Why do rechargeable batteries only have 1.2 volts vs disposable batteries have 1.5 volts
In: Technology
The electric potential depends on the specific chemical reactions in the battery cell, which are different for the different materials in different types of batteries.
For example, due to the chemistry of a lead-acid car battery, each internal cell has a nominal voltage of 2.1 volts.
Standard electrode potentials for different materials are listed in tables like this: https://en.wikipedia.org/wiki/Standard_electrode_potential_(data_page)
Some chemical reactions can be reversed easily by applying a reverse (charging) voltage to the cell, without destroying the battery cell’s structure. Other kinds of battery cells would get damaged internally if you tried that, so those cells are sold as “one-time use” batteries.
Disposables go down to 1.2V pretty quickly, and then hang out there until they’re used up (at around 1V). Lower charge rechargeable last longer, so I guess they decided that was enough to not push over into lower life expectancy.
They use different chemicals that result in different voltages. The voltage is the result of a chemical reaction and the voltage depends on the chemicals
The common AA sized non-rechargeable are Alkaline batteries with Manganese (IV) oxide cathode and Zinc anode that result in a nominal voltage of 1.5V
The common AA sized rechargeable uses a Nickel oxide hydroxide cathode and in principle, a hydrogen anode is the form of a Metal hydride. That result in a nominal voltage of 1.2V
Both types might be the same physical shape but the content if different. For most application a 1.2V battery will work even if it was designed for 1.5V but there are esceptions.
None electric cars have lead-acid batteries with Lead dioxide cathode and Lead anode and the nominal voltage for them is 2.1V. You have 6 cells in each battery for a total of 6*2.1 =12.6V but as just called 12V
The most common rechargeable batteries today are likely not at 1.2V but at 3.7V as that is the nominal voltage of common Lithium-ion batteries. The use of different kinds of lithium cathodes like Lithium cobalt oxide with a Graphite. Cellphones and other devices with build-in batteries use them. This is the type of battery in an electric cat, you just have a lot in series to get to the voltage for the engine that is around 400V
There are Li-ion batteries with the same shape as a AA battery at 3.7V but they are called 14500 batteries. Some flashlights can use both but they likely would kill a lot of other devices.
Buy lithium-ion 1.5v AAA and AA rechargables. I use them in my Samsung TV remote, which doesn’t like the 1.2v. They are expensive, but better then chewing thru AAA alkaline batteries every few weeks like I was. Amazon has them. They have a USB plug at the top of them to charge them. $25 for 4.
You cannot control what voltage a battery will be, that depends on the chemicals inside. In order to have a rechargeable battery, they had to use different chemicals that result in 1.2 volts rather than 1.5 volts.
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