Dewalt 20V Battery Problems?

[lund]

I like to use small 2 Amp Hour 20V batteries in my Dewalt impact driver. I am just a DIY guy, but i use this combo heavily for years. My original battery lasted about 5 years before a cell went bad. That was ok performance to survive over many (probably 100s of) charge cycles. But since i replaced the battery, i have been through about 4 batteries in 3 years. The most recent warranty replacement only lasted 2 charge cycles. I also have larger Dewalt batteries of 5 AH and 9 AH (for yard tools) that have been going strong for over 5 ish (3 5 AH packs) and 2 ish years (the larger 9 AH packs for yard tools) over many charge cycles. The impact driver works fine with the large batteries. The tool does not discharge the larger, known good batteries when not in use, and the tool works perfectly fine/normal. The small batteries, if i can get them to charge at all, will discharge even off the tool within a day or so with a rapid onset from good to bad. This suggests to me that it is bad cells.

Are others having this problem? These DeWalt battery packs are not cheap and should be using better quality cells from a reputable battery manufacturer. Batteries this lousy are also likely a fire hazard: there is a lot of energy in a fully charged cell. Did Dewalt change their cell vendor to cheap out production and maximize profit? They are now chargeing higher prices for junk if this is the case. I am also puzzled why this is only happening with small battery packs and not the larger ones. I would not think they would be using lower grade cells selectively in smaller battery packs, though results suggest this may be the case.

Pics of the most recent warranty replacement battery (2026 manufacturing date) are attached below. This one did not even have time to pick up any dirt ...

This poor battery performance is souring me on DeWalt products. DeWalt is good at warranty replacement without requiring me to send back the pack for replacement with a simple (once you find it) online form. But it takes weeks each time the battery dies to get a replacement, it is an inconvenience to need to go through the process, and the tool is harder to use while waiting for a replacement with a high capacity batteries (much heavier) along with not knowing when the next small battery will meet it's end (comes on rapid and complete so you carry the tool somewhere and the battery will be stone dead and will not charge).

Info added in edit:
* 2 AH battery packs were tried on several Dewalt chargers that work fine with known good batteries (over many charge cycles). So it is unlikley the chargers are bad.
* DeWalt chargers refuse to charge (most) of the bad packs since they are stone dead (checked with multimeter). I think the chargers refuse to charge a stone dead pack since it suggests a bad cell.
* I can sometimes charge one of the bad packs by jumpering to an external power supply. This may burn out any bad spot on a cell. However, when I do this, the battery pack has not stayed working for long and I do not feel I should need to "fix" an almost new battery pack.
* The impact tool the packs are typically left on is brushless. That may have different that "usual" discharge characteristics that is putting stress on the cells (all I can think of). But the small capacity 2 AH battery packs also die when left on a drill and other tools. Larger battery packs work and store fine on all tools (including the impact driver).
* All DeWalt batteries are dated (probably so they know roughly if under warranty or not between that and claimed sale date) with a factory stamp. This has happened with 4 cells over the last 2 years. One got returned to Amazon and the others were warranted by Dewalt. I now have 3 bad 2 AH battery packs. I am tempted to cut out the cells and test individually and see if can assemble a good one. BUT they cells are tab soldered at the ends and that is hard to remove and resolder without heat damaging the cells.
* I would assume the cells going bad are from different manufacturing batches from whatever vendor DeWalt is using.

I feel this is ridiculously bad performance for an expensive tool/battery pack that should be decent quality. Others are not reporting problems so I think something about the impact discharge characteristics (bad tool brushless motor) might be damaging the small capacity cells.

 

[lund]

There are no replies here. Am I the only one having this ridiculous problem with DeWalt 20V battery packs? If so, this is gets all the more strange. Lucky me!

Or maybe all you guys are super strong since this is Garage Journal and use high capacity batteries for everything and thereby bypass this low capacity battery death issue !

 

[Jeff Ivers]

I have been using a whole suite of Dewalt 20V Max tools since 2013. About 2 weeks ago, I had my first battery fail - it will not recharge. I have always preferred the 4.0 and 5.0 amp hr batteries. Do you have multiple chargers? If so, is there any chance one of your chargers has failed? Do you fully charge the new batteries before trying to use them?

 

[niget2002]

None of mine are newer than at least 2 years old, so I can't comment. I have 4 2aH, 2 9aH, and 1 6aH. Two of the 2aH are new enough to have the little button on the front to show charge and are the yellow/black 2-tone. The other two are older, solid-black ones.

 

[designer485]

I have owned many 18v, 20v and 12v DeWalt batteries and the only time I have any trouble getting one to charge is when they sat mostly depleted for too long...however all I had to do was jump the battery with a fully charged one, put it on the charger and it was back in action. When the batteries get too low, they will not register on the charger and need to be jumped. I am not sure that is what is going on the with OP, but it is worth mentioning for others who may have issues charging their batteries.

OP do you have any other DeWalt tools other than the impact driver? Do any other tools show the same discharge rate as the impact driver with those smaller batteries?

 

[aka Larry]

All my cordless tools use the Dewalt 20V stuff. I don't have nearly as many as I'd like but I do have a pair of 3/8" drills, Impact Driver, Ocillating Multi-tool, Desktop Fan, and a Leaf Blower.

I prefer the larger 4aH or 5aH batteries, but I do have a pair of the 2aH ones that I rarely use. I've not had a problem with a single one, and all are at least 5 years old.

I recently bought a pair of 6aH Chinese knockoffs from Amazon for $50. I use these in my camper and they are 'OK' I guess, but their discharge rate is about 2X the factory ones, which tracks since they are half the price. I won't be buying any more knock-offs that's for sure.

 

[Steve_P]

Mine are 3-5 years old, homeowner use, no issues.

 

[NUTTSGT]

I would consider a different charger if you are going through batteries at that speed.

I would also suggest numbering your batteries and add a date when you put them in service for tracking purposes.

 

[Etchase]

No issues with mine.

 

[wandrur]

Some of mine are going on eight years, I think. No issues. I have 2Ah, 4Ah, and 5Ah variations.

 

[JohnX14]

No issues here with Dewalt batteries. I also like the small 2 ah for my impact driver. (Although I use Makita drivers) I have tons of Dewalt, and a few guys that work for me use the dewalt drivers. I have had issues with Milwaukee recently.

 

[MichaelP]

I use 2AH batteries whenever possible due to their lower weight and size, but aslo have many larger 20V and 20/60V ones. Never noticed any problems you describe.

I'd look closely into your chargers. Do you use quick or regular ones? OEM? Quick charges may decrease battery life, theoretically, but not as drastically as you describe.

 

[lund]

I have been using a whole suite of Dewalt 20V Max tools since 2013. About 2 weeks ago, I had my first battery fail - it will not recharge. I have always preferred the 4.0 and 5.0 amp hr batteries. Do you have multiple chargers? If so, is there any chance one of your chargers has failed? Do you fully charge the new batteries before trying to use them?

Thanks. I have two chargers and both fail to charge the small 2 AH packs (sometimes flash bad, sometimes do nothing) and charge known good cells with no issue. So I do not think it is the charger. The pack also measures stone dead with a meter.

 

[lund]

None of mine are newer than at least 2 years old, so I can't comment. I have 4 2aH, 2 9aH, and 1 6aH. Two of the 2aH are new enough to have the little button on the front to show charge and are the yellow/black 2-tone. The other two are older, solid-black ones.

All my battery packs are new enough to have the touch switch charge indicator. All work except the bad 2 AH packs. Also on the bad batteries, they measure stone dead with a multimeter. That suggests a bad cell.

 

[lund]

I have owned many 18v, 20v and 12v DeWalt batteries and the only time I have any trouble getting one to charge is when they sat mostly depleted for too long...however all I had to do was jump the battery with a fully charged one, put it on the charger and it was back in action. When the batteries get too low, they will not register on the charger and need to be jumped. I am not sure that is what is going on the with OP, but it is worth mentioning for others who may have issues charging their batteries.

OP do you have any other DeWalt tools other than the impact driver? Do any other tools show the same discharge rate as the impact driver with those smaller batteries?

Thanks.

No, these have not been discharged fully before recharged. The 2 AH batteries typically go dead while connected to the tool and not in use. Other larger capacity batteries left on the tool do not discharge at all and can work after sitting for months with the charge they had initially.

I have tried reconditioning the bad batteries by connecting to higher capacity batteries and/or power supplies in an attempt to burn off the damage area(s) shorting the cells. I had limited luck with the temporarily reviving a damaged battery, but it does not last long. It seems the cells are surprisingly bad.

 

[lund]

All my cordless tools use the Dewalt 20V stuff. I don't have nearly as many as I'd like but I do have a pair of 3/8" drills, Impact Driver, Ocillating Multi-tool, Desktop Fan, and a Leaf Blower.

I prefer the larger 4aH or 5aH batteries, but I do have a pair of the 2aH ones that I rarely use. I've not had a problem with a single one, and all are at least 5 years old.

I recently bought a pair of 6aH Chinese knockoffs from Amazon for $50. I use these in my camper and they are 'OK' I guess, but their discharge rate is about 2X the factory ones, which tracks since they are half the price. I won't be buying any more knock-offs that's for sure.

Thanks. This is more what I was expecting. But I am getting worse than junk battery performance from the OEM 2 AH Dewalt battery packs (I do not think they are counterfeit) bought at high cost. It is a pain and annoying.

My situation (lucky me) seems weird as hell though and contrary to what others are saying. I suspect something is odd on the particular brushless impact I am using but it working fine with larger capacity battery packs is hard to understand. It does not make a lot of sense to me from an engineering standpoint (I am a scientist/engineer in the day job).

 

[lund]

I would consider a different charger if you are going through batteries at that speed.

I would also suggest numbering your batteries abs add a date when you put them in service for tracking purposes.

If you notice from the PIC, DeWalt stamps them with a date code anyway. I think this is due to a large number of warranty requests so they know when it is likely whatever years beyond purchase date so they can deny replacement.

It happens with two chargers that work fine with larger batteries. So I do not think it is that. However, I can get them to charge by connecting to a high capacity external power supply that likely burns off whatever damage spot on the bad cell. But they have not stayed "fixed" after I do that.

I may start cutting these apart so I can isolate bad cells and just make a good working pack. It seems rediculous to need to do that. They are also tab soldered on the ends so it is not easy to remove the individual cells without heat damaging them.

I mark bad battery packs of course too ... and I have 3 ones now (one was returned to Amazon).

 

[lund]

Some of mine are going on eight years, I think. No issues. I have 2Ah, 4Ah, and 5Ah variations.

This seems to be the more usual experience with DeWalt battery packs. My "luck" is so surreal bad with the 2 AH packs that it has to be something else going on. I wish I knew what since the impact is otherwise great. The drill it came with is trash though: too bulky, bad balance, low speed, and VERY loud if hammer drilling to the extent it will give you hearing damage and is hard to noise protect from.

 

[lund]

I use 2AH batteries whenever possible due to their lower weight and size, but aslo have many larger 20V and 20/60V ones. Never noticed any problems you describe.

I'd look closely into your chargers. Do you use quick or regular ones? OEM? Quick charges may decrease battery life, theoretically, but not as drastically as you describe.

Regular chargers. These are also dying very early in the life cycle. So it is not accelerated aging. This is bad cells quickly.

The Dewalt chargers have protection built in and refuse to charge a stone dead cell (full discharge likely flags bad). But if I jumper wires to an external power supply, I can charge the damaged cells ... at least temporarily. I think this may burn out a short location. But the "fix" does not remain and the low capacity packs discharge dead again while everything continues to work fine with larger capacity packs. I find this VERY strange from a technical standpoint. Perhaps it is something from the way the brushless motor discharge cycle damages the small capacity cells. That is all I can think of. I have not tried to hook up a scope and recorder to analyze what is going on but I am not DeWalt's engineer ... that is something THEY should have checked with a mass market product sold at high profit. If they are selling something they know is incompatible with small capacity batteries, that is kinda sleazy. But I would expect high use pros would all have this problem and I seem to be relatively unique here. It is very strange.

 

[lund]

No issues here with Dewalt batteries. I also like the small 2 ah for my impact driver. (Although I use Makita drivers) I have tons of Dewalt, and a few guys that work for me use the dewalt drivers. I have had issues with Milwaukee recently.

It is likely that all the manufacturers are buying standard Lithium-Ion cells for their tools. Bad batches are possible (battery tech is not easy but they make in mass). I would hope at the prices charged they would buy high quality cells. But there is likely temptation to go lower cost to boost profit margins -- particularly since so much goes to low use home consumers who might go beyond warranty cycle with little use (sleazy but thinking like a corporate bean counter here).

 

[Renegade1LI]

I had one 5ah pack go bad, I left it in an adapter that caused it to fully discharge & could not recover it. Other than that between home & work I probably have 50 plus packs with some being 8 plus years old. It seems like fully draing the pack usually kills it.

 

[tarbellb]

Odd situation

IMO DeWalt (and the others) likely cutting corners on these, low qc, variable suppliers, etc.., it's the "free" battery that comes in kits.
It's simply a gateway product that either -
barely gets used and goes unnoticed if the quality is bad
or
leads to heavy users thinking/needing a bigger battery

Keep us posted on what you find.

 

[Nobody-named-Olli]

Have you brought this to DeWalt customer service for them to connect the dots? (Or escalate it higher up the food chain when contacting 1st level support didn’t give a satisfying result?)

That’s what I would do. Detailed description, including all serial#s and clearly state it’s a recurring issue that is to some point reproducible.

I did a quick search last night, and unless I overlooked something, it doesn’t seem that there is an explicit connection between the usual “my DeWalt* tool/battery died” chatter and 2Ah batteries.

*Like can be found for every brand.

Since you stated later that you run the batteries down in that tool up to the point where they are completely depleted/discharged, this might already be the “problem”. I have no idea where DeWalt puts the brain/electronics, but if for some reason there is no or actual miscommunication between the tool and the 2Ah batteries so they get discharged beyond a healthy state, what you’re experiencing would be a possible/likely result.

I think this is an issue for DeWalt to give some thoughts on. I’d contact them if that hasn’t already happened beyond the plain warranty claim/ replacement.

Kind regards,
Olli

 

[Tchicken]

Like most everyone who has responded here, I have had no issues with any of my DeWalt 20V batteries, I have a range from 1.5A to a pair of 5.oA. Depends on the use - I will use the smaller batts where the extra weight of the big ones is onerous, the bigger ones if heading out back with the chainsaw to cleanup the large willow branch that fell overnight.

I do notice in the responses some that seem to want to have DeWalt in some sort of fault position whether the experiences support that or not.

 

[dnschmidt]

Easy solution. Buy the tiny 1.7 A-hr Powerstack batteries. I typically throw any Milwaukee 2.0 batteries than come with deals into the recycle bin at the Home Depot before I ever use them. When I have a room full of CP 3.0 M18 batteries at home the 2.0 make zero sense to me. I've had good like with the Powerstack on my smaller DeWalt tools and the batteries are tiny and charge quite quickly.

 

[lund]

I had one 5ah pack go bad, I left it in an adapter that caused it to fully discharge & could not recover it. Other than that between home & work I probably have 50 plus packs with some being 8 plus years old. It seems like fully draing the pack usually kills it.

If you fully drain a battery pack, you may have to first charge it on an external power supply. I think DeWalt (and others) build into their chargers to refuse to charge a very low voltage pack since it likely flags a damaged cell. You can measure the polarity of the terminals on a known good battery (charged) and then connect the battery to an external power supply (jumper wires pressed into battery terminals) to charge it. This can also be used to "condition" a pack with a minimal bad cell by using the power of the external supply to burn off the bad spot (short) if it has enough capacity to do so. But a damaged cell is likely iffy if it can be salvaged this way.

Hope this helps.

My problems is very strange and I seem to be relatively unique. It has to be something about the small capacity battery and the specific impact driver and the way that I am using it that quickly damages the cells.

 

[lund]

Like most everyone who has responded here, I have had no issues with any of my DeWalt 20V batteries, I have a range from 1.5A to a pair of 5.oA. Depends on the use - I will use the smaller batts where the extra weight of the big ones is onerous, the bigger ones if heading out back with the chainsaw to cleanup the large willow branch that fell overnight.

I do notice in the responses some that seem to want to have DeWalt in some sort of fault position whether the experiences support that or not.

Not sure. Outside of my odd experience, most seem to be reporting that their low capacity DeWalt cells work fine. I actually like the compact, brushless "Atomic" impact that I am having the problem with a lot. It works very well outside of the battery issue. I also have their paired drill and that is hot trash: poor balance, slow speed, VERY loud (to the extent in hammer drill mode it can cause hearing damage). I do not have anything against DeWalt and I prefer to stick to their line since I use their batteries and have had good performance overall outside of this very annoying issue and their lousy drill. I am just a DIY guy, but my use can be pretty heavy in spurts.

 

[lund]

Easy solution. Buy the tiny 1.7 A-hr Powerstack batteries. I typically throw any Milwaukee 2.0 batteries than come with deals into the recycle bin at the Home Depot before I ever use them. When I have a room full of CP 3.0 M18 batteries at home the 2.0 make zero sense to me. I've had good like with the Powerstack on my smaller DeWalt tools and the batteries are tiny and charge quite quickly.

I am not sure what Powerstack is? Is this some alternative brand battery and charger with DeWalt connector compatibility? I have been thinking of trying some other brand rather than buying another battery (think may be getting close to warrantied out from the original purchase time with most of the time being dead packs).

 

[lund]

Have you brought this to DeWalt customer service for them to connect the dots? (Or escalate it higher up the food chain when contacting 1st level support didn’t give a satisfying result?)

That’s what I would do. Detailed description, including all serial#s and clearly state it’s a recurring issue that is to some point reproducible.

I did a quick search last night, and unless I overlooked something, it doesn’t seem that there is an explicit connection between the usual “my DeWalt* tool/battery died” chatter and 2Ah batteries.

*Like can be found for every brand.

Since you stated later that you run the batteries down in that tool up to the point where they are completely depleted/discharged, this might already be the “problem”. I have no idea where DeWalt puts the brain/electronics, but if for some reason there is no or actual miscommunication between the tool and the 2Ah batteries so they get discharged beyond a healthy state, what you’re experiencing would be a possible/likely result.

I think this is an issue for DeWalt to give some thoughts on. I’d contact them if that hasn’t already happened beyond the plain warranty claim/ replacement.

Kind regards,
Olli

You may be right, but my experience is the big brand customer service is little help outside of just warranty replacements. If I could talk with one of their engineers, I might be able to get to the bottom of it. I am also an R&D scientist with some electrical engineering skills and equipment. But chances are those engineers are in Asia (most everything is outsourced outside of financial stuff). These companies rarely have any way to discuss matters. You get connected to an office worker that just will send a replacement till the warranty times out. That cycle has been back to square one for me.

Something is indeed odd in my case. The impact tool must be damaging the small capacity packs and then they do not work well on anything or even discharge sitting disconnected.

Yes, once batteries are discharged too low the vendor charger may refuse to charge since it flags a bad cell. I bypassed this (see my edit to the original post if interested) with an external supply to recharge. That can temporarily "fix" it but then they are discharging again and seem to be damaged in a not easily addressable manner. I should also not have to do this in proper use cycles with a new battery (from a high cost vendor too).

 

[lund]

Odd situation

IMO DeWalt (and the others) likely cutting corners on these, low qc, variable suppliers, etc.., it's the "free" battery that comes in kits.
It's simply a gateway product that either -
barely gets used and goes unnoticed if the quality is bad
or
leads to heavy users thinking/needing a bigger battery

Keep us posted on what you find.

Maybe. I am also suspicious of this. The temptation to buy cheap cells in mass is high since it will boost company profit and not get noticed by 95% of customers. But 2 of the deaths have been on a replacement 2AH pack where the original was bought individually ... so not part of a kit.

I think I will cut apart some of the bad packs and see where the cells are from.

Most people use too big a battery on small handheld tools. 2AH is fine for impact. If you keep one in reserve and use one you can typically go for hours on almost continuous use. That is good enough and the tool is way more balanced and less fatiguing with a small battery. When this problem happens I go to a 5 AH or 9 AH (yikes) batteries and work becomes noticeably more cumbersome.

 

[logical]

I've just been buying the much cheaper off brand Dewalt-style batteries and they have held up over many years and hundreds of cycles.

 

[dnschmidt]

I am not sure what Powerstack is? Is this some alternative brand battery and charger with DeWalt connector compatibility? I have been thinking of trying some other brand rather than buying another battery (think may be getting close to warrantied out from the original purchase time with most of the time being dead packs).

These are the pouch batteries DeWalt introduced about three years ago. They don't use cylindrical cells like typical batteries do they use pouch cells like the ones used in notebook computers. They now come in a large variety of sizes (1.7, 3.5, 5 and 8 Amp-Hr) but the 1.7 was the first introduced.

 

[NUTTSGT]

If you notice from the PIC, DeWalt stamps them with a date code anyway. I think this is due to a large number of warranty requests so they know when it is likely whatever years beyond purchase date so they can deny replacement.

It happens with two chargers that work fine with larger batteries. So I do not think it is that. However, I can get them to charge by connecting to a high capacity external power supply that likely burns off whatever damage spot on the bad cell. But they have not stayed "fixed" after I do that.

I may start cutting these apart so I can isolate bad cells and just make a good working pack. It seems rediculous to need to do that. They are also tab soldered on the ends so it is not easy to remove the individual cells without heat damaging them.

I mark bad battery packs of course too ... and I have 3 ones now (one was returned to Amazon).

I realize the packs are stamped from Dewalt. Marking and dating them with a Sharpie is for owner reference. You have 5 batteries and buy two more in August of '26. You mark one battery #6 and the other #7, both get date of 8/26. This allows a quick reference point of how old a battery is if you have problems and can differentiate between multiple batteries if they have the same bought on date.

Are you putting batteries on the charger hot ? If you don't allow them to cool, I'm pretty sure the smart chargers will fault them until cool, then charge them.


If you are trying to hot charge them, get a fault indicator and immediately hot spiking, dead shorting or over powering those batteries, I belive those actions are what is killing your batteries.