Many batteries now come with a battery tester. How does a battery tester work?
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Battery tester is a thin film of material which changes its color when current/voltage is applied. The thin film of material  is formed into a strip pattern which is then coated with conductive material at the end of the strip. By adding supply at the end this particular material changes its color.\n\nYou can open and see a DURA CEL Battery
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You can't really get an accurate result with a multitester.  NiMH batteries have a fairly flat discharge curve with a sudden drop-off when they're discharged.  Like all batteries, if they’re measured open-circuit (no load), they will also display a higher voltage that will immediately drop when placed under load.  \n\nMeasuring NiMH battery voltage to determine charge levels means that you have to be able to be able to measure down to .01 or 0.001 volts under load to get an idea for how charged the battery is.  Even this method will only give you a relative result, since NiMH batteries lose capacity for each charge/discharge cycle they go through.  A fully charged battery after 200 uses may only have 90% capacity.\n\nBattery chargers for the newer battery technologies like NiMH or Li-Ion typically use several different methods at the same time when charging batteries:\n\n - Time (14 hrs) \n - Temperature (gets hot when fully charged)\n - Voltage (peaks when charged)\n - Charging current (drops when fully charged)\n\nNiMH batteries only provide about 1.2V VS 1.5V in an alkaline abttery.  A measurded no-load voltage on the battery of 1.5 volts is probably ovr 50% charge.
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It may be related to the humidity in the air and the contact interface.  If you have some batteries of this type, try them in a humid room like the bath.  Let the batteries and device sit out in the humidity for 30 minutes or so.
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Individual atoms in the battery are made up of a nucleus (protons and neutrons) surrounded by electrons.  The chemical reactions in batteries cause these atoms to gain or lose electrons so that electrons become free to be conducted to another atom, or conversely the atom that has lost an electron becomes open to accepting an electron because it has a hole where an electron used to be. This flow of electrons (or holes) are what is called electrical current. The potential between atoms is measured in volts. The flow of electrons is measured in amperes (or amps).
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A battery eliminator is a device powered by an electrical source other than a battery, which then converts the source to a DC voltage that may be used by a second device originally designed to be powered by batteries.\n\nA battery eliminator does away with the need to replace batteries but may remove the advantage of portability. A battery eliminator is also effective in replacing obsolete battery designs.\n\nFor circuit diagram and working visit this link:\nhttp://homepages.which.net/~paul.hills/Emc/BecBody.html
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You'll need, as the name may suggest, a voltmeter.  Also applicable is a multimeter - which you'd then set to voltmeter mode.\n\nAt which point you'd just put one contact on one one end of the battery, and one on the other, and see what the equipment reads.\n\nMy money's on 1.5V :)
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"Repairing" your battery really depends on what kind of damage/use it has been subjected to. However, there are some ways to revive the battery life.\n\n1) Clean the contacts with a dry swab.\n2) Run several complete charge and complete discharge cycles.\nif this doesn't work...\n3) Place the battery in a freezer in a plastic bag for 12 hours. Remove it, wipe off any condensation, and let it thaw for 12-24 hrs before running more charge/discharge cycles.\n\nIf these don't work, it may be time for a new battery :-)
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The conducting ink forms a resistor which does load the battery.  The thermochromic strip lies along the resistor and responds to the heat it generates.  The resistor is tapered, so its resistance per unit length increases as it gets narrower, and so does the temperature due to current flow.  The point along the strip where the temperature reaches the color-change value depends on the amount of current flowing in the resistor.  Thus the length of the changed color section indicates battery freshness.  This is a very approximate test.  A better tester loads the battery similarly, but measures the battery voltage under such loading.
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check the batteries! hit the reset switch!
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"Their intention is to try to make them last longer prior to use. I think everybody has had the experience of putting a bunch of batteries in a flashlight and then putting it in the trunk of their car, and they go back when they need the flashlight and it doesn’t work. Because just on standing, batteries actually deplete themselves. So the idea is that there’s a certain amount of chemical inside—it’s a chemical reaction that’s taking place in the battery—and the chemicals basically get used up. They basically just run out of active material.\n\nMost chemical reactions are affected by temperature, and the lower the temperature the slower the chemical reaction. So what people are trying to do is slow down the self-depletion mechanisms of the batteries by keeping them cold.\n\nIn general, it does extend the battery’s life. Whether there’s a significant difference that would be measurable to the consumer between room temperature and a refrigerator.... To be honest, I don’t know. But in general it does work—that if batteries are kept cooler while they’re not in use it will extend their shelf life.\n\nSo then what about the freezer? Is it even better?\n\nI think one would have to be careful about that. Because it’s the freezer, and the freezer is quite cold. Depending upon the type of batteries, you can actually freeze some of the internal components, and that would not be good. So probably the refrigerator is a safe bet and it will improve things a little bit.\n\nWhat if there are batteries that you’ve been using but will not use again for a while. Would placing them in the fridge in the meantime help at all?\n\nYeah, if you plan on storing them for a long time, it probably would. I think typically people put them in the refrigerator before use. Certainly people should not try to use the battery or activate the battery while it’s cold. It may not work very well. But if they let it warm up before they use it, it should help. \n\nWhat about batteries that are starting to run low?\n\n\nNo, that won’t help. When they start to run low they’re basically used up."
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IC tester is a simulator kind of circuitry which checks for any short circuits and impedance matching.It can be controlled by a microprocessor or even a stand alone circuitry 'll do good.
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This is the best answer you'll get -\nhttp://electronics.howstuffworks.com/battery.html
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you must use some one plug to fill your battery. but make sure your battery can bear the  power of plug.\n\nhahahahahahahahahahaha
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Let's just say......it takes batteries!
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Make a battery from a lemon!\n\nhttp://www.energyquest.ca.gov/projects/lemon.html
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Well, I don't know what your car looks like, so I don't know if I can help much, but here are a few tips I've learned from working in robotics.\n\nIf your car is working sometimes and completely dead other times, then it's probably not the batteries.  But just to be on the safe side,  get some batteries that you know are fresh, and use those.\n\nDo you have access to a multimeter?  It's generally a little hand-held device about the size of a brick with a couple of probes on it.  If you have one, you can use it to check the wires for disconnections anywhere.  Look for an icon that's sort of like this: >|  Only it will have a horizontal line going through it.  That function will test for continuity in your circuit.\n\nWith regards to mounting the motor, if the car came from a kit, it probably has instructions.  If not, it kind of depends on what kind of motor it is.  If it has screw holes, you can easily bolt it to the body of the car with a simple drill and a couple of screws.  If that's not an option, a hot glue gun will work fairly well.\n\nGood luck on your project.
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Well, NiCd and NiMH batteries can be charged and stop charging at full charge without the help of some device to determine if it's full. Once the NiCd and NiMH is full, the current will just pass through and waste your electricity (and if it's left charging at full charge for extended periods, it can also damage the batteries). So it doesn't actually disconnect the current. Just passes through.\n\nBut in Lithium ion batteries, you need some kind of device to determine if it's fully charged. Cellphones, PDA, and iPods kinds of turn on (like, it shows the charging display, but it's not actually on and in your normal thing) when it's plugged into a current so it can detect if it's fully charged. So basically, the device is the mini-computer that determines the charge of the battery.\n\nSo, to answer your question, don't try to create a circuit that will disconnect the current when a Lithium Ion battery becomes fully charged, unless you have the capability, materials, time, and patience to do it. And steady hands. It's really tricky to build a Lithium Ion Battery charger.\n\nPS Penguins!!!