question: Why are some batteries rechargable while others are not?
comment: You can actually recharge non-rechargeable batteries such as alkaline batteries. However, they perform very poorly and take a very long time to recharge (Up to one day). They will also only last a handful of cycles before completely dying. I highly advise against trying this as your normal battery charger will likely cause the battery to overheat and catch on fire. Essentially what recharging a battery does is reverse the flow of electrons, pushing all of the electrons from one side to the other. Nearly all batteries can do this, but only ones such as NiCad, NiMh, Lead-Acid, and Li-Ion/Po can do this efficiently. The only reason that alkaline batteries still exist is that they're cheap, durable and relatively safe.
passages: Different battery chemistries require different charging schemes. For example, some battery types can be safely recharged from a constant voltage source. Other types need to be charged with a regulated current source that tapers as the battery reaches fully charged voltage. Charging a battery incorrectly can damage a battery; in extreme cases, batteries can overheat, catch fire, or explosively vent their contents.
  
  Section::::Charging and discharging.:Rate of discharge.
   In the latter case, the problem occurs due to the different cells in a battery having slightly different capacities. When one cell reaches discharge level ahead of the rest, the remaining cells will force the current through the discharged cell.
  
  Many battery-operated devices have a low-voltage cutoff that prevents deep discharges from occurring that might cause cell reversal. A smart battery has voltage monitoring circuitry built inside.
   Section::::Active components.
  
  The active components in a secondary cell are the chemicals that make up the positive and negative active materials, and the electrolyte. The positive and negative are made up of different materials, with the positive exhibiting a reduction potential and the negative having an oxidation potential. The sum of these potentials is the standard cell potential or voltage.
   BULLET::::- "Primary" batteries are designed to be used until exhausted of energy then discarded. Their chemical reactions are generally not reversible, so they cannot be recharged. When the supply of reactants in the battery is exhausted, the battery stops producing current and is useless.
  
  BULLET::::- "Secondary" batteries can be recharged; that is, they can have their chemical reactions reversed by applying electric current to the cell. This regenerates the original chemical reactants, so they can be used, recharged, and used again multiple times.
   The energy used to charge rechargeable batteries usually comes from a battery charger using AC mains electricity, although some are equipped to use a vehicle's 12-volt DC power outlet. The voltage of the source must be higher than that of the battery to force current to flow into it, but not too much higher or the battery may be damaged.
   Section::::Charging and discharging.:Lifespan and cycle stability.
   Devices which use rechargeable batteries include automobile starters, portable consumer devices, light vehicles (such as motorized wheelchairs, golf carts, electric bicycles, and electric forklifts), tools, uninterruptible power supplies, and battery storage power stations. Emerging applications in hybrid internal combustion-battery and electric vehicles drive the technology to reduce cost, weight, and size, and increase lifetime.
  
  Older rechargeable batteries self-discharge relatively rapidly, and require charging before first use; some newer low self-discharge NiMH batteries hold their charge for many months, and are typically sold factory-charged to about 70% of their rated capacity.
   Section::::Categories and types of batteries.:Cell types.:Molten salt.
  
  Molten salt batteries are primary or secondary batteries that use a molten salt as electrolyte. They operate at high temperatures and must be well insulated to retain heat.
  
  Section::::Categories and types of batteries.:Cell types.:Reserve.
   Rechargeable batteries have lower total cost of use and environmental impact than non-rechargeable (disposable) batteries. Some rechargeable battery types are available in the same form factors as disposables. Rechargeable batteries have higher initial cost but can be recharged very cheaply and used many times.
  
  Common rechargeable battery chemistries include:
   Section::::Categories and types of batteries.:Secondary.
  
  Secondary batteries, also known as "secondary cells", or "rechargeable batteries", must be charged before first use; they are usually assembled with active materials in the discharged state. Rechargeable batteries are (re)charged by applying electric current, which reverses the chemical reactions that occur during discharge/use. Devices to supply the appropriate current are called chargers.
   Small rechargeable batteries can power portable electronic devices, power tools, appliances, and so on. Heavy-duty batteries power electric vehicles, ranging from scooters to locomotives and ships. They are used in distributed electricity generation and in stand-alone power systems.
  
  Section::::Charging and discharging.
   Attempts to extend the life of primary cells, for example by recharging alkaline batteries, meet with variable results. Third-party devices are manufactured and represented as being able to recharge primary cells. The internal chemical reactions of a primary cell are not easily reversed by externally applied currents, so reactants do not entirely return to their initial state and location. Recharged primary cells will not have the life or performance of secondary cells. Manufacturers of primary cells usually warn against recharging.
  
  Section::::Polarization.
   Although these batteries can be used in any device that supports a standard size (AA, AAA, C, D, etc.), they are formulated to last longest in periodical use items. This type of battery is better suited for use in low-drain devices such as remote controls or for devices that are used periodically such as flashlights (torches), television remote control handsets, portable radios, etc. If they are discharged by less than 25%, they can be recharged for hundreds of cycles to about 1.42 V. If they are discharged by less than 50%, they can be almost fully recharged for a few dozen cycles, to about 1.32 V. After a deep discharge, they can be brought to their original high-capacity charge only after a few charge-discharge cycles.
   Commons types of Secondary cells (namely NiMH and Li-Ion) due to their much lower internal resistance do not suffer the large loss of capacity that Alkaline, Zinc–carbon and Zinc chloride ("Heavy Duty" or "Super Heavy Duty") do with high current draw 
  
  Reserve batteries achieve very long storage time (on the order of 10 years or more) without loss of capacity, by physically separating the components of the battery and only assembling them at the time of use. Such constructions are expensive but are found in applications like munitions, which may be stored for years before use.
  
  Section::::Recharging primary cells.
   Primary batteries, or primary cells, can produce current immediately on assembly. These are most commonly used in portable devices that have low current drain, are used only intermittently, or are used well away from an alternative power source, such as in alarm and communication circuits where other electric power is only intermittently available. Disposable primary cells cannot be reliably recharged, since the chemical reactions are not easily reversible and active materials may not return to their original forms. Battery manufacturers recommend against attempting to recharge primary cells. In general, these have higher energy densities than rechargeable batteries, but disposable batteries do not fare well under high-drain applications with loads under 75 ohms (75 Ω). Common types of disposable batteries include zinc–carbon batteries and alkaline batteries.
   Battery manufacturers' technical notes often refer to voltage per cell (VPC) for the individual cells that make up the battery. For example, to charge a 12 V lead-acid battery (containing 6 cells of 2 V each) at 2.3 VPC requires a voltage of 13.8 V across the battery's terminals.
  
  Section::::Charging and discharging.:Damage from cell reversal.
   Primary (single-use or "disposable") batteries are used once and discarded; the electrode materials are irreversibly changed during discharge. Common examples are the alkaline battery used for flashlights and a multitude of portable electronic devices. Secondary (rechargeable) batteries can be discharged and recharged multiple times using an applied electric current; the original composition of the electrodes can be restored by reverse current. Examples include the lead-acid batteries used in vehicles and lithium-ion batteries used for portable electronics such as laptops and mobile phones.
   The terminal voltage of the battery is not constant during charging and discharging. Some types have relatively constant voltage during discharge over much of their capacity. Non-rechargeable alkaline and zinc–carbon cells output 1.5V when new, but this voltage drops with use. Most NiMH AA and AAA cells are rated at 1.2 V, but have a flatter discharge curve than alkalines and can usually be used in equipment designed to use alkaline batteries.
   Section::::Secondary cell.
  
  A secondary cell, commonly referred to as a "rechargeable battery" is an electrochemical cell that can be run as both a galvanic cell or as an electrolytic cell. This is used as a convenient way to store electricity, when current flows one way the levels of one or more chemicals build up (charging), while it is discharging they reduce and the resulting electromotive force can do work.
  
  Section::::Fuel cell.
   Some types of primary batteries used, for example, for telegraph circuits, were restored to operation by replacing the electrodes. Secondary batteries are not indefinitely rechargeable due to dissipation of the active materials, loss of electrolyte and internal corrosion.
  
  Section::::Categories and types of batteries.:Primary.
   Primary batteries readily available to consumers range from tiny button cells used for electric watches, to the No. 6 cell used for signal circuits or other long duration applications. Secondary cells are made in very large sizes; very large batteries can power a submarine or stabilize an electrical grid and help level out peak loads.
  
  Section::::Hazards.
  
  Section::::Hazards.:Explosion.
  
  A battery explosion is generally caused by misuse or malfunction, such as attempting to recharge a primary (non-rechargeable) battery, or a short circuit.
   Subjecting a discharged cell to a current in the direction which tends to discharge it further to the point the positive and negative terminals switch polarity causes a condition called "". Generally, pushing current through a discharged cell in this way causes undesirable and irreversible chemical reactions to occur, resulting in permanent damage to the cell.
  
  Cell reversal can occur under a number of circumstances, the two most common being:
  
  BULLET::::- When a battery or cell is connected to a charging circuit the wrong way around.
  
  BULLET::::- When a battery made of several cells connected in series is deeply discharged.
   Electric-vehicle batteries differ from starting, lighting, and ignition (SLI) batteries because they are designed to give power over sustained periods of time. Deep-cycle batteries are used instead of SLI batteries for these applications. Traction batteries must be designed with a high ampere-hour capacity. Batteries for electric vehicles are characterized by their relatively high power-to-weight ratio, specific energy and energy density; smaller, lighter batteries reduce the weight of the vehicle and improve its performance. Compared to liquid fuels, most current battery technologies have much lower specific energy, and this often impacts the maximal all-electric range of the vehicles. However, metal-air batteries have high specific energy because the cathode is provided by the surrounding oxygen in the air. Rechargeable batteries used in electric vehicles include lead–acid ("flooded", deep-cycle, and VRLA), NiCd, nickel–metal hydride, lithium-ion, Li-ion polymer, and, less commonly, zinc–air and molten-salt batteries. The most common battery type in modern electric cars are lithium-ion and Lithium polymer battery, because of their high energy density compared to their weight. The amount of electricity (i.e. electric charge) stored in batteries is measured in ampere hours or in coulombs, with the total energy often measured in watt hours.
   Rechargeable batteries typically initially cost more than disposable batteries, but have a much lower total cost of ownership and environmental impact, as they can be recharged inexpensively many times before they need replacing. Some rechargeable battery types are available in the same sizes and voltages as disposable types, and can be used interchangeably with them.
  
  Section::::Applications.
   The most common power source for flashlights is the battery. Primary battery (disposable) types used in flashlights include button cells, carbon-zinc batteries in both regular and heavy duty types, alkaline, and lithium.
  
  Secondary, rechargeable, types include lead acid batteries, NiMH, NiCd batteries and lithium ion batteries. The choice of batteries will play a determining role in the size, weight, run time, and shape of the flashlight. Flashlight users may prefer a common battery type to simplify replacement.
  
presuppositions: You cannot recharge non-rechargeable batteries. Non-rechargeable batteries can't be recharged.
corrections: You can recharge non-rechargeable batteries, but they perform very poorly and take a long time to recharge. Non-rechargeable batteries can be recharged but take a long time to do so.
raw_presuppositions: You cannot recharge non-rechargeable batteries. Non-rechargeable batteries can't be recharged.
raw_corrections: You can recharge non-rechargeable batteries, but they perform very poorly and take a long time to recharge. Non-rechargeable batteries can be recharged but take a long time to do so.