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  ASUS A43  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 ASUS A43  Laptop 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.

Terminal connection of a typical laptop battery

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 ASUS A43  Laptop 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 ASUS A43  Laptop 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  ASUS A43  Laptop 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.

Simple Guidelines when Repairing Battery Packs

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.

Include a temperature sensor that disrupts the current on high heat.

Apply a slow charge only if the cells have different state-of-charge.

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.

If your laptop keys are sticky, or some of them are missing, or the keyboard isn’t working at all, you can usually replace the entire keyboard yourself for between $20 and $60. The operation isn’t as hard as you might think, and performing it has the advantage that you don’t have to remove and replace each key individually. Though every laptop is different, removing your laptop’s keyboard usually involves simply unsnapping a cover, removing a few screws, and disconnecting a cable.
If you’re up to the challenge, you can tackle this project in the comfort of your own home. Take care, though: A working laptop is a terrible thing to waste, and PCWorld accepts no responsibility for any damage to your machine that might occur if you try to take it apart. Furthermore, if duplicating our process requires actually opening your entire laptop–if, say, you have to remove anything more than a handful of screws–you should call a professional. And finally, before you do anything else, check to see whether the laptop is still under warranty. If it is, you may be able to get it replaced for free.
Find a Replacement IBM ThinkPad R61 Laptop Keyboard

The first step of the replacement process is to obtain the right keyboard for your laptop. Compare prices by checking eBay, Google, and online stores that specialize in replacement hardware, such as LaptopKeyboard.com, Spare Parts Warehouse, and LaptopsKeyboard.com. Make sure that the keyboard you buy is for your laptop’s exact model number, which you may find printed on your screen bezel or on a label attached to the underside of the laptop. You can simplify your search further by specifying the keyboard’s part number, which you may be able to find on the laptop manufacturer’s website or by calling their support/service department.
Replacing theIBM ThinkPad R61 Laptop Keyboard

For more-precise instructions on how to replace your particular laptop keyboard than the general steps provided here, check online. There’s a small chance that your laptop is unique and has a very different replacement process from the standard one outlined here. Check with your laptop manufacturer and with the site where you bought the replacement keyboard to see whether they offer specific instructions for DIY repair. Some manufacturers provide service manuals with detailed instructions on a variety of servicing tasks; if not, try searching the Web for “how to replace keyboard” with your laptop’s model number.

Now let’s get started! Confirm that you purchased the appropriate replacement, by placing the new one on the laptop, and seeing if it appears to be the right shape and size. Next, gather your tools: a small Phillips screwdriver for removing the small screws, and a butter knife or other small, thin, flat tool for prying off any covers.

Make sure that the laptop is powered completely off: Unplug the power cord and take the battery out.
Examine the cover/trim piece that sits between the keyboard and the screen; it usually affords access to the keyboard. Check for and remove any screws that appear to be helping hold the cover piece on. Some pieces also cover the screen hinges, which may have small screws on their backs.

Before removing the cover, be aware that it may have a data cable on the back that’s connected to the laptop. This cable is important and usually doesn’t have much slack, so be very cautious when removing the trim piece that holds your laptop’s keyboard in place. You don’t want to rip the cable from the laptop and ruin the connector or the cable.
When the cover is loose, gently remove the cover/trim piece with your bare hands; if necessary, carefully use a butter knife or other thin flat tool to pry it up. The cover should snap off fairly easily with a small amount of force–don’t use extreme force or you may break it. If it doesn’t seem to be coming off, recheck for any remaining screws that may be holding it on–even underneath the laptop–and remove them.

Once you’ve removed the cover/trim piece, set it aside. If it’s attached to the laptop via a data cable, carefully try to move it out of the way without damaging the cable. Then find and remove the screws holding the keyboard in place; there are usually two to five such screws, located along the top of the keyboard.

Before pulling the IBM ThinkPad R61 Laptop Keyboard up, note that the back of the keyboard attaches to a data cable that in turn is connected to the laptop. This cable usually doesn’t have much slack either, so be very careful when pulling it up. It is crucial to avoid ripping the cable from the laptop and ruining the connector.

Carefully pull the keyboard up (without ripping the data cable from the laptop) and unlatch the data cable connector, usually by flipping up the small latch on the connector. Next, remove the data cable and set the old keyboard aside.

Pick up your new keyboard, align it (without setting it down), and attach the data cable to the connector on the laptop, usually by inserting the flat cable as far as it will go and then flipping the small latch on the connector back down to grasp it. With the data cable connected, set the keyboard in place, being careful not to pull at or damage the cable in any way. Reinsert the screws to hold the keyboard down and reattach the cover/trim piece, which usually requires a little force to snap back into place. If you removed any screws from the cover earlier, reinsert those as well.

Once you’re done with these steps, you can reinstall your battery and boot up the laptop. If everything went smoothly, you should have a perfectly working keyboard at a fraction of the cost of having a professional repair service do the work!