How to Troubleshoot a Battery Charger

By eHow Home & Garden Editor

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Electric toothbrushes, cordless shavers, cordless drills, cellular and portable phones, and a whole mess of kitchen appliances rely on rechargeable batteries to keep them running. What do you do if they won't charge?

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Instructions

Difficulty: Moderate

Things You’ll Need:

12-V Battery Chargers
Battery Chargers
Laptop Battery Chargers
Cotton Swabs
Nail Files
Voltmeters

Step1

Make sure the charger cord is plugged in and the outlet is getting power.

Step2

Look closely at the battery pack. Is there corrosion or leakage? If so, replace the battery immediately.

Step3

Test the charger. For DC chargers, set a voltmeter to 25 VDC and touch the contacts with the probes. The meter should read about 1 V more than the charger's rating. If the reading is zero, switch the probes.

Step4

Test an AC charger by setting a voltmeter to 25 VAC. Touch the contacts with the probes. The transformer in the charger is bad if you get no reading at all.

Step5

Check the contacts. These are metal strips or points located on the appliance and in the charging base. With the charger unplugged, wipe them with a cotton swab. Use a fine emery board to remove visible corrosion.

Tips & Warnings

If you've noticed that the appliance has been holding a charge for shorter periods, suspect the battery, not the charger.
A charger's rated output is usually located on a label on the bottom of the unit.
Avoid testing AC chargers rated higher than 25 V.
Be careful with leaky batteries. The highly corrosive contents can damage just about anything they touch.

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Comments

Anonymous said

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on 4/1/2006 A few switch mode battery chargers(such as used on some wheel chairs) may not show any voltage on the output unless they sense the presence of a minimal acceptable battery voltage level. This is a safety feature to prevent attempted and potentially damaging charges on bad batteries. Always check with a known good set of batteries first to see if the voltage goes at least 1 volt higher than the initial measured battery voltage. If you read the voltage that existed prior to plugging in the charger, then there is a good chance that it is the charger or connection between ac mains to charger or charger to battery. Bear in mind that some chargers perform a slow start that can take anywhere from 3 seconds to a couple of minutes before you see any voltage increase. If your charger has LEDs that give a particular pattern when the unit is properly charging, then become familiar with this pattern when you get the charger (aka READ THE MANUAL)so that you can quickly spot unusual behavior and take it to the dealer for service.
Switch mode battery chargers contain lethal voltages (300 to 700 vdc or more) that can kill. Refer servicing of such chargers to authorized qualified personnel.

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