battery tester


Hyper-Simple Battery Capacity Tester

The circuit described here is eminently suitable to indicate the capacity of a battery. We use a cheap electric clock for this. By connecting a resistor across the battery terminals, the battery is discharged somewhat faster than with the clock alone. If we pick a resistor with a value of 5.6R, the discharge current amounts […]


Battery Tester For Deaf and Blind Persons

Many blind and deaf-blind persons use portable electronic devices to assist their everyday lives but it is difficult for them to test the batteries used in this equipment. Talking voltmeters are available but there is no equivalent usable by deaf-blind persons. This battery tester uses vibration and a user-settable control to enable blind and deaf-blind […]


High-Current Battery Discharger

If you have a motley collection of 12V batteries in varying states of health, this simple circuit will allow you to easily check their capacity. It’s basically a high-current discharge load which is controlled by the NiCd Discharger. This involved increasing the existing 10µF capacitor across LED1 to 100µF, to enable it to supply the […]


Improved Vibrating Battery Tester

Many blind and deaf-blind people use portable electronic devices to assist their everyday lives but it is difficult for them to test the batteries used in that equipment. Talking voltmeters are available for the blind but there is no commercially available equivalent usable by deaf-blind persons. This device enables blind, deaf-blind and sighted people to […]


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 […]


Variable High Power “Resistor” For Power Supply Testing

Current handling capability of a power supply system often needed to be checked. Finding high power rated variable resistor to provide variable load testing might be difficult. There is wire wound type but it’s not always available at your local store, and the price and performance might be disappointing. This variable high power “resistor” uses […]


Low Power Under- and Over-Voltage Monitor

This voltage monitor has two  threshold, VTH for undervoltage and VTH’ for overvoltage. Using the component values shown in the schematic diagram below, this circuit give 6V for VTH and 15V for VTH1. Above 6V, the LED indicator of this voltage monitor  circuit will increase the flash rate until reach 15V.  This circuit will stop […]


Two Transistors Lead Acid Battery Monitor

Three separated LEDs is used on this battery monitor circuit. For red LED, it’s turn on from 6v to below 11v and turns off above 11v. For the orange LED, its illuminate between 11v and 13v and turns off above 13v. The green LED illuminates above 13v. This battery indication is suitable for monitoring your […]


Single Transistor Lead Acid Battery Monitor

We can make a very simple battery monitor using a dual-colour LED and a few additional components. When the red and green LEDs are illuminated, the LED produces orange. The following battery monitor circuit turns on the red LED below 10.5v. The green LED illuminates above 11.6v. The orange LED illuminates between 10.5v and 11.6v. […]


Battery Level Indicator

A battery level indicator circuit is depicted in the schematic diagram below. This circuit is designed for 9V battery operation, as this circuit will start dimming below 7V and will be completely turned off at 6V.  If you want the LED indicator not to dimming but just abruptly turns off at below 6V, then you […]