Expanded Scale Analog Battery Voltmeter

This metering circuit was developed by Electron Connection Limited for its customers. While Electron Connection encourages you to build this circuit for your own use, we do reserve all commercial rights to this design. The idea is to use an analog dc ammeter in a circuit that will accurately measure the batteries voltage. This circuit produces an expanded scale voltmeter. Most analog voltmeters start reading a 0 volts. This is really a waste for battery systems as a lead acid battery will have about 10 to 11 volts even when just about empty. So the portion of the meter's scale between 0 and 10 volts is not used.

Wasting this portion of the meter's scale decreases the resolution and thereby the accuracy of the meter. This circuit allows the meter to start reading at 11 volts and to display full scale at 16 volts (a very fully charged battery while still under charge). This is called an expanded scale, and makes the meter much more accurate to use.

All the components for this metering project are available at most Radio Shack stores, or from just about any electronics supply house. Cost of the parts should be between $20. and $40., depending on your hardware sources. Construction time is about 1 hour for an experienced assembler. This circuit is powered by the battery under measurement, and never requires the use of small batteries to power the meter.

We don't have space here to give an electronics primer for those not familiar with electronic construction. What we do offer is the schematic for the circuit on the next page. If you can't figure out how to build this meter from the schematic, then please seek out an electronics person who can aid you. For those wishing the meter already constructed and calibrated, please send $75. to Electron Connection Ltd., POB 442, Medford, OR 97501, and allow six weeks for delivery because we hand build each and every one to order.

DIY Battery Repair

DIY Battery Repair

You can now recondition your old batteries at home and bring them back to 100 percent of their working condition. This guide will enable you to revive All NiCd batteries regardless of brand and battery volt. It will give you the required information on how to re-energize and revive your NiCd batteries through the RVD process, charging method and charging guidelines.

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