DeWalt 20V Max 6.0Ah Pack Teardown & Analysis

It’s been a little while since I’ve had a shiny new tool battery to tear down!  This one showed up in the mail for some analysis and evaluation - so analyze and evaluate it I shall!

This is a companion discussion topic for the original entry at

(Comments from Blogger)

2017-04-23 by Ned Funnell

Neat! Is this the cell that Tesla is calling its 2170?

2017-04-23 by Russell Graves

No. Tesla’s 21700 format cells should be a bit larger around, and are Panasonic cells using some proprietary chemistry details.

2017-05-07 by Joe the Jerk

Type 2: XR/“20V MAX” packs
Type 1: Old bayonet-type, including XRP

Also, the DCA1820 isn’t quite “straight through”. I bodged a COB from a Philips 120V LED bulb into a DW908 flashlight after the halogen blew; works flawlessly with a NiCad battery, but with the adapter and a DC204? The fucking thing blinks every second. For that matter, so does the LED on my “18V” impact when used with the adapter. If you ever get a bead on what the fuck that’s all about, I’ll be eager to read about it. Cheers.

2017-05-07 by Russell Graves

Interesting. I didn’t realize it was a smart adapter. I may have to find one to play with!

2017-06-13 by Miguel

Well done!
You wrote about other purposes. Do you think it’s OK do put these two packs in series to make a 36V 6Ah battery, without any modifications, to use in a e-bike? Thank you in advance for your comments.
Cheers, Miguel

2017-06-13 by Russell Graves

That would work just fine!

2017-09-08 by Gullster

Miguel - Did you use DeWalt batteries for an ebike? I’d like to do that too. I bought a Bionx with a dead battery but it doesn’t seem suitable for conversion (too complicated) so I think I may have to buy a generic 36v hub and start over.

2017-09-08 by Joe the Jerk

You need not start over, Gullster. You can definitely run a 36V (“37V”) Bionx by “piggybacking” DW batts if it’s the older I2C protocol (i.e. from before 2009 or so). If not, it’s not too complicated to convert a Bionx hub to run with a generic motor controller and battery. Go do some searches on Endless Sphere, especially by “DOCTORBASS”. You will be pleasantly surprised. Cheers.

2017-10-02 by Joe the Jerk

Addendum/erratum: I just noticed my DCG412 mini-grinder (“20V Max”) is Type 3, so my association above may be incidental.

2018-03-23 by Unknown

Hi Russel,

I’m currently looking to “bypass” the usage of a battery pack. I’d like to use an old pack, remove all the accus and use only the empty pack with the contacts that I’ll connect to an external power 18-20VDC power supply.

On my crimping-tool, I’ve got 4 contacts use: B+, B-, ID and C4.

I have connected +18V to B1, 0V to B-, an 800ohms resistor between B- and ID and applied 4VDC on C4.

But nothing works; the status LED on the tool always shows up the “empty battery” signal.

Any idea what I’m missing?

Roger, Switzerland

2018-03-27 by Russell Graves

I’m sorry, I don’t have any information beyond what I’ve posted in my various teardowns. I’d love to know what they’re doing, but I have enough of the legitimate 20V Max packs laying around that I haven’t had a need to replace them.

2018-03-28 by Joe the Jerk

Roger: Have you done anything with the “TH” terminal? I’m not sure if the tool cares about the temperature, or only the charger. Please report back on your progress. Very interesting!

2018-05-29 by Joe the Jerk

I was totally wrong above about the “types”. Black and Decker (hence DeWalt) uses “Type 1”, “Type 2”, etc. to indicate revisions of a given tool or accessory. I saw an ancient (1970s at the latest) Canadian-made B+D 1/2" chuck mixer motor/drill a while back, and it was a “Type 1”. Hope this helps anyone else who was wondering!

2018-07-10 by Jose

Fantastic post, very encouraging. After trying using some super heavy lead acid batteries which led to brakes, balance and weight issues, i then moved to panasonic 18650 3200mAh but not enough juice and too much risk due the use of un-proper charger, so drooped the idea for a doable ebike for hills, for the past year.

So after reading you post, will try to get some of those dewalt batteries + charger and put them in series to see if they can withstand the 20A peak of my 36V-40V system.
Any idea if there is a review coming for the dewalt 9Ah batteries, that would be fantastic.

2018-07-10 by Russell Graves

These should handle 20A no problem. I push them up to 40A frying an egg, and they take it fine, though I might not do that every day… you should be fine with 20A from this pack.

If you’d like a 9Ah pack reviewed, ship me one and I’ll poke at it!

2018-09-06 by Joe the Jerk

FYI: I bought a two-pack of DCB230 packs (slim, 3.0 Ah), expecting to find some Panasanyos inside. Nope! Five Samsung INR21700-30T cells. I mean, all I can see is “SAMSUNG” but it’s a 3.0Ah, (1P)5S pack. Rated for the same 30 amps, so I guess I shouldn’t be disappointed.


2018-09-06 by Joe the Jerk

As I said to Russell elsewhere, I just bought DeWalt DCB230 packs and they contain (what I think are) 30T cells.

2019-06-29 by “-sc”

Interesting that your 3Ah and this 6Ah are both reading ~800 ohms from B- to ID. My 5Ah packs are about 1 M-ohm. My 6AH are only about 600 ohms. My 2Ah packs are about 1.2 M-ohm. It appears the lower the pack size, the greater the resistance at the ID pin.

2019-09-19 by wlbryce

Thanks for taking the time to do this and the 6ah teardown! Saves me a lot of time! Will be using the 6ah pack to power some security cameras on our off grid home.


2019-10-06 by JJ

Thanks. Very useful.

I’m starting a new electronic project and this 20v 6ah battery is exactly what I need. Much cheaper than buying 20700 batteries separately. I can’t find however any BMS protection PCB for the 20700, only for the 18650. Do you think that 18650 BMS PCB’s could work on 20700 batteries?


2019-10-08 by Russell Graves

It’ll be totally fine. The BMS only really cares about the cell voltages, and if it’s a low capacity 18650, high capacity 18650, 20700… whatever. As long as you’re in the same chemistry, it’ll be perfectly fine.

2019-11-20 by Unknown

Just so you know that is not a 5s pack if you charge it on a non DeWalt charger like a lipo or lion charger u charge it as a 2s two outside terminals are positive and negative the 3 inner terminals are for balancing and reflect the cell count three terminals mean one will be another negative and the other two are cell 1 and cell 2 if you charge that on a 5s setting and it will blow up!

2019-11-23 by Joe the Jerk

No, friend. It’s a 5S pack. For the “last” two cells, probe “C1” and “B-” (the “first” cell; really the last in logical order), then “C4” and “B+” (the “last” cell; really the first).

You use a hobby-type balance charger to charge any DeWalt “20V Max” battery pack, and you don’t even have to open the case. You can also use “20V Max” chargers to charge any 5S li-ion (or lipo, I guess) pack with compatible charge rate, as long as the charger “sees” 10kOhm resistance from “TH” to “B+” (emulates a 10kOhm-at-25C temp sensor), and ~1kOhm from “ID” to “B-” (DW’s pack identification scheme, which presumably controls charge rate). I’m lazy and just plug a separate DW pack’s “TH” and “ID” terminals into the corresponding terminals on the charger.

To sum up, the cell groups are as follows:

POS(+) NEG(-)
B+ to C4
C4 to C3
C3 to C2
C2 to C1
C1 to B-

Hope that helps. I had to type this out twice, so I really do mean it! lol

Hi, sorry to jumpstart an old thread:
I have the 18v batteries which seem to have an identical layout. I’m trying out one of the dewalt to two-wire adapters and intend to add a low voltage cutout, but am curious how the dewalt tools handle this. My 18v drill has just 4 connectors:
B+ B- and in the lower row ID and C4
Anyone know what is being done here?

thx AndyD

I think many of the tools just cut out on the overall voltage of the pack. (Leaving balance and cell voltage concerns to the charger.)

When building custom stuff around DeWalt batteries, I use 15 volts as the minimum threshold, but I think the OEM tools use a bit lower threshold than that - not sure what it is exactly though.

As far as I know, the tools only use the bulk pack voltage as a cutoff threshold - they’re not doing per cell monitoring at all, and there’s nothing in the pack to do that, either. 13-15V is reasonable for a 5S pack.

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Some tools seem to cutout on battery temperature, but I have no real proof of that beyond “it seems they do it”. Maybe some of the extra lines are temp lines? I know the charger will refuse to charge my Milwaukee’s if they’re hot.