You are correct, battery chargers convert 115 volt AC to 12 volt DC, typically. If the charger supplies less than 1 amp, it would be called a "trickle charger." Lead/acid storage batteries contain a liquid electrolyte, that contains water and sulfuric acid. If the battery is very old, or has lost its electrolyte for some reason, it cannot be charged. Small amounts of hydrogen gas are released during the charging cycle, therefore this should be done in a ventilated area. I prefer a garage with the door wide open. Since the battery contains sulfuric acid, which is corrosive, it must be handled with extra care if there is any sign of leakage. I would put a leaking battery into a plastic tub, and take it to the recyclers. Small spills can be cleaned up with baking soda and water. The baking soda will react with any acid and neutralize the acid. Batteries do not benefit from overcharging. If the battery feels warm to the touch, it is likely fully charged, and time to stop. You should know the capacity of the battery in ampere-hours or ampere-minutes before you begin to charge. That number will guide you in knowing how long to charge. For instance, a 100 ampere-hour automotive battery being charged at 5 amps would take 20 hours to receive a full charge. That is, 5 amps times 20 hours equals 100 ampere hours.

Probably some gook in another country didn't know what it meant, but put it in there anyway! As long as it charges the battery like it should--don't worry about it. If the battery started the car-you're home free, except for what the initial cost was!

Thanks kalining, My car battery is good, but one bad thing about my Honda Odyssey is that if you accidentally leave on the dome light switch, its dead in the morning. We try to always leave the switch in the off position, but **** happens. haha One time I dusted off the dash area, and forgot to check on that switch and ended up with a dead battery in the morning. Bummer. My van is 11 years old, so hopefully the newer ones have an auto shut off for that dome light.

Hi Jerry. Looks like the hook is set.. :) Trying to understand exactly why certain things happen is what keeps me studying and reading everything I can. It also keeps me asking questions when a further solution isn't really necessary at times as well. Thats why I'm an automotive tech, there is so much to feed the curiosity beast. Alternators in general use a delta or(triangle) or "Y" shaped stator. The stator is the wires that are visible just inside of the case of the alternator. The ends of the wires that make up the stator are connected to the diode bridge. The bridge typically consists of six diodes which allow the current to flow to the alternator output, and of course from the alternator case. If someone does not really understand how diodes work, they can do some web searching on the subject, or just accept the fact that they act like a one way valve. The diodes are connected to allow electrons to be pulled from the + (positive) side of the circuit, and then pushed onto the - (ground) side. Inside the alternator there is a component called the rotor. Basically it's a coil of wire that has a current flowing through it to create a magnetic field. The rotors ends are designed to pull the magnetic field around the sides of the coil, and into a series of + and - magnets as viewed from the side. The rotor is connected to the pulley and is turned by the belt. This "series of magnets" rotate inside the stator, and the result is electrons are pushed and pulled in the stator creating an AC voltage. This AC voltage is rectified by the diode bridge, and we see it as DC on a volt meter. But looking closer with an ocilliscope we can actually see something else. The DC voltage isn't steady. On a normally operating vehicle with little electrical load (low current flow) there will be small humps as each diode begins and stops conducting. Charging systems also have a capacitor across the output of the alternator. The capacitors job is to slightly charge up higher than the present system voltage, and then discharge when the voltage it stored is higher than the system voltage. This effect is used to smooth out the humps from the alternator. There are two things that happen when a stator or diode fail. The diode failing can either short, or open circuit. If it shorts, generally the result is an alternator that drains the battery and is pretty easy to diagnose. (I'm not going to be real specific here, there isn't enough time but there are other possibilities as well) When a diode fails open though what you get is a space where instead of overlapping diodes conducting, there is a conductive hump, a period where the capacitor has to discharge longer, and then another conducting hump. I have seen situations under load where the AC voltage on top of the DC output gets up between 2 and 3 volts. (A shorted diode could have an even more dramatic voltage change) Now take a sensor where the output is an analog signal, and allow the system voltage to vary like this and you can get a computer reacting to inputs that are not really occuring. One such example would be false cylinder ID pulses, or incorrect crankshaft speed calculations by the computer. To an inexperienced tech, they pull the car in, it's running erratic, missfiring, maybe an incorrect idle speed. The use a volt meter and see the system voltage around 14v where they expect it to be and they end up running around and testing, and maybe even replacing all kinds of parts trying to fix the problem. It's added a whole dimension to testing when it comes to todays cars. Things like diode suppression when solenoids are operated can be really important to prevent voltage spikes on the system voltage. Getting used to looking closely at voltage waveforms has been really important when it comes to sensors like a wheel speed sensor. Litterally the difference between a sensor that is working, and one that the computer thinks is not can be 1/100th of a volt. With an AC voltmeter, it's impossible to interpret this change in the signal, heck it's hard with a scope by eye. I end up relying on trapping the waveform and using cursers to provide the voltage measurement. (Ahh the luxury of a digital storage ocilliscope) With an alternator I do exactly the same thing. I trigger my scope off of an injector current, or secondary lead if available, and then set the scope to 100mv/div and position the voltage line on the display and look at it between 2ms and 5ms/div. (Sometimes faster, sometimes slower depending on the needs) Here is a link that might be useful: A tutorial on alternator ripple, not just my rough interpretation