Every rechargeable battery stresses, “Only use the charger approved for use… blah blah blah”
Assuming I find a transformer with the same output specs (12V, 300 milliamps) shouldn’t it work fine? Is there special circuitry in the charger that wouldn’t also be in a plain jane power adapter for my cordless phone, say?
Why I ask? The recharger in my (very old) laptop seems to no workie. I’ve got two perfectly good batteries and I need to charge’em. I could buy a stand alone charger for $200, but I’m just tempted to hold the wires of a power adapter to the + and - of the laptop battery and count to 3,000 (or more, or very slowly).
If you want to go for the worst case, the wrong charger could start a fire or cause the battery to explode. If you don’t know what you are doing, use the charger specified by the device’s manufacturer. Lithium batteries in particular, respond poorly to improper charging. The battery and the charger are a matched system, designed to safely charge the battery. The charger and/or battery may contain circuits that prevent unsafe conditions in the battery.
Look like the google ads may have answered your question. If not, why not try a universal adapter like this:
You are correct, there is no special circuitry. Just match up the voltage, amperage draw and pick the right connector. hint: there is a selectable switch for amperage draw but you must pick a model with the right voltage for your need.
One potential hangup. I checked out my IBM,s adapter and see that it outputs at 16V. May be hard to get a universal for that! The google ads shows one for my computer for $69.99. Not to terrible.
At the very least you need a current limiting circuit. If you connect a regular 12-volt supply to a depleted 12-volt battery, there will be enough current flow to melt the wire or blow the fuse. (I speak from experience. Hey, I was 10 years old.)
If the dc output voltage is right,if the charger capacity in amps or milis is right,if the polarity is right --------then the battery doesn’t give a damn where the voltage is coming from.
If I have a small charger go bad I dig one out of my junk box that fits the system----correct the polarity if necessary----- and it’s the light brigade all over again—or mayb San Juan Hill!
Or,as the ladies like to say it,----------------CHARGE!
Did you ever stop to think that perhaps there’s a reason some battery chargers cost $200? Do you think it’s nothing more than a ploy by manufacturers to rip off hapless consumers?
Most modern battery chargers are sophisticated devices. This is understandable, as they have a tough job to do: they must charge a battery rapidly, efficiently, and safely, while at the same not overheat it. Furthermore, each battery chemistry is idiosyncratic in how it likes to be charged. Some require a current-limited constant voltage source. Some require a constant current source. Some require both modes w/ a crossover voltage point. Some require monitoring dV/dt. Some require temperature monitoring (dT/dt). And while most chargers are linear, PWM schemes can sometimes be used for better efficiency. Click here for more info.
Of course, I suppose a person can grab any 'ol charger in the junk pile and try it. But because there’s a strong likelihood that the charger will not be matched to the type & capacity of the battery being charged, the end result is that the battery will not be efficiently charged. It could also decrease the life of the battery. And in some cases the battery could overheat.
I strongly urge people to use only battery chargers suitable for their particular battery pack.
In particular, LiIons when they explode produce stuff that the people on staff at your local Emergency Room won’t know how to handle.
Because of all the finicky things about LiIons, the chargers for them are quite complicated compared to the old ones for NiCads. The charges to the cells have to be balanced, the current carefully controlled, etc.
Note that even NiCads, while chargable by simpler circuits, are not something you really want to play Mr. Science with. They contain Cadmium after all.
All batteries contain Very Bad Things and charging them wrong is the easiest way to have the Very Bad Things get all over you.
Just look at the thread in CoCC about the article on lead-acid battery dangers. That’s very old tech with really simple charging circuits. (And I didn’t even post my “stupid BIL and a motorcycle battery” story to that thread.)
If not, why not try a universal adapter like this: