How To Fix Common Ryobi 40v Battery Problems

In Cordless Tools by Aaron Green87 Comments

ryobi 40v battery problems
In my opinion Ryobi 40V 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.

Attempting to DIY repair batteries can be dangerous. We recommend not attempting any of these methods unless you are 100% sure of what you are doing and are wearing the appropriate PPE.

ryobi 40v battery problems

Common Ryobi 40V Battery Problems

Ryobi 40V Charger Red and Green Lights Flashing

So your Ryobi charger is showing green and red flashing lights? Well don’t panic yet because it isn’t always a sign that your battery needs replacing. There are ways to attempt to fix this problem; take a look at the possible fixes below.

But first:

Are you sick of the problems? Well, you can currently save 10-52% on Greenworks 40V cordless tools on Amazon. If you want to give something else a go, check out the savings on Amazon now.

Battery Too Hot or Cold

So while we all love the Li-Ion technology of modern day batteries, it does have some problems that older styles of battery didnt 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 sand paper.

Dirt on the terminals can be removed with 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.

Battery Entered Sleep Mode

ryobi 40v batteryThe most common cause for your Ryobi 40V Charger showing flashing red and green lights is that the battery has been over-discharged.

What this means is the battery has been discharged to such a low level that the charger has trouble detecting if the battery is healthy or not and decides to not risk charging it – showing the dreaded flashing red and green lights. This is commonly known as the battery being in “sleep mode” The problem here with Ryobi 40V chargers, is that they don’t incorporate a “boost” feature to allow a sleeping battery to be woken up again.

Now, there is a way to possibly fix this;

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. There are two ways to try and wake up a sleeping battery.

The Fix Option 1:

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 2:

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.

The Fix Option 3:

This method should only be used if you don’t have a spare battery or power supply as per option 1. Patience is required here – so read these instructions carefully and find somewhere comfortable to sit!

    1. Connect you 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.

What If None Of These Solutions Work?

Unfortunately, if none of these solutions solve your Ryobi 40V 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.

If you want to ask my advice direcly, feel free to send me an email at aaron (at) or leave a comment below and I will do what I can to help. Be sure to tell me your model numbers of your batteries/chargers etc so I can give the most relevant advice. Alternatively, use the contact form here or use one of our social media channels (links at the very top of the page) to say hi.

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 Amazon’s selection of Ryobi 40V Batteries and Chargers.

87 Comments on “How To Fix Common Ryobi 40v Battery Problems”

  1. 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?

  2. Fantastic, I plugged my battery in and unplugged it 3 times and now it is fully charged.

    How did you know this?

  3. Hi,
    Thank you very much for sharing your insight. I have a 40v Ryobi battery than when plugged into the charger the charger light stays green but the battery doesn’t charge. At this time what can I do? Please help me?

  4. Aaron, thank you, Fix Option #3 worked like charm for my Ryobi 40V. Required about 4-5 minutes of in-and-out but then the green stayed solid and battery is charging. Thanks!

  5. Hey Aaron,
    I have the ryobi mower with 2 batteries. This year I have one battery that won’t work in the mower despite showing its fully charged by the tester. The charger works fine to charge the other battery and the mower works. Any ideas?

  6. Arron my Ryobi charger shows solid red the battery has no charge and the light stays red when i try to use the weed eater it goes for a second then stops then goes the again any suggestions will be nice

    1. It sounds like the battery is not being charged – or possibly even that the charger is not detecting that a battery is plugged into it at all.
      This could be a tricky one to diagnose. First thing I would do is clean the terminals on the battery and the charger. The second thing I would do is try to ascertain whether it is the charger or the battery that is faulty. Do you have any other batteries that work in that charger?

  7. Aaron
    I have two Ryobi 40 volt Lith to run a chainsaw, 1 battery shows fully charged both on the charger and on the lights on the battery but will not even try to run the saw, the second battery shows defective on the charger ( red & green Lights flashing) with only one light on on the battery but runs the saw just fine.
    Any idea’s


  8. I bought a 40v weed eater and charged it last night to full. This morning I used it until it quit and tried it again and it quit again so I put it in the charger and got no lights. I left it in for a couple hours and still nothing. Any suggestions?

  9. I have a 40 v mower with 2 batteries about 4 yrs. old one battery works fine the other stops with 1/2 charge showing on the indicator can it be fixed or should i replace it ?

  10. Just bought tjhe ryobi 40v mower and after charging all night, I used the next mor ing and the charged last 10-15 min. I called support, they said thats not normal and to try fully charging 3-4 times and it “should” last longer. It doesnt make sense to me as to why it would make a.difference but I’ll try. Dpes this sound normal to anyone??

  11. Hey this is Sam Peters. I have a battery ryobi trimmer with attachments. I bought a new battery. However when i was outside trimming the yard, the trimmer stopped and then started again. That is even with the battery in and the triggers engaged, it was unresponsive. Then i took the battery out and put it back in and still nothing. Then after a couple of minutes it started working and I was able to get finished. Wondering what it could be?

    1. It sounds like it could be a heat issue? Maybe the battery is getting too hot, and when you leave it for a few minutes it cools down enough to work again. Does it happen only in hotter weather?

  12. I bought a Ryobi line trimmer that has a 40V lithium ion battery and charger. I have it plugged in to (re)charge, the “charging” light is pulsing. I don’t think it’s charging because the “charged” light has not come on and it’s been on for several hours.
    Do I have a faulty battery?, faulty charger? This is new equipment purchased a couple of months ago. Should I take it back to the Home Depot where I got it and get a replacement battery or charger?
    Thanks, Sarah.

  13. Hi! My battery has worked great for about 5 years—this year however, I noticed that neither the charger or battery are lighting up when I attach the battery to the charger. The battery held its full charge from the fall and I used it, but now that it died, it won’t recharge. Does that sound like the battery or the charger? I just ordered a new battery online, I’m hoping it wasn’t the charger

    1. Hi Sharon, Sorry but it does sound more like a charger issue to me. It seems like the battery has gone completely dead, and because the charger is dead (no lights) the battery won’t work anymore either. Look at the positive side though, you will now have two batteries to use!

  14. An issue with this battery…any advice?
    The battery works to start the mower but once you turn the mower off, if you go to restart the mower you have to pull the battery out and reinstall it for it to work?

  15. Arron,
    Can you tell me what signal the t1 terminal needs to tell the charger to put out the 40 volts? If I connect the ground it goes to defective even though the battery has 39 volts. I’m just trying to get the power supply in the charger to turn on.

    1. Hi Vincent, Sorry but I am not sure. I havent currently got any of the devices here to check how they work at the moment. Maybe someone else can help out if they read this.

  16. Is there a way on the charger to bypass the sleep check function?

    Or if I had another charger from a different manufacturer with the correct voltage does anyone know what the electrical connections are inside the battery that need to be connected to.
    I saw one source online that showed the hook up, but it was for a ryobi 40v but the main board inside was constructed different than the board in mine

  17. I habe a 40v ryobi battery than when plugged into the charger the charger light stays green but the battery doesn’t charge nor work in any tool. Can that be fixed

  18. I had the same issue as Larry W. Connections are clean. Continued trying the fix even though the lights were just flashing red & green continuously. Now my charger just flashes red & green even without a battery attached. Any advice?

  19. Hi Aaron, I think you are the expert I should ask my question. I got a Ryobi 36v charger BCL3620S. When the charger is empty and first plugged in, it showed flashing red light ( the manual says it should be steady red light). After I put the battery in, it was still flashing red lihgt and not charging.
    Then I tried plugged in the charger with the battery already in it. This time the flashing red light quickly turned into flashing green light for a couple of seconds than came the alternating red and green light. I had tried option 3 but the battery still couldn’t charge.
    Do you think I got a defective charger or a defective battery?

    1. Hi Josh, How old is it? If it is reasonably new, then it would be best to get both checked under warranty.
      I would think that it is most likely a charger fault….

  20. 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

      1. 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

  21. 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

  22. 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?

    1. 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?

  23. 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

  24. 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

  25. 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!

  26. 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?

    1. 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.

  27. 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.

    1. 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.

  28. 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?

  29. 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

    1. 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.

  30. 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.

    1. 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.

  31. 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?

    1. 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.

  32. 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?

    1. 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.

  33. 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

  34. 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.

  35. 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!

    1. 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

      1. 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.

        1. 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?

  36. 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.

  37. 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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