Battery charger

Easy dry cell charger with CMOS IC 4011

The dry cell charger circuit can be fully charged about 12 hours.When used with a 9 volt supply,the equipments in the circuit for the AA type cell.When using the C and D type cell, should reduce the value of the resistance Rx to be 68 ohms.In charge of the cell, you should not be charged to the same series, may cause cell damage is fully charged.
If the cell voltage is below 1.6 volt,The compared circuit to leave the square wave oscillator by the CMOS gate,then the transistor made a charge until the cell voltage is 1.6 volt.The comparison circuit will cut the charging LED blinks, notice prevents over-charging.

Be the first to comment - What do you think? Posted by admin - April 9, 2011 at 7:47 am

Categories: Battery charger, Digital Tags: 4011 cmos, dry cell battery charger

Simple Battery Isolator

This circuit is even simpler and employs a 6V feed from one of the stator connections on the vehicle’s alternator. This is connected to a 6V automotive relay (RLY1) which controls a Continuous Duty Solenoid (RLY2). This solenoid electrically connects or isolates the batteries. When the engine is started and the alternator stator voltage rises, the 6V relay turns on. This turns on the Continuous Duty Solenoid to connect the two batteries in parallel. As long as the engine is running, the vehicle’s alternator will maintain charge in both batteries.
When the engine is shut down, the alternator stator voltage drops and the Continuous Duty Solenoid switches off, thus isolating the second battery from the vehicle’s electrical system. Provided that camping accessories are only connected to the second battery, the main battery should never discharge. Because the concept is entirely dependent upon the alternator’s stator output voltage, you cannot forget to turn the system on or off as it happens automatically.
Copyright: Silicon Chip Electronic

Be the first to comment - What do you think? Posted by admin - October 20, 2010 at 2:26 am

Categories: Battery, Battery charger Tags: battery control circuit, battery isolator

Li-Ion Charger using LP2951

The LP2951 regulator is manufactured by National Semiconductors. The choice of values is from an application note “Battery Charging”, written by Chester Simpson.

Diode D1 can be any diode from the 1N00x series, whichever is conveniently available. It functions as a blocking diode, to prevent a back flow of current from the battery into the LP2951 when the input voltage is disconnected.

Charging current is about 100+mA, which is the internally-limited maximum current of the LP2951. For those wondering, this is compatible with just about any single-cell li-ion battery since li-ion can generally accept a charging current of up to about 1c (i.e. charging current in mA equivalent to their capacity in mAh, so a 1100mAh li-ion cell can be charged at up to 1100mA and so on). A lower charging current just brings about a correspondingly longer charge time. IMHO 100mA is quite low, low enough that the circuit can be used for an overnight charger for many typical single-cell li-ion batteries.

The resistors are deliberately kept at large orders of magnitude (tens/hundred Kohm and Mohm range) to keep the off-state current as low as possible, at about 2?A. Resistor tolerances should be kept at 1% for output voltage accuracy. The 50k pot allows for an output voltage range between 4.08V to 4.26V – thus allowing calibration as well as a choice between a charging voltage of 4.1V or 4.2V depending on the cell to be charged. The capacitors are for stability, especially C2 which prevents the output from ringing/oscillating.
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author: Izhar Fareed – izhargmx.us – extremecircuits.net