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Battery Monitors / Testers
Battery Monitors
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Last Updated: November 30, 2017 10:28 AM

Circuits Designed by Dave Johnson, P.E. :

Ground Resistance Tester -  UL requires that an electrical system using a metal chassis earth ground connection have a resistance of less than 0.1ohms.    This resistance must be tested with actual line current in excess or 10 amps.    The circuit shown uses a couple of LEDs to indicat . . . Hobby Circuit designed by Dave Johnson P.E.-April, 2001

Low Battery Voltage Flasher -  This circuit is designed to monitor two alkaline cells (3v) that form the battery often used in portable electronic equipment. . . Circuit by David Johnson P.E.-January, 1998




Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

GMR Sensors Manage Batteries -  09/02/99 EDN-Design Ideas The past few decades have seen remarkable progress in magnetic-sensor technology.  Early and current sensors exploit the Hall effect; more recent devices use an effect called giant magnetoresistance(GMR].  GMR sensors use semiconductor processing of materi __ Circuit Design by D Ramirez and J Pelegri, University of Valencia, SpainSeptember 2, 1999

Ground Resistance Tester -  UL requires that an electrical system using a metal chassis earth ground connection have a resistance of less than 0.1ohms.    This resistance must be tested with actual line current in excess or 10 amps.    The circuit shown uses a couple of LEDs to indicate . . . Hobby Circuit designed by Dave Johnson P.E.-April, 2001

HF AC Millivoltmeter adapter -  Intended for use past 200 kHz, this adapter changes HF AC voltages between 2 mv P-P and 200 mv P-P to the corresponding DC level with linearity of better  than 1 millivolt.  A on-board calibration signal aids in calibration prior to use. __ Designed by Dick Cappels

HF/VHF/UHF Test Oscillator -  This test oscillator covers 16 MHz to 300 MHz in six bands, using varactor tuning.  It has a high level output to drive a frequency meter and two sine wave outputs, one of which is 50 Ohms.   This article was published in Croatian in infoelektronika magazine in June, 2012 (cooperatively) __ Designed by Dick Cappels

High Capacity Alternative to 9 Volt Battery -  Get ten times the capacity of a 9 Volt battery to power your devices. __ Designed by REUK-Renewable Energy UK website

Indicates a Low battery -  02/03/14EDN-Design Ideas It may seem a bit counterintuitive to power on an LED when a battery is already low, but this Design Idea does it with aplomb __ Circuit Design by James Wood

Inductance meter for RF Inductors  -  needed a way to measure hand-wound RF inductors in my second lab, and since I would only be doing this occasionally, I didn't need anything fancy, and since once a friend finishes his AT90S1200-based design, I plan to make one myself, I figured I'd use this for less than a year, so I didn't want to invest __ Designed by Dick Cappels

Inductance meter for RF Inductors  -  needed a way to measure hand-wound RF inductors in my second lab, and since I would only be doing this occasionally, I didn't need anything fancy, and since once a friend finishes his AT90S1200-based design, I plan to make one myself, I figured I'd use this for less than a year, so I didn't want to invest __ Designed by Dick Cappels

In-Situ Battery Test Probe -  This item describes a simple probe that allows in-situ AA and AAA battery voltage and current drain measurements without removing the cells from the holder.  In use, the probe is simply pushed between the positive end of one cell and either the negative end of the adjacent cell or the battery holder terminal.  The probe [?]|

LC Determination by Resonant Frequency Measurement ATtiny2313, AT90S2313 -  A well known L/C measurement circuit is pressed into service to make a bare bones measurement circuit. __ Designed by Dick Cappels

Lead-Acid Battery Low Voltage Indicator -  Lead-acid batteries should not be discharged below a certain voltage.  Discharging a cell below about 1.8v and can often damage it, which will result in a lower amp-hour capacity.  Large battery banks are critical in off-grid energy storage systems.  One. . . Circuit by David A. Johnson P.E.-July, 2006

Lead-Acid Battery Monitor -  This mini-project came about from building a garden shed.  I decided to re-purpose an old UPS battery along with some spare halogen downlighters for illumination.  But as I researched lead-acid technology, I decided that I needed something rather more sophisticated than a simple switch if I wanted the batteries to survive __ Designed by Mark Hennessy

LED 12 Volt Lead Acid Battery Meter -  In the circuit above, a quad voltage comparator (LM339) is used as a simple bar graph meter to indicate the charge condition of a 12 volt, lead acid battery.  A 5 volt reference voltage is connected|

LED Battery Condition Indicator -  In the circuit below, a quad voltage comparator (LM339) is used as a simple bar graph meter to indicate the charge condition of a 12 volt, lead acid battery.  A 5 volt reference voltage is connected to each of the (+) inputs of the four comparators and the (-) inputs are connected to successive points along a voltage divider.  The LEDs __ Designed by Bill Bowden

LED Flasher Indicates Low Battery Condition -  01/02/97 EDN-Design Ideas Many portable electronic devices could benefit from a visual indication when their battery requires replacement.  Typical low-battery indicators simply turn on an LED when the battery voltage drops below a certain value.  Such circuits actually accelerate the battery's extinction by drawing excessive current.  The circuit in Figure 1 draws a mere 1 m A in its standby mode and averages only 20 m A when activated.  The low current imposes a minimal burden on any battery circuit.  An off-the-shelf, undervoltage sensor IC(IC1) monitors the battery voltage-- __ Circuit Design by David Johnson, DiscoverCircuits.com

Lithium Battery Tester -  I bought some lithium ion rechargeable batteries a while back.  I was planning on using them to modify some solar powered LED spot lights.  What I like about these new batteries is that they are the same size as a standard 1.5v alkaline AA cell . . . Hobby Circuit designed by David A. Johnson P.E.-February, 2012

Lithium Ion Battery Stack Monitor with Both Signal & Power Isolation  -  Software to communicate with the EVAL-CED1Z and AD7280A is provided with the AD7280A evaluation board package.  Connection between the EVAL-CED1Z and the USB port of a PC is via a standard USB 2.0 connection cable that is provided as part of the EVAL-CED1Z package.  , Getting Started Complete details of setting up the hardware and installing the software are contained in UG-252__ Analog Devices from the Lab

Little More Serious Frequency Meter/CounterATtiny2313, AT90S2313 -  Maximum input frequency is specified to be 30 MHz in the multi-chip configuration, and in single-chip configuration, there are both 5 MHz and 10 Mhz versions operating with 10 and 20 MHz crystals, respectively.  All versions have 9 1/2 digit resolution.  I haveused __ Designed by Dick Cappels

LM3914 Battery Monitor -  This circuit should be powered by its own battery, otherwise you might get an innacurate reading.  hook the to-be-monitored battery to pin 5 of the chip. __ Designed by Andy Wilson

Low battery cut-off for a car or truck -  Also acts as a Master On / Off Switch.  NOW, Also a New P-Mos Version.  Supplies Positive voltage to grounded devices. __ Designed by G.L. Chemelec

Low Battery Indicator -  File contains several designs, please scroll to find this circuit.  Here is a low battery indicator that flashes a lamp when the battery voltage falls below about 5 volts.  The circuit draws about 25 microamps when not flashing so battery life is not significantly shortened by the circuit.  The two 1 megohm resistors set the switching point at V/2 (plus a little due to the emitter-base diode drop) and when this voltage is above the zener voltage the circuit cannot turn on.  When the battery voltage drops below 5 volts, the base voltage drops to 2.5 volts and the emitter can reach a voltage sufficient to turn on the PNP (2N4403 or similar).  When the PNP conducts, the NPN also conducts dropping the voltage across the circuit even more and the circuit snaps on.  When the 4.7 uF capacitor has discharged, the circuit turns off and the capacitor begins charging again. __ Contact: Charles Wenzel of Wenzel Associates, Inc.

Low Battery Indicator Ii -  This circuit indicates the remaining battery life bAy varying the duty cycle and flash rate of an LED as the battery voltage decreases.  In fact, the circuit actually indicates five battery conditions: (1) a steady glow assures indicates that the battery is healthy; (2) a 2Hz flicker (briefly off) indicates that the battery is starting|

Low Battery Monitor Delays System Shutdown -  App Note #134__ Maxim Integrated

Low Battery Voltage Flasher -  This circuit is designed to monitor two alkaline cells (3v) that form the battery often used in portable electronic equipment. . . Circuit by David Johnson P.E.-January, 1998

Low Voltage Battery Disconnects -  Find out more about low voltage battery disconnect (LVD) circuitsused to protect batteries. __ Designed by REUK-Renewable Energy UK website

Low Voltage Indicator for Lead-Acid Battery -  Lead-acid batteries should not be discharged below a certain voltage.  Discharging a cell below about 1.8v and can often damage it, which will result in a lower amp-hour capacity.  Large battery banks are critical in off-grid energy storage systems.  One . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

Low-Battery Detector Preregulates Input Voltage -  08/15/96 EDN-Design Ideas The circuit in Figure 1 uses the comparator and voltage reference of a low-battery detector to preregulate the input voltage.  The circuit provIdeas an additional regulated voltage output at VOUT1 and significantly reduces the linear regulator's (VOUT2's) power dissipation.  The two outputs (12V at 50 mA and 5V at 100 mA) are independent. __ Circuit Design by Khy Vijeh, Analog Devices Inc, Santa Clara, CA

Low-Battery Indicator has High-Efficiency -  05/03/01 EDN-Design Ideas The usual method for implementing the low-battery warning featured in most battery-operated equipment is to illuminate an LED.  However, the LED exacerbates the low-battery condition.  You can greatly reduce the LED's power consumption by operating it at a low frequency and a low duty cycle. __ Circuit Design by Joe Neubauer

Low-Battery Indicator Uses Fleapower -  4-Sep-03 EDN-Design Ideas It is always desirable to use a low-battery indicator that consumes as little power as possible.  For a 9V, 450-mAhr alkaline battery, a 50-?A low-battery indicator can by itself run the battery down in a littlethan a year.  Battery-powered devices that need to run continuously for a long time require battery indicators that consume minimal power __ Circuit Design by Yongping Xia, Navcom Technology, Redondo Beach, CA

Low-battery voltage cutoff consumes just 1 mA -  09/11/98 EDN-Design Ideas NOTE : File has several circuits, please scroll to find this one.  A low-battery voltage-cutoff circuit prevents overdischarge of a rechargeable battery.  An obvious requirement of this circuit is extremely low power consumption.  Figure 1a's simple circuit has a measured current consumption of approximately 1.2 mA and uses only two __ Circuit Design by Yongping Xia, Teldata Inc, Los Angeles, CA

Low-cost active load draws constant battery power -  04/13/00 EDN-Design Ideas Unlike nickel-metal-hydride and lithium-ion rechargeable batteries, the discharge voltage of alkaline batteries is not constant and tends to vary from 1.5 to 0.8V per cell.  Alkaline-battery manufacturers specify the discharge life of their batteries under constant powerloads.  Because of the varying discharge voltage, you can't simply connect a load resistor to the cells to verify or measure power profiles without incurring a lot of error in your measurements.  The circuit in Figure 1draws a constant power from the battery pack.  Thus, as the battery voltage decreases, the load current increases.  A single potentiometer allows a user to set the desired wattage draw.  The circuit is simple and inexpensive to build. __ Circuit Design by Doug Farra

LT1304: Micropower DC/DC Converter with Independent Low-Battery Detector -  DN120 Design Notes__ Linear Technology/Analog Devices


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