The Definitive Guide: Tool Adapters Good, Bad, How Bad? 

It seems DeWALT has yet again done a good job of confusing consumers and many people still believe yellow batteries with the same number of Samsung 21700 30T model number cells inside as the Milwaukee has 2 more volts for 20V. They are the same, they just dont advertise as 18V in the USA (but do everywhere else) to not get sued by Milwaukee. This is why they advertise 20V MAX* with an asterisk

Whenever I use an adapter I always feel like I'm getting away with something.

These adapters come in handy for older cordless tools. I was about to toss out an old Craftsman drill that has a bad battery. That's when I discovered that they made m18 and DeWalt adapters. It's a decent drill and the adapter brought it back to life.

Some tips if you plan to use adapters. 1. Don't leave them attached to the battery. Some batteries do not protect themselves and will discharge until cell damage. 2. Not all adapters for a brand work on everyone of those brands tools. I had to cut some plastic off of one to work with an auger. 3. The battery levels may not work with adapters so to avoid cell damage I wired in small voltage displays and calibrated it based on my multi-meter. 4. Use good batteries. The point of the adapters was to spend more on higher quality batteries but use less batteries overall. Buying the cheapest battery of any brand is asking for under performance, lower tool life due to higher current draws and significantly reduced run times.

It would be cool to see this adapter comparison on Makita LXT tools since their own batteries are so far behind the competition.

The channel Tool Scientist did some great testing on M18 batteries as far as depth of discharge, and they noted that the low-voltage cutoff does not work if you are using an adapter. As in, the tool will discharge the M18 battery's cells to absolutely dead and permanently kill the battery in no time if you're not careful. Just something to keep in mind when talking about battery adapters. Edit: This was for M18 batteries, I assume other tool battery brands may have the low voltage cutoff circuitry in the battery, rather than a negotiation between the battery and the tool like Milwaukee.

I feel a bit cheated by the lack of Makita here, especially after the beans battery. Even with the losses I'd rather suffer those than buy a whole extra battery system, worrying to see one melting though.

Ingersoll rand relaesed a new impact driver boasting 3800inch pounds love to see how that performs

I standardized on the inexpensive Kobalt 24V Max batteries and made custom adapters for my Hitachi 18V tools out of old Hitachi batteries. This makes for a factory fit on the tools and supercharges them. Noticable gains on a circular saw and sawzall.

One of the best Power Tool testing videos I’ve ever seen! We need more content like this. Hope it becomes a recurring series!

Great video. I nearly burnt one tool because of these adapters, It started melting just like in the video. I opened it up and noticed that the wires used are so pethaticly weak. Replaced them with bigger guage wires and high melting solder, works great. Every time I buy one of these adapters out of the box I open it and replace its silly wires and never had an issue.

It would be interesting to see if older tools that ran NiCad batteries would benefit from using an adapter for a more modern Lithium battery, and if it would be a cost effective way to breathe new life (higher output, runtime, etc) into older cordless tools that still work fine. I have a bunch of 18v Dewalt NiCad tools but most of the batteries are not great anymore. I'd personally be interested in this test.

I've been using a Kobalt battery to Ryobi tool adapter. It's been great, especially for the circular saw that had been really underpowered.

If you did a few testes with kobalt 24v into 18v tools that would have made this episode perfect!

Great stuff, appreciate all the testing you do!

Just changing to thicker wiring on the Amazon adapter would be a neat for comparison. Or a better made 3d printed unit for same voltage adapers.. Thanks for the hard work!

I 3d printed a ton of Ridgid to Ryobi battery adapters since Ridgid's lineup is so space. Now I have a 50/50 mix of the tools, but all using Ridgid's batteries with the LSA (lifetime "warranty")

Awesome show! Great to see what makers can do in the small batch manufacturing arena these days, bringing good stuff to market.

I use many adapters, including Makita, Hilti,Bosch, Metabo Hpt and all of those that you have to Dewalt batteries. I also have a bunch of 12v adapters too. This video was extremely interesting for me to see, and i wish you do more of those to all the tools with all the batteries. Another TTC blockbuster, thanks!

Really not bad considering. I have milwaukee stuff at work but couldnt pass up the $40 ryobi grinder for quick light work and the $20 adapter still had me at less than half the price of the milwaukee grinder😂

I've been wondering about battery adapters for a while, you've helped me make my mind up. Thanks for a great video 👍

This is a great topic. I'm balls deep in the Milwaukee ecosystem but the fact is the red tax is pretty high for some of the tools I don't think I'll use often or work hard. I would like to be able to buy some HF tools and use adapters so I can at least keep a single battery eco system. So I think it's very valid that people might want to use the expensive batteries on cheap tools - sometimes. But Milwaukee not having the low voltage protection built into the battery is an issue I worry about.

One thing to note is which part has the low voltage protection. If you run a Milwaukee battery in a Ryobi, you can run the voltage all the way to zero and ruin the battery

Absolutely love your channel, thank you for all the testing that you do! An important note on this topic not covered here, not all batteries can protect themselves from over-discharge. For example, when you tear down a Ryobi pack you can see that it does have FETs to disconnect the battery and protect it from over-discharge and permanent damage. Smart battery, dumb tool. However, Milwaukee M18 batteries do not, they rely on the tool to stop drawing power. "Dumb" battery smart tool. For that reason I will not use an adapter to use my M18 batteries on another tool because it could be permanently damaged and they are more expensive anyway. Additionally, you are absolutely correct, anytime you add an adapter you are adding 2 terminals and a wire on the positive path, and 2 terminals and a wire on the negative path, every single element there increases resistance and fundamentally will reduce efficiency. That's a simple physics issue. The only way to maintain the output of the tool would be to overvolt to adjust for the power being lost in the adapter. So adapters can be useful. Some batteries have slightly higher voltage or current capacity and could possibly get you slightly better performance out of your tool. However, simply using an adapter comes with an efficiency penalty, some of the energy in the battery will be lost to heating up the terminals and wiring in the adapter. Lastly, you need to dig into the details on any battery to make sure that it can safely shut itself down without damage. M18 batteries should not be adapted to other tools, but Ryboi would be fine. I haven't dug too deeply into the various other manufacturer's batteries, if other people in the community have it would be really helpful to share here which batteries protect themselves and would be safe to adapt to other platforms.

24 volt Flex batteries on the Dewalt dcf900 impact would be cool to see those numbers since it gave a big boost to the Milwaukee.

You should’ve tested end voltage and protection and such. The extra runtime on the grinder with the yellow pack, maybe the voltage ran real low depending whether the tool has the battery management or it’s done by a BMS inside the battery pack. Doesn’t DeWalt do protection and balancing with the tools and charger? But M18 packs have the BMS in the battery.

This is important information. It's good to know when to be tempted, and when not to waste your money.

I have an old Ingersoll Rand IQV 14.4 Volt Right Angle Die Grinder that I really liked, but the batteries died over the years. I would like to adapt to a Milwaukee or something similar. I also have an old school Milwaukee drill that I need to adapt to the new M18 battery. I’m glad you tested the adapters. Thanks for the honest reviews.

Thank you so much! I’ve been wondering about this! I’ve had great success using a cheap ryobi chop saw with my dewalt batteries courtesy of an adapter.

Would've loved to see you tested the adapters on Makita 18v tools since they don't update their batteries.

Awesome! This is right up my alley - call me an "adapter aficionado". I own tools from many different brands and I've purchased adapters for all of them. I mostly use them as backups since I also have brand-matching batteries for my tools - yet it's handy to be able to use other batteries when I want more runtime. This testing correlates with my anecdotal observations and armchair theorizing. I've always feared to run high-draw tools for any length of time on an adapter - seems like that's warranted. I suspect the wiring in many adapters just can't handle the load. Blowers and grinders for example, I don't like to risk it. On the other hand, some tools seem to run faster and better with an adapter and "good" batteries. My Ryobi tire inflator is audibly faster when I run it with my Dewalt batteries. I'm not worried running lights, drills, rotary tools, etc. with adapters. While there are some losses (something I appreciate knowing), it seems like an acceptable compromise in a backup situation. I might discourage someone though, based on this information, from buying tools and batteries from different brands intentionally.

Another great video! Anytime you add more connections there is going to be a power loss. I.E. like adding battery adapter. However it may be worth it if you are locked into a certain battery brand.

I use them mainly for Dewalt batteries on m18 finish nailers. Works great.

Years ago i had a snap-on 9.6v ni-cad 3/8th impact and a snap-on 14.4v nicad 1/2in impact. Discovered i could trim some plastic tabs on the 14.4 v battery and make it work in the 3/8 impact. The 3/8 impact is now long dead. I still have my 14.4v impact and still using it almost 20 years later. Bought a battery rebuild kit from amazon, and then the motor died. Went on ali-express and found a motor that would work. She's back into action, and going strong.

I bought an adapter for my old 18V Dewalt to M18. Makes the circular and reciprocating saw useful again for the occasional use.

Great and informative video! I can honestly say that I wasn't aware just how many adapters are out there. I've got an old Craftsman impact that they no longer make or sell batteries for, so I might give a Craftsman to Milwaukee adapter a shot and use some M18 batteries. Would make it a lot more useful than the paperweight it currently is 😂

That increased voltage performance bump was what I also noticed with our chinese leafblower. It is a 20v tool which didn't performe well. We wanted to return it but the seller offered to send another battery in exchange for the one the tool came with incl. another charger. It is a 28V battery and with the new battery that leafblower moves some serious air. Maybe an idea for tool testing to include higher voltage on some models and thereby making them more attractive with higher power.

Can't wait to see more content on adaptors, especially using Flex batteries. Thanks!

this sort of stuff really scratches an itch of mine. awesome work.

Thanks for a great video! I have another idea for follow-up : charging using adapters. Possible at all, without all the communications? Risks, draw-backs? I think the biggest risk is missing over-heat protection and risk of unbalanced charge. I would love to use my 6 port Ryobi charger to charge my Dewalt packs. It is so convenient: you click in up to 6 packs in the evening and next day morning all of them are fully charged, ready to go. It charges one pack at a time @2.5A, so it should be "reasonable" for most of my 5Ah packs...

I wish you included some Makita 18v tools using other batteries. Their older batteries don’t have the beans anywhere near what the other brands have with better cells and larger sizes. I recently bought a couple adapters on Amazon to use my DeWalt XR 6.0Ah packs on my Makita 18V angle grinders and it makes a world of difference in runtime for sure. It would be nice to see your measurements to confirm what I feel.

I use Dewalt 20v batteries on Ryobi and Ridgid power tools without issue. Many years ago I had an old Dewalt 18v angle grinder and all my batteries died, I hooked two 12v deep cycle batteries in parallel and used a 12ga extension cord to power the grinder via a hacked up 18v batter shell.

I recommended this test to another RU-vid friend , im so glad you guys did it

A few years from now, we will see a computer chip module to make sure the batteries that go into the drill are official. "In case it damages the drill" which it of course won't but it will damager thier money

Ryobi offers a lot of affordable tools and I'm already on the DeWalt 20V system. So, I have considered buying Ryobi to DeWalt battery adapters several times. Cool test!

I would love to see some behind the scenes in how you make your videos. I get the feeling in all of your videos that there's so much more that we don't see. It's easy to tell how much effort you put into your videos but I would still enjoy actually seeing some of it

My assumption on the melting adapter is that I would expect the adapter to be made of inferior plastic... like ABS. Unfortunately, I can't imagine the adapter companies would be bothering to add that info into their molds, like the tool companies do. 😊

Always answering all the most important questions of the universe 😁 👍

I've been thinking of using an adapter from makita lxt to the makita 18v nicd tools that I have. Old wimpy tools, but an additional small circular saw can come in quite handy.

I'd like to see you test how much the adapters run down the batteries even when the tool is idle. I have a Dewalt drill 18V, Dewalt adapter 18-20V, Dewalt 20V battery. Leaving battery plugged into adapter runs the battery dead in 24 hrs or less.

Been impressed with cost/power/warranty from hercules stuff so started buying those when on sale. I've liked em enough but their platform isn't that wide so I've been using the adapters for my dewalt tools and I've noticed comparable performance so no complaints from me

Over in Europe they started something called the Cordless Alliance System. Basically every battery of the same voltage works on any manufacturer's tool of the same voltage.

This was an interesting video. I have kinda stayed in the M-12 and M-18 platform because I have a bunch of the batteries and chargers already. However there's a few tools that I would like to get, however I don't think they would get used very much. I think a Bauer or Hercules would do what I want, I just don't want to have another battery platform. I may need to see if they have a m-18 to harbor freight adapter.

I have a couple of adapters that I bought expressly to run _low_ demand tools. Specifically, my Ryobi power inverter. It was a really inexpensive way to get some more run time out of it with the Milwaukee batteries I already had.

Super cool video - got an adapter to use Bauer tools with my DeWalt batteries but have not used it yet, no Bauer tools.

Thanks for all your answers man

This very interesting for me, because the knowledge of which batteries work with tools you don't want to get rid of, when gradually up-scaling your power tools.

I do this. I've got a bunch of Milwaukee batteries but Project Farm's review of right angle drills showed the Ryobi one+ HP was a better option. I just bought the Ryobi tool-only and an adapter off Fleabay. Rarely used but always available.

Would be an interesting to test the dyson vacuum with the power tool battery adapters

For those that are considering using Flex/Hilti/Kobalt 6s batteries on tools designed for 5s packs (most other brands) while the voltage under load will probably sag into the safe operating range of the tool, the low voltage cutoff in the tool would cutoff far too low and damage the batteries, especially under light loads. That is, if the tool has a cutoff based solely on the input voltage. Not all do--some rely on a sense pin from the battery to initiate the low voltage cutoff / protection, e.g. Hitachi/Metabo HPT where the battery pulls the LD pin to ground when it gets to ~16v, otherwise the tool will just keep pulling power as the voltage sinks lower and lower...

Great video and unsurprising results. For future testing please continue test with the brands own batteries. I would have no problem with adding an additional test with a “standard” battery and adapter

One thing to keep in mind is over/under charge protection for the batteries. With Ryobi having a battery version of just about everything, I was considering a way to use my supply of DeWALT batteries with Ryobi tools instead of needing to maintain additional batteries. I came across several discussions stating that Ryobi has their protection circuit in the battery, while DeWALT has it in the tool. As a result, if you use a cheap adapter to run a Ryobi tool with DeWALT batteries, you could drain the batteries below the minimum voltage they need to charge, killing the battery.

Really interesting findings. I really liked the adapter stack. I could only imagine how awkward that would be to use

I'm on the Makita 18v platform. I really liked the Milwaukee vac so I bought an adapter. I would start and work once. After shut off it wouldn't start again until you pulled and reinserted the battery. I thought maybe it was a defective vac so I tried a second and same thing. I returned the vac and just bought the Makita which I ended up very happy with.

I just tried an adapter for our Dyson V8 vacuum to use 5ah M18 batteries. I was able to use the Dyson on high quite a bit longer than the standard Dyson battery. It worked. I weighed the junk I picked up before switching and had .7oz including the plate. Using the M18 over the exact same sections of carpet I was able to pick up an additional 1oz. I could feel the difference. The vacuum was harder to move around as it was more powerful. Not sure I am going to keep it though. It’s a PITA to go to the garage first to get a battery.

It’s nice to know there are some adapters that actually are worth it and that there are some for Hercules batteries as well! Of all these adapters, which would you recommend? Great video y’all!

Awesome video, I will say I have been using a Ryobi to M18 for lots of one off tools IE nail gun my reason is for a non professional I don't want or need to spend double for a tool I use a couple of times. The Milwaukee tax is real!! But IMO they have the best batteries.

Would love to see adapters on makita, since Milwaukee and dewalt have newer battery tech. Maybe the dewalt powerstack would give the blue tools some more power.

I use the Dewalt 20v->18v adapter keep my old tools going. Even if that adapter gives up some of the beans, I think the net gain over the 18v NiCad is a winner.

so thankful you tested this. but all had failure issues except the one you linked? i have ridgid batteries and they dont have that option

I'm mainly in the Makita battery environment. Although, I also have a Milwaukee charger & batteries, as well. Most of my tools are Makita, but I do have Milwaukee, DeWalt, and Ryobi. I do have adapters for Makita to Mil, DeW, & Ryo, as well as adapters for Milwaukee to Mak, DeW, & Ryo. They work pretty good. I'd love to see this same test with the Makita batteries and adapters, using the meters and test benches.

Talk about timely. My next purchase is going to be the Ryobi right angle die grinder and I was looking at getting an adaptor.

I've noticed the wonderful improvements using flex on my makita tools, but be careful with the flex on makita knockoffs.. It runs those too fast for the cheap internals they have. Flex on ridgid is great too!

I would love to see a comparison with older, outdated tools also. Specifically, the old Ni Cad from DeWALT. I have their old 18V and 14.4V Ni Cad tools. I would love to know the numbers when adapted to the new 20V batteries.

Great episode

Seeing the graph at 13:23 made my jaw drop. I'm just a person who does DIY stuff and has the 4th gen m18 hammer drill with 3, 5ah (because they came with the kit for free) and I cant believe how much more power that drill has! I'm most likely gonna buy a flex battery if and when those 3 batteries die!

Watch for overheating! Ryobi Rotozip melted with Dewalt (so did the adapter). Angle Grinder, air pumps, and airstrike nailer all worked fine for me.

I think that pulsing on the ryobi is possibly something to do with the speed controller safety with the motor being able to pull more amps than the speed controller is rated for. Possibly miss matched motor/speed controller or just ryobi batteries not able to out out as many amps

Adapters eliminated any reservations I had for purchasing certain tools from brands outside my platforms. I've had great luck with adapters for a over 5 years now. Makita used to have the only cordless biscuit joiner so an adapter to dewat batteries was perfect. Also have ryobi to dewalt for ryobi nailers/inflator/compresor/planer, bosch to dewalt for my bosch miter saws, and dewalt XRP to dewalt 20v for the old dewalt 18v nailer. No notable loss of power on any tools other than the makita biscuit joiner requiring at least a dewalt 3.0 with 21700s, 4.0 with 18650s, or 1.7 PS. Notable gains of power with dewalt batteries on the ryobi nailers. All of these tools are pretty low demand and I wouldn't use them on high demand tools requiring constant output. Never had any heat issues or battery/tool damage. All my adapters work for both dewalt and Milwaukee batteries. Awesome video sir. It will definitely introduce adapters to a lot of people who never knew they existed.

Been running Ryobi tools on Bosch 21700 pixies for a while now. It makes using two platforms so much easier

A detail that would be interesting to point it out, in my opnion, is that the work on your RPM X Time chart is that the work is also the area below the lines. So because the one with the adapter has a smaller area, it means that it did less work. This is more a pet peeve from me knowing a lot about engineering and I don't think is that important in the end as pointing it out as the amount the RPM also works but a more correct way of pointing it is the area

This is perfect timing I wasn't happy with Milwaukee's heated apparel so I just bought a Makita heated jacket, an adapter and I'm troubleshooting the power supply

Out of 15 dewalt 20v batteries I've only had 2 quite working. I've a 2ah since 2014 and it still working.

Man, I wish you would have done the Metabo HPT g3615dv 6” in this episode or another because finding adapters for that is very challenging a and B wouldn’t it be sick to see one of the new multivolt batteries that actually are “true” 36v nominal batteries and that to Makita XGT adapter they both are a 40 volt max

Nice, appreciate the review of some adapter/battery combos. Now, can you do every possible tool/battery/adapter and rank them? I'm sure it would only take infinite time and money.... 😀

I primarily have Dewalt 20v tools . On Craftsman v20 I use an adapter to my Dewalt 20v battery. I bought a v20 Jigsaw, because I use it infrequently and didn't want to pay $100± more for a Dewalt to just lay around most of the time.

That snap on the end lol, this opens the doors to good Walmart special brands that show up in the marketplace, those batteries could be used elsewhere

Very useful video! I am in the Hercules ecosystem from Harbor Freight and, shockingly, the Bauer brand (also from Harbor Freight) is not interchangeable!

BE CAREFUL when using adapters with ryobi tools. Ryobi does the voltage management on the battery instead of the tool. If you use other brand batteries with Ryobi tools, they will drain your batteries below the safe voltage level and kill then. You need to install a low voltage disconnect module such as xh-m609, but these are good up to around 20 amp. Also, the losses are mainly due to the voltage drop caused by the thin wires used inside the adapters connecting the different terminals. They are easy to replace.

i use makita lxt on my 18g ryobi brad nailer. so cost effective!

Man you guys are like in my head it seems -- I discovered 3DPrintedAdapters last night and ordered some 😂. I would love to see high quality adapters for other batteries, I'm a little concerned about overvolting long term. Do any of the adapters work with the chargers? Can I charge other 18v batteries on the milwaukee charger? Thanks and keep up the good work.

I've used milwaukee tools for years, when i want a garden tool, find them too expensive for the small jobs and have had a ryobi tool to milwaukee battery for years, fantastic way to have one battery system and use over multiple brands where it does not matter as much, im sure whatever losses my hedge trimmer have are minimal :)

There have been several 12v impacts and power ratchets from dewalt and Milwaukee that it would be interesting to see on 20v packs, especially eith the 12v offering already performing close to the 20

us Makita bros are feeling particularly left out :(

Nice video, thanks. Is there a way to run bosch and/or metabo angle grinder on milwaukee batteries vs original? Would love to see that

you showed Milwaukee 1/2 with flex bat, it would be nice to see how much dewalt 1/2 improves with that bat..and as always great vid..

Im pretty surprised to see the performance loss from some of these adapters. Ive got one to use my Milwaukee batteries on bauer tools but I think im going to branch out to some ryobi stuff because I really like their lineup and price.

In other words: Batteries should be standardized.

Have the Milwaukee cordless vacuum with an adapter to run my Dewalt batteries. Shorted out one vacuum right away got it replaced and I can tell this other one has some issues as well. So yeah in certain tools they would be good idea

Great video! Can we get a video on the Milwaukee Insider ratchet? Waiting to see the gauntlet before I buy one.