you add the voltages together.
Your typical alkaline battery, whether it’s AA or C or D, has a nominal voltage of 1.5V — that is, it can exert 1.5 “units” of “electrical pressure” on a circuit it’s installed into.
That’s not a super useful amount of voltage, but 3V is — and by placing two batteries in series, you end up at 3V because you add the voltages together.
The voltage put out by a battery is determined largely by the materials used. While you can increase the available current by making it bigger (or ganging up a bunch of smaller ones in parallel), the voltage is somewhat fixed.
The standard batteries used for many years had a natural voltage of about 1.5V. But for the transistors of the time, that voltage was not optimal.
There’s a hack for that. If you “stack” two batteries in series, then their voltages add up. Two 1.5V batteries will output 3V. If you stack four of them you get 6V. Which was pretty useful when the “standard” for many transistors and integrated circuits was 5V.
A lot of things have changed since those days, of course. Different battery materials are in widespread use, and integrated circuit technology has changed such that 5V is not only undesirable, it’s not acceptable.
As transistors were made smaller and smaller (“shrunk”), it became necessary to reduce their supply voltages. This has gone through many phases, from 5V -> 3.6V -> 3V etc. etc. A lot of integrated circuits now are very happy to run on 1V or so. If a gizmo uses only such ICs, it can use a single battery.
But there are at least a couple of reasons to use higher voltages. One is that there are still some old technology devices around that run on a 3V standard, or use signaling busses between them that use a >1V standard. There are also some components, such as certain displays, that work on higher voltages.
It is possible to boost voltages, but a better strategy is often to use a power source that provides the highest voltage needed. For the lower voltage devices, it’s relatively easy/cheap to drop the voltage down.
So you use two batteries in series and that provides a nominal voltage of 3V (actually less pretty quickly). For things that don’t need that, you reduce the voltage.
The voltage put out by a battery is determined largely by the materials used. While you can increase the available current by making it bigger (or ganging up a bunch of smaller ones in parallel), the voltage is somewhat fixed.
The standard batteries used for many years had a natural voltage of about 1.5V. But for the transistors of the time, that voltage was not optimal.
There’s a hack for that. If you “stack” two batteries in series, then their voltages add up. Two 1.5V batteries will output 3V. If you stack four of them you get 6V. Which was pretty useful when the “standard” for many transistors and integrated circuits was 5V.
A lot of things have changed since those days, of course. Different battery materials are in widespread use, and integrated circuit technology has changed such that 5V is not only undesirable, it’s not acceptable.
As transistors were made smaller and smaller (“shrunk”), it became necessary to reduce their supply voltages. This has gone through many phases, from 5V -> 3.6V -> 3V etc. etc. A lot of integrated circuits now are very happy to run on 1V or so. If a gizmo uses only such ICs, it can use a single battery.
But there are at least a couple of reasons to use higher voltages. One is that there are still some old technology devices around that run on a 3V standard, or use signaling busses between them that use a >1V standard. There are also some components, such as certain displays, that work on higher voltages.
It is possible to boost voltages, but a better strategy is often to use a power source that provides the highest voltage needed. For the lower voltage devices, it’s relatively easy/cheap to drop the voltage down.
So you use two batteries in series and that provides a nominal voltage of 3V (actually less pretty quickly). For things that don’t need that, you reduce the voltage.
1.5 volts is too small a voltage to do most things. AA, AAA, C, D batteries all put it 1.5v per cell because of the chemistry involved. Things that use lithium batteries actually do often just use 1 cell sometimes because the chemistry of them puts out about 3.7 volts. Same with things that use 9v batteries. 9v batteries are actually lots of little 1.5v batteries (watch battery size) stacked up inside that case.
1.5 volts is too small a voltage to do most things. AA, AAA, C, D batteries all put it 1.5v per cell because of the chemistry involved. Things that use lithium batteries actually do often just use 1 cell sometimes because the chemistry of them puts out about 3.7 volts. Same with things that use 9v batteries. 9v batteries are actually lots of little 1.5v batteries (watch battery size) stacked up inside that case.
1.5 volts is too small a voltage to do most things. AA, AAA, C, D batteries all put it 1.5v per cell because of the chemistry involved. Things that use lithium batteries actually do often just use 1 cell sometimes because the chemistry of them puts out about 3.7 volts. Same with things that use 9v batteries. 9v batteries are actually lots of little 1.5v batteries (watch battery size) stacked up inside that case.
Also, a single alkaline battery at 3v, if in the same form factor as a AA batter would have double the voltage, but half the capacity. You’d still want two batteries.
Essentially, 1.5v is a legacy voltage that we keep. Higher voltage, assuming same chemistry, would be at the expense of capacity, assuming the form factor stays the same.
Or simply put, watt-hours would be the same regardless.
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