Battery and LED questions..

[dog812]

Hey everyone i am new here.. and fairly new to electronics.. I have a few really basic questions..

1. Why does a rechargeable AA say 1.2 volt. But a 4 x AA,connected in series, charger is known as a 6 volt?

2. What will happen if you hook the 6 volt 100 ma charger , up to only 3 batteries in series? Will they over charge? Will it still work? will the batteries still work.. cuz i only need 3.6 volts... not 4.8

3. LED's : some led's say they are 3.6 volt, some 2.2 volt.. but i see some people hook them all up to the same line with no resistor... What happens to the 2.2 volt led when it is hooked up to the 3.6 line? suck more juice? shortne life of LED? ??

4. When calculating using OHMS law, for the supply voltage on 4 AA rechargables do i put 4.8 or 6 volts?

Thanks in advance..

 

[neon]

1] that is a voltage aprox. usualy we take as a standard 1.2 but it could be more or less.
2] 3 bat. in series will be 1.2x3= 3.6v you may connect to any dc higher dc voltage provided that you limit the current.
3] leds comes in all kind of shapes and sizes and with different color and dif. voltage and/or current.
that is the way that are specified as 1.8v 20ma or 4v 400ma. leds are diodes and follow an exponential curve so for every current there will be a dif. voltage and viceversa. any volts will do so any current will do as long as you don't exceed power dissipation. for the device
4] 4 batteries means 1.2 x4=4.8v now here is the thing batteries could care less about about the voltage [as long as is over 1.2v each] all they care is current as specified by manuf. lithium bat. are another item current voltage and temperature must be controlled when charging.

 

[dog812]

Thanks for the info..
I got a question about chargers....
So i only need 3.6 volts which is 3 AA batteries. I am looking for the cheapest battery charger i can find.
What should i be looking for? well a power supply that supplies 4.5volts work to charge rechargeable batteries?
Like something like this? on ebay:
TRIQUEST-7908-AC-DC-ADAPTOR-CLASS-2-POWER-SUPPLY-300-mA

If it wouldnt can you explain why?

Thanks.

 

[neon]

look THE BATTERY NEEDS current amps per manufacture specification whatever that may be.100ma 500ma. the voltage is not essential except for the fact that it must be higher then the battery voltage. you could run from 120 AC with a diode and add a current limiter to xxxma. that is very eneficient because the resistor in series must dissipate the watts [heat] supose need 500ma now 120-1.2=118v with a 200ma requirement guess what lot of watts wasted as heat. that is why you need a transformer votage to be near where it should be. my choise is LM117 regulator for something what youneed.