Charging trickle

Ni-MH cell 1-h charge (3.5 A) to thermal cutout followed by trickle charge of 0.350 A is acceptable. The Ni—Cd charger can be used with these cells. Ni—Cd 1-h charge (2.0 A) to thermal cutout followed by trickle charge of 0.200 A is acceptable. 

Small-format lead-acid batteries with immobilized electrolyte are still used in some applications such as hand lanterns. Low-cost six or twelve-volt batteries (e.g. 6 Ah size) are used in child-driven toy cars and other sizes in emergency-light or alarm systems, kept on trickle-charge. Efforts are being made to produce bipolar systems which give 30 percent improvements. 

It must be emphasized that the most appropriate charging regime is very dependent on the cell system under consideration. Some are tolerant to a considerable amount of overcharging (e.g. nickel-cadmium batteries), while for others, such as zinc-silver oxide and most lithium secondary cells, overcharging can result in permanent damage to the cell. Sealed battery systems require special care float charging should not be used and trickle charge rates should be strictly limited to the manufacturer s recommended values, since otherwise excessive cell temperatures or thermal runaway can result. 

Because the association of the expression passivation potential with the potential of the maximum leaves something to be desired as a definition of passivation, another potential, the Hade potential, is sometimes used to define the phenomenon of passivation. This potential can be described quite loosely (see Fig. 12.62) as the potential at which (while moving the potential back in the cathodic direction) the current begins to increase from the low trickle charge value. 

Trickle charging — A continuous, low level, constant current charging of secondary - batteries (cells), with the purpose of maintaining the battery fully charged, offsetting spontaneous self-discharge or low current drain. Accomplished by a current source, with preset constant current, trickle current , that is carefully adjusted to maintain the battery in the fully charged condition, at... 

Trickle charging is used only for Pb cells. The current used in trickle charging is very much less than the rated battery current. The method is used for storage batteries which supply little or no current as a normal condition. They therefore remain charged for long periods and a small trickle of current is sufficient to maintain the charge. 

NiCd cells should not be trickle charged, and they should be given a heavy discharge-charge cycle occasionally to ensure that their internal condition remains in good order. 

Lead/acid batteries are used for many diverse remote and standby duties and hence are manufactured with a wide range of voltage and current capabilities and capacities. Pb/acid batteries do self-discharge slowly because of some reaction between the active materials and water as a result the batteries are often on constant trickle charge. 

To maintain a battery in good condition it should be regularly trickle-charged. 

Power requirements for field instruments are important considerations. The use of low-consumption light-emitting diodes (LEDs) in sensors, and photovoltaic sensors which convert incident light directly into electrical energy, reduces power needs to a minimum. Solar panels are useful to trickle-charge instruments and dataloggers. 

Ni-MH cells have a 5-10% self-discharge rate at the beginning of life but stabilize around 0.5-1 % per day. Cooler storage temperatures have lower discharge rate and longer battery life. Continual trickle charging of small Ni-MH cells can cause permanent deterioration in cell performance. 

The NiMH battery is sensitive to the amount of trickle charge applied to maintain full charge. In spite of its inherent high self-discharge, the trickle charge of the NiMH must be set lower than that of the NiCd. A trickle charge that is acceptable for the NiCd will overheat the NiMH and cause irreversible damage. 

Tridde chaise Maintenance charge to keep the battery in full-charge state after the charge cycle. Trickle charge compensates for self-discharge. 

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