Hi all
How batterys are charged , with constant current or
constant voltage ?
I am especially intrested in wind turbine battery chargers .
Elico
elico:
How batterys are charged , with constant current or
constant voltage ?
The details heavily depend upon what type of battery, especially the chemistry used in the cell. However, all rechargable batteries have to be supplied a voltage at least a little above their present voltage in order to charge (the exact voltage varies some based on the level of charge, this fact is why a battery powered device can estimate how "full" its batteries are). Therefore, to fully charge a battery the voltage source has to be a bit greater than the voltage it would have when it's fully charged, which will always be higher than the nominal voltage. If possible, it's good to keep the voltage constant for all types of rechargable batteries Yet as long as the voltage higher than that threshold, some variation in voltage level isn't a problem, especially for lead acid based cells. Current can usually vary some as well, but usually needs to be some significant faction of the battery's C value. Again the details are largely determined by cell chemistry, with lead acids being a prime example of having a wide range of acceptable charging currents. In all cases it's the current available that will determine how long it takes to charge the battery.
I suggest reading this to give you some background before moving on to more specific questions.
Both, the voltage is limited to the max charged value and the current is limited to the max possible without heating the battery beyond a set point which is determined by the battery physically and the chemistry... Look at your cell phone battery terminals the third lead is either connected to a monitor circuit or a diode. The Monitor can tell the charger what kind of battery as well as the other required information temp, voltage and log it's performance as well. Some monitors are just simple thermistors or PN junctions, BE junction of a transistor or a plain SI diode...
Doc
Many thanks you all .
Very informative
Elico