How do you restore a rechargeable battery?

Answer 1

= How to restore your rechargeable batteries = Note: Keep in mind that heat is not your friend. Lukewarm is OK, but if the batteries get any hotter, STOP what you are doing! I claim *no* responsibility. This information is for you to enhance your own knowledge. It is in no way a tutorial on how to work with electronics. You need a voltmeter for this. Step 1:Determine what kind of battery you have. This usually does not require cracking open the case, but you will most likely have to in the later steps. Plastic outer cases, such as on laptops and camcorders usually have "protection circuitry" that blocks you from working with the battery. Lithium-Ion / Lithium-Polymer (LiIon, LiPoly) Nickel-Cadmium (NiCd, NiCad) Nickel-Metal-Hydride (NiMH) -- Not sure. Solution 1 of Ni-Cad most likely won't work, but solution 2 could. ---- Lithium battery behavior is poorly documented and very few people know about it, both because lithiums have excellent retention and life-span characteristics, and because the lithium protection circuit keeps the battery in good condition. (In most cases) Lithiums do have a memory effect, but it works entirely differently from a ni-cad's. If you think about it like dirty water in a leaky tank, when you leave your Lithium alone for too long (a month or so), the dirt settles and the faucet begins to get clogged. There may be plenty of water there, but it doesn't come out very fast, which makes the circuitry think that the battery is low, even when it's not. This is called internal resistance. A battery that has been left at one state (fully charged, fully discharged) for a long time will show this effect. In order to clear it up, you need to get the battery to deliver power. As the damaged battery drains, it's performance "unclogs" and the battery meter sometimes even thinks that the battery's charge is going up. Don't completely discharge -- just keep drawing power (quickly is better), and recharge it as normal. Aside from having my hands on the physical battery, I've also had success with a Palm-Pilot with a built-in 3-year-old lithium battery that had been sitting for over a year. ---- If your batteries don't work at all, skip down to the next section. It is common knowledge that Nickel Cadmium like full discharge/recharge cycles. The reason is that Nickel Cadmiums store their energy in crystal form. When it is charged, crystals are created. As the battery is discharged, the crystals shrink in size. When you charge the battery before most of the crystals are gone, it both creates small crystals and enlarges the old crystals. After a few half-discharge cycles like this, you can end up with many larger crystals and not very many small ones. The result is that the energy is still there, but there is less surface area (many small crystals have more surface area than a few large ones of the same mass), resulting in decreased output. You'll need to completely wear-down the larger crystals. The problem is that modern electronics can't operate on just a few crystals that are slowly giving their power up, so the oversized crystals never go away. Read and open the case: Nickel Cadmium batteries don't need protection circuits, so you might be able to do this without opening the case. It's not very likely to be a problem, but I would recommend opening the case anyways. Worry not, if your batteries are shot, what good is the case anyways? If you do fix it, a little glue (I recommend cyanoacrylate) ought to put it back together. Look on your case and determine the total capacity (mAh) and voltage (V). My laptop battery shows 11.1V, 3800mAh. If you don't see it written anywhere on the case, you may be able to calculate it. Determine your resistor: You'll want to discharge the battery over about a 1 hour period. Since the capacity (3.8A, or 3800mAh for me) is expressed as amp-hours, it will be our draw-amperage. Calculate the size of your resistor with this formula: ohms = volts / amps. Go to Radio Shack or Digikey, or make your own and find the closest resistor to this value. It needs to handle a power (watts) of at LEAST battery volts (11.1V for me) multiplied by draw-amperage (3.8A for me) (11.1V * 3.8A = 42.18 watts). This is going to be a big resistor, and it will get hot when you're using it. Be sure that the batteries aren't getting hot. If you're comfortable dissipating more energy, you could discharge the battery much faster (at 4C, for example), or if you can't find a resistor that can handle the watts, you could try lowering your draw amperage and finding an appropriate resistor. Connect the resistor: Connect the resistor across your battery pack (the pack itself; not the + and - output on the protection circuit), and a voltmeter (in parallel). Because of various voltage drops and anomalies I'm not going to go into, you may need to leave the battery discharging for more than an hour! You're not done until the voltage is very low (such as .1 volt per cell or lower) If you're also using an ammeter (in series), your measured amperage should drop as the voltage drops. If your resistor is adjustable, you can decrease the ohmage in order to keep the amperage the same, but you don't need to. Another problem Nickel Cadmium has is it can develop conductive fibers which short-out the battery. To get rid of these, they must be burned away with a high voltage source. To do this, you absolutely must open the battery case. You will have to zap each of the cells individually. You will also need a high-power source. A wall transformer rated for 2A or more at 3V to 6V volts may work, but I recommend a fully-charged battery, since they can really pack a punch. The total voltage for the source batteries should be 3V to 6V. Put the positive to the positive and the negative to the negative for about 3 seconds, for each cell. Charge the battery normally. ---- Lithium batteries have 3.7 volts (nominal) per cell, Nickel-based batteries have 1.2 volts per cell. These voltages add-up when the batteries are in series (end-to end; the positive of one battery touches the negative of the next). The voltage does not change when the batteries are in parallel (positive on battery A touches positive on battery B, andnegative on battery A touches negative on battery B). Capacity (mAh) works in the opposite way. When batteries are in parallel, the capacity adds up, when in series, the voltage adds up. Some battery configurations are set up in both parallel and series. Find the parallel batteries first, then treat them as a unit to calculate them in series next. ---- You will need: Pencil lead (graphite), two wires, a tray of water, and ohm-meter. Strip (1" or more) and wrap one wire to the end of your graphite so that it is snug and makes a good connection. Connect the other wire to the other end. Now measure the resistance (put each lead of your ohm-meter to the ends of your two wires). Slide the two wires wrapped around your graphite closer and farther until you read the right value (+-10% should be good). Since you'll be wasting a lot of power, you should break off the unused ends of the graphite and put it completely inside a tray of water can carry the heat away. It will bubble and fizz as it's being used; just don't let extremely large amounts of the fizz get to an open flame. (Ie. Don't collect/store the bubbles.) I recommend using a second amp-meter to monitor the quality of your custom resistor by putting it in series (not parallel, it could blow your meter fuse, melt your battery or create pure lithium!) with the resistor. When the circuit is connected, the ammeter should read about equal to your drawing-amps.

Answer 2

You have to deep discharge ,, recharge and deep discharge that means making sure it is deed.deed.. you can do this with a small light bulb,,when the light is out let the bat, cool recharge and do it again after a few time it will hold a charge