Nickel-cadmium batteries using nickel-cadmium rechargeable battery applications

basic electrical formulas
first to introduce a few very simple formula for the basic electricity, no electronics background to let the readers to the concept a little bit of several physical phenomena.
voltage (V) = current (I) x Resistance (R)
charge quantity (Q) = current (I) x time (T)
power (P) = V x I
energy (W) = P x T
Any object has a resistance, the impedance at both ends with a potential difference will produce a charge flow through the impedance, the greater the impedance per unit time (second) flows through the smaller amount of charge, the smaller the unit of time impedance amount of charge flow through the more. If we increase the potential difference per unit time amount of charge flowing through the more, the potential difference per unit time decreases the amount of charge flowing through the less. This potential difference is called Voltage (V), in volts (V), per unit time flowing through the amount of the charge amount is called the current (I), ampere (A), impedance is called resistance (R), in units of ohms (). current (I) the greater the intensity per unit time that the charge flow through the more the number, then? in T seconds in the charge flowing through the resistor number of total I x T, used to describe the amount of the charge amount of the term for the amount of charge (Q), commonly known that power, in units of Coulomb (Q). resistor power consumption (P) for the I x V, in units of watts (W), the greater the consumption of power on behalf of more power., consumption of energy (W) for the P x T, in units of joules (J), the longer the greater the consumption of energy, the same time, the greater the power consumption of the greater consumption of energy.
example: the battery connected to a 1.5V lamp bulb 0.5 , consumption current is 3A, power consumption is 4.5W, 10 seconds total flow through the charge of 30 Coulomb, consumes 45 joules of energy.
nickel-cadmium battery materials, batteries Classification There are many kinds of chemical batteries in the non-rechargeable batteries run out on the throw as a battery, you can re-use many times the battery charge is called secondary battery, and nickel-cadmium batteries are rechargeable batteries in an alkaline battery. Ni-Cd battery anode material is the use of peroxide hydroxide, cadmium compounds used cathode active material, the electrolyte is potassium hydroxide and other alkaline aqueous solution used. When Ni-Cd battery, it will produce in the anode above the nickel hydroxide, in above the cathode of metal cadmium, thus forming a potential difference between two poles. the nickel-cadmium battery anode and cathode ends of external load discharge, the cathode produce negatively charged electrons flow to the anode through an external load, thus providing energy for the external load consumption .

overcharging
the process of charging the battery voltage will increase with the storage capacity increased gradually stored in the battery power when the saturated charge electrode materials can not continue, if continue to charge the electrolyte will be from electrolysis, and produce oxygen in the anode, the cathode produces hydrogen gas, so the battery will be sealed within the internal pressure caused by rising, it will damage the internal structure of the battery. as a phenomenon known as over-charging.
in order to avoid over-charging the battery were damaged, usually the capacity of the cathode than the anode production capacity, such as over-charging the anode will first reach saturation and produce oxygen, while the cathode has not saturated and will not produce hydrogen, the anode to the cathode produced by oxygen diffusion After the charge will produce cadmium metal from the chemical reaction of oxygen absorbed, and the reaction speed and the speed metal cadmium produced a balanced, it can effectively avoid the pressure of the battery up. However, if the charge current is too large (when using the fast charge) lose balance, the battery internal pressure relief valve opened the General Assembly on the battery, hydrogen and oxygen will leak to the external battery until the battery before closing the pressure reducing valve seal up again. But the gas leak has been made of chemical materials within the reduced, resulting in shortened battery life.

charging voltage change
battery from overcharging, because the anode and cathode oxygen generated from the chemical reaction will produce heat, so hot the battery temperature will rise shell. As The higher the temperature the battery charge voltage will become lower, thus charging the battery voltage will continue to rise until the over-charging, the battery temperature will suddenly speed up, the rise in turn to the peak voltage began to decrease.

Nominal voltage
standard nickel-cadmium battery discharge conditions in the discharge, the voltage will slowly drop until the release when the power is almost finished, the voltage will drop substantially, this voltage is called the nominal voltage. General nickel-cadmium battery nominal voltage of 1.2V, 1.5V and general battery is the same marked point, are marked at the top of the battery case. Nickel-cadmium battery as long as power voltage must be at least 1.2V above the nominal voltage, storage The more power the higher voltage.

discharge termination voltage
battery discharge when the voltage will decrease as the battery level decreases, when the voltage down to the required standard bits do not let it continue to discharge, known as the discharge end, and this voltage to the discharge termination voltage is called. usually the manufacturer's suggested the discharge termination voltage is about 0.9V ~ 1.1V or so, this quasi-voltage discharge capacity at time almost up light, and this condition is called completely discharged. Ni-Cd battery has fully discharged its not removed to load and discharge it to go, then? becomes excessive discharge, the voltage will drop rapidly until 0V up. If the voltage has not dropped about 0V to terminate discharge, the battery voltage will be automatically and quickly rose to around 1.2V nominal voltage.
excessive discharge
nickel-cadmium battery is a fatal over-discharge, the discharge termination voltage is set, and in situation, not only failed to promote the load power, battery life can also cause damage. and once accidentally allow voltage to drop to almost equal to 0V, even to terminate the discharge of the load I'm afraid it is too late to remove the battery's voltage can not automatic recovery, then the general power charger can not charge in, it fixed the voltage will remain at 0V has been fixed. at the moment it like a stroke-like paralysis in there, not to mention shortening his life on, and it is often can not use expired Alas.


definition of battery capacity battery capacity means the battery discharge voltage until the voltage dropped to end up, during which the discharge amount of charge that can be achieved. If the required standard discharge current and temperature conditions, on fully charged battery to discharge until the discharge end, the resulting volume is called the rated capacity (or nominal capacity). capacity of the size of the electrode material and its consumption the active material, whereas the standard discharge conditions are in accordance with the provisions of the battery types have different. capacity is based on the definition of battery discharge reaction, rather than charging reaction to define, so we often say how much battery capacity is means the discharge amount of charge available to the cumulative number of discharge rather than charging the amount of charge flow into the number.
battery capacity, battery capacity,Do not confused see Intel notebook CPU woven type, said method
size, you can use [(discharge current) x (voltage down to discharge through the discharge termination voltage of the time)], calculated to represent the value obtained. prior to the introduction of the basic electrical formulas, the power for the current x time, the unit is Coulomb (Q), if the battery Coulomb to indicate the number of battery capacity, then, may be more difficult to understand, so the battery capacity is the value of the current x time, directly to the C = IT (units in mAh or Ah) to indicate which C is the capacity (with the Coulomb the same meaning), I is current, A is amps, mA, said the current size of high security (thousandths of amps, A), h on behalf of an hour (hour), that is to one-thousandth of one ampere of current discharge hours accumulated discharge amount of 1mAh. so C = I x T = the number of mAh, mAh is the equivalent Coulomb representation. usually the battery shell packaging will be marked above the rated capacity of the battery, used to represent the maximum capacity of the battery. The new nickel-cadmium battery when the first charge and discharge capacity can be up to the rated capacity, but capacity will increase with the number of charge and discharge is reduced.
examples: 1 Amp current discharge take two hours to shine battery That? battery capacity of about 2000 mAh. If we come to that battery capacity to Coulomb, then? C = I x T = 1A x 7200 sec = 7200 coulomb. you also find that with the 2000 mah to 7200 than Coulomb to represent less hollow and more clear it
C expression
battery in addition to amp (or mA) units that do charge the battery discharge current size, but also use the letters C (capacity) to as the rated capacity (current x time) of the current part, to its current size as a measure of the unit. For example, the rated capacity of 600mAh battery, C is the meaning of 600mA, so the current 1C is 600mA, the current 2C is 1.2mA, the current 0.1C is 60mA. after buying the battery if it can not find in standard amperage current charge and discharge time, please do not worry, do not forget to look around to see how many have written in C Oh.

charge
so-called charge-discharge rate (discharge) rate is the total capacity of electric charge up (charging) the time required to complete, as the charge (discharge) when the standard electric rate. generally used to describe the release (charge) of electricity How much speed, for example, the discharge rate of two hours, is the current use of 0.5C, in two hours all the battery capacity is done and .20-minute rate that the current use of 3C within 20 minutes all the rated capacity of batteries had finished. in the battery manufacturers specifications above, and is often used to represent the standard hour rate discharge time, as long as the conversion under the rated capacity to know how much a standard discharge current. normally provided by the manufacturer specifications of the rated capacity is at 20 ℃ , while the discharge rate of 0.2C by the conditions of 5 hours to measure.
can not charge the battery charging efficiency
number of power can be stored into the number of electricity will be wear and tear, in addition to leakage between the anode and cathode insulator leakage, the material can not be flawless to store all the power. Remove the battery when the battery discharge and charge into the battery when the flow ratio, called the charge efficiency.
usually charge the battery manufacturers are recommended amount of must be 1.5 times the rated capacity to the battery fully charged. that if the current charging needs 0.1C charge for 15 hours to charge the current needs of 3C charge half an hour, although theoretical fill volume is 1.5 times the rated capacity, However, the actual fill volume is almost exactly the rated capacity.
utilization
Theoretically, the rated capacity of the battery much, but in fact fully charged and then discharge electricity available is often less than the theoretical capacity, said The actual storage capacity of the battery can store not it? large, the actual capacity relative to the theory of capacity utilization ratio of call. usually the larger the battery discharge current, or ambient temperature decreases, the utilization rate will be reduced.
discharge when the depth of
battery discharge the stored electricity discharge and discharge rate is called the depth of more than a percentage. For example, 20% depth of discharge electricity discharge to the extent of the remaining 80% of the electricity.

cycle life of nickel-cadmium batteries are usually
applications are used as a cyclical repeated charge and discharge work, battery life is limited, the capacity can not always maintained and not fall under a certain working conditions After repeatedly charging and discharging, the battery capacity will drop to 80% of rated capacity (or defined at 60%). This number is called repeatedly charge and discharge cycle life, cycle life, said the higher the longer the battery life. Some battery will be marked with the reference specifications of the above charge and discharge cycles, depth of discharge written about the number of how many times the intention of the cycle of life. As the charge and discharge current, discharge depth and other conditions of the different charge and discharge, cycle life expectancy with the changes, especially When using the high current discharge, the phenomenon must be shortened life expectancy. Now as long as nickel-cadmium battery manufacturers in accordance with the attached note purchase normal use, often can be used repeatedly for more than 500 times.

battery inside resistance and voltage
battery is internal resistance of voltage source, can be seen as an ideal voltage source (no internal resistance) in series a resistance output. missed both ends of load capacity to the battery terminal voltage is ideal voltage source voltage, called the open circuit voltage, when the battery is an external load, the load resistance in series with the receipt of an ideal voltage source, so the load on the resulting partial pressure is the battery terminal voltage will be less than the ideal voltage source of voltage, called closed-circuit voltage. The higher the internal resistance of the battery load voltage can be smaller share, so the battery is not the ideal resistance.
nickel-cadmium battery's internal resistance is very low, generally only a few milliohms to tens of milliohms or so, so different sizes of the external load is very stable discharge voltage, discharge current curve is very flat, you can enlarge the current discharge. general dry battery internal resistance of tens of ohms, the discharge voltage instability in the discharge current curve is not flat, compared to nickel-cadmium batteries are the ideal characteristics of the battery.


battery self-discharge will be from a chemical reaction due to internal relations, the internal will self-discharge, although not stored in external load, but the battery The power will gradually disappear over time. self-discharge rate is called self-discharge rate, the higher the ambient temperature, the greater the self-discharge current. According to experts, the results of experiments, nickel-cadmium battery will be about three months at 0 ℃ discharge residual capacity of the remaining 20% to 80%, about one month at 20 ℃, discharge 25%, 40% three months of discharge, if the higher the temperature 45 ℃, 70% a month already let go of the capacity. So , in the summer after fully charge the battery as long as a few days time, capacity on the remaining 80% or 50%, and no wonder experts suggest the best way is to save battery sealed properly packaged and placed in cold storage refrigerator (not moisture), is not without reason.

continuous discharge with intermittent discharge
continuous discharge is the battery during the discharge process is not interrupted, continuous discharge until the battery voltage down to discharge termination voltage was stopped and intermittent discharge refers to the process of battery discharge current path between the load and off, sometimes turn sometimes circuit until the battery voltage drops until the discharge termination voltage. battery voltage during the discharge continued to decline slowly, if the process of being will immediately stop the discharge of the voltage rise back to a quasi-bit only stop, if more continue to discharge the voltage and from the quasi-position start to decline.
continuous discharge mode during the actual discharge time and discharge the same, and intermittent discharge The actual discharge time is the discharge current path during the on-time accumulation and fragments. Comparison of the same capacity in two ways to discharge the battery when the voltage at the same end, as the battery voltage will return to the relationship between the intermittent discharge mode the actual discharge time than a continuous discharge of the actual discharge time is also long, and the intermittent discharge capacity released by way of a continuous discharge than the discharge capacity also means more.
normal cells have this phenomenon, with large current to discharge reduce the discharge capacity will impose a lot, but the use of indirect discharge means way more than the more continuous discharge capacity, especially when the battery external heavy load (the smaller the load resistance) is the more obvious differences in behavior. nickel-cadmium battery internal resistance Small short-circuit current characteristics of a large flat discharge curve good, in general, using a continuous discharge with intermittent discharge capacity is insignificant, but the electric gun and start the motor still running start by the occasion, very low impedance loads are heavy, the battery discharge current is quite large, the effect produced by intermittent discharge method is very obvious.
experience using the automatic electric gun firing at a few hundred hair cells do not often played on the appalling no electricity, and this with the advert called the continuous shooting between 1000 issued boast far, I do not know how the battery is still good quality, young age not to be destroyed on you and weak, or begin to doubt the stun gun's mecabox internal problems. but if you willing to try a little restraint and not that? excited to make use of single shot and fired indiscriminately squandering less automatic BB shells, you will find that your battery can also play a good few hundred hair no problem, good quality, good battery can also launch bomb to do more objective analysis.

the impact of temperature on the battery nickel-cadmium battery is *
chemical reaction to action, chemical materials, often self-consumption, high temperature environment in the self- consumption situation is more serious, capacity will be reduced, there may be leaking and rusty cases, to charge and discharge at high temperatures is caused by damage will reduce the battery life. Nickel-cadmium batteries can be fairly stable working temperature range wide, charging about 0 ~ 45 ℃, discharge of about -20 ~ 60 ℃, kept about -30 ~ 45 ℃, usually the best preserved in cold but not damp places.
temperature for the battery life and charge discharge characteristics are greatly affected if the ambient temperature when charging and discharging the higher, the battery material is damaged, very functional version of the active substances to reduce the capacity decreases, the anode cathode separation edition version of insulation between the lower isolation caused by short circuit, and the temperature increase the battery voltage becomes lower, reducing the number of charge-discharge efficiency, greatly reduced the capacity of the battery. Therefore, unless the use of nickel-cadmium batteries is heat resistant, and otherwise monitor the battery charge and discharge when the temperature, do not use The current discharge is too large to avoid overheating.

charging nickel-cadmium batteries if
to as standby power for the purpose, but by repeatedly charging and discharging of use, in accordance with current size of the battery charge can be divided into the standard charge and fast charge (fast charge), with the standard battery charger is the reference to 0.1C current rated capacity of the battery for 14 to 16 hours of charging, that is charge capacity is about 1.5 times the rated capacity of the battery can fully charge the battery is almost full. rapid charge the use of high current charge, and the late charge on the voltage and current control to prevent overcharge. rapid charging current size of about 0.3 General C or so, so can charge 4 to 6 hours to complete, and now some ultra-rapid type of cell, able to 1.5C or more ultra-rapid charging current to do, in less than an hour to complete a very short period of time charging action.
General terms of type of nickel-cadmium battery fast charge mode to charge, the resulting gas can not be fast absorbing battery life will be seriously affected, although the standard charging time-consuming for several hours, the battery can use a little bit longer to follow the way of good charge better. fast filling of the battery is more able to withstand high current, but with large current charging the battery case is definitely not good, the quality of different brands of batteries good bad mixed, on the users companies advertised specifications have not exaggerate the facts from that, unless the reputation of a reliable battery performance, or time is not pressed, then the best way is the standard charge.
in use in the rapid charging detection methods to prevent overcharge , more common with constant voltage control, temperature control, and increase control, or mixed in three ways.
voltage control
be detected when the battery voltage up to set the voltage to stop charging when. This approach is the easiest way to know if the battery under the battery voltage characteristic rising curve, you can detect when fully charged voltage is set to the nearest quasi-spaces, different styles of batteries fully charged when the voltage level is not Like, old and new batteries are not the same characteristics, compared with this method can not set the ideal voltage. in this way is simple but also quite dangerous, as stated earlier at a higher temperature will reduce battery voltage to high current will increase the battery charge is temperature, so there may have been fully charged battery but the voltage has not yet reached the standard set by bit, and the battery is fully charged voltage is not increased and began to decline, so too the consequences of very serious charge, if coupled with an internal short-circuit the battery charger not have the protection circuit, once the current is too dangerous consequences would be disastrous, so in this manner during charging, the user must pay attention.
temperature rise control
battery charge to produce the oxygen saturation in the cathode and cadmium oxide reaction heat, the battery temperature will start rising rapidly, take advantage of this phenomenon to detect when the temperature reaches a certain level of both the end of charge. in the same amount of charge under the charging current increases the temperature rising higher, and therefore if charge current is too large, to achieve predetermined temperature battery may not yet saturated, but the current if too small, absorbing fast temperature oxidation will not significantly increase, the charge movement would go on forever but I do not know an end. In addition, this approach will be ambient temperature, can not determine the battery temperature is within the self-produced chemical heat, or the surrounding environment caused by the heat misjudgment, so this way will be charged under high temperature and low temperatures will be less than charging excessive.

control
charging voltage of the battery charge capacity increased with the increase, when the charge has reached capacity, the voltage rises to peak, and instead began to decline slowly. use of the characteristics of this voltage drop can be to control the charging end, to be reached when the voltage drop to stop charging, typically 1.2V nickel cadmium battery will be 20mV its decline is almost over (the actual size of the data may refer to the battery), the charging process can be clearly observed meter out . battery charge voltage curve by the charge current and temperature, on the same charge capacity, the current is greater or lower the temperature, the voltage increases greatly, the decrease is also obvious. current temperature of the smaller or more high, the voltage rising rate of young, the decrease is also more difficult to distinguish between flat. Hence, the control method in fast charging more for the way in, and in order to avoid temperature to detect the failure, usually with the temperature increase control of use to to prevent overcharge.
nickel-cadmium batteries, if saved by the lack of use, or have already twilight, then? first few minutes before re-charging, voltage will occur not only charge up the situation and also to decrease and then increase the situation resulting in a miscarriage of justice charge termination. control method is a better control mode, the batteries of different characteristics of properties still available for full Chongdian Lai pair of batteries, Bijiao She worries about voltage or temperature set control problems and injuries battery.
present, many advanced microcomputer-controlled chargers are the use of such control, and the price is expensive than the charger, although the name of the name some, in fact, the control program and the charging circuit is not designed How good of a miscarriage of justice cases often occur, not the battery charge to be fried eggs, that are not even fully charge the battery to determine the strike has been fully charged, so good addition to increasing the temperature outside the control of the charger , then under the charge time, voltage and current changes in the size of the calculated charge capacity, and determine whether the battery really has reached saturation.