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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.
In physics and engineering, a free body diagram (FBD; also called a force diagram) [1] is a graphical illustration used to visualize the applied forces, moments, and resulting reactions on a free body in a given condition. It depicts a body or connected bodies with all the applied forces and moments, and reactions, which act on the body(ies).
Under certain conditions, some battery chemistries are at risk of thermal runaway, leading to cell rupture or combustion.As thermal runaway is determined not only by cell chemistry but also cell size, cell design and charge, only the worst-case values are reflected here.
The open-circuit voltage is 1.55 V, the average voltage during discharge is 1.25 V. [9] While the energy density is only around one third as that of a lithium battery, the distinctive virtue of the nickel–hydrogen battery is its long life: the cells handle more than 20,000 charge cycles [4] with 85% energy efficiency and 100% faradaic efficiency.
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.
The cut-off voltage is different from one battery to the other and it is highly dependent on the type of battery and the kind of service in which the battery is used. When testing the capacity of a NiMH or NiCd battery a cut-off voltage of 1.0 V per cell is normally used, whereas 0.9 V is normally used as the cut-off voltage of an alkaline cell ...
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.
How fast self-discharge in a battery occurs is dependent on the type of battery, state of charge, charging current, ambient temperature and other factors. [2] Primary batteries are not designed for recharging between manufacturing and use, and thus to be practical they must have much lower self-discharge rates than older types of secondary cells.