How to Fix a Dead Laptop Battery By Jacob Stover, eHow Contributor • • • •
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Though it can be difficult, it is possible to modify an existing battery to give it new life. Laptop computers are valued for their portability and usefulness on the go, but a failing battery can quickly strip the device from any sort of portability or extended usefulness. Unfortunately, like all rechargeable batteries, your laptop's battery will lose its ability to hold a charge over time and repeated use. Eventually a battery that could once last for 5 to 6 hours may only be able to hold a charge of twenty minutes or so. There are a few options for squeezing more life out of your batteries, though eventually your best option may simply be to replace them. Related Searches: • •
Battery Li Ion Laptop Batteries
Difficulty: Challenging
Instructions Things You'll Need • • • •
Screwdriver Lithium-ion batteries Soldering iron Safety goggles
1. Modifying your Existing Battery o
1 Remove the battery from the back of your laptop.
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2 Open up the battery by carefully unscrewing any screws found on the casing.
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3 Locate the small lithium-ion battery cells inside. They should be about the same size as a double-A battery. These are the cells that provide the power to your computer. Over time, the chemicals in these batteries become less efficient at conducting electricity as a result of repeatedly receiving and discharging an electrical current. Carefully remove these batteries, taking note of their voltage.
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4 Locate a suitable vendor for replacement lithium-ion cells. You may choose cells of a higher milliamp rating for increased battery life, but remember that the batteries must be of the same size and voltage.
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5 Remove the old cells from the battery, and place the new cells in the same casing. Ensure that the battery polarity is the same as the old cells.
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6 Solder the new cells to the connective wiring of the battery. Use caution when soldering these cells, as it is possible for batteries to explode when exposed to high heat, or when their casing is ruptured. Once the cells are properly soldered, you may close up the casing of the battery. If this procedure is performed correctly, the battery should now function like new. Consult the "Laptop Battery Hack" video in the resources section for more information.
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Read more: How to Fix a Dead Laptop Battery | eHow.com http://www.ehow.com/how_6153309_fix-dead-laptop-battery.html#ixzz1joYlbFlK
How to Repair a Laptop Battery Most laptop batteries are smart. This means that the pack consists of two parts: the chemical cells and the digital circuit. If the cells are weak, cell replacement makes economic sense. While nickel-based cells are readily available, lithium-ion cells are commonly not sold over the counter, and most manufacturers only offer them to authorized pack assemblers. This precaution is understandable given liability issues. Read also about Safety Concerns and Protection Circuits. Always use the same chemistry; the mAh rating can vary if all cells are replaced. A laptop battery may have only one weak cell, and the success rate of replacing the affected cell depends on the matching with the others. All cells in a pack must have a similar capacity because an imbalance shortens the life of the pack. Read more about Can Batteries Be Restored?. Furthermore, the state-of-charge of all cells being charged for the first time should have a similar charge level, and the open-circuit voltages should be within 10 percent of each other. Welding the cells is the only reliable way to get dependable connection. Limit the heat transfer to the cells during welding to prevent excess heat buildup. The typical SMBus battery has five or more battery connections consisting of positive and negative battery terminals, thermistor, clock and data. The connections are often unmarked; however, the positive and negative are commonly located at the outer edges of the connector and the inner contacts accommodate the clock and data. (The one-wire system combines clock and data.) For safety reasons, a separate thermistor wire is brought to the outside. Figure 1 illustrates a battery with six connections. Figure 1: Terminal connection of a typical laptop battery
The positive and negative terminals are usually placed on the outside; no norm exists on the arrangement of the other contacts. Courtesy of Cadex
Some batteries are equipped with a solid-state switch that is normally in the “off” position and no voltage is present on the battery terminals; connecting the switch terminal to ground often turns the battery on. If this does not work, the pack may need a proprietary code for activation, and battery manufacturers keep these codes a well-guarded secret. How can you find the correct terminals? Use a voltmeter to locate the positive and negative battery terminals and establish the polarity. If no voltage is available, a solid-state switch in the “off” position may need activating. Connecting the voltmeter to the outer terminals, take a 100-Ohm resistor (other values may also work), tie one end to ground, and with the other end touch each terminal while observing the voltmeter. If no voltage appears, the battery may be dead or the pack will require a security code. The 100-Ohm resistor is low enough to engage a digital circuit and high enough to protect the battery against a possible electrical short. Establishing the connection to the battery terminals should now enable charging. If the charge current stops after 30 seconds, an activation code may be required, and this is often difficult if not impossible to obtain. Some battery manufacturers add an end-of-battery-life switch that turns the battery off when reaching a certain age or cycle count. Manufacturers argue that customer satisfaction and safety can only be guaranteed by regularly replacing the battery. Such a policy tends to satisfy the manufacturer more than the user, and newer batteries do not include this feature. If at all possible, connect the thermistor during charging and discharging to protect the battery against possible overheating. Use an ohmmeter to locate the internal thermistor. The most common thermistors are 10 Kilo Ohm NTC, which reads 10kΩ at 20°C (68°F). NTC stands
for negative temperature coefficient, meaning that the resistance decreases with rising temperature. In comparison, a positive temperature coefficient (PTC) causes the resistance to increase. Warming the battery with your hand may be sufficient to detect a small change in resistor value when looking for the correct terminal on the battery. In some cases the chemical battery can be restored, but the fuel gauge might not work, is inaccurate, or will provide wrong information. After repackaging, the battery may need some sort of initialization/ calibration process. Simply charging and discharging the pack to reset the flags might do the trick. A “flag” is a measuring point to mark and record an event. The circuits of some smart batteries must be kept alive during cell replacement. Disconnecting the voltage for only a fraction of a second can erase vital data in the memory. The lost data could contain the resistor value of the digitized shunt that is responsible for the coulomb counter. Some integrated circuits (IC) responsible for fuel gauge function have wires going to each cell, and the sequence of assembly must to be done in the correct order. To assure continued operation when changing the cells, supply a secondary voltage through a 100-Ohm resistor to the circuit before disconnection and remove the supply only after the circuit receives voltage again from the new cells. Cell replacement of a smart battery has a parallel with open-heart surgery, where doctors must keep all organs of the patient alive. Anyone repairing an SMBus battery needs to be aware of compliance issues. Unlike other tightly regulated standards, the SMBus allows some variations, and this can cause problems when matching battery packs with existing chargers. The repaired SMBus battery should be
checked for compatibility before use. More information on SMBus is available on www.sbs forum.org and www.acpi.info.
Simple Guidelines when Repairing Battery Packs •
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Only connect cells that are matched and have the identical state-of-charge. Do not connect cells of different chemistry, age or capacity. Never charge or discharge Li-ion batteries without a working protection circuit unattended. Each cell must be monitored individually.
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Include a temperature sensor that disrupts the current on high heat.
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Apply a slow charge only if the cells have different state-of-charge.
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Pay special attention when using an unknown brand of cells. Some may not contain a high level of intrinsic safety features. Li-ion is sensitive to reverse polarization. Observe correct polarity. Do not charge a Li-ion battery that exhibits physical damage or has dwelled at a voltage of less than 1.5V/cell. When repairing Li-ion, assure that each cell is connected to a protection circuit.
Laptop Battery Problems Laptop batteries can be one of the most frustrating parts of an older laptop. They only last 15 minutes, or maybe only 2 seconds, perhaps explode, etc. I created this site to try to document and analyze these problems.
How notebook batteries work The battery consists of a plastic outer case, metal electrical contacts, an inner metal case filled with a chemical and special electrical contacts called electrodes, and lastly, perhaps some control circuitry. Note that the actual charging circuit is usually part of the laptop mainboard. Battery chemistry
• Lithium Ion (LIon) • Nickel Metal Hydride (NiMH) • Others... Control circuitry
Different batteries may have none, some, or all of these circuits.
Overheat protection: A themal sensor and circuit cuts off charging and/or usage if the
battery gets too hot. Over-current / short-circuit protection: Like a circuit breaker, if the current is too high this
will cut off the electricity coming from the battery to prevent explosion or fire. Over-discharge protection: Certain battery chemistries, such as Lithium Ion, will break
down if the battery gets discharged below a certain point. This circuit cuts off usage just before this point is reached. Status meter / battery tester: Many modern battery have a button you can push, and a meter
of LEDs will show you how charged the battery is.
Reconditioning Sometimes, battery performance can be improved through a process called reconditioning. This is usually a special pattern of charges and discharges designed to get the chemicals back to their original state. I suppose shaking might also be involved, as certain substances may build up near the electrodes inside.
Case Studies & Anecdotes Gataway Solo 5300
Once fully charged, the charging circuit will not reactivate until after you have used the laptop under battery power. However, the battery slowly drains itself over time. The result is that if you have had the laptop plugged in to the AC for too long, the result will be a dead battery. The solution? Unplug the laptop from the AC for just a minute, and then reconnect. The battery will recharge. Additionally, when using the battery, the power level detected by Windows when the computer first comes on sometimes is very low, such as 5%, causing Windows to automatically go back into standby. However, by turning it on again, you discover that now the battery is almost fully changed. HP Pavilion N5000 series (N5430)
By the end of the first year of use, the battery charge ended up only being good enough for 30 seconds of operation. :-/ Warranty service would have been a good idea.
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