Battery - Revision history

Yash: /* Comparison between the batteries */

2018-02-06T19:46:11Z

‎Comparison between the batteries

Yash at 19:45, 1 February 2018

2018-02-01T19:45:06Z

Yash at 19:37, 1 February 2018

2018-02-01T19:37:32Z

Yash at 19:37, 1 February 2018

2018-02-01T19:37:16Z

Yash at 19:36, 1 February 2018

2018-02-01T19:36:05Z

Yash: /* Charge Current Rate */

2018-01-25T16:55:13Z

‎Charge Current Rate

Yash: /* Charging Voltage and Voltage Regulation */

2018-01-25T16:54:52Z

‎Charging Voltage and Voltage Regulation

Yash: /* Comparison between the batteries = */

2018-01-25T16:54:37Z

‎Comparison between the batteries =

Yash at 13:31, 25 January 2018

2018-01-25T13:31:12Z

Yash at 13:30, 25 January 2018

2018-01-25T13:30:20Z

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 === Comparison between the batteries ===
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 |'''System'''

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 In this method, battery is charged with a constant current until voltage reaches the end-of-charge(EOC) voltage. Thereafter, charger switches to a constant voltage charging, where the charging current falls with time. The battery is said to be charged when the charging current drops to a predetermined limit. This is the preferred mode for charging Li-ion batteries.
-[[File:BatCharge.png|frame|center|Constant Current Constant Voltage Mode of Charging]]
+[[File:BatCharge.png|frame|center|Constant Current Constant Voltage Mode of Charging. Image reproduced from [http://www.ti.com/lit/ds/symlink/bq2057.pdf here]]]
 == Battery Discharging ==

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 The surfaces of battery terminals that extend inside the battery case need to be insulated with potting materials to prevent unintentional contact with other conductors inside the case and also to prevent bridging by electrolyte leaks. Wires inside the battery case should be insulated, restrained from contact with cell terminals, protected against chafing and physically constrained from movement due to vibration or bumping.<ref name = "nasa"/>
 Certification of the crimp is critical for ensuring that individual cells will not leak after launching.<ref name = "nasa2"/> Cell terminals need to be protected from contact with other conductive surfaces. <br \>
 If you are done reading this page, you can go back to [[Electrical Subsystem]]
 ==References==

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 The surfaces of battery terminals that extend inside the battery case need to be insulated with potting materials to prevent unintentional contact with other conductors inside the case and also to prevent bridging by electrolyte leaks. Wires inside the battery case should be insulated, restrained from contact with cell terminals, protected against chafing and physically constrained from movement due to vibration or bumping.<ref name = "nasa"/>
 Certification of the crimp is critical for ensuring that individual cells will not leak after launching.<ref name = "nasa2"/> Cell terminals need to be protected from contact with other conductive surfaces. <br \>
 If you are done reading this page, you can go back to [[Electrical Subsystem]]
 ==References==

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 A PTC (Positive Temperature Coefficient) switch can also be used to prevent short-circuiting by inhibiting high currents. As temperature increases above a limit, material resistance faces a large increase and being reversible they cycle back to conductive state when we have normal condition again.
 CIDs (Current Interrupter Devices) can prevent further charging of a battery until internal pressure(of battery) is alleviated. These devices prevent venting of hazardous electrolytes and bursting due to buildup of high pressures.<ref name = "nasa2">https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150020899.pdf </ref> However, both PTCs and CIDs may fail when exposed to high voltages due to other failures. The use of bypass diodes is recommended to prevent these failures.<br \>
-The surfaces of battery terminals that extend inside the battery case need to be insulated with potting materials to prevent unintentional contact with other conductors inside the case and also to prevent bridging by electrolyte leaks. Wires inside the battery case should be insulated, restrained from contact with cell terminals, protected against chafing and physically constrained from movement due to vibration or bumping.<ref name = "nasa">
+The surfaces of battery terminals that extend inside the battery case need to be insulated with potting materials to prevent unintentional contact with other conductors inside the case and also to prevent bridging by electrolyte leaks. Wires inside the battery case should be insulated, restrained from contact with cell terminals, protected against chafing and physically constrained from movement due to vibration or bumping.<ref name = "nasa"/>
 Certification of the crimp is critical for ensuring that individual cells will not leak after launching.<ref name = "nasa2"/> Cell terminals need to be protected from contact with other conductive surfaces. <br \>
 For example, in lithium energy cells,

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 Decreased capacity, voltage, and life and increased IR losses and heating are seen with higher discharge current rates, along with a more rapid decrease in voltage during the discharge. If we discharge keeping cutoff voltage constant, lower current rate would have additional capacity available, above that cutoff voltage, than higher one. Discharge rates are commonly specified as multiples of the C rate, which is the current that will discharge the battery to the cutoff voltage in one hour. 1C rate means battery will be discharged completely in 1 hr by the discharge current.
 === Charge Current Rate ===
- Less capacity is restored and increased heating occurs when higher charge current rates are used. The magnitudes of the capacity decrease are temperature dependent. When a cell is charged at a higher current rate to the end-of-charge voltage, more . To add more capacity below the cutoff voltage, lower rate is preferred. Charge rates are also commonly specified as multiples of the C rate.
+Less capacity is restored and increased heating occurs when higher charge current rates are used. The magnitudes of the capacity decrease are temperature dependent. When a cell is charged at a higher current rate to the end-of-charge voltage, more . To add more capacity below the cutoff voltage, lower rate is preferred. Charge rates are also commonly specified as multiples of the C rate.
 === Continuous or Intermittent Discharge ===
 When a battery rests after discharge, voltage recovery happens due to certain physical and chemical changes happening. Thus, the voltage of a battery that has dropped during a high-rate discharge will rise after a rest period. This improvement is generally greater after discharge at higher currents and also is dependent on the end-of-discharge voltage, temperature, and the length of the rest period.

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 === Charging Voltage and Voltage Regulation ===
- Allowing the lowest possible end-of-discharge voltage and the widest voltage range leads to the highest available capacity. A voltage regulator can be used to convert the varying output voltage of the battery into a constant output voltage consistent with the equipment requirements. This allows the full capacity of the battery to be used; the only tradeoff is that the voltage regulator has losses.
+Allowing the lowest possible end-of-discharge voltage and the widest voltage range leads to the highest available capacity. A voltage regulator can be used to convert the varying output voltage of the battery into a constant output voltage consistent with the equipment requirements. This allows the full capacity of the battery to be used; the only tradeoff is that the voltage regulator has losses.
 === Vibration and Shock ===

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 Significant advances have been made in the cathode materials and electrolytes for Li-ion cells and batteries. Several new cathodes with high specific capacity approaching 250 mAh/g, coupled with high voltage and improved thermal stability have been identified. Likewise, several new electrolytes for enabling operations at -60 °C have been demonstrated. These advances are expected to results in advanced lithium-ion cells and batteries with high specific energy and wide range of operating temperatures, as desired in future space missions. <ref name = "ieee"/> However, the polymer li-ion cells have an additional problem with electrolyte leakage under abusive conditions.<ref name = "nasa">https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090023862.pdf</ref>
-=== Comparison between the batteries ====
+=== Comparison between the batteries ===
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 == Factors affecting battery performance ==
 === Capacity ===
-Capacity is adversely affected by high storage and high and low operation temperatures than cell optimum temperature, higher discharge rates, the stand time between charge and discharge. State of charge, the extent to which the battery is charged, opposite to [[#Depth of Discharge]], should also not be kept very high during storage.
+Capacity is adversely affected by high storage and high and low operation temperatures than cell optimum temperature, higher discharge rates, the stand time between charge and discharge. State of charge, the extent to which the battery is charged, opposite to [[#Depth of Discharge| Depth of Discharge]], should also not be kept very high during storage.
 === Voltage ===
 The voltage of the cell decreases during the discharge, and the shape of the discharge voltage curve is affected by temperature, discharge rate, cycle life, service life, and the electrochemical reactions occurring within the cell. The voltage typically is lower and decreases faster with increased discharge rates and longer cycle life.