Nicad-batterv-analyzer


Posted on Aug 8, 2012

Because NiCad batteries maintain a constant output voltage, it is difficult to determine how much of the battery`s charge remains. The circuit provides a way of determining the capacity of a battery by draining it at a preset current to its depleted voltage of 1 Vi cell. Measure the discharge time ofthe cells and perform a simple calculation to obtain the battery`s capacity. Set the drain current (!D) to 0.5C (C = battery capacity in mA/hr) by selecting an appropriate value for R4. Choose R5 such that: ID x R5 = 1 V. VREF is set so the comparator turns off the drain current and timer when the battery reaches its depleted voltage, V8 (usually 1 V/cell).


Nicad-batterv-analyzer
Click here to download the full size of the above Circuit.

With the battery in place, activate the circuit by grounding VREF with the momentary switch. The battery drains at ID until it reaches V8, turning off the drain circuit and the timer. Hysteresis keeps the circuit from restarting. The circuit shown tests 4.8 V, 180 mA/hr batteries. ID is 100 mA and V8 is 4 V.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Small circuit forms programmable 4- to 20-mA transmitter
Mosfet 75W Power Amplifier
Light dimmer circuits
PIC micro Tetris game
Voltmeter with LED for car battery PCB
Arduino GH-2 integration for time lapse
A LOW-BATTERY ALARM FOR 13.6 VOLT LEAD-ACID BATTERIES
Tuned-base Armstrong oscillator
Dynamic braking with the two-speed motor reversing control circuit



Top