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Author Topic: Proper care and maintenance of li-ion batts?  (Read 1689 times)

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Offline tim in jersey

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Proper care and maintenance of li-ion batts?
« on: January 14, 2006, 11:08:30 PM »
Just wondering if anyone has some basic guidelines for maintaining li-ion batts?

Like is it bad to completely discharge a li-ion as is the case with a SLA? If no, do they need to be conditioned every 10 or 12 cycles like nimh batts do?

Offline esteyes

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Re: Proper care and maintenance of li-ion batts?
« Reply #1 on: January 15, 2006, 02:27:26 AM »
About Rechargeableable Battery

There are five types of rechargeable batteries commercially available. The following table compares their performance and application. Currently the most popular rechargeable batteries are Ni-Cd, Ni-MH and Li-Ion in consumer electronic industry.

Using rechargeable battery can save the Environment and save you  money. For example, one AA size NiMH battery can be used at least 500 times and is equal to 500 pcs AA alkaline battery, costing you less than $0.002 for each time.


Performance Comparison of various Rechargeable Batteries

Parameters
   

                                              Lead acid          Ni-Cd          Ni-M-H          Liquid Li-Ion          Polymer Li-ion

Voltage (V)                                   2                   1.2            1.2                   3.6                        3.6
Weight energy density (Wh/Kg)      35                  50             80                    125                       170
Volume energy Density (Wh/l)         80                 150           200                   320                      400
Cycle life (times)                            300                500           500                    800                      1000
Selfdischarge (%/ month)               0                   25-30         30-35                6-9                        2-5
Electrolyte state                         Liquid               Liquid          Liquid                Liquid                     Polymer Gel
Min. thickness                           > 10 mm            >3mm       >3mm                >3mm                    <1mm
Memory effect                              no                    yes            no                     No                        No
Pollution                                      yes                   yes            No                     No                        No
Production cost                           lowest                Low        middle                 High                      Middle
Advantages                       High drain current
                                           and low cost
                                                               Middle drain current &  low cost,smaller volume

                                                                                  Middle drain current and cost, higher capacity
   
                                                                                                                  higher capacity and lighter weight
                                                                                                                                          Highest capacity, lighter weight                                               
                                                                                                                                                       and flexible shape
Disadvantages                    Too heavy
                                                                    Environmental not friendly
                                                                                  Higher self-discharge and weight
                                                                                                             Low drain current and higher cost
                                                                                                                                           Low drain current and
                                                                                                                                                     very high cost
                                                                                                                                                 
Applications                  Car and lighting             
                                                                    Power tool, cordless phone and emergency lighting etc.
                                                                                  Toy, PDA,, MP3 and digital camera etc
                                                                                                             Cellular phone and laptop computer
                                                                                                                                             Laptop computers

 
What is the life of a rechargeable battery?

When a battery experiences a charge and discharge, we call a cycle or a period. When you charge and discharge a battery within the max and min spec's, the total cycles it can undergo is defined as the battery cycle life.

What is rechargeable battery self discharge?

Primary battery or full charged secondary battery, when put aside for a period, its capacity will decline, this phenomenon is called self discharge. It is decided by the inner electro-chemistry system, similar to water leakage from pond or reservoir.

What is battery inner impedance?

Battery impedance is the resistance when the current flow through an operating cell, in general the internal resistance is included both d.c. and a.c. resistance. For the rechargeable cell resistance is small and electrode is easy to be polarized along with producing a polarization resistance while measuring, so d.c. resistance can’t accurately be measured.

What is the memory effect?

Memory effect only happens on Ni-Cd batteries. As in traditional technology a Ni-Cd battery’s negative is agglomeration with thick Ni crystal, if Ni-Cd batteries are recharged before they have been fully discharged, Ni crystal easily gathers to form agglomeration, which makes the primary discharge platform come into being. The battery stores the platform, which will be considered as the end of discharge for the next cycle even though the capacity decides that the battery can be discharged to a lower platform. The battery will store this process in its memory so during the next discharge, the battery only remembers this reduced capacity. Similarly any further incomplete discharge in each use will aggravate the effect making for a  lower capacity. There are two methods to remove the effect: firstly deep discharge at trickle current (i.e. 0.1C to 0V), secondly several cycles at high currents (e.g. 1C).

What is the ambient temperature that affects the battery performance?

Low temperatures (e.g. -15deg) will obviously reduce Ni-Cd and Ni-MH battery discharge rate. At -20deg electrolyte is at its freezing point, charge speed will greatly slow down. At low temperature (under -15deg) charge will raise the internal gas pressure and probably unseal the safety vent. Ambient temperature of 5 to 30deg is the best range to get effective charge. Generally with temperature rising, charge efficiency will become higher. But when the temperature rises to 45deg or higher, the material performance in the battery will be degenerated and battery service life will be shortened greatly.

How does  overcharging affect the battery performance?

The continual charge action after fully charged. the positive capacity is raised higher than the negative capacity of the design, the generated oxygen in the positive can composite, through the separator, with Cd generated in negative. Generally, the internal pressure will not rise, but if the charge current is so heavy or the charge time is so long, and the generated oxygen can not be used up in time, there will be some  internal pressure increase causing battery distortion, leakage and so on. Meanwhile its performance will decline.

How does Over discharging affect battery performance?

If a cell’s voltage reaches its  designed min value, that means the battery has discharged its stored capacity, but one still discharges the battery - over discharge will result. Commonly the end voltage can be identified through discharge current, for example the end voltage is set at 1.0V/cell as discharged at 0.2C-2C, and 0.8V/cell at 3C or more, e.g. 5C or 10C. Over discharge may cause disaster, especially at heavy current or repeated over discharge. Most often, over discharge can make the cell's inner pressure raise, and the reversibility of the active materials both in positive and negative will be damaged. Even by recharging, only part can be recovered and the capacity is reduced.

How do  short circuits affects battery performance?

Any kinds of conductive material being bridged with the external terminals of a battery will result in short circuit. Based on the battery system, a short circuit may have serious consequences, e.g. rising electrolyte temperature or building up internal gas pressure. If the internal gas pressure value exceeds the limitation of cell cap endurances, the electrolyte will leak, which will damage battery permanently. If safety vent fails to respond, an explosion may occur. Therefore don’t short circuit your bnatteries. Dropping batteries can also cause short circvuits and shortened lifespans.

What is the performance of Nickel Cadmium battery?

    * Low cost;
    * Excellent overcharge endurance;
    * Excellent quick charge performance;
    * Long cycle life;
    * Extensive temperature range;
    * Mid-degree self-discharge;
    * Good safety performance.

What is the performance of Nickel Metal Hydride battery?

    * Low cost;
    * Good quick charge performance;
    * Long cycle life;
    * No memory accumulation;
    * Green energy sources, no pollution;
    * Extensive temperature range;
    * Good safety performance.

What is the performance of Lithium ion battery?

    * High energy density;
    * High operation voltage;
    * No memory accumulation;
    * Long cycle life;
    * No pollution;
    * Light weight;
    * Very low self-discharge rate.

What is the performance of Polymer Lithium ion battery?

    * No liquid electrolyte, so never leak;
    * Can be made into various shape;
    * Can be made into thin battery, such as 3.6V, 400mAh, the thickness can decrease to 0.5mm;
    * Battery is transmutable and can be crooked: the maximum angle is 900;
    * High voltage in an battery: several battery with liquid electrolyte can be connected in series to get a high voltage only; the Li-polymer battery can get high voltage in an cell through multiplayer combination;
    * Same volume Li-polymer batteries` capacity is two times of Li-ion battery.

What is the performance of Lithium MnO2 and Li-SOCL2 battery?

    * High energy density;
    * Long shelf life;
    * Wide operating temperature;
    * Good sealing feature;
    * Steady discharge voltage

Why do batteries packs measure  zero voltage or low voltage?

(1) One of the cells voltages is 0V;

(2) Plugs are short or open circuit, or ill touched;

(3) Lead wires are broken from the soldering or weakly soldered;

(4) Wrong battery connection or the connection tabs are miss or weak weld or broken off.



hope this helps
neil in san marcos

who runs a marantz 671 and shure fp33 w/ akg's and sennheisers on a single 14v 10oz LiION battery pack for _many_ hours!!
Neil Sturtevant
San Marcos, CA
AKG 451's + CK1/CK8/CK9
AKG 460's + CK61/CK63 or A60M + CK1/CK8/CK9  or MK46/CK1X/CK8X
Sennheiser K3U + MKE-2, ME20, ME40, ME80, ME88
Sennheiser MKH 110/2 x2 + MKH 110/1 powered via custom battbox
Busman BSC1-K1/K2/K3/K4
Shure FP33 or Sony DMX P01
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stealth: M1 > MKE-2/ME 20/ME40 in the hat
all cabling LINK (made in Germany) balanced or balanced miniature w/ Neutrik ends

making custom cables and serviceable (non-epoxy) ultraflush right angle cables plus other custom projects

 

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