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Charging a battery

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WG1337

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Hi!
Is there a difference in charging a battery with a different voltage?
For example, I remeber that I chanrged a car battery with an old USSR battery charger with 5V, it took a long time, but it did charge. Now I have a universal notebook battery charger, that allows me to choose voltage. What will happen if I charge (if there is a difference) with a wrong voltage a Li-ion battery trough a notebook and a NiCd(or some other, non Li-ion) battery?
 
If the voltage is too low, it won't charge. If the voltage is too high, it may blow the notebook charge circuitry. Your should always charge with the proper voltage.

Also, your universal battery charger is just a voltage source. Each battery also needs or has a charging circuit for proper charging.
 
Different batteries require different types of charging topologies. Li-Ion are the worst as these have very precise charging requirements. generally all batteries require a current source to charge them. With Li Ions, you look to see when the voltage reaches 4.1V or 4.2V (depending on the type of battery) then terminate the charging. This voltage has to be measured with a 100mV accuracy.

NiCads and NiMH are charged with a constant current until the voltage starts to dip, or the temperature starts to rise rapidly.

Lead Acid (car batteries) are charged with a voltage limited current source, then terminated with a current limited voltage source (1.25V per cell). (This is from memory, but I think itis correct).

You cannot mix and match chargers and batteries, especially with Li-Ion batteries as they tend to explode.

Laptop batteries also have intelligence in them (a micro of some sort) that include charge/discharge cycle counting, coulomb counting etc, so you might be doing irreversible damage to the battery (and yourself if it explodes) if you hook up any birds nest of circuitry to it to charge it

I am surprised you charged a car battery (12V) with a 5V source as the charging voltage always has to be higher than the final battery voltage
 
Oh, so the notebook circuit only allows the right voltage to charge the battery.
Thanks!

I didn't say that the battery lasted long either :p
 
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Oh, so the notebook circuit only allows the right voltage to charge the battery.
Thanks!
The notebook allows the correct voltage to the battery, but if the external charging voltage is too high it may damage the notebook.
 
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