ELI5. Why do most devices requiring AA or AAA batteries need at least two. Why not create a standard battery that is the equivalent of two or have common circuitry that only relies on one battery of a similar low profile?
In: Engineering
AA and AAA are the standards. Easier to stack them in series/parallel to get the required voltage/current than it is to make another standard. Lipos are 3.7v but good luck getting one to click into your TV remote.
Bumping 1.5v up to 3v is doable but it costs a few bucks and you lose some efficiency. Most devices that could afford this circuitry would just have its own internal lithium battery.
Actually a lot of devices don’t require two.
Many devices are simply big enough they can easily house two or more batteries. And by allowing you to add them, the total capacity of energy goes up and you don’t have to change them as often. Eg, two batteries takes longer to drain than one *because there are two of them*.
Then to get a bit more technical, the 1.5v label is a lie. As they lose power a AA’s voltage can drop as low as 0.9v. If your device absolutely requires 1.4v, the battery will appear dead in it even if you can put the battery in a device that uses less power, like flashlight and turning it on. By using two batteries and adding a regulator after it, you can drop the 3~1.8v to 1.4v and keep it consistent until the batteries have nothing left in them. This also makes them seem like they last longer, because you’re tossing them in the trash when they reach <1% charge instead of 50% or so.
Which kind of takes us to the main point. Your device has battery expectations, with standardized batteries they can adjust to them. Sort of like how cell phones use different hardware, but they all use standardized methods to recharge them. Offering to many batteries for devices, or charging cables for cell phones, and users will have problems matching them up and have left over batteries & cords they cannot use.
Many button batteries are 3 volts, which is the voltage of two aa or aaa batteries. So they do make them.
A battery is 1.5Volts.
If you connect two batteries one on top of the other (connecting them in series) you create a 3V battery circuit.
If you connect their tips together and their bottoms together (connecting them in parallel) you create a 1.5V battery circuit that will last twice as long.
Creating new standards is hard cause it messes up compatibility. The current system for AA and AAA batteries gives designers a lot of flexibility to choose how to power their circuits and a lot of devices that have different power needs use internal batteries that can be recharged.
Total Energy output stays about the same even if you adjust voltage. Watt hours is the constant. Watt hours = amps x volts. Therefore You could make a higher voltage battery or a higher amperage battery but without increasing the size of the batter you can’t increase both. Therefore you end up with about 1.5v x 2.0ah.
That’s what a 9v does, if you cut one open you’ll see its actually 6 tiny 1.5 batteries. But to answer your question its easier to do it that have if there is space for the batteries.
They did and my early digital camera used them. It was hard to find and cost twice as much. I used the standard AA instead. It is cheaper to produce a lot of one thing in huge quantities than change equipment produce a few and set up for the next. Less set up time so the line keeps making products.
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