Hi All, You can see I am a noob. I would like to know how to charge batteries? For example, if I have a 1.5v AA battery, what circuit can I use to charge it? Resistors? Caps? what about 12V batt? Thanks, Brian
Experience, and a knowledge of lead-acid battery characteristics.
A fully charged "12 volt" lead-acid battery (as used in cars) will be about 12.6 volts at rest, some time after the charger is disconnected.
13.6 volts is the "float voltage", at which the battery may be left on the charger indefinitely, and will be maintained at full charge. With the engine running, a car's electrical system will be somewhere in the
13.4 - 13.8 volt range, depending on engine speed.
Further information is available from the battery manufacturers, and from "alternate energy" web sites.
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
To obtain optimum life from the battery, it is recommended that, if the battery is to be operated continuously above or below +20°C, the charger should be fitted with temperature compensation to prevent over and under charging. With an increase of temperature the charge voltage should be reduced and, conversely, with a decrease of temperature the charge voltage should be increased. The temperature coefficient is:
(1) For cycle use ? 5m V / °C / cell
(2) For standby use (trickle charge of float charge) ? 3.3m V / °C / cell
For short-term temperature changes of between 5°C and 35°C it is not essential to apply temperature compensation, although it is recommended. For temperature fluctuations below 5°C or above 35°C, temperature compensation is necessary. Refer to Figure 5 for further details with regard to charge voltage set points in relation to temperature. Two curves are shown: one for cyclic applications and the other for stand-by use.