Ryobi 40V battery won't charge. 

Glad to hear it helped. I also have another video that answers some questions about these batteries. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-WKY1-JNijqo.html Thanks for watching, and please share.

You are welcome

You are welcome. Thanks for watching.

I have a video that I have to upload about powering my ebike with 2 ryobi batteries.

I am glad you enjoyed it and Thanks for watching.

:)

I was super nervous when he was fumbling around with the board exposed lol. Those capacitors don't play!

Thank you very much!

Thank you. :)

Somehow, I missed this comment until now. I am glad you were successful, and thanks for watching.

Glad you enjoyed it.

I have a couple more you may like coming soon.

Well thank you for the compliment, and please share.

You are welcome. Thanks for watching. :)

I use an old laptop power supply to convert 120V ac to 18V dc. Then I add the dc-dc boost converter to get 18V up to 40V. Hope that helps.

Thanks for the super thanks!

I have a couple newer batteries, but they both work fine so far. I was thinking of doing another video just talking about these new batteries and how to check them and possible alternative charging.

You may be able to charge up individual cells on the Mikita to get a little more life from them. Unfortunately I don't have any to play with to know for sure.

It depends on which charger you have. I think the older ones will, but the newer ones may not. Thanks for watching.

Yes, the mod does bypass the BMS charge circuit and you become the BMS for the battery. Only charge the battery while you are there to monitor it. I hope that clears things up for you. Thanks for watching.

I have several of these batteries and worked on figuring out some stuff, but I did find a schematic online that someone made that helped.

Thanks for watching, and feel free to share the video on other sites.

I power mine with a 12 power supply from a computer so yes it is a boost converter. I checked my purchase and its not available any more, but I will see about finding a similar link for you. www.droking.com/150W-Power-Supply-Module-DC-10-32V-to-10-46V-16A-Adjustable-Boost-Converter-DC-12V-24V-Voltage-Regulator-Adapter-Charger-Driver

@@thecityviking It appears that link is in stock. Though the Amazon affiliate links were out of stock. So I'll try ordering directly from droking.com.

The gate resistance is not critical for slow switching. Many gate resistors are around 1k and higher resistance will still work but may slow down the switching on of the FET. Since this is just on or off not rapidly switching back and forth I picked a larger value. The formula is something like this. IGPEAK=(VG(on) - VG(off))/(RG+RG(int)). Keep in mind though, that if you go too small, you could kill the FET, or the drive circuit. Often, most BMS circuits I have seen have many FETs, but it is to increase the current they can switch. If you need to switch 100A, you would have to use many FETs to accomplish this. I have never seen a BMS that has seperate charge and discharge FETs like these Ryobi boards. The earlier Ryobi 40V batteries only had one FET, and maybe they found an issue that they felt warranted this. Most BMS circuits have FETs in parallel to increase their current switching, while these Ryobi BMS circuits have them in series. I think they may have done this as an extra safety. FETs can fail as a short or as an open, so to have a runaway short circuit you would have to have 2 FETs fail the same way.

higher capacity is good, but make sure the cells are also high output. I believe the cells in the Ryobi are capable of outputting 15A each. I use this site to find the specifications of my used cells. secondlifestorage.com/index.php?pages/cell-database/ good luck with your project.

Resistor is not critical. You could be thousands of ohms off. The FET usually is not broken, the circuit just won't turn it on..this mod forces it on.

I can not give a definitive answer to that. The Ryobi charger communicates with the battery, and that is what determines weather or not the Ryobi charger will work or not. I have had some luck with the older battery packs working with the Ryobi charger, but no luck with the newer battery packs. Thanks for watching.

Have you watched my other video Ryobi 40v battery questions answered? What is the voltage across the individual cells?

The problem seems to be with the circuit that turns on and off that FET. The mod I show just allows the FET's to be controlled together by the other part of the circuit. Instead of the two FET's being controlled separately, they both work together. You are bypassing some of the protection of the BMS, so do not charge it unattended.

@@thecityviking tyvm

@@thecityviking Agree but as you stressed, 1A charge should have no problem. I found a nice booster on eBay as now Jan 2021 Amazon still nil stock. Good video. Thanks.

Thanks for watching!

Good question. The resistor I used is 1/4 watt. There is virtually no current through this resistor as it just passes the 10 volts from the one spot to the other to turn on the FET. Make sure you do have 10V at the other side. Good luck.

@@thecityviking Thanks so much for the nearly instant reply! YOU rock!

You are welcome

The charger and the battery communicate on the T1 pin. If the battery tells the charger the battery is no good, there is not much you can do to get the Ryobi charger to charge that battery. I have been trying to get an older Ryobi charger to see if I can "hack" it.

@@thecityviking Thank you! I have got it...

Thanks for the sub!

amazon.com link for power supply I use: amzn.to/3hXIysX The link was in the description. It works with an input between 10-32V and has adjustments for voltage and current on the output. Output has to be higher than the input. I use a 12V power supply from and old Computer but you could use a laptop power supply as well for the input. I Don't set the current higher than one amp for safety. Looks like they are currently out of stock but should get more. It's usually under $20. Good luck!

The board measures the voltage of all the banks of cells, so you should have access on the board. You may have one of the newer boards that is very different, but all cells should be accessible from there.

This mod may not fix your battery but it could. I'm working on another video to show some of the problems with this battery

@@thecityviking link to the next video?

I am not sure what you are talking about. Can you explain?

I noticed the same problem when trying to power my bike in my other video. I just run on one until dead and then switch. I know this is not a solution, but there is no real easy way to get around this, at least not safely.

From Amazon Yeeco Boost Converter Module DC-DC Step Up Converter Board 8-32V to 9-46V 8A 150W Voltage Regulator Booster Module Adjustable Voltage Step Up Power Supply Module I use a laptop power supply to provide input power.

@@thecityviking Thank you. Any thoughts on the 2nd half of my comment? Also, any idea if we can use the "rst" location on the board to reset the chip? The available pins are: CLK, DAT, GND, 3.3v, RST. I wonder if we would briefly shunt the 3.3v to RST? Now that I have every cell at full charge I am wondering if it is possible to manually reset the chip using these locations on the board?

Sorry I didn't see the second part. I believe I know exactly what you're talking about. The voltage is not being restricted the pack shuts off the FET when the pack is not being used if you hook a small load up to the main terminals and then measure it you should get the proper voltage but it only lasts for about one minute and then shuts off. I will make another video explaining this for others.

I have a couple batteries that show a charge like that but when I open and measure individual cell packs usually there is at least on set of cells that are dead(below 2.5 volts). I have tried charging the cells individually but they discharge quickly. I will harvest the rest of the cells for building a a new battery.

It is possible that tour FET is faulty but in my experience it is unlikely. Basically what happens is the intelligence on board determines that the pack is defective and it doesn't allow charging. I will be making another video shortly that will describe how the pack works and why it fails and how to properly check each cell set.

@@thecityviking Thanks for the info. I will do your mod and see how it goes. I'll let you know. Cheers Marty.

I have had a couple of those single mosfet boards. While you could completely bypass the mosfet, I would not recommend it. If you get all the cells to approximately 3.5V and are fairly balanced, you may be able to charge it, but I have no other advice at this time. Thanks for watching, and check out my other video if you haven't seen it yet. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-WKY1-JNijqo.html

@@thecityviking thanks for replying. When I tested the voltage across the battery (not from the contacts) it gives me a 39.25 V but the contacts only give me 18.94 V. Is it safe to bypass the mosfet? Or have it replaced?

You would need to purchase a 40 volt high current power supply.

I have 20 and plan on making a battery pack. I have some ideas but not sure what final voltage I want. If I make it for my trailer it will either be a 24v or 12v. I may make one for my new bike motor. A 1000W mid drive that runs on 54v

When I have a battery that won't take a charge, I always leave the screws loose that hold the cover on. That way I can easily open it for charging and also monitor individual cells to ensure even charging. The BMS in these batteries seem to lock out charging from the factory charger once they have detected a problem with the cells. The mod I show in this video with the resistor only works on older firmware.

If I get some ill take a look to see what I can do

That would help for overheating, but the bms also makes sure the individual cells don't discharge too low or charge too high. Thanks for watching.

I agree that will work. The reason I decided to cut the trace and tie it to the gate of the other FET is to possibly get some protection. If the pack starts to overheat or overcharge I was hoping the intelligence in the pack may try and shut down the other FET to protect itself. By modding either way you are defeating a safety mechanism that is why I never charge my modded packs unattended.

@@thecityviking That's a safety minded approach and is probably the better idea, but it is based on hope and not fact, but it is the better idea. And any item that is modded without having an accurate understanding of how the mod _WILL_ effect the circuit should always be personally monitored.

Check out my new video that shows other options for the single FET.

Blinking lights o. Your battery probably means you have an unbalanced pack. You need to check all the individual cell pairs and see if they are all at the same voltage. I would try and charge them equally and see if it charges on your charger first.

The second link is valid. I don't think it has an led on it though.

To tring to use the reset terminals (I think that is what it is called). And he thinks its something to do with the "Mof" thingy (atleast what he thinks its called. Idk didnt watch the full video). Any suggestions or?

Check the voltages of each cell. They need to be above 3V each, and all cells should be about 0.100 or less of each other.

Reset works if no lights will illuminate on battery…older packs do not have a reset button.

There is also a transistor that fails that causes the battery to not charge. I can't remember where I saw that though. Check out my other video about these batteries ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-WKY1-JNijqo.html

I like the switch idea! I cut the trace so that high signal from the resistor mod doesn't feed back into the low signal coming from the rest of the circuit. It could cause more damage to the circuit.

if its brand new i would take it back. Does the battery have any charge? maybe check out my other video where I give more details

I agree. Never disassemble electronics without understanding the risks.

Basically you are cutting the trace for the gate of the FET and then tying it high to keep it turned on. Remember though that you are bypassing the BMS, and now you have to monitor cells to ensure safe charge/discharge. Thanks for watching.

you could try bypassing the other FET to see if your tool starts to work.

I have bought completely dead ryobi batteries and was able to bring them up to full voltage with no problem. I show how in one of my videos. Good luck with your batteries.

I had a pack like that and it turned out to be a couple bad cells. It was on a pack that had a single FET and when fully charged would run lawn mower for about 2 mins then it would cycle off and on. I bypassed the FET and found that the pack would get hot in one set of cells. That set of cells would be much lower then the rest of the pack. You can not recover the pack but I did salvage individual cells to power other things.

Thank you for the response. That was my initial thought too. And yes, it’s the one with single FET. I guess it’s time for salvage. Btw, I found out that it’s not a AA size. What projects are these cells useful for if you don’t mind me asking? Thank you

@@bbg5939 These cells are lithium Ion and are 3.7V nominal, that do charge to 4.1-4.2v with a proper charger and you can use them in laser pointers, vapes and special torches, most people use them for those things but they can also be used as E-bike or E-skateboard packs, there are other uses like batteries for your solar power storage, but you need a bit more expertise to do that and a ton more batteries. BTW if you let them discharge too low it reduces the cell life, with these cells you're best not to let them get below 2.5V each but charge them when they are somewhere between 2.5 and 3.5V up to say tops 4V (as overcharging at 4.2V+ also reduces their life!) Overcharging and over-discharging Lithium cells is dangerous and can make them explode and set fire to stuff like houses and garages so beware, this is why they have a battery management system to limit the discharge.

Just make sure you are charging all the cells evenly as you do this. You don't want any cells over 4.2V!

I am looking at making another video about a Rev Q board that is in the newer Ryobi batteries. Perhaps that is what you have in your batteries. Coming soon

@@thecityviking I also have a Rev Q battery and it is definitely a little different.

I would charge up the battery and then try the reset method. Make sure you charge up the cells evenly though. I hope that works for you.

Wow 4 days!

amzn.to/3fL2ct0 Link for resistors that should work.

Sounds like one of 2 possible problems. 1. The FET is damaged and not working and turning on. 2. The signal that is supposed to turn on the FET is damaged or not coming on for some reason. If it doesn't work in a tool, you could try jumpering the FET to bypass it.

You need to check voltage of the pack and the individual cells. It could be that one of the banks of cells is low, or the whole pack is too low to charge properly. thanks for watching

@@thecityviking Thanks for answer. It has the right voltage when i measure inside (around 37v) but between the + and - terminal its only half the voltage. i can take the - inside from circuit board and it will run a motor.

I unfortunately don't have any of those batteries, but if I find some at a garage sale or somewhere cheap enough, I will. Thanks for watching

I currently do not have any defective newer style batteries, but I am thinking of making a video on the newer batteries.

This mod will not increase your battery at all, it just allows it to be charged. Manually balancing the cells may help increase battery life a bit.

They are not parallel they are series

@@thecityviking weren’t you tying the gate of the charge FET to the gate of the discharge FET through a 51K resistor? Given the high gate impedance, it seems this is driving the two gates with the same signal.

@@thecityviking Thanks. So if the BMS turns both gates to the two FETs off, is there a way to turn them back on to allow charging?

Sorry, I read your original post incorrectly. You are correct, the gates are paralleled. The charger does not charge the battery on the newer battery packs because there is communication between the charger and the battery pack. If the pack tells the charger that it is defective, the charger does not provide the charge voltage. I think possibly we need to modify the charger and the battery?

@@thecityviking perhaps so. Unfortunately, I’m not familiar with the details of the circuitry in the charger or the battery. So I have no intelligent feedback on the best way to approach it. You’re probably much further along on ideas for the best way to do that.

They won't do that in Australia. You have to return the tool and battery with original packaging. I now have 3 dead batteries and I will be trying this mod.

Have you opened the battery and checked the voltage of each pair of cells? All of the cells inside should have a voltage that is close to all the others. It could also be your charger. I will be posting another video soon about these batteries and how to check cell voltages. Stay tuned!

@@thecityviking I think you got it because I think I have forget it about that it's been like 6 months ago the charger it bloud a spark lights made this with like a shot because the charger goted spilled some water inside but i didn't think it was it was the charger because it is still working regularly with all the function

I would check to see if the batteries are balanced first(all within .01of each other)

@@thecityviking i brought them back and balamce

Unfortunately its difficult to buy just one resistor, but here is a link to a pack that should work. The resistor value is not critical, so pick the closest one. Good luck.

@@thecityviking Thanks, it would be great if you ever have a chance to make a video for Ryobi 40V 4ah. That seems most people have problem with.

Not at the moment. I do not have any of those batteries. If I get some I will see what we can do. :)

@@thecityviking I can send you some to play with.

I am looking at making another video about a Rev Q board that is in the newer Ryobi batteries. Perhaps that is what you have in your batteries. Coming soon!

It could be a bad FET, but as I explained in my other video, you do need to load the battery before checking the voltage at the + and - terminals.

10 batteries in series 2 parallel. 20 batteries total. So its a 10s2p pack.

@@thecityviking batteries meaning cells?

Yes sorry for the confusion. 10 cells in series and each cell has a parallel as well.

Thanks for watching.

Not sure. I'll see if I have one and try and figure it out

Awaiting the same!

Thanks City Viking, great video tutorial, my battery is dead as we forgot to leave it charging last winter, but it's the model with one FET, what would you suggest to do in this case, just desolder the FET completely, force charging it to some charge, then replace the FET and charge normally?

I would try charging it like I describe in the video using alligator clips. One on the positive and one under the screw(negative)

The FET's rarely fail, it is usually a faulty cell or other board component. I have removed the board and disassembled a dozen packs. The board is usually damaged from disassembly and even if you could find the faulty cell and just replace it, it would be almost impossible to do it without removing the board first. You would have to buy a separate 40V BMS to protect your pack. I am planning a similar build and will post once I have gotten all the parts. Thanks for watching

@@thecityviking Thank to the replying, so even being very carefule with the board, if we need another 40 volts bms to rebuild a new battery, I have seen another Guy on youtube, doing battery for e bike and he use new bms, he ordered from internet, As I remember, that Guy even as written a couple books related of doing battery. I have looking forward to see you new video. thank again to help us with dose ryobi battery that don't last much.

Accessed grd & voltage points on 18v with accessing in plastic case. no Chang in board change. Is this a good idea?

I think that's a great idea.

It may be possible but I would not recommend. Look at videos showing how to revive , reset current interup device in 18650.

Cells may be just drained to 0V. I would try charging individual cells slowly. Start with 1V and 500ma. If it charges to 1V, then try 2. Once over 3V you can try charging quicker.

All the Ryobi stuff I have is from Kijiji or pawn stores or tossed out on the road. I picked up 2 batteries brand new in the package for $200. Thanks for watching

I am not sure. Sorry.

I don't like to use continuity or ohms on live circuit boards. The risk of damage to the meter is too great for me. Thanks for watching.

@@thecityviking hmm.. maybe an LED + resistor?

I like that idea!

In the video, I talk about this and explain why I don't do this. I tie the gate to the gate of the other FET so the BMS can still shut off the power. Thanks for watching.

All the lights sometimes light when the battery is very depleted. Check the charger on the battery to know if it is truly fully charged.

@@thecityviking I have 2 chargers, both see the battery as fully charged. Occasionally it shows error when first plugged in but I remove it and slide it back in it shows full. Definitely strange. Also when checking the charge by the button on the end it shows full.

Well, I can't go back in time, but I can give you my word that they did not charge on the Ryobi charger before the mod. I have a second video where I answer a bunch of questions about these batteries. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-WKY1-JNijqo.html Thanks for watching.

It would have to be a 40volt tender. I don’t even know if those are available. ✌️

The screw itself is not actually connected to the negative of the battery, but rather is just a spot where I connect the alligator clip and the side of the clip touches the negative pads. I hope this helps. :)

@@thecityviking Thank you that makes since.

Thanks for letting me know that the link is not available. I will try and find a similar one to put in there.

The FET is probably not on and so the voltage does not read correctly. This is normal operation. I explain it in my other video "Ryobi battery questions answered". Thanks for watching

There is no relay in the battery pack. The battery uses FETs to turn off charging and discharging of the battery. I would check individual cell voltages and see if you have one set of cells that is low. While you can bypass the FETs, you will effectively be bypassing the safety features of the battery pack. Please only do this if you understand the risks involved.

@@thecityviking Thank you for responding. I don't know enough about the battery, so will give up on it and most likely buy a gas push mower.

You are welcome. Sorry to hear i wasn't able to help you.

I think this only works with the older packs, but you could try it.

Link is in the description and here. amzn.to/3xWVVkJ Thanks for watching.

@@thecityviking link isn't in the description. It is only the resistor and power supply and similar power supply.

@@thecityviking I guess you just labeled it wrong, I see now. Thx

*I found a video of someone with the same type of battery having the same issue ....* ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-T6xMwPbcvn0.html

All BMS have at least one FET, at least all the ones I have ever seen. The FET is like a switch. When it is fully charged, it switches off to stop overcharging. When discharging, it switches off again to stop over discharge. This is done to preserve the life of the cells and for safety. The BMS will also switch off the pack if the cells are very out of balance. I would first make sure all cells are close to each other, say 3.600V. If all the cells are within 100mV or .100V of each other, they should be OK. Thanks for watching and check out my other video on these batteries. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-WKY1-JNijqo.html P.s. a FET can come in different packages, so it may look different, but it always has 3 connections.

Are you sure the problem is in the battery? Do you have a second battery to try in your weed whacker? Can you connect some other load up to + and - terminals? I use a 100w incandescent(old style filiment) bulb conneced to those terminals and it draws .5 maps and the bulb glows but not at full brightness.

@@thecityviking My weed eater is good have tried on a different battery and it works fine, this battery that i want to revive went into the sleep mode. I tried to charge it by pushing it into the charger a few times and it started to charge. After the full charge it wont turn my weed eater.Checked the voltage on +ve and -ve terminal it was at 19 volts. Checked the voltage between battery ground and +ve terminal it reads 41 volts. Checked the charge on the battery all the lights comes on. The charger shows its fully charged. I am lost

I have found a few batteries where the board looked the same, but they act differently. I suspect that there are different software running on the boards. Have you measured the 10 pairs of cells individually and are they around the same voltage? I am going to be making a new video about these batteries shortly.

I have the exact problem with my battery, 18 volts between the + and - terminals 40 volts between the + and main ground on the board. Today I ran a jumper wire from the main ground and + terminal to the trimmer and it ran for almost an hour. The battery discharged to 32 volts so I put it back together and charged it. No change still 18 volts between + and - , 40 volts between main ground and +.

@@eddiedavis346 can you post the picture

Thanks for asking. Usually the FET's are not the problem. I have yet to find one with a bad FET.

Unfortunately I don't have any single FET boards. If I come across any I may make a video on it. You could bypass the FET with a short across the source and drain, but you would have to monitor all cells to prevent overcharge or fire.

All lithium batteries have a limited lifespan dependent on how hard they are used. While the first batteries did have problems, I have some of the newer batteries and they seem to be fine so far. I have a lawn mower, chainsaw, blower, and trimmer. I imagine that if you sell millions of tools that use the same batteries, you will have some failures, especially in the beginning. I always try to stay clear of the newest tech as a rule. The leading edge is the bleeding edge! In my field the newest equipment ALWAYS has the most problems and the older tech has the bugs worked out. Look at Tesla in the beginning, nothing but complaints. Thanks for watching.