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Circuits designed by David Johnson, P.E.
Last Updated on: Thursday, April 07, 2016 02:04 PM

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Battery Tester Circuits

6v NMH/NiCd Battery Tester -  I designed this circuit to test rechargeable six volt battery packs under constant current conditions.  As designed, the circuit applies a 10 Amp load to the battery pack.  A heat sink must be used on the main power transistor… [Circuit by Dave Johnson P.E., 12/12/04]
 

9v Battery Voltage Monitor -  This circuit turns on a LED whenever the voltage of a standard 9v battery connected to the circuit drops below 7.2 volts.  It uses a LTC1440 comparator, which also contains a 1.18v reference diode.  In standby mode, the circuit draws only 4uA… [Circuit by David Johnson P.E., 7/09/06]


Button Battery Cell Internal Resistance Measurement Circuit  -  The open cell voltage of a small silver oxide button cell battery remains very close to 1.5 volts over most of the life of the cell.  However, there is a relationship between battery health and the internal resistance of the cell. This circuit when used . . . [Circuit by David A. Johnson P.E.,  07/11/06]


Ground Resistance Tester  -  UL requires that an electrical system using a metal chassis earth ground connection have a resistance of less than 0.1 ohms.  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.,  04/28/01]

 

Measure Button Battery Cell's Internal Resistance   -  The open cell voltage of a small silver oxide button cell battery remains very close to 1.5 volts over most of the life of the cell.  However, there is a relationship between battery health and the internal resistance of the cell. This circuit when used . . . [Hobby Circuit designed by David A. Johnson P.E.,  07/11/06]


Nine-Volt Battery Voltage Monitor  -  This circuit turns on a LED whenever the voltage of a standard 9v battery connected to the circuit drops below 7.2 volts.  It uses a LTC1440 comparator, which also contains a 1.18v reference diode.  In standby mode, the circuit draws only 4uA . . . [Circuit by David A. Johnson P.E.,  07/09/06]

 

NMH/NiCd 6v Battery Tester  -  I designed this circuit to test rechargeable six volt battery packs under constant current conditions.  As designed, the circuit applies a 10 Amp load to the battery pack.  A heat sink must be used on the main power transistor . . . [Hobby Circuit designed by Dave Johnson P.E.,  12/12/04]


Resistance Tester got UL Ground Requirement  -  UL requires that an electrical system using a metal chassis earth ground connection have a resistance of less than 0.1 ohms. This resistance must be tested with actual line current in excess or 10 Amps.  The circuit shown uses a couple of LEDs to indicate . . . [Circuit by David Johnson P.E.,  04/28/01]

 

Small Battery Capacity Tester  -  I have a client who uses a lot of batteries.  His sells a device which is powered by a 3v lithium coin cell and he sells thousands of them. It seems that many of the batteries he has been importing from China have a milliamp-hour capacity which is much . . . [Hobby Circuit designed by Dave Johnson P.E.,  09/07/08]


Tests UL Ground Resistance  -  UL requires that an electrical system using a metal chassis earth ground connection have a resistance of less than 0.1 ohms.  This resistance must be tested with actual line current in excess or 10 Amps.  The circuit shown uses a couple of LEDs to indicate if in fact the resistance is less than 0.1 ohms - modified on july 10, 2006 . . . [Hobby Circuit designed by David Johnson P.E.,  04/28/01]


UL Ground Resistance Tester  -  UL requires that an electrical system using a metal chassis earth ground connection have a resistance of less than 0.1 ohms.  This resistance must be tested with actual line current in excess or 10 Amps.  The circuit shown uses a couple of LEDs to indicate if in fact the resistance is less than 0.1 ohms - modified on July 10, 2006 . . . [Circuit by Dave Johnson P.E.,  04/28/01]

 

Voltage Monitor for a 9v Battery  -  Nine voltage batteries are used in a wide variety of electronic devices.  But, you often don’t know when it is time to change the battery until the device stops operating.  The hobby circuit below provides a visual indication when the battery needs to be . . . [Hobby Circuit designed by Dave Johnson P.E.,  07/09/06]

Battery Tester Circuits

Master Category List - Dave's Circuits

 


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