I've always killed nicads absolutely dead -- with a flashlight -- before most recharges. i've also left them on (sloooow) chargers for months when they weren't in use. I have some I bought in 1980 that still work well. Of course I've thrown about as many away, too. Biggest problem I've found is internal shorts, usually after a few years of use. Cells that are allowed to get hot frequently seem to fail quicker, but I don't know the mechanism or chemistry. I use a short-buster made from a couple of capacitors and some diodes (it charges off house current) to zap shorted cells. It clears a bad short maybe a third of the time. I think bigger capacitors would do better but I don't know at what point the cases might split. I've had two cells, I think, of maybe 100 reverse polarity. don't know why, couldn't fix 'em. I've replaced cells in packs but it's a pain without the appropriate equipment. The memory effect thing is one of the most fascinating issues I'm aware of. The popular press (a member of which pays my pitiful salary) turned early sketchy reports into a really scary sure thing -- scared me enough to cause the behavior i described above. But the current thinking that seems most believable to me is that it takes repeated partial discharges to create a charge memory, and the loss is usually only about 10 percent. Three full-charge, full-discharge cycles supposedly eliminate that. Of course there may be a new and different scientific finding at any time. Or maybe not -- nicads are being replaced as Dave Danger says so maybe the issue will finally go away. Don't worry: Writers of popular press articles will perpetuate lots of other questionable information.

horsepen, the data you provided in your second post is quite a bit different from your first post. Here is why. In your first post you state ***"120 vac in and 12 vac out at something like 1 amp""*** 120 VAC means 120 Volts, Alternating Current in. 12 VAC means 12 Volts, Alternating Current out. In your second post, we learn the real output is actually Direct Current, though at 300 milliamp (.300 Amp, or 1/3 Amp roughly). This transformer is indeed "rectified", and will impart a very small charge to a battery..........IF, it is connected with correct polarity. At only .3 Amp, feeding a battery of 230 CCA (for example), I would venture to say that you may be observing a placebo effect. Or you may actually be getting enough activity to stave off some of the changes that occur on the surfaces of the cell plates that cause batteries to degrade from lack of activity. Bottom line here: A rectified transformer of .3 Amp will do no harm to the battery if connected correctly with regard to polarity.

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

Sorry for the delay, haven't checked this thread for a long time. CSO=Community Service Officer. I should have clarified, since many communities have different names for the same thing. In my area CSO and "Code Enforcement" are the two most common name for the non-sworn officers that do various assistive tasks for the police department. They get a lot of the barking dog calls, traffic control, vehicle lockouts, delivering mail to council members etc. They don't carry guns and cannot drive a squad with red lights on them, (they must be amber lights) and they also must wear a different color uniform than sworn officers so they're not confused, but to the average citizen, they seldom know the difference. See if they're carrying a firearm. If so, they're sworn, if not, they're non-sworn. BTW, when they come out, they'll always run a vehicle check and a DL check. If your keys aren't in the ignition, you're not too likely to get help. And now with the computer chipped keys for the high-end vehicles it's getting harder to steal these vehicles. So does this mean my old beater is going to become a more attractive target?? I guess not. (heavy sigh) Although your comment about stealing a car did remind me that when AAA came to help with my friend's car, all they wanted was the AAA card and they loaded up the car and off they went. Could quite easily be an unwilling and unwitting accomplice. I learned years ago to carry a GOOD set of jumper cables. Louie Anderson used to joke about Minnesotans and their jumper cables, but there's some truth to it. You hope to never need them, but they can literally be a lifesaver if you're ever in need of them. I'm amazed how few people carry cables. I'm often asked if I have cables to borrow. And for the 1 or 2 times I've ever needed a jump, I'm glad to be able to say I've given "jumps" to literally hundreds. There's a lot of things you should carry with you, flashlight, a shovel, blanket & extra clothes in the wintertime, at least a jug to carry water if not a jug of antifreeze, qt of oil... but that's another thread! I still think the best security all-in-all is a prepaid cell phone (with a car charger - they're no good if the battery is dead). If you break down you can call for help and the cost is far less than an auto club. Plus it gives you many more abilities. If you're late for work or an appointment, you can easily call, if you see someone in an accident or stranded you can call for help for them or yourself if it's you and all for about $5/mo. I'm also thinking about splurging on a set of FRS radios for when I'm caravaning with someone to keep in contact with them. Aside from the initial investment you don't have the ongoing costs of operation as with a cell, although its use is more limited. So maybe if I see some at a garage sale or something.... Maybe.