How To Fix Common Ryobi 40v Battery Problems

In my opinion, Ryobi cordless tools are some of the best available, although it does seem that the batteries can suffer from numerous problems. Replacement batteries are certainly not cheap, and most of us will want to avoid the need to buy a new battery if at all possible.

So I have some good news for you; it is possible to fix most Ryobi 40V battery problems yourself.

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

ryobi 40v battery problems

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Why Do Ryobi 40V Batteries Fail?

The most common reason a Ryobi battery fails is because it has entered sleep mode. But other common problems, such as extreme temperatures and dirty battery terminals, can also cause these batteries not to charge.

When a battery has failed, it will cause the charger to flash green and red. If your charger lights up like a Christmas tree every time you put the battery in, you know you have a problem. Below, we’ll look at all the common reasons for battery failure and how to fix them.

Ryobi Charger Red And Green Lights Flashing

Whether you have a Ryobi cordless mower, pole saw, leaf blower, or one of the many other tools available, you’re likely to deal with battery failure eventually.

If your Ryobi charger is flashing red and green when you attempt to charge the battery, then you already know what I’m talking about.

Here are the most common reasons for Ryobi battery failure and some straightforward options for fixing the issue.

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Ryobi Replacement Battery

Genuine Ryobi 40V Battery

  • 4 aH High Capacity Battery
  • Compatible with all Ryobi 40V Tools
  • Built in battery life indicator
  • Genuine Ryobi Warranty and Support

Ryobi Battery Entered Sleep Mode

battery sleep mode

The most common cause for your Ryobi Charger showing flashing red and green lights is that the battery has been over-discharged.

This is commonly known as the battery is in “sleep mode”

Batteries often enter sleep mode when they’ve been used until completely dead and then stored without charging for a long period of time. The charge on the battery becomes so low that the charger cannot detect whether the battery is healthy or not. To avoid damage to the charger from a potentially faulty battery, the charger will stop charging and enter error mode.

The problem with Ryobi 40V chargers is that they don’t incorporate a “boost” feature that would allow a battery that has entered sleep mode to be woken up again.

Luckily, there are a few ways you can boost a sleeping battery yourself. But, as with any DIY fix with cordless tool batteries, it does have some dangers involved. Battery university recommends not boosting batteries that have been in sleep mode for a week or longer.

So keep this in mind when carrying out the following recommendations.

The Fix Option 1 – Micro Charges

This method is the easiest, safest and simplest method to try to revive your Ryobi battery that won’t charge.

Patience is required here – so read these instructions carefully and find somewhere comfortable to sit!

  1. Connect your charger to the power outlet
  2. Place the battery in the charger until the green indicator goes solid
  3. Just before the red/green lights start flashing, remove the battery from the charger
  4. Re-insert the battery into the charger again and repeat steps 2-3
  5. Do this until the green light flashes constantly (might take up to 30 minutes)

Why does this work? Well, each time you insert the battery into the charger, it gives it a small amount of charge before detecting the battery as sleeping.

So repeating this process over and over results in the battery slowly being charged in very small increments each time.

Eventually, this results in enough charge for the battery charger to resume normal charging operation.

It may sound crazy, but the graph below shows why it works. Also, take a look at the many pages of comments below this article to see just how often it actually works!

ryobi battery problems

The Fix Option 2 – Use a Second Battery To Jump Start The Sleeping One

ryobi battery fix

Use a second healthy, fully charged battery of the same voltage and connect the terminals matching polarity (positive-positive, negative-negative) using wires and leave them connected for a few minutes.

Then try charging the battery again – this may be enough to kick the battery back into life. You can see a video guide on how to do this here.

The Fix Option 3 – Use a DC Power Supply

Use a DC power supply set at the same voltage as the battery and connect the positive output to the positive battery terminal and the negative output to the negative battery terminal.

Once again, leave this connected for a few minutes then try charging the battery.

Genuine Part
rgenuine ryobi battery

Replacement Charger

Ryobi 40V Battery Charger

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Battery Too Hot or Cold – Ryobi Charging Temperature

While we all love the Li-Ion technology of modern-day batteries, it does have some problems that older styles of battery didn’t have to worry about.

One of these being the narrower range of temperatures that they will operate, and charge in: Li-Ion batteries will generally charge between 32°F to 113°F (0°C to 45°C).

So, the first thing to check if you are having problems with your Ryobi batteries is if they are indeed too hot or too cold.

If it is exceptionally cold where you usually store/charge your batteries, bring them inside and let them warm up to room temperature and then try charging them again.

If it is a hot day, or you have been using your batteries already and they are quite hot, try throwing them in the fridge, or taking them to a cooler area for a short amount of time before trying to charge them again.

Corroded or Dirty Battery Terminals

If the metal contacts on the battery or charger become dirty or corroded, then it can cause the Ryobi charger to incorrectly assume that the battery is faulty.

If your terminals are corroded: then the corrosion can be removed with a piece of sandpaper.

Dirt on the terminals can be removed with a wire brush or an alcohol-soaked wipe.

Sometimes getting to the actual terminals can be difficult due to them being recessed, if this is the case you will need to try different tools or items to reach them for cleaning purposes.

What If None Of These Solutions Work?

Unfortunately, if none of these solutions solve your Ryobi battery problems then it is likely you have one of two problems: 

  • Either your battery is faulty
  • or your charger is faulty

Here is what you can do next:

The best way to test which is the faulty part is to take your battery down to your local store that sells Ryobi 40V tools and try it on one of their chargers.

If the same fault occurs then you have a faulty battery, if the problem does not happen on a different charger then it is likely a faulty battery charger.

Related Article: Ryobi 18v String Trimmer Troubleshooting

Where Can I Buy Replacement Parts?

If you need your replacement Ryobi 40V battery parts in a hurry, then you will want to head straight down to the closest supplier and buy it locally.

If you aren’t in too much of a rush and are looking to save some cash, then consider purchasing from a reputable online store such as Amazon.

Click here to see a selection of Ryobi 40V Batteries and Chargers.
Also Available at Home Depot

Are Non-Genuine Ryobi Parts Available?

Yes, they are! Some are great and work well, others are not worth the time or the money.

rgenuine ryobi battery

Ryobi Replacement Battery

Genuine Ryobi 40V Battery

  • 4 aH High Capacity Battery
  • Compatible with all Ryobi 40V Tools
  • Built in battery life indicator
  • Genuine Ryobi Warranty and Support

Ryobi Battery FAQ

Can a Ryobi cordless tool battery be repaired?

The short answer is yes, but the longer answer is that it probably isn’t worth the time or the hassle.

Opening up the batteries can be difficult and depending on what part if 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.

Photo of author
Aaron Green
Aaron is the founder of and Essential Home and Garden. He likes to spend his spare time with his family, and doing DIY projects in the home and garden.

275 thoughts on “How To Fix Common Ryobi 40v Battery Problems”

  1. 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

      • 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

    • 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?

    • 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

  2. 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

  3. 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?

  4. 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

  5. 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

  6. 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!

  7. 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.

  8. 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.

  9. 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?

  10. 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.

  11. 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.

  12. 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.

  13. 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: By all reports these batteries are just as good as genuine Ryobi’s.

  14. 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

  15. 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.

  16. 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?

  17. 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.

  18. 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!


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