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A battery charger, recharger, or simply charger, [1] [2] is a device that stores energy in an electric battery by running current through it. The charging protocol—how much voltage and current, for how long and what to do when charging is complete—depends on the size and type of the battery being charged.
A nickel–metal hydride battery (NiMH or Ni–MH) is a type of rechargeable battery. The chemical reaction at the positive electrode is similar to that of the nickel–cadmium cell (NiCd), with both using nickel oxide hydroxide (NiOOH). However, the negative electrodes use a hydrogen-absorbing alloy instead of cadmium.
Trickle charging is the process of charging a fully charged battery at a rate equal to its self-discharge rate, enabling the battery to remain at its fully charged level. This state occurs almost exclusively when the battery is not loaded, as trickle charging will not keep a battery charged if current is being drawn by a load.
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.
Pump Express Plus supports elevated voltage levels of 7, 9 and 12 volts, whereas the specification for Quick Charge 2.0 lacks the 7-volt level. A 20-volt level was added in a revision named "class B" of the specification. [12] [13] The voltage range of the successor Pump Express Plus 2.0 is between 5 volts and 20 volts, with 0.5 volts steps.
However, a Ni–Cd battery has a lower self-discharge rate (for example, 20% per month for a Ni–Cd battery, versus 30% per month for a conventional NiMH under identical conditions), although low self-discharge ("LSD") NiMH batteries are now available, which have substantially lower self-discharge than either Ni–Cd or conventional NiMH ...
As a result of this current, the battery absorbs a charge and its voltage rises. The charger limits the maximum voltage to U max, a constant or temperature-dependent maximum, typically around 2.4 V per cell. Once the U max voltage is reached, typically when the battery is charged to 70–80% of its capacity, [1] the charger enters the Uo-phase ...
Nickel–zinc batteries have a charge–discharge curve similar to 1.2 V NiCd or NiMH cells, but with a higher 1.6 V nominal voltage. [5]Nickel–zinc batteries perform well in high-drain applications, and may have the potential to replace lead–acid batteries because of their higher energy-to-mass ratio and higher power-to-mass ratio – as little as 25% of the mass for the same power. [6]