How To Test A Ryobi Battery Charger (Do This!)

Dennis Howard
by Dennis Howard
Ryobi battery chargers last for a long time and are easy to rely on. However, they sometimes require that you test them if something seems off. Follow along as we explore how you can easily test a Ryobi charger.

Cordless tools have become common in most homeowners’ tool collections. These battery-powered devices are convenient and handy. However, when the batteries don’t charge, the frustration quickly grows. How do you test a Ryobi battery charger if you don’t know if the charger or the battery is bad?

The easiest way to test a Ryobi battery charger is to put a known good battery in the chargers. This method doesn’t require any special tools or testing devices. If you do have a voltmeter, you can easily check the output of the battery charger.

The problem is determining if the Ryobi battery charger is at fault or if the Ryobi 18 volt battery is bad. You can test both the Ryobi battery charger and the Ryobi battery using a voltmeter. Performing these checks is safely done by following a few easy steps.

Step 1 – Gather a Few Tools

You won’t need many tools to check your Ryobi 18 volt battery charger and a Ryobi 18 volt battery. Multi-meters are not expensive and can be useful for other things around your house. If this is your first time using a multi-meter, read through the user manual to familiarize yourself with the operation.

You can expect to pay as little as $15 for a decent multi-meter. Check at your local home improvement store or a discount tool retailer to find the best value on a multi-meter.

Step 2 – Gather your Ryobi Battery Charger and the Batteries

Find a clean space to work and gather the Ryobi battery charger and the Ryobi batteries. Check everything at once while you have your multi-meter ready. It will save time and frustration.

Step 3 – Set your Multi-meter

Set your multi-meter to DC mode and a range of 10 to 30 volts. Multi-meters vary the settings, so read your user’s manual. Some more expensive multi-meter models will automatically sense the type of voltage and the range of voltage it is testing.

Step 4 – Plug in Your Ryobi Battery Charger

Your Ryobi battery charger must be operating to check the output voltages with a multi-meter. Be careful from this point onward when handling the battery charger. If you accidentally short circuit the Ryobi battery charge’s electrical connections, you can damage the charger beyond repair.

The red LED indicator on the battery charge should come on and glow without blinking. The steady red LED shows that the charger has input power and is ready to charge a battery.

If the red LED doesn’t come on when plug in the Ryobi battery charger, it will not get power. If you are certain that the outlet is working, the Ryobi battery charger has problems that require a trained service technician to repair.

Step 5 – Examine the Ryobi Battery Charger and Find the Metal Contacts

Look inside the Ryobi battery charger hole where the neck of the battery goes when charging. There are four metal tabs at the bottom of the opening in the Ryobi battery charger. Two of these tabs have a plus or a minus. The other two tabs have no markings.

The negative tab pairs with one of the tabs with no markings. These two tabs are much narrower than the positive tab and the other unmarked tab.

Step 6 – Test the Voltage with Your Multi-meter

The problem with testing a Ryobi battery charger is the protections built into the charger. The Ryobi battery charger is a smart charger. The charger senses both the battery type and the recharge needed. Unless a Ryobi battery is in the charger, it will not read the full 18-volt output.

Two effectively test the charger, your negative multi-meter probe must touch both narrow tabs simultaneously. When you touch the two tabs, the red indicator LED on the charger will begin to blink.

A blinking red LED is an indication that the charger is trying to test the battery. Touch the positive (red) probe to the positive tab on the charger. Your multi-meter may change numbers rapidly for a few seconds and then settle on reading around 1 mV.

Step 7 – Test with a Known Good Battery

If you are getting a small voltage reading from the Ryobi battery charge, it is time to test the charger with a known good battery. Insert the Ryobi battery into the charger and watch the LED indicators on the Ryobi battery charger.

The red LED should flash several times. At this point, the Ryobi battery charger is testing the battery. After a few seconds, you will see the indicator LED’s change to one of the following states.

  • A Slow pulse of the red LED indicates a fault with the battery
  • The red LED glows steadily and the green LED blinks indicating the battery is receiving a charge.
  • The red LED goes off and the green LED glows steadily. A solid green LED shows the battery is fully charged and the charger is in maintenance mode.
  • The green LED pulses slowly shows that the charger is in energy-saving maintenance mode.

The Dreaded Defective Battery Indicator

If you have determined that the charger is working and the red LED pulses slowly, your battery has a problem. More than likely, one of the cells in the battery is defective. The battery cells are not replaceable, and you should recycle the battery properly.

Do not attempt to repair the battery. Lithium batteries can explode if not handled properly. Most home improvement centers have battery recycling stations where you can drop off your battery safely.

My Ryobi Battery Shows to Have A Full Charge but it Won’t Work

Your Ryobi battery may be in sleep mode. To wake up a Ryobi battery can be a simple process.

Do A Mini-Charge on the Battery

Put the Ryobi battery in the charger for a few seconds and then remove it before the LED indicator lights begin to flash. You may need to repeat this process several times in a row.

If this doesn’t work, your Ryobi battery may have a defective cell in the battery or other problems. Sometimes the battery level indicator or a multi-meter will show a full charge. If one cell is bad, it will prevent the battery from delivering the proper voltage to the tool.

In this case, recycle the battery and purchase a replacement.

If My Ryobi Battery Charger is Dead, Can I Repair It?

Probably not. The Ryobi battery charger has some complex electronic components that manage the recharge cycles. Finding the problem requires training and knowledge that most homeowners don’t have.

Also, the Ryobi battery charge has electronic components that can be dangerous even after being unplugged for some time. The power circuits use capacitors that store electrical energy. These capacitors store up to 350 volts. If you touch the wrong place on the circuit board, you risk serious injury.

We suggest that you not try to open the Ryobi battery charger. The better choice is to take the defective Ryobi battery charger to a trained technician. These trained Ryobi technicians have the knowledge and tools to find and repair the problem.

Protect your Ryobi Batteries and Chargers

You can prolong the life of your Ryobi batteries and chargers with a few good habits. These good habits include

  • Protect your batteries and chargers from moisture. Water is not a friend of batteries or chargers.  Keep your batteries and chargers in a dry environment and avoid getting them wet.
  • Don’t expose your Ryobi batteries to extremes of heat and cold. This is especially true for batteries.
  • Be careful with batteries after a drop or fall. A crack in a battery case or damage to the battery’s internal parts can lead to battery failure.  Damage to a lithium cell can release the lithium and cause fires or explosions.

The Good, the Bad, and the Frustrating

Cordless power tools are convenient and efficient. However, they can also be frustrating. When you need a tool and the batteries are dead, you are stuck without recourse until the battery is charged. If the charger isn’t working, your frustrations can double.

We hope that this article has given you some insight into checking your Ryobi battery charger. Unfortunately, if your Ryobi battery charger breaks, there is not much more most homeowners can do. Good luck and be safe.

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Dennis Howard
Dennis Howard

Dennis is a retired firefighter with an extensive background in construction, home improvement, and remodeling. He worked in the trades part-time while serving as an active firefighter. On his retirement, he started a remodeling and home repair business, which he ran for several years.

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