With a suitable load, the terminal voltage of a NiCd or lithium-ion battery is proportional to the quantity of saved power. This relationship, which is linear over a large range, will also be utilized to build a easy battery capability meter.
Circuit Image :
Voltage Tester for Model Batteries Circuit Image
This model battery tester has two carry outs: it gives a load for the battery, and on the similar time it measures the terminal voltage. In addition, each operates will moreover be switched on or off by the use of a adaptation remote-control receiver, to steer clear of draining the battery when it isn\'t essential to make a measurement. The load neighborhood, which consists of a BC517 Darlington transistor (T2) and cargo resistor R11 (15 Ω /5 W), is quickly evident. When the burden is energetic, the base of T1 lies pretty much at floor stage. Consequently, T1 conducts and allows some of the LEDs to be illuminated.
Voltage Tester for Model Batteries Circuit Diagram
The utterly acquainted voltmeter circuit, which is in step with the LM3914 LED driver, get to the bottom ofs which LED is lit. The values of R6 and R7 depend upon the type and choice of cells in the battery. The objective here is to not measure the complete voltage fluctuate from zero V, but reasonably to show the component of the diversity between the fully charged voltage and the definitely discharged voltage. Since an entire of ten LEDs are used, the display will be very precise. For a NiCd battery with 4 cells, the dimension runs from four.8 V to 5.5 V when R6 = R7 = 2 kΩ. The measurement scale for a lithium-ion battery with two cells fluctuates from 7.2 V to 8.0 V if R6 = 2 kΩ and R7 = 1 kΩ.
For remote-control operation, each jumpers must be positioned within the upper position (between pin 1 and the center pin). In this configuration, each a good or negative sign aspect will most certainly begin the dimension course of. A sure area set offs IC1a, whose output goes High and set offs IC1b. A poor side has no impact on IC1a, however it for sure set offs IC1b immediately. In any case, the burden will more than likely be activated during the heartbeat from monostable IC1b. Use P12 to set the coronary heartbeat width of IC1a to an sufficient price, taking care that it\'s shorter than the pulse width of IC1b.
If the voltage tester is equipped into a remote-controlled adaptation, that you can exchange the jumpers with simple wire bridges. However, if you need to use it for various performs, any suchs measuring the quantity of cost left in a video digicam battery, it is recommended to glue double-throw push-button switches in position of JP1 and JP2. The most continuously closed contact corresponds to the upper jumper place,while the generally open contact corresponds to the lower place.
Parts :
Resistors: R1,R2 = 47kΩ
R3 = 100kΩ
R4 = 500kΩ
R5 = 1kΩ
R6,R7 = see textual content (1% resistors!)
R8 = 1kΩ5
R9 = 1kΩ2
R10 = 330Ω
R11 = 15Ω 5W
R12 = 15kΩ
P1 = 100kΩ preset
Capacitors:
C1 = 10nF
C2 = 100nF
Semiconductors:
D1-D10 = LED, purple, excessive effi-ciency
T1 = BC557
T2 = BC517
IC1 = 74HC123
IC2 = LM3914AN
Miscellaneous:
PC1,PC2,PC3 = solder pin
JP1,JP2 = jumper or pushbutton
PCB Layout :
Voltage Tester for Model Batteries PCB Layout
Copyright : Elektor
