How To Fix a Ryobi 40V Battery Not Charging: The Definitive Guide

Ryobi 40v battery not charging

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Is your Ryobi 40V battery not charging? We have some good news for you: it is possible to fix many common Ryobi 40V battery problems yourself.

The Ryobi 40V ecosystem offers a fantastic combination of power and convenience for a huge range of yard tools, from mowers to leaf blowers. However, this convenience comes with a significant investment, as replacement batteries are certainly not cheap.

When a battery fails to charge, often signaled by the frustrating flashing red and green lights, the thought of buying an expensive replacement can be daunting. The good news is that many of these issues are diagnosable and repairable.

This guide moves beyond simple fixes to address the full spectrum of failures, from basic user errors to complex internal faults.

Let’s take a look at the most common Ryobi 40V battery problems and how to fix them.

Ryobi 40V Battery Diagnosis Wizard

Use our specially built wizard below to quickly diagnose your 40v battery problem. Continue reading the article for more in depth information.

Ryobi 40V Battery Diagnostic Wizard

Ryobi 40V Battery Wizard

Let’s find out why your battery isn’t charging. We’ll start with some essential pre-checks.

Essential Safety Warning

Li-ion batteries store massive energy and can trigger thermal runaway—a deadly chain reaction causing fires, toxic gases, and explosions.

Never attempt repairs if you see swelling, hear hissing, smell chemicals, feel excessive heat, or see smoke.

Critical triggers: Physical damage, short circuits, overcharging, extreme heat.

Required safety gear:

  • Safety goggles
  • chemical-resistant gloves
  • well-ventilated workspace
  • Class ABC/D fire extinguisher
  • dry sand nearby.

Never use water on Li-ion fires.

If you can’t meet these conditions, buy a new battery instead.

Foundational Diagnostics: Is It the Battery, the Charger, or Something Else?

Before assuming a complicated internal fault, a careful check over can often identify a simpler issue. Many charging problems are caused by the charger, dirty contacts, or temperature…

Not the battery itself.

1. Systematic Charger and Terminal Inspection

The physical connection between the battery and charger is a common failure point.

  • Inspect the Contacts: Examine the metal contact blades on both the battery and the charger. They should be clean, straight, and free of damage or corrosion.
  • Cleaning Procedure: If the terminals are dirty, use a cotton swab lightly dampened with high-purity (>90%) isopropyl alcohol to wipe them clean. For light corrosion, you can gently use a small piece of fine-grit sandpaper (600 grit or higher) or a fiberglass scratch pen on the contacts, followed by another wipe with alcohol to remove any debris.

2. Is Your Battery Too Hot of Too Cold?

Li-ion batteries are very sensitive to temperature. The internal Battery Management System (BMS) will prevent charging if the battery is outside its safe operational window, which is generally between 32°F and 113°F (0°C to 45°C).

  • Too Cold: Attempting to charge a battery below freezing can cause an irreversible process called “lithium plating,” which permanently reduces capacity and increases risk. If your battery has been in a cold garage, bring it inside and let it acclimate to room temperature for at least one to two hours before charging.
  • Too Hot: Charging a battery immediately after heavy use (e.g., mowing the lawn on a summer day) accelerates chemical degradation and shortens its lifespan. Let a hot battery rest in a cool, shaded area for 30 to 60 minutes before placing it on the charger. Do not place a hot battery in a refrigerator or freezer, as this can cause condensation and internal moisture problems.

3. Faulty Ryobi Battery Charger

Testing if the charger itself is faulty can be tricky. Ryobi 40v chargers have sensors that prevent them from outputting voltage unless a battery is detected, so you can’t simply test the output with a multimeter.

First, try a simple power cycle. Unplug the charger from the wall, wait a full minute, and plug it back in. This can sometimes resolve temporary electronic glitches.

If that doesn’t work, the best way to test the charger is with a second battery or a second charger.

  • Use Another Battery: Try charging a known-healthy 40V Ryobi battery. If it fails to charge and gives the same error, your charger is likely the problem. If the second battery charges correctly, your charger is fine, and the original battery is the issue.
  • Try Another Charger: Plug your battery into a known-working Ryobi charger. If it still fails to charge, your battery is confirmed to be faulty. If it charges up properly, your original charger is the problem.
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Understanding the Ryobi Charger Light Codes

The LED lights on your charger are your primary diagnostic tool.

The “Testing” mode is especially important, it is not an error. It means the charger is actively conditioning a battery that is too hot, too cold, or too deeply discharged.

Be patient and allow the charger time to complete this process.

Red LED StatusGreen LED StatusOrange LED StatusCharger DiagnosisDetailed ExplanationRecommended User Action
ONOFFOFFPower On / StandbyThe charger is plugged into an AC outlet and is ready. No battery is inserted.Insert a 40V battery to begin charging.
OFFFlashingOFFChargingThe charger is in the primary charging phase. This is normal operation.Allow the battery to charge until the green light becomes solid.
OFFSOLIDOFFCharging CompleteThe battery is fully charged and in maintenance mode.Remove the battery from the charger for use or storage.
FlashingFlashingOFFDefective BatteryThe charger has detected a critical fault like a short circuit or severe cell imbalance.Attempt deep discharge recovery methods below. If unsuccessful, the battery may be permanently failed.
OFFOFFFlashing/SolidTesting – Hot BatteryThe battery’s temperature is above the safe charging limit (approx. 113°F).Remove the battery. Let it rest in a cool, shaded area for 30-60 minutes before retrying.
OFFOFFFlashing/SolidTesting – Cold BatteryThe battery’s temperature is below the safe charging limit (approx. 32°F).Remove the battery. Bring it indoors to warm to room temperature for 1-2 hours before retrying.
OFFOFFFlashing/SolidTesting – Deeply DischargedThe battery’s voltage is too low for normal charging. The charger is trying to revive it.Leave the battery on the charger. If it doesn’t switch to “Charging” (flashing green) after 30-60 minutes, proceed to manual recovery.

Ryobi a “Sleeping” Battery: Deep Discharge Recovery

The most common reason for the flashing red and green lights is a battery in “sleep mode.” This happens when a battery is over-discharged, and its voltage drops so low that the charger’s safety circuits refuse to recognize it. Our goal is to manually raise the battery’s voltage just enough for the charger to accept it again.

Method 1: The Patience Method (Micro-Charging)

This is the safest and simplest method, but it requires patience.

  1. Plug your charger into a power outlet.
  2. Insert the sleeping battery into the charger just long enough for the indicator light to appear (1-2 seconds).
  3. Immediately remove the battery before the red and green lights begin to flash.
  4. Wait a few seconds, and then repeat the process.
  5. Continue this cycle for up to 30 minutes. Each time, the charger delivers a tiny pre-charge current, slowly “walking” the battery’s voltage up until the charger recognizes it and begins a normal charge cycle.

Also Read: Ryobi Pressure Washer Troubleshooting

Method 2: The Peer Jump-Start

This method uses a healthy, charged Ryobi 40V battery to jump-start the sleeping one. It is faster but carries more risk if done incorrectly.

  1. You will need a healthy, fully charged Ryobi 40V battery and some insulated wire (speaker wire with insulated alligator clips is recommended).
  2. Identify the positive (+) and negative (-) terminals on both batteries.
  3. CRITICAL STEP: Connect the positive (+) terminal of the healthy battery to the positive (+) terminal of the sleeping battery.
  4. CRITICAL STEP: Connect the negative (-) terminal of the healthy battery to the negative (-) terminal of the sleeping battery.
  5. DOUBLE-CHECK POLARITY. Reversing this connection will cause a dangerous short circuit.
  6. Leave the batteries connected for 10-15 minutes.
  7. Disconnect the wires and immediately place the revived battery on its charger.

Warning: Experts advise against boosting Li-ion batteries that have been deeply discharged for a long time (a week or more). Microscopic structures called dendrites can form inside, creating a latent short-circuit risk when current is reintroduced.

Use a DC Power Supply To Jump Start Your 40V Battery

This is the most precise and safest manual method, but it requires a lab-style variable DC power supply.

You will need:

  1. Set the power supply’s output voltage to 40V.
  2. CRITICAL SAFETY STEP: Set the power supply’s current limit to a very low value, like 200mA to 500mA (0.2A to 0.5A). This prevents a dangerous rush of current into the battery.
  3. With the power supply on, connect its leads to the battery terminals, ensuring correct polarity.
  4. Monitor the voltage on the power supply’s display as it slowly climbs.
  5. Once the battery voltage reaches about 34V to 36V, disconnect the power supply and place the battery on its standard Ryobi charger.

This method is essentially the same as using a second battery, but instead we use a DC power supply set at the same output voltage (40v)

Advanced Internal Repair (When External Fixes Fail)

If the above methods fail, the problem is likely internal. This process carries significantly higher risks, and the safety protocols outlined at the beginning of this article must be followed strictly.

Disassembly and BMS Reset

You will need a Torx Security screwdriver (size TR10 or T10H) and plastic pry tools.

  1. Remove the four (or more) Torx screws holding the case together. You may need to cut the Ryobi sticker along the seam of the case.
  2. Gently use plastic pry tools to separate the case halves, releasing the internal clips.
  3. Once open, you will see the battery cells and the “brain” of the battery—the Battery Management System (BMS) circuit board.
  4. Sometimes, the BMS can be reset by momentarily shorting two specific pins on the circuit board with a small piece of insulated wire. This can clear a “soft fault.” The correct pins vary by model.
Battery Model NumberReset Pins to ShortNotes / Location Description
OP40501, OP40401RST and GNDThe pins are clearly labeled. RST is a single pin, and GND is a nearby ground pad.
OP40602RESET and GNDThe pins are located on a header on the board and are labeled.
OP40404RES and GNDThe reset pin is labeled RES. It should be shorted to a nearby ground (GND) pad.

Model OP40501 and OP40401

Pin location:

Connect wire between: RST and GND


Model OP40602

Pin location:

Connect wire between: RESET and GND


Model OP40404

Pin location:

Connect wire between RES and GND

A Critical Warning: The “Un-resettable” Modern Battery

A major change in newer Ryobi batteries (roughly post-2021 models) has rendered the simple reset procedure obsolete.

When these more sophisticated BMS units detect a severe fault, they can log a permanent fault. To prevent unsafe repairs, the BMS locks itself down and may be programmed to deliberately drain the entire pack to zero volts, making revival impossible.

If you have a newer battery and the reset procedure fails, it has likely entered this permanent, unfixable state by design. Further attempts are unfortunately not possible.

Is The Battery Too Old?

Unfortunately, it could simply be that your Ryobi tool’s 40-volt lithium-ion battery is simply getting old. 

Typically, a Ryobi battery or any 40-volt lithium-ion battery maintains its performance for two to three years, or approximately 300 to 500 charge cycles. 

One charge cycle describes the timeline between completely charging the battery, utilizing it until it’s fully discharged, and then charging it up once more.

Once your Ryobi 40-volt battery reaches its third or fourth year, you may begin noticing performance issues. 

This could mean the battery’s inability to retain enough charge or, in more serious cases, it might fail to recharge entirely. Should you encounter this situation, replacing the old battery pack with a new one is recommended.

You can purchase a new battery here.

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Proactive Care: How to Maximize Ryobi Battery Lifespan

The best way to fix a battery problem is to prevent it from happening in the first place.

  • Implement a Cool-Down Period: One of the most damaging practices is to take a hot battery from a tool and place it directly on the charger. Always let it cool in the shade for at least 30-60 minutes first.
  • Avoid Deep Discharges: Constantly running your battery until the tool dies puts maximum strain on the cell chemistry. It’s far better to swap to a fresh battery when you notice a drop in power or the gauge hits one bar.
  • Smart Storage is Key (The 40% Rule): For any storage period longer than a few weeks (like over winter), store the battery at a 30% to 50% charge level. This usually corresponds to two lit bars on the fuel gauge. Storing a battery at 100% (especially in the heat) causes rapid capacity loss, while storing it at 0% risks it entering the problematic “sleep mode.”
  • Climate Control: Store batteries in a cool, dry place, ideally between 50°F and 77°F (10°C and 25°C). Avoid unheated garages in winter and hot sheds in summer.
  • Remove When Fully Charged: While chargers have protections, it’s best practice to remove the battery once it’s full to avoid minor heat buildup and stress on the cells.

Buying a Replacement 40V Battery

When a battery is truly beyond repair, you’ll need a new one.

  • The Aftermarket Gamble: The low prices of third-party batteries on sites like Amazon can be tempting, but it’s a market filled with risk. Many use low-grade cells that can’t handle the power demands of a tool, have fake capacity ratings, and may lack critical safety features, creating a serious fire risk. It is strongly recommended to buy genuine OEM Ryobi batteries or those from highly reputable aftermarket brands.
  • Market Comparison:
    • Ryobi: Offers the best versatility with over 85 tools in the 40V line, making it ideal for homeowners who want one battery system for everything.
    • DeWalt: A professional-grade brand built for job site durability. Their FlexVolt batteries are backward-compatible with their 20V MAX tools, offering great value for existing DeWalt users.
    • EGO: A specialist in high-performance outdoor power equipment. Often the leader in power and runtime for lawn tools, but their system isn’t as broad as Ryobi’s.

You can purchase genuine Ryobi batteries and chargers from online retailers like Amazon or locally at Ryobi dealers.

Frequently Asked Questions

Can a Ryobi cordless tool battery be repaired?

Yes, you can repair a Ryobi cordless battery. But, it might take too much time and effort.

Opening up the batteries can be difficult; depending on what part is faulty, it may be quite expensive to fix.

Remember that batteries can be dangerous, so it’s best to get a qualified technician to check the battery for you.

Is it OK to leave a Ryobi Lithium-Ion Battery On The Charger?

No, you should charge the battery after use until it is full, then remove it from the charger and store it in an area that doesn’t get too hot or cold.

The ideal battery storage temperature is around 59℉, but standard room temperature is usually fine.

Do you have any questions relating to this article? Email us at [email protected] or call us on +1 (310) 961-4908

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Author
Aaron is the founder of and Essential Home and Garden. With over 15 years of hands-on experience in home ownership, lawn care, and gardening, Aaron is a seasoned expert in areas like lawn care, DIY, HVAC, and pest control.

284 thoughts on “How To Fix a Ryobi 40V Battery Not Charging: The Definitive Guide”

  1. Avatar photo

    Hi there!

    When I plug in my Ryobi 40V Lithium Ion battery charger without the battery attached it has a solid red light. I attach battery and it blinks red three times, then blinks green three times, then solid red, then no lights whatsoever. The indicator lights on the battery show depleted charge, but it isn’t completely dead – I used the weed eater briefly, but it had slowed power.

    • Aaron Green

      Hi Bridgitt, that could be a faulty charger or battery. Sorry I can’t be more specific but it’s hard to tell without testing a few things. I would guess its likely the battery though.

  2. Avatar photo

    I have two 40v battery/chargers(1 less than 1 year old) both stopped working.

  3. Avatar photo

    Hi DG,
    Yes I did get the situation resolved. I called Ryobi and they sent me a new battery.

  4. Avatar photo

    Ryobi 40V battery (96 Wh), 3 years old, will charge. All four lights illuminate after charging. Put battery in mower and will operate for 10-15 minutes. Check battery fuel gauge, 3 lights illuminate. Will not operate mower. What gives with the lights being illuminated but short run time? Has the battery lost capacity? what is a good indicator to recycle this current battery and purchase a replacement?

    • Aaron Green

      That is usually a sign that the battery has had it. I would think that a new battery would solve your problems.

  5. Avatar photo

    my battery is a 2016 battery and it will not charge. its not the charger because i have another battery and it charges fine.

    • Aaron Green

      Sounds like you have a faulty battery!

  6. Avatar photo

    My batteries stop functioning after they are only about 60-70$ discharged in my mower, weeder, and edger. Can they be bled down to zero? Seems like a memory issue. When I set them in the charger, they blink with at least 1 light on, sometimes 2……

    • Aaron Green

      How old are the batteries? If they are over 3 years old then it is likely just that they are getting old.

  7. Avatar photo

    I don’t get any lights on battery or charger when I plug them in. Is it the charger? The battery still works for a few seconds. The weed eater and blower are only 18 months old and not used much.

    • Aaron Green

      That sounds like a charger problem to me.

  8. Avatar photo

    My 40volt battery won’t charge. The green light on the charger and battery flash for hours without charging the battery.

    • Aaron Green

      Checked if the contacts are dirty?

  9. Avatar photo

    My Ryobi battery is ok. Because I had a replacement and tried with that also. The problem is that It cuts off when I first start the thing. It doesn’t stay running. Like I said its not the batteries. This machine is only 1 year old.

    • Aaron Green

      Well that indicated it could be the charger? But if it is only a year old I would go for a warranty repair/replacement.

  10. Avatar photo

    The battery lights on the battery do not show up at all and when I put it on the charger it goes to green as if the battery is fully charged. When I put the battery in the trimmer is does not work. Any suggestions?

    • Aaron Green

      Hi Victor, it’s hard to say but it could be a charger issue? Or even a faulty battery.

    • Avatar photo

      I have the same problem Victor. Did you ever get it fixed?

  11. Avatar photo

    I put a multi meter on the + and – terminals on my 40v charger and it is only putting out 26ish volts. Bad charger?

    • Aaron Green

      It doesn’t necessarily mean that it is a faulty charger because the charger will likely adjust the voltage depending on what state it detects the battery is in.

  12. Avatar photo

    Just bought a Ryobi 40v cordless hedger. I cannot remove the battery from the hedger to charge. Help

    • Aaron Green

      Hi Christine, the manual should tell you how to get it out. If it is a strength issue, then you might need to ask a friend or a neighbor for help? But if you find this is an ongoing issue I would recommend returning it to the store and choosing one that has an easier release mechanism.

  13. Avatar photo

    I currently have a Ryobi Trimmer Model P117 18 volt which is approximately 6 years old. I have arthritis in my hands and it is very difficult if not impossible to remove the battery from trimmer. Is the Ryobi One + String trimmer 18 volt 13″ String Trimmer / Edger have the same battery or has design changed so it is easier to remove from trimmer?

    • Aaron Green

      Hi Marlene, I have never considered that before – but I am sure it is a problem that many people face when using these tools!
      Because the severity of arthritis can differ so much from person to person, I would recommend going to your local hardware store and having a look at what they have there. Tell them your problem, and ask them if you can see and try the battery removal process for each model. That way you can be sure to get one that you can actually use!

  14. Avatar photo

    Hi Aaron, my 40V battery was working fine and then i dropped it about two feet on the pavement. when i went to charge it, my charger light is green but the cells on the battery do not light up. Can dropping the battery cause it to be inoperable?

    • Aaron Green

      It certainly can! Batteries are quite heavy for their size and they also contain breakable parts (circuit boards, electronic connections, plastic etc). You could try opening the battery houding (just the plastic bit) up to see if you can see anything – but do be very careful as it can be dangerous.

  15. Avatar photo

    Aaron any idea on a Ryobi 40v hedge trimmer when the battery shows fully charged but the trimmer does nothing at all?
    All 4 green lights on the battery and solid green light on charger. I put in on the trimmer and nothing happens at all.

    Thanks

    • Aaron Green

      Have you checked the battery terminals? Is there any sign of life from the trimmer at all? Do you have a multimeter to test the battery voltage?

  16. Avatar photo

    I have an Ryobi 40 volt string trimmer that is 5 years .code CS1305.
    It charges according to the the charger lights.
    I get to 4 green lights and if I use it it will just stop and when I put it back on the charger it show 3 green lights and charges up to the 4 green light and works for awhile.
    What do you think I should do?

    • Aaron Green

      Sounds like a battery that has just gotten old and tired. These are common symptoms. I can;t find any info with the code you included – can you provide a model of the battery itself?

      • Avatar photo

        My Battery is LI-ION 40V 93.6WH OP4026 CS13055D390457

          • Avatar photo

            Thankx for the help. I decided to purchase a reconditioned Ryobi Weed Blower from Home Depot that came with the same type of battery and charger for $89.00.
            I hope I can use this battery for both units.
            Thankx again you are doing a great job
            .

          • Aaron Green

            No problem! Glad we could be of help 🙂 Be sure to sign up to our newsletter here!

  17. Avatar photo

    My Ryobi 40v charger is flashing red and green with no battery in it. Is this a bad charger and is there a fix?

    • Aaron Green

      Sounds like a faulty charger to me. Sorry – no way to fix it that I know of.

  18. Avatar photo

    40v ryobi trimmer: Depressing trigger does not cause trimmer head to turn and no sound. battery charger green light stays on with battery in dock. battery reads 18v dc across terminals. bought new rebuilt charger. same experience. why would battery charger light stay green if battery is defective (only charges to 18 v)?

    • Aaron Green

      Hi Stephen,

      Im not sure why, but it would seem that the battery is faulty. Since a different charger produces the same results.

  19. Avatar photo

    My OP400 charger repeatedly stops charging after about 15 minutes and all lights go dark. Removing and then replacing the battery does not cause the charger to wake up.
    However unplugging the charger from the 110v for about 30 seconds and then plugging the charger back in, does reset it and it will continue charging for about another 15 minutes. then it shuts down again.
    What can be done to fix this??

    • Aaron Green

      Sounds like either the battery or the charger has a fault. How old is it?

  20. Avatar photo

    my Ryobi trimmer stopped working after the string coiled up twice, jamming in between. recharged the battery and tried again with no results. still not working, any suggestions?

    • Aaron Green

      That could be a number of things – maybe there is still some string jammed in it? It is possible (but not likely) that the motor could have burned out.

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