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Battery Chargers
All Battery Chargers:   #'s - B       C - K      L - R       S - Z

Also see:      Alkaline       Lead Acid        Lithium      Nickel

Last Updated: June 02, 2021 01:44 PM

Circuits Designed by Dave Johnson, P.E. :

+5v Powered Charge Pump Battery Charger   -  The circuit below will trickle charge a four cell pack of AA or AAA NiMH batteries.  The circuit draws current from the +5v available a USB connection and pumps about 70ma of current into the battery.  This should be enough current to fully charge a pack of . . . Circuit by Dave Johnson P.E.-February 07, 2010

12v_To_24v_Solar_Battery_Charger   -  A while back I received an email from a Discover Circuits visitor.  He wanted to know how he could use a single 12v solar panel to charge a 24v lead acid battery bank.  He said he used the 24v battery to run an emergency 120vac power system.   By using the higher 24 volts instead of 12v, his DC to AC inverter could pump out more peak power, for starting things like well pumps and window air conditioners. . . . Hobby Circuit by David Johnson P.E.-July 23, 2017

1W Solar Path Light with COB   -  Chip on board (COB) LEDs are all the rage.  These devices assemble multiple tiny LED chips onto a metal backed circuit board, then cover the assembly with a plastic cover.  The metal back allows the assembly to be mounted to heat sink to keep the device cool.  The multiple LED chips can be wired into any number of series/parallel configurations.  Some are wired for 12v operation while other COB LEDs in flashlights are all wired in parallel, with an operating voltage of about 3 volts. . . . Circuit by David Johnson P.E.-May 23, 2017

2-12v Battery Isolator Circuit with a LTC4412   -  Has just announced a neat little chip (LTC4412).  It has been designed to be used in conjunction with an external P-channel power FET, to form an ideal diode function with a very low 0.05v voltage drop.  The chip monitors the voltage on eit . . . Hobby Circuit designed by David A. Johnson P.E.-August 07, 2006

4_D-Cell_LED_Lantern_Modified   -  While shopping at a sporting goods store one day, I spotted a compact LED lantern.  It looked like the kind of lantern I could modify. The lantern LEDs were grouped into three sections of 7 LEDs each, oriented into 120 degree angles.  The LEDs were standard T 1-3/4 epoxy types.  The lantern had a three mode switch which selected between off, full power and half power modes.  At the half power mode, only half of the 21 LEDs were illuminated.  At full power all LEDs were illuminated. . . . Hobby Circuit by David Johnson P.E.-September 21, 2017

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.-December 12, 2004

8 Solar Cell LED Light   -  I have been modifying a lot of solar garden and path lights for the last several years.  I buy some units from home improvement stores, then I gut them completely.  I take out the battery, electronic control board, LED and solar panel.  I then replace those components with new units.  I increase the size of the solar panel and battery.  I use a more efficient and brighter LED . . . Circuit by David Johnson P.E.-September 22, 2017

8-Solar Cell Lithium Ion Battery Charger Version 2   -  Jim Wilber looked at my design for a battery charger and sent me some suggested changes.  He suggested using the LTC4412 ideal diode IC to switch off the current path from the solar cell to the battery in darkness.  He also noted that the 2.5v regulator from Seiko I had selected was no longer in production and suggested using the shunt reference . . . Circuit by David A. Johnson P.E.-May 21, 2013




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

+5v Powered Charge Pump Battery Charger -  The circuit below will trickle charge a four cell pack of AA or AAA NiMH batteries.  The circuit draws current from the +5v available a USB connection and pumps about 70ma of current into the battery.  This should be enough current to fully charge a pack of. . . Circuit by Dave Johnson P.E.-February, 2010

1W Solar Path Light with COB -  Chip on board (COB) LEDs are all the rage.  These devices assemble multiple tiny LED chips onto a metal backed circuit board, then cover the assembly with a plastic cover.  The metal back allows the assembly to be mounted to heat sink to keep the device cool.  The multiple LED chips can be wired into any number of series/parallel configurations.  Some are wired for 12v operation while other COB LEDs in flashlights are all wired in parallel, with an operating voltage of about 3 volts. . . . Circuit by David Johnson P.E.-May, 2017

1.3V Power Supply -  This is a replacement power source for 1.3V mercury cells or other small batteries.  It has many uses and I use this circuit in my computer to power a front panel multi adapter which has a digital thermometer __ Designed by Andy Collinson

12 Volt Gel Cell Charger -  Recently, a fellow amateur was looking for a gel cell charger which would first charge at a fixed rate and then later switch to a trickle charge when the cell was fully charged.  After reviewing several catalogs and web sites, the MAX712 IC was discovered.  This IC meets all the requirements for almost any type of battery charging system.  The circuit in Figure 1 was designed specifically for 12 volt gel cells __ Designed by Radio Amateur Society of Norwich

12v Battery Charger-Cum-Variable Power Supply -  The circuit presented here can charge a 12V lead-acid battery of 50Ah to 80Ah   (even up to 100Ah) capacity and can even be used as up to 18V DC variable power __ Electronics Projects for You

12V input 12V battery charger -  Well suited for charging gelled batteries from a car, with the engine running or stopped. __ Designed by Manfred Mornhinweg

12V, 4-AA Cell Differential Temperature Charger -  This project makes a number of improvements over my Temperature Controlled NIC D Charger circuit.  The new circuit runs on 12VDC, allowing it to be used in a car or from a 12V solar power system.  Additionally, a current sensor LED verifies that the cells are receiving charging current.  Note that the current sensor circuitry __ Designed by G. Forrest Cook

12v_To_24v_Solar_Battery_Charger -  A while back I received an email from a Discover Circuits visitor.  He wanted to know how he could use a single 12v solar panel to charge a 24v lead acid battery bank.  He said he used the 24v battery to run an emergency 120vac power system.   By using the higher 24 volts instead of 12v, his DC to AC inverter could pump out more peak power, for starting things like well pumps and window air conditioners. . . . Hobby Circuit by David Johnson P.E.-July, 2017

2 Cell Lithium Ion Battery Charger -  This circuit was build to charge a couple series Lithium cells (3.6 volts each, 1 Amp Hour capacity) installed in a portable transistor radio.  The charger operates by supplying a short current pulse through a series resistor and then monitoring the battery voltage to determine if another pulse is required.  The current can be adjusted by changing the series resistor or adjusting the input voltage __ Designed by Bill Bowden

2-12v Battery Isolator Circuit with a LTC4412 -  Has just announced a neat little chip (LTC4412).  It has been designed to be used in conjunction with an external P-channel power FET, to form an ideal diode function with a very low 0.05v voltage drop.  The chip monitors the voltage on eit . . . Hobby Circuit designed by David A. Johnson P.E.-August, 2006

2-Cell Solar Panel Li-Ion Battery Charger -  This circuit shows a compact solar-powered battery charger using a LTC3105 as a boost converter and a LTC4071 as Li-ion shunt charger.  A 2-cell 400mW solar panel provides the input power to the LTC3105 to produce over 60mA of charge current in full sunlight.  Maximum power point control prevents the solar panel voltage from__ Linear Technology/Analog Devices App Note, Jul 1, 2011

3.3V lithium-cell supply requires one inductor -  08/05/99 EDN Design Ideas:  Because of growing popularity of lithium-ion (Li-ion) batteries and 3.3 V power supplies, portable-equipment designers must often create a 3.3 V supply that a single Li-ion cell can power Design by Matt Schindler and Jay Scolio, Maxim Integrated Products, Sunnyvale, CA

4-Cell Ni-Cad Regulator/Charger for Notebook Computers -  DN54 Design Notes__ Linear Technology/Analog Devices

4_D-Cell_LED_Lantern_Modified -  While shopping at a sporting goods store one day, I spotted a compact LED lantern.  It looked like the kind of lantern I could modify. The lantern LEDs were grouped into three sections of 7 LEDs each, oriented into 120 degree angles.  The LEDs were standard T 1-3/4 epoxy types.  The lantern had a three mode switch which selected between off, full power and half power modes.  At the half power mode, only half of the 21 LEDs were illuminated.  At full power all LEDs were illuminated. . . . Hobby Circuit by David Johnson P.E.-September, 2017

5 Volt Regulator -  Scroll for this one - You need to add a 5 volt regulator to power a USB device and this regulator needs to be a low-dropout type that consumes "micro" power so that it doesn't discharge the battery on its own.  There are commercial regulators like the TPS76750Q in the PWP package that will do the job with just a couple of good ceramic bypass capacitors. (There are a bewildering number of suitable regulator choices.) But if you like to build your gadget from parts on hand, below are a couple of circuits that will work. __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

5v Solar Charger -  This project uses the 1.2v rechargeable battery and solar panel from a Solar Garden Light.  These lights can be bought for less than $5.00 in most $2.00 shops or similar shops that sell general household items.   __ Contact Collin Mitchell

6 Volt Gel Cell Charger -  This circuit needs a regulated 10V-DC front end capable of supplying 2 Amps.  Starts the charge cycle at 240mA and at full charge switches automatically to a float condition (trickle charge) of 12mA.   __ Designed by Tony van Roon  VA3AVR

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.-December, 2004

7.2V Field Charger -  This charger was designed by me in 1993 to fill a need that I had. This was I had two R.C. model boats that needed 2 batteries each and I needed to charge them simultaneously, from my car battery. I could not find a commercial unit to do this, so came up with a neat project to fill the bill. Layout was done on a 2 proto-boards, one lays flat, and the other vertical for the bar graph displays. The displays a need red filter in front of them. __ Designed by Tony van Roon  VA3AVR

8-Solar Cell Lithium Ion Battery Charger Version 2 -  Jim Wilber looked at my design for a battery charger and sent me some suggested changes.  He suggested using the LTC4412 ideal diode IC to switch off the current path from the solar cell to the battery in darkness.  He also noted that the 2.5v regulator from Seiko I had selected was no longer in production and suggested using the shunt reference . . . Circuit by David A. Johnson P.E.-May, 2013

8 Solar Cell LED Light -  I have been modifying a lot of solar garden and path lights for the last several years.  I buy some units from home improvement stores, then I gut them completely.  I take out the battery, electronic control board, LED and solar panel.  I then replace those components with new units.  I increase the size of the solar panel and battery.  I use a more efficient and brighter LED . . . Circuit by David Johnson P.E.-September, 2017

9-V Nicad Charger -  Circuit Only __ Designed by Jan Hamer

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Battery Charger Circuits:  #'s - B       C - K      L - R       S - Z


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