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 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 Status | Green LED Status | Orange LED Status | Charger Diagnosis | Detailed Explanation | Recommended User Action |
ON | OFF | OFF | Power On / Standby | The charger is plugged into an AC outlet and is ready. No battery is inserted. | Insert a 40V battery to begin charging. |
OFF | Flashing | OFF | Charging | The charger is in the primary charging phase. This is normal operation. | Allow the battery to charge until the green light becomes solid. |
OFF | SOLID | OFF | Charging Complete | The battery is fully charged and in maintenance mode. | Remove the battery from the charger for use or storage. |
Flashing | Flashing | OFF | Defective Battery | The 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. |
OFF | OFF | Flashing/Solid | Testing – Hot Battery | The 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. |
OFF | OFF | Flashing/Solid | Testing – Cold Battery | The 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. |
OFF | OFF | Flashing/Solid | Testing – Deeply Discharged | The 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.
- Plug your charger into a power outlet.
- Insert the sleeping battery into the charger just long enough for the indicator light to appear (1-2 seconds).
- Immediately remove the battery before the red and green lights begin to flash.
- Wait a few seconds, and then repeat the process.
- 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.
- You will need a healthy, fully charged Ryobi 40V battery and some insulated wire (speaker wire with insulated alligator clips is recommended).
- Identify the positive (+) and negative (-) terminals on both batteries.
- CRITICAL STEP: Connect the positive (+) terminal of the healthy battery to the positive (+) terminal of the sleeping battery.
- CRITICAL STEP: Connect the negative (-) terminal of the healthy battery to the negative (-) terminal of the sleeping battery.
- DOUBLE-CHECK POLARITY. Reversing this connection will cause a dangerous short circuit.
- Leave the batteries connected for 10-15 minutes.
- 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:
- A DC power supply capable of outputting 40 volts DC
- Some wire – standard speaker wire or similar will do the job
- Set the power supply’s output voltage to 40V.
- 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.
- With the power supply on, connect its leads to the battery terminals, ensuring correct polarity.
- Monitor the voltage on the power supply’s display as it slowly climbs.
- 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.
- 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.
- Gently use plastic pry tools to separate the case halves, releasing the internal clips.
- Once open, you will see the battery cells and the “brain” of the battery—the Battery Management System (BMS) circuit board.
- 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 Number | Reset Pins to Short | Notes / Location Description |
OP40501, OP40401 | RST and GND | The pins are clearly labeled. RST is a single pin, and GND is a nearby ground pad. |
OP40602 | RESET and GND | The pins are located on a header on the board and are labeled. |
OP40404 | RES and GND | The reset pin is labeled RES. It should be shorted to a nearby ground (GND) pad. |
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.
Aaron you are the expert. I picked up one of these units. When I go to use it it runs around high speed for a few seconds and then completely stops. I put the battery on the charger and it lights up steady green. If I then put it back on the weed eater it will do the same thing. Just runs a few seconds and shuts off
Hi Brian,
That certainly sounds like a faulty battery. How old is it?
I’m not sure of the age. I picked it up second hand. The entire unit, battery and weed eater are both in exceptional condition. I would doubt if it was used more than once or twice. Is there a date code anywhere?
Two other things I’ve noticed. First, the battery indicator on the battery does not work. Second, if I run the weed eater at a slower speed, it will run quite awhile. By ower speed ,I mean somewhere between half power and full power
Yep, certainly sounds like a battery that needs replacing.
I had the same problem, just as you describe. Found that if I give the battery a nudge with my fist in the direction to reseat it, it runs again, for a while. I believe there’s a connection somewhere that’s lossening up with the vibration and this method serves to reconnect it?
Got to LOVE the fist motivating method! A hammer works just a good too btw 🤣
I had that problem and actually had to be fixed by a repair person and it was still under warranty and it had nothing to do with the battery it was another piece and it works like a champ
Hi Aaron, I have a Ryobi cordless drill, I don’t use it often and it won’t charge it just continues to flash red? does this mean it is stuffed? I have never dropped this drill and it is still in mint condition but I think it would be out of warranty? help
Did you try the any of the methods listed in the article? Which ones?
I tried method three, and all it did was ruin my charger. Now the charger flashes red and green as soon as it’s plugged in, without even having a battery mounted on it. Is there a fix for this?
Hi Larry,
The only thing that I can think of is that you have accidentally bumped one of the contacts out of place? Check that the contacts on your charger and battery are clean and look to be where they are meant to be.
What is the model number of your charger and battery?
I have a 40 volt Ryobi that displays a 100% charge, but only has 19 volts on the terminals. Initially, it had 40 volts across the terminals, and would not power a trimmer, so I assumed the trimmer was bad and replaced it. The new battery works fine in either tool.
Not sure why it would display 100% charge, and have 40 volts on the terminals, but still not power anything. I am equally unsure why the battery initially showed 100% with 40 volts across the terminals, but now only has 19 volts and still shows 100%.
Thinking the circuit board must be bad, but interested in your thoughts
To me it seems like the battery might be going into a protection mode for some reason? How old is the battery?
When I press the button on the battery all green lights work but go out when button released
When I place battery on charger red light flashes but no green lights work
Are you able to check a different charger?
I also experienced a battery failure, under warranty, and Ryobi shipped a replacement battery and charger. The new charger didn’t work! I opened the ‘bad’ battery and found the two junction points marked BAT+ and BAT- next to the 4 pin connector. I jumped from the good battery charging terminals, to the defective battery +- terminals (with a spark!). In 1 minute increments, followed by a charge attempt. After 4 minutes I put it in the good charger and it fully charged! So, I have two good batteries and know how to resuscitate them. Good luck!
Good evening. I haven’t used my trimmer since August. Brand new battery in July and the battery was left on the charger in the garage . Garage is not heated and I just went out and saw that the charger was red. I pressed the button on the battery to see if It was fully charged and nothing lit up. I attached It to the trimmer and It did not work obviously because It is not charged. Not sure if the cold has anything to do with it? Any thoughts?
Have you got a multimeter to test the battery voltage? I would try bringing the battery charger and battery inside, let it warm to room temperature then try charging again. But it is possible that for some reason the battery has lost all of its charge causing it to enter sleep mode.
Hi, Aaron! I recently purchased a new Ryobi OP4015 40v battery. I’m trying to charge it. 1st the charger was flashing green, & I had 2 lights flashing, then a little while later the charger turned flashing red, & battery went down to 1 cell being charged. I’ve already tried your 3rd option & worked for a while, but could I possibly have a bad charger? It’s what I’m beginning to think. Anyway, could you please give me some insight on what you think it might be? Thank you very much! Alan Brinkman.
Hi Alan,
I think the best bet is to take the charger and battery into your local tool shop and get them to give it a quick check. They should have new chargers in stock to test your battery on to work out which is at fault.
Otherwise, you might need to contact Ryobi support.
Thanks for sharing your insight.
I have a brand new battery – never been charged since original purchase at HD on a blower.
I have two batteries so have had them hooked together as described for over one hour with no results. It has been sitting in my garage for several months, so the idea of “sleeping” makes since but it does not seem to take the charge from the other battery. Have you had any luck contacting Ryobi or is there a warranty on these batteries?
Thanks.
Hi Dan, When did you purchase the battery? If it is under warranty still then there should be no problem – you can find more details here: https://www.ryobitools.com/support/warranties
Hello Aaron. I have 2 40 volt ryobi batteries with a similar problem. The first one showed as faulty on the charger. I eventually tried a different charger and it took a charge! I used it one time in my trimmer and charged it. It showed a full charge but wouldn’t work again. It’s showing 19 volts more or less with a volt meter. I have the same symptoms with a battery someone gave me. Lights showing full charge, 19 volts and not working. I left them in the charger several hours just to see if the lights were incorrect but the voltage stayed around 19. A common occurrence? Thanks
Have you tried option 3? It is highly possible that your batteries are faulty though. If you want to let me know the model number of your tools/battery I can look up a replacement for you.
So, Aaron. You said if solution #3 wouldn’t work for me, I might have a dead battery, which I assumed I did in the first place. So if that is the case, what’s my answer? Is there no other way to reserrect the battery? Should I keep trying to slide it in & out of the charger until the charger recoginizes the battery? I’m stumped here. Just trying to find a quick fix, so I don’t have to purchase a new or used battery! Thanks, again! Alan Brinkman.
It is certainly sounding like you have a dead battery Alan, which unfortunately means replacing it. Send me more details if you like: aaron (at) essentialhomeandgarden dot com and I can help you source what you need.
Hi Ken,
I have a 40 volt blower and use it to blow fluffy snow off my drive. I have 3 batteries and it takes all three to do my drive and our elderly neighbors too.
A few days ago I tried to charge one of the batteries and it would not take a charge, thinking it might be too low,due to being cold, I sat it in the house near the register and left it for an hour. When I put it back on charge, it took a charge just fine. Then today I cleared the snow again and following the cleanup, I placed that battery in the charger again, and again, it will not take a charge. The air temp is 18 degrees today, so I did not do the warm up thing again, but maybe tomorrow.
Can the cells be replaced, making it new again, if this continues to happen?
Hi Bill, if your batteries are too hot or cold then they may not take charge until the temperature normalizes. While you can replace the cells in the batteries, the amount of time it takes you, the cost of the cells and not to mention the possible safety implications make this barely worth it.
I would highly recommend looking for new batteries (non-genuine are fine.) If you are having trouble finding a replacement let me know and I can help find an exact match, but Amazon should have you covered.
I have a P104 lithium battery that shows full charge on both the charger and on the battery, but will not work when placed in any of my Ryobi tools. Any suggestions?
Has it got dirty terminals perhaps? You could try testing the output voltage with a multimeter to see if there is voltage present. But that does sound suspiciously like it could be faulty circuitry on the batter control board.
Otherwise there are some third party batteries on Amazon that are a direct replacement for the P104’s here: http://amzn.to/2lzxc2f By all reports these batteries are just as good as genuine Ryobi’s.
I am trying to determine if I have a bad batteries or a bad charger. When I plug the charger into the wall, the red light comes on. When I plug a battery into the charger, the charger flashes green 6 times, then red, green, red, then the light goes out. The light will not come back on unless I unplug the charger for several minutes then plug it back in.
Has anyone experienced this? If the battery is bad, it is supposed to continue flashing red/green (not turn off completely from my understanding
Hi Chris, have you tried checking the voltage of the battery with a multimeter?
since there are no flashing lights, I didn’t think any of the solutions you offered would apply. after trying #3 I still have a battery the charger indicates is ready for use, only to get a second of power from the tool you sent. if this is the quality of your items, I would like to return the tool and get a refund.
Hi Ken, I am not Ryobi – for their support I suggest you try this page: https://www.ryobitools.com/support/warranties
the charger light changes from red to green within seconds and battery remains uncharged
Hi Ken, what have you tried?
Hi, Aaron! I have a bit of a problem. I tried the solution #3, out & in for 30 minutes, but the red & green lights keep flashing. Do I need to do this for a longer period of time? Or what is the actual “key” do doing step 3? I really need to get this battery going, again! Is it possible the battery is frozen inside, & won’t budge? Please try to let me know if you can! Thank you!
Hi Alan, Sorry it took me so long to reply. Unfortunately, if fix 3 isn’t working for you then you may just have a dead battery. Is there any reason that you can’t replace the battery? Feel free to email me for a quicker response on admin (@) essentialhomeandgarden DOT com
Hi, Aaron! Yes it is possible to replace the battery, I’m trying not to because of the expense. So let me ask you, if my battery is dead, is there no other way to bring it back to life, short of re-building the parts, which I have no knowledge of? Or does it have to be discarded at this point? I use it for my snow blower, which only gets used a few times a year.
Hey Alan, unfortunately if you don’t feel like replacing the individual cells and/or the circuit board in the battery then there is no magical way to revive them – apart from those I mentioned in the article.
Amazon has the new ones, Otherwise if you are looking to save some money then maybe look for second hand units?
I had discovered method 3 myself. I have, however, a different problem. My charger APPEARS to be charging – green lights flashing on both charger and battery – however, the battery is not charging above the current level. I have two chargers and three batteries (multiple Ryobi 40 v. tools.) Two of the batteries have solid green on the first of four lights and flash on the second. The third, flashes on the very first light. Both chargers have the same “manifestations.” This all started after using my leaf blower with all three batteries, and trying to recharge. No previous problems.
Hi Sherm thanks for the comment. So none of your 3 batteries are working?
Dear Lord, thank you thank you thank you thank you thank you for these tips! The one that requires patience, the last one that you suggest, it works like a charm. And thank God! YOUR WEBSITE JUST SAVED MY BUTT!!! Thank you thank you thank you! Hahaha! I’m thrilled to say the Ryobi is charging now, and truly thanks to you! Praise the Lord!
Ashley, your comment has made my day! Thanks for letting me know that our fixes worked for you! Maybe head across to our facebook page and like us there!
Option 3 worked great thanks
Awesome, thanks for letting me know!