SECRET To Reviving Dead Portable Tool Batteries | Super Easy!
In this video I will show you a really fast and easy way to fix and revive most dead portable tool batteries!
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Have you ever run into this issue? Did you end up just replacing the batteries?
I wonder if this could be done with RC batteries?
As long as you're using an identical battery pack to try this and they are rechargeable, you should be fine. @@jc2200
I still have my dead batteries, so I'm going to try this. You're awesome. Thank you so much. I'm going to try this now.
I didn't replace them because I had already seen the 700 OTHER videos that explain this procedure on you tube.
@andys5562 cool. But that’s definitely an exaggeration 😂
I have just tried this with my Milwaukee 18v battery that has been dead for 4 years. It absolutely works beats paying $100’s of dollars in batteries. Thanks brother love your work….
I am gonna try this as well with my Milwaukee M18 battery
Agree, not cheap. Escpecially higher volt ones.
I have several 40V Greenworks outdoor power tools; mower, trimmer, leaf blower. About 3-4 years ago one of the expensive (more then $100 at the time. They've come down in price since then) 5 amp batteries stopped working. Wouldn't charge, wouldn't run. So, having nothing to lose, I took it apart. On top of the batteries is a circuit board. On the circuit board was a flat automotive fuse, soldered into 2 slots on the board. The fuse was blown. I unsoldered the fuse and pulled it out. Got a new one of matching amperage from my tool box, trimmed about 1/8" off of the blades so it would sit low on the board like the original, and soldered it in place exactly like the original. Worked perfectly. I'm still using that battery.
They do this with televisions, they do this with washer and dryers and microwaves. I know because I have replaced a fuse on all these in every single one was a Samsung. What a scam.
@@billp.365 it's not a scam, it's a fuse. It protects the electronics. If there was no fuse it would have blown an expensive or difficult to replace component in the electronics when it could have been easily protected with an inexpensive and relatively easy to replace fuse. Almost every electric and electronic device has internal fuse protection with troubleshooting and replacement details in the owners manual.
Is that what they call ‘planned obsolescence’?
@@rupertcornelius8924 You are partly right. The fuse certainly does protect the electronics. But in this case there is no mention of it in the owners manual or any literature, and it is in no way intended to be replaced if it blows. What they want to happen is for the owner to declare the battery dead, trash/recycle it, and spend >$100 on a new battery. THAT is the scam. The fuse should be in a fuse socket in a user-accessible location so when it blows it can be replaced.
@@redfo3009 Not so much planned obsolescence as planned premature failure.
Just came across this video and had a DeWalt 20v battery I was about to take to recycle it. Figured I’d give this a shot, and you just saved me a battery! Working again like a charm!
My procrastination finally paid off! Have several of these batteries in garage intending to go to recycling. Yay!! Thank you!!!
What is occurring here is that the battery packs contain a fuel gauging and safety IC. The charger must communicate to this IC, before the battery can charge. If the battery gets to a low enough voltage, the IC will be unpowered, and unable to communicate. There is a way in most of these IC solutions to provide a slow charge path for a deeply discharged battery. The issue is that some manufacturers, because of their cell chemistry, don't want a battery which has dropped below about 1V per cell, to ever be used, as it can cause plating of the current collector materials into the carbon matrix, which can then become energized when the cell gets charged, resulting in shorts and localized heating, which can then lead to what is referred to in the battery industry as "rapid disassembly", more often called an explosion by consumers! If the battery reaches low voltage because it was stored uncharged, and left in that state for a long period, it would typically take multiple months, it may reach a low voltage. Such cells are usually safe to recharge, but to be sure you really need to get the info from the cell makers datasheet. The other reason the cells can reach such a low voltage, is because they are wearing out, and their impedance is increasing and capacity is starting to rapidly decline. This can cause a cell to go to zero volts during storage due to increased leakage currents within the cells. Such cells are typically unsafe to recharge! If you are going to do this, be very careful. Recovery of such packs is at a greater risk of catastrophic failure for the cells. Watch such packs carefully during charge, and even for half a day after the recharge. I have seen cells fail after such recovery charging as long as 8.5 hours after charging was complete. A single fire can cost you much more than the price of a replacement pack. I wanted to make sure people are warned of the potential consequences. Please be extremely careful. I highly suggest replacing such packs unless you know they were stored uncharged and left for a multiple months. Li based cells are fickle, they contain tremendous energy. When things go bad, they go bad quickly and violently. Please take this warning seriously. I would hate someone to lose someone they love to such a senseless accident!
Excellent analysis
Absolutely true Brian. Lithium ion cells are far too unpredictable for messing about with. If they lose their charging ability replace them.
Thanks for your technical advice Brian. Very good information
u are right on point.
“ but to be sure you really need to get the info from the cell makers datasheet. ” Lmafo, don’t even bother. If you can even find the original manufacturer and get a data sheet they NEVER have this information. They usually don’t even have actual capacity at various discharge rates or even temperatures sometimes they don’t even have the capacity which is insane. The data sheet says almost nothing beyond “what you want? It’s a BATTERY”.
The wife here. My hubby ran away from home. Left me with some old Ryobi tools and DEAD BATTERIES. I'm so blessed to find this process. I have friends with working Ryobi batteries. Now I can fix mine. Thank you!
Who needs a man around the house anyway with plenty of batteries on charge 😂
@@21stcenturycaveman33 Or youtube. Hey at least he left some tools.
Tell your hubby don't come back and your keeping the tools
He ain't coming back, ran off with the cute secretary 😅
@@joegonzalez1941 Most men choose ugly women for their secretary for a reason(wife is insecure). Then I thought, if they were real men they would not chase a better looking woman. So there is th at. You probably won't agree with my unpopular opinion. Looks fade.
Wow, I'm glad I watched this. I have a bunch of new batteries that have been sitting around for years going dead. I am so glad I can revive them now that I'm able to use power tools again.
You absolute legend! Had a Worx battery that had appeared dead after only a few months of owning. Luckily Worx replaced it within warranty. However I kept the dead one 'just in case'. It now lives thanks to this genius tip. Thanks again!
I did that scissors trick when I was 4 with a 120v outlet. Much more memorable. Now that I am an 61 with a EE degree I would recommend a fuse and alligator clips.
I second the fuse and alligator clips. You REALLY don't want to see a Li battery fire inside your house or garage.
What size fuse would you suggest?
30 amp most likely. As thats around the max output of a samsung high output cell
Ha ha! I did that same trick with a pair of wired toy “Rabbit ears”. I was 5 years old and was curious as to what would happen if I stuck those ears into a 120v outlet. Poof!!! One scared kid and a blown fuse. 😅
I wish you had done this video. ❤️
I wish i had seen this before I bought a new drill battery. Thanks so much for the tip, and you always have good info.
An excellent video. This illistrates the principle that a good battery sacrifices toward a dead battery. They will share the electricty equally. In the old days truck mechanics used this to start an exhausted battery.
Thanks for this great tip. I used your method on my 20 volt rechargeable battery and brought it back to being able to charge it fully again.
Totally works. Did it with Dewalt 40V yard tool batteries. Took about an hour to reach "threshold voltage" that the charger would recognize. Thanks man!
THAT'S AWESOME!!! It's just like boosting a car battery with another car battery. Thank you one million times!!!
Thanks! You just saved me money. I was just about to get a replacement for a battery I thought was dead. Thanks again.
Oh wow, wished I had known this a few years ago, would have saved me lots of money in new batteries. Thank you!!
You're welcome! Really glad to hear you liked it. Thanks a lot for the feedback!
I've never had to buy a battery, I use a plug! These types of batteries cannot be recycled so it's just adding to a pollution problem that IS KILLING our planet!
I haven’t had this issue yet. But I’m glad you showed how to jump start as a first test of a battery’s health!
D😮ttd
This is a brilliant idea. Thank you so much. Also, you've provided a very clear explanation of the situation and how to correct it. A breath of fresh air.
Thank you so much for posting this!! Now I will never throw away another battery until I try your "jump start" technique which is brilliant!
The scissors trick is jankiest of solutions in the best way. Love it!
For the 18volt dead battery, instead of wires or scissors to charge off of another 18 volt battery. Just use a typical 9 volt battery and place upside down on the prongs for about a min. Should send a charge to get it recognized by the charger. Super easy!
👍
Do you have to match the + and - on the 9v to certain sides of the battery your sending the charge to?
That is an intelligent question since it is definitely a DC battery@@jmar8507
Do a video, I'd like to see you do that... before I try it.
@@jmar8507this
3-5 minutes might be generous. It can be a lot faster. I learned this last summer from a different video and listed much shorter times. So I tried what they said. 20v dewalt - I connected the wires for about 30 seconds and that was all I needed to have just enough juice to get the charger going. I'm glad people are sharing this information. Seems a shame for batteries to be getting tossed / recycled unnecessarily.
Yeah, completely depends on the battery. Sometimes shorter can work as well. Appreciate the input!
yes a few seconds is more than enough - it is nothing to do with the explanation he gave, it is about individual cell polarity reversal which occurs when a lithium 'bank' (group of cells) approaches 0v of charge : as if the cells are not perfectly balanced (they can't ever be) then one cell will reach zero first because the others, and that cell ends up with a NEGATIVE voltage (or reversed polarity) -- the inbuild BMS detects this condition and tells any devices which respect it to shut off power from it. the hot 'jump' technique to the battery+/- terminals forces those flipped cells back into positive voltage levels by overpowering them. BRIEFLY! a few seconds is all it takes. any more can be dangerous.
These cells don't actually reach zero. The charger will cut them off between 3 and 2.5 volts. They will not let you discharge them completely because it would likely catch on fire. What happens is the battery is charged up to 4 Volts. It is used till it hits its cutoff voltage around 3 volts then instead of charging it you put it into your bag for three or four days and the battery self discharges to less than 2.5 at which point you need to do what he says here to charge them. The reason I t takes so little time is that you are only bringing the battery from around 2.4 to 2.6 volts enough where it is recognized. If your battery hit zero you would never be able to charge it again. If a lithium battery ever reached a negative voltage it would quickly achieve thermal runaway. The battery packs don't look for negative voltage to stop charging. They test each set of batteries for the low voltage cutoff. You are right about the imbalance though it happens at much higher tha zero volts. I'm not sure how lithium batteries deal with imbalanced cells but in lead acid deep discharge batteries you overcharge them up to about 14 or 15 volts for a short time. This brings all the individual cells up to the same voltage.
@j 😊lrinc1420
These types of batteries don't get recycled. Green ain't all that friendly!
I have a brand new hammer drill with a bad battery that I purchased. I'm glad I kept it. Just saw your video and tried it out. It's currently charging. Thank you for sharing the trick.
Wow! I tried it on a Ryobi 40W battery with speaker wire and the technique worked. Thanks.
Tries it on a newer dead battery - worked like a champ !!!! thank you for the video
Thanks for helping me to save money once again! You ROCK Brother!!!
You’re very welcome! Really glad you found it helpful. Thanks a lot for the feedback!
👍👍👍👍👍👍👍AWESOME!!! I'm so glad I watched your video. I have tossed "dead" batteries and almost tossed a $250 9.0AH Flexvolt 60V battery. I used this method to resurrect it and I couldn't be a happier camper ( I needed to flatten the wires i used with a hammer to make them fit). I connected them for 10 minutes just to be sure. Based on this I recommend not to connect for more than 3 min. They almost equilibrated and got pretty hot. That much charge that fast probably wasn't too good for the "dead" battery but it was certainly better than tossing it in the recycle bin. THANK YOU!!!!!!!!
This was AWESOME!! Thanks SO MUCH for sharing this knowledge with us! This "hack" rebooted my completely dead DeWalt 20v battery.
Wife likes all kinds of ambiance low power stuff around the house. I made her switch to rechargeable batteries due to how many she was going through. The problem with these devices is that they will suck a battery to 0. So i built a board to be able to jump-start them and get them to change easily. Works really well. I've also done this on car batteries, Zegway batteries, and many others threw the years. Never had an issue.
This is one of the most useful videos I have ever seen. Thanks for posting.
You're welcome! Really glad to hear you liked it. Thanks a lot for the feedback!
Ones it work on lithium batteries?
Thanks for sharing. One of my 20v batteries crapped out a few months ago. Going to try to jump it tomorrow!
Hey. I tried this on a dewalt flex volt and it worked. You’ve saved me $200🤙 Thanks so much. Great video 🙏🏻
I did jumped the dewalt 18v xrp batterys according to your instructions for my dewalt 18v xrp batterys. And so far it worked. No errors on the charger. Time will tell. The 20v adapter puts every tool out of balance and too tall. And my problem is I purchased about 10 major 18v tools and really don't want to add an adapter. All my Dewalt 18v tools are still in their hard cases, most only used once. Thanks for the video.
Awesome! Glad to hear it was able to help. Thanks a lot for the feedback Doug!
EE? Eat Everything?!
I’ve done this with Ego56v batteries and it does work. I had a battery that wouldn’t take a charge and registered a fault, ran the wires like he showed and it gave the “bad” battery just enough charge for the charger to recognize it as a good battery in need of charging.
I fix my black and decker batteries with your video thank you!!!!
Wow .. 😊. I have a newer DeWalt driver . One of the batteries went to no charge mode in no time. Came across your video. This works like a champ . I can't thank you enough. Now I will dig out some 18 volts and try those....thanks again👍
Nice. We seem to replace a lot of B&D batteries for our weedeater(s) - I'm trying this next time!
Nice tips, my addition would be to flatten your solid copper wire ends rather than forcing them in. Mechanically spread and damaged connector terminals inside the pack will also render it unusable in a much less fixable manner. It can overheat and melt the plastic around it in your battery pack and leave a burned pitted spot in your tool's contacts as well.
when you insert the battery into the charger it spreads the terminals apart to make a good connection. It's designed to handle this over and over again. Its a non issue.
Thank you for taking the time to do the step by step resurrecting of the battery
Outstanding video!!! I need to and will try this myself soon, LORD willing. Thank you!
Love your channel! Concise, short, but extremely informative. Great job!
Glad you liked it. Thanks a lot for the feedback!
I've had this issue before. In the past, I've just left the battery in the charger, and sometimes, after a few hours, the battery starts taking a charge. Perhaps the charger recognized a slight charge during the process. Will use your tips, though - much easier!
That’s what I did on 2 lightly used older Milwaukee 20’s.
Yes cause even though charger doesn't recognize battery when dead to give charge, when u connect the dead battery the charger, the charger still gives a very small amount discharge naturally and after hours of that miniscule amount of electricity going to the battery, it gets it to the point where it builds up enough stored electricity to have the charger recognize it
I just tried your solution. It worked! Charging the DOA battery right now.
Thank you for sharing this it was the source of my temporary out of service battery back into action.... Thanks again for sharing your knowledge. Cheers....
What a good and simple way of explaining how to revive these batteries! I am a retired electrical engineer and never gave this a thought. Keep up the good work!
The batteries are not being revived. li-ion, lipo and similar chemistry batteries once they are discharged below their lowest discharge voltage rating (normally around 2.2-2.5v per cell) they become useless. Yes you might get them to take a charge but, it'll never be 100% and the capacity is severely reduced.
I think those are rated as 80% capacity. You never get back to 100%. Anyway, use the battery until it can no longer takes a charge. Squeeze every volt out. @@Blueknight1960
@@Blueknight1960 A reduced capacity is far better than a zero functioning brick.
yes a few seconds is more than enough - it is nothing to do with the explanation he gave, it is about individual cell polarity reversal which occurs when a lithium 'bank' (group of cells) approaches 0v of charge : as if the cells are not perfectly balanced (they can't ever be) then one cell will reach zero first before the others, and that cell ends up with a NEGATIVE voltage (or reversed polarity) -- the inbuilt BMS detects this condition and tells any devices which respect it to shut off power from it. the hot 'jump' technique to the battery+/- terminals forces those flipped cells back into positive voltage levels by overpowering them. BRIEFLY! a few seconds is all it takes. any more can be dangerous.
Is there a way to do this without another good battery, Say a power supply or a stack of 9 volt batteries?
Ingenious! Love this! Thank you so much for the wonderful tip! Gonna save people some serious bucks!❤
Not really because once you drain one of those batteries down too low, they become worthless. Yes you might get them to take a charge but, the capacity of the cells will be too low to be of any use.
@@Blueknight1960 As I stated to another such comment, I jump-started a battery about 2 years ago and have used it many times since...never having to jump-start it again. It had been unused when it previously went completely dead (from lack of use), so admittedly that may be a factor. But it may not be a factor as well. I only know that it's operated as well as any new battery I ever owned for two years now, and I use my tools heavily...auto repair and home maintenance.
@tim9430 don’t try and give them actual facts Tim, many of them don’t like facts 😂. Appreciate the input.
If the batteries are any good they should hold a charge on the shelf as it were…. I have probably 20 DeWalt batteries in my collection and the only ones that go dead on their own are the ones that i know are weak… I have a 9 ah 60v that’s in my chainsaw and 2 years on the shelf and it still shows 3 bars
WOW, It worked on my 18v Black & Decker dead battery. Fully charged and holds charge well. Thank you for the tip. Super.
You are very welcome! Really glad to hear it was helpful to you. Thanks a lot for the feedback!
Thanks for this tutorial, I tried it on my M18 red lithium, it sparked a little but all it took was less than a min and now its charging, this is awsome!!
Never had this condition before, but I have had the charger say the pack is bad a lot. But I gotta add that a current limited power supply would be a better choice for this. The dead battery could overheat and die from the potential short circuit current draw if the dead battery cell is defective.
Did you mean the Good battery could die?
a few seconds is all it takes, it is indeed dangerous to do this for the stated 3-5 minutes. it is nothing to do with the explanation he gave, it is about individual cell polarity reversal which occurs when a lithium 'bank' (group of cells) approaches 0v of charge : as if the cells are not perfectly balanced (they can't ever be) then one cell will reach zero first before the others, and that cell ends up with a NEGATIVE voltage (or reversed polarity) -- the inbuilt BMS detects this condition and tells any devices which respect it to shut off power from it. the hot 'jump' technique to the battery+/- terminals forces those flipped cells back into positive voltage levels by overpowering them. BRIEFLY! a few seconds is all it takes. any more can be dangerous.
Scissors is a neat idea. Variation on this works of phone batteries too, but very low voltage using a phone charger. The BMS battery management system on Lion batteries can't read a fully empty battery is why they won't charge and why this works. Better trick is to not leave them in place to lose charge, give them a check once in a while and a top up.
Thank you for sharing tips to revive batteries. I found it very helpful!
Super advice thank you, I have done this a few times, recently on those solar lights that gets too low during winter and can't charge in the spring
Very nice. Never would have thought of using scissors.
What if red light continues to flash and no change to green after 20 minutes? Is it unrechargeble battery?
@maryreyes9926 yes. That is letting you know something is actually wrong with the battery and needs to be replaced.
Thank goodness I searched for "scissoring videos." This was helpful.
😂
Nice 😂
🤣
😮
🤦♂️
Awesome idea, have not had any batteries go dead yet but will now know what to do.
Perfect timing. I just had a 20v dewalt stop charging for some reason. Can’t wait to try this
Thank you! I have wasted so much time cleaning contacts and bending them back and forth thinking it was a bad connection. Then wasted lots of money on new batteries. This video is going to save me a ton of time and money.
You are very welcome! Glad you liked it. I’ve been there and done that too. Thanks a lot for the feedback!
N no
Very helpful... any suggestion for a blinking charger and the battery isn't charging?
I don’t have a solution but i DO have the same problem with one of my Ryobi batteries. It flashes the “maintenance charge” sequence (slow, gradual flashing).
Good video. Done this before and several times and it worked well. I've also jump these type batteries with car battery charger... but on low and just a quick hit!
Very useful and Excellent demonstration to revive dead batteries! I learned something today. Thank you.
FYI - if batteries sit on the shelf unused they undergo a process called self-discharge. See wikipedia topic "battery self-discharge" for details. I have several Ryobi tools each with a battery and I rotate thru them so a battery doesn't sit unused for months on end. A lead-acid car battery can also self-discharge over time if left unused but also after years of use the chemistry degrades so they no longer hold much of a charge and need replacing. A table in the article notes lead-acid batteries self-discharge around 4-6% a month and eventually won't have enough charge to crank the engine. Lithium-Ion self-discharges 2-4% month and eventually won't have enough charge for the charger to recognize the battery as good. So the trick in this video seems like a good way to give a still-good battery a kick so the charger will charge it. But you will know if the battery is really degraded when it only runs the tool for a few minutes after "full" charging.
Not necessarily true, lithium holds onto its charge for a very long time. The only reason they self discharge here is because the BMS system is usually parasitic and requires a tiny bit of power to keep itself alive. The difference is that the lead acid discharge is because of its chemistry, and the lithium is because of its BMS. Does it really matter? No, but it is not a flat rate, a lithium battery with the same BMS but twice as large as another will bleed through the BMS twice as slow.
I've done this before but, although the batteries will then "charge", at least in my case, they were able to hold very little power.
Maybe the battery was aging out? I did this several months ago to a 20v dewalt and it seems to be working just fine. I just do not jobs (not contractor) so it would be hard for me to tell if it had a few percent less charge but if so it is not obvious. I have used it for a number of misc jobs since I charged it and have not yet had to recharge it.
I would expect different results depending on the age and wear ofnthe revived battery
Each pack has 5 cells to make up its voltage 18v/20v. The BMS cuts off charge when one of the 5 reaches 4.15v. So open battery and either discharge all to same voltage or use likes of a tp4056 and individually charge each of 5 cells to 4.15 v Also note the discharge curve of lithium ion batteries shows that from fully charged they drop from 4.15v to around 4v in first 4% of discharge. Then slowly drop down to around 3.2 v and if kept in use again the curve drops like falling off a cliff
@@patomahony9747 Thanks!
Storing flat batteries will ruin them.
WOW!! What a simple yet brilliant video. Thank you!
I got a new battery for my Black and Decker Matrix drill. The old one still works as well as the day it was new. It was new about a decade ago and is still working perfectly. But, I've wanted another for longer household jobs. So, I ordered one. It arrived today. And when put on the charger the red light flashed, meaning the battery was defective. It had been on the shelf since 2020. So, I tried this using some speaker wire. And it worked like a champ. The new battery is charging with the green light on. Thanks for the tip.
Great video. Great comment section. To avoid any kind of battery fire due to over charging or failure. Get your self a metal garden shed run a 120v GFCI circuit to it and make a charging and battery storage set-up insde it for your rechargeable battries. Locate it as far as possible from occupied structures garages and any flamable materials. Dont ask how I know... a thief leaves the coat hangars, fire leaves nothing... I'm a retired Electrical Contractor. ✌️🙏😇 Stay Safe. ❤
You can also use a spade connector for the 18v one
What is a spade connector?
I agree, much safer. A short piece of wire with 2 female connector at the ends.
I watch your video and tried it on two car batteries using un insulated wires about a month ago. Since then, I am really enjoying it up here in heaven.😀
it was a little anxiety-inducing but just revived an 18v using the scissors method, thank you so much! living in the city without a car, jumper cables and insulated wires aren't something I have on hand.. so this really helped!
Give a new meaning to scissoring
There's a lot of good knowledge on KZhead, with real peoples that can help all of us save money.😊
We've (Hubs & I) started a shared Windows Notebook - Set up categories & sub-categories then include the info, links/pics or attach files if necessary
Thank you for this new idea. Great reference 👌 to spark new style of thinking saving time & energy.
Just did mines and it's charging now great 👍 information thank you 👍😎
While this does work, there is nothing to regulate the current when you connect the positive wire. There's always a chance with Lithium that you'll have a fire if you charge or discharge too rapidly. I recommend using a current limited bench power supply, or be ready to chuck the whole thing outside because it's on fire.
Probably a good idea to not just walk away from it while doing this. I don't even leave a battery on a charger any longer than it takes to charge it. I keep checking on it and when charged it comes out of the charger and unplug the charger.
@@tsmartinI know you can leave Bosch, DeWalt, and Milwaukee in the charger since they implement a charge protection timer. Ryobi still doesn’t last I checked. RTFM
I've done this before. one way for the manufacturers to prevent this issue is to have a jumpstart button on their chargers. I suppose that would be counter profitable because they can't sell more batteries that way…
For once it's actually got nothing to do with making more money. These batteries can be dangerous when handled by fools. Including the numb nuts that made this video.
Great tips! I actually bought two different tools that came with two batteries, and one worked, and the other didn't in each package; I figured the companies were disposing of non-working batteries through me! Good to know they just need a jump.
Ok, I have a 40v lithium battery for my Black & Decker weed trimmer. Over a year ago the battery was dead as any door nail. But I kept it for later recycling with other batteries. I saw this video and went to work to see if your jumper trick would work. I fully charged the good battery. Then I made my connections and gave it time. I came back in about 10 minutes and the "dead" battery was warm. I removed the wires and put that battery on the charger! It works! The red light started flashing. It's now working to be fully charged. I now have two 40v batteries to work with. Thanks for this great tip.
Been doing this for years, however the dead battery doesn’t ever fully recharge or last as long as it should.
I did this only once but the battery that I charged is still working fine about 2 years later. I use it often too. When it was dead it had never been used before. It was purchased, then sat unused for several years causing it to lose all of its' charge. Possibly that is a factor in why it has worked so well since I charged it??? I don't know.
Just replace the cells inside.
@@StopWars420unless you have nothing to do, the time to change cells out isn't worth the cost savings.
@veganpotterthevegan it's much cheaper and you can always fix them even when Dewalt discontinue them. But then again I expect a vegan to be overwhelmed by a simple task.
@itsallinyourheadbiotch never said it's hard clown. But time is money. I have a lot more money than time for something so inexpensive
Just be very careful if with Li-Ion batteries if they have drained all the way down to zero volts, they can reverse polarity and if they do you will have a nice fire as you try and charge it.
ho a does polarity reverse?
@@jerrygiarratana9462 Cell reversal in lithium ion (Li-ion) batteries is the condition of the anode electrochemical potential rising above that of the cathode, resulting in a negative voltage measured at the cell level. There are two primary reactions that occur at the anode at high potentials which increase cell impedance: oxidation of copper current collector, and oxidization of the carbonate electrolytes to CO2. At the cathode, the reducing potential can lead to the electrodeposition of copper to form dendrites, which pose a shorting risk if they bridge the anode and cathode. Cell reversal can be caused by poorly matched cells, a failure of the battery management electronics, or a defective cell in a pack. Under these conditions, one or several of the cells can go into reversal causing performance decreases or even a dangerous thermal runaway event. This is why BMS systems won't allow over discharge of the batteries, however if sitting around for long periods, the BMS system can't work if the cell(s) discharge beyond what it can prevent.
Thanks for taking the time to share your knowledge
I got a bunch in my junk drawer. I will try this. Thanks you Sooooooo much.
The 20v and 18v are actually the same voltage. They each have 5 cells in series. Normally the cells are specified by their nominal voltage of 3.7v so 5x is 18.5v. However at full charge the cells are at 4.2v, so 5x is 21v. But there isn't much capacity between 4.1 and 4.2v, and it is better for the usable lifetime of the battery to not charge it up all the way, so 20v is a nice round number pretty close to the typical upper limit.
@Sylvan_dB Thanks. I appreciate knowing the details of "why".
correct, that's why Dewalt has the 20V MAX * and if you go to the fine print it says " *Maximum initial battery voltage (measured without a workload) is 20 volts. Nominal voltage is 18. "
this is true if they are both lithium ion batteries but the 18 volt batteries shown in this video are nickel cadmium and are a very different technology
@@jbbolts no they are not. Ryobi changed from nicad many years ago and no mainstream tool brand has been nimh.
@@Sylvan_dB except the ones in this video are dinosaur dewalts
In case you don't have a second battery to jump start the dead battery, I did the same thing using my car battery and a set of jumper cables. I had to clip a piece of wire onto one end of each jumper cable so I would have something small enough to fit into the grooves on the Dewalt battery. I used an old guitar string because I had one handy. I only jumpered them together for less than a minute. The 12-14 volt car battery shouldn't cause any harm to the 20V battery...and it didn't. I have used that rescued battery for about 2 years since then and never had to jump start it again.
I've been using this method on AA batteries for years - also saw it on YT. My charger sometimes won't recognize an older battery but after I connect + to + and - to - for 5 minutes it charges just fine and even holds the max amp-hours.
GOD KNOWS-this video is absolutely timely. I was fixin to chunk a 20v battery...
Beware - this trick can definitely work if the problem is that all cells have a too low voltage. However if all cells but one are good and one cell is dead short - which definitely commonly happens too - it's an easy way to start a fire. To prevent this, chargers for n-cell batteries tend to refuse to charge when the measured voltage is smaller than the fully charged voltage of (n-1) cells. Some chargers are more clever than this and look at the charge/discharge curve to detect this condition more reliably - these chargers will have better chances at reviving a dead battery. Thus, when doing this, best do it outdoors, with no flammable material nearby, and also thoroughly test the battery afterwards - either by fully charging, discharging and recharging once to see if it gets a good charge (on a single cell short you likely will have an "empty" - as in, too low voltage - battery soon after use again) or fully charging, discharging a bit (like a minute of power drilling into the air) and checking its voltage to see if it is near its design voltage (if it has a single cell short, it will go below design voltage very soon after charging and even drawing a small amount of energy from it).
Yes but those chargers also blink in a way showing that something is wrong. This method would only introduce enough power so that the charger can recognize it and either start charging it again like normal or if there is an issue, at that point would blink, usually rapidly, to let you know there is an issue and needs to be replaced.
Fantastic info! I have several dead batteries that I am going to try this out on.
Very good information. I wasn't aware that this was possible. Thanks for this.
Holy electrical safety Batman! If you don't have alligator clips, go buy some alligator clips!
Agree. That scissors thing is crazy!
Not really.
For what?
Caution! Safety warning! (I add these here, because they are missing from the beginning of the video). The method presented here pose a significant risk of starting an unextinguishable fire, burning a hole through your workbench, burning your house down with chance of severe personal injury "Dead battery" can be caused by many things. All this works, if the problem is overdepletion and the charger does not want to start the charging detecting voltage below its safe limit. However, you can have many other issues: damaged cell, shorted cell, bad contact, or in case of lithium, a malfunctioning protection circuit. Sometimes the protection circuit is not even in the battery, but the tool and the charger. All these can result in pushing huge currents between two batteries with the risk of destroying both and causing injury and damage. If you want to do this safely, read up on battery chemistries and charging parameters, get a precision current limited power supply, properly disassemble the battery packs then analyze and charge each cell according to its specifications. Dear Uploader, I am sure that you mean well with this video and that as a former law enforcement officer, you don't want to put anyone at risk. Please add cautionary warnings, before someone uses this technique innaproriately and injures themselves or destroys something. Thank you, and wish you all a safe and creative new year!
Hot scissoring action. ✂✂ Nice! 👍😃 I need to share this with my friend who has a lot of battery powered tools.
Dude, you need to mention that if the two scissors touch, you gd ot a dead short. The good battery could explode or catch fire. Somebody is gonna start a fire and sue you. You need a little safety disclaimer...lol
Everything at your own risk wtf are you going on about. Part of the stupid label generation
Thanks so much! Wish I had’ve known this decades ago. 👏
You're welcome! Really glad to hear you liked it. Thanks a lot for the feedback!
Thank you 🙏 Sir for the great information given to the world to save money.
Simple, cheap, and smart!! Thank you
You are very welcome! Really glad to hear you liked it. Thanks a lot for the feedback!
can't wait to try this. I know I have at least 3 dead Ryobi 18 volts in the shed
This works, thank you so much for making the video. It actually works.
Worked on nickel cadmium battery in my case., a 20 year old Milwaukee drill battery pack.
I’ve found throwing them in the freezer can sometimes help too. Milwaukee batteries have a board on top that you can replace, they’re about $23 for two boards, and that can fix a battery with good cells that won’t take a charge
You just saved me on two batteries. Thanks so much 😊
This worked. Thank you. You saved me having to buy another Makita battery.