(Comments from Blogger - Continued)
2018-12-30 by Unknown
Very late reply but, if it is a CC/CV charger, no. The little “BMS” should do the balance charging for you!!! Please monitor the first few cycles to make sure it is balancing sufficiently! And regularly check that the pack is not drifting out of balance. But these packs seem well suited to repurposing, weird honestly.
2019-01-07 by Michael Y
Excellent report!
Quick Question:
Are over discharge protection built-in to the battery itself? Or is that being monitored by the tools themselves?
2019-01-07 by Michael Y
Not sure my post got published?
My question about if over discharge protection is built-in to the battery itself or is being monitored by the tools themselves?
2019-01-08 by Russell Graves
The over-discharge protection is built into the tool. There is no way for the battery to shut off discharge current.
2019-01-08 by Russell Graves
Sorry, I have comment moderation on due to spam issues (lots of people trying to sell Best Solar in Kondwaku or somewhere totally irrelevant to my blog). I have to approve non-spam comments on older posts.
2019-04-26 by Unknown
I thought the blog post was excellent, but the comments section also have alot of great info.
I found this blog while trying to research a way to make my 20v dewalt tool run off 110v ac. The tool itself has 4 pins which make contact w the battery B+/- and two inner pins TH and C3.
What i was hoping to do is seat a battery and charger together as my power source. and just jump those same the 4 pins over to the tool. Any reason that wont work? Like the battery knows its on a charger and wont output?
I did something kinda similar to this with my dewalt corded/20v vacuum. I modified vac to charge a battery while plugged into 110v but still use the battery as power source when unplugged. Only thing i had to do was dremel out a way to swap the battery terminal. The charger board/guts fit fine.
2019-04-27 by Russell Graves
It should work fine - C3 won’t be an issue, but you might need to interpose TH somewhat. I don’t know what the tool/charger side of that looks like to know if it would be dragged out of range by two devices trying to read it.
There’s no way for the battery to shut off output - the output terminals are wired quite firmly to the battery terminals, with nothing in the way that could terminate current.
2019-05-16 by Unknown
I appreciate the work done here and the information provided. This gives me the ability to use these Dewalt batteries for other purposes around my home. These batteries will be useful with the inexpensive DC-DC step-up and step-down boards available from China to run other DC devices.
For those of you on a budget, you can sometimes find cheap cordless tools at second-hand stores. People donate these because replacement batteries are too expensive, so they just buy a new tool set. Years ago my wife bought a nice Ridgid 3/8" drill and 1/4" hex impact driver set with charger, bag, and three batteries that didn’t work, all for $10. I took a battery apart and used a $22 switching power supply (24 V at 15 A) to power the impact driver (I adjusted the supply to 18.5 V). Though it’s a now corded driver, I don’t mind because I keep it on my shop bench (it also runs the drill). It’s a nice way to continue to use the drill and driver, which are well-made and didn’t have to get tossed out.
2019-05-31 by Unknown
my 20V battery is out of balance. the 3 lower cells are 3.6ish when the upper 2 reach 4.2 and it quits charging. I dont think think the DCB115 does balance charging. even when I leave it on over night, the voltages never equalize.
There is one more pin called ID. The little chip could be an eeprom. or it could be a voltage monitoring chip that works when the battery is in a tool.
Either way, by batteries are only reaching 2 bars on when the test button is pressed… my 5A packs are missing a lot of watts…
2019-06-01 by Russell Graves
Try using a load resistor of some variety and bringing the upper cells back down to 3.7V or so and see if it improves.
But if the pack is out of balance and you don’t know why, it’s likely some weak cells.
2019-06-05 by Unknown
Russell,
I travel a lot and need to take DeWalt 20 v batteries with me to power such tools as a cordless drill, battery powered light, etc. I also have to carry a laptop and have an extended battery, but it is finicky. I noticed that my wall adapter shows a 19.5V 3.33Ah output for 65Wh. I was thinking about ripping the bottom off an old Dewalt Tool and Frankenstining it to a laptop adapter cord. I know I can bring the voltage down to 19.5 fairly easily. What I don’t know is if the Ah can be pushed up a bit to get to 3.33Ah and 65Wh.
Thoughts?
Thanks,
Sam
2019-06-05 by Russell Graves
Your laptop charger isn’t rated in amp-hours (Ah) - it’s rated in amps (A).
The DeWalt packs will supply 3A easily, but the packs will be below 19.5V when drained. That’s 3.9V/cell, which is still nearly fully charged. You’d want a buck/boost converter with a configurable low voltage cutoff, and then it will probably work fine, unless the laptop and charger have some sort of communications among themselves.
2019-06-16 by Pegua
R1, R3, R4, blow up, jump then as a fuse
2019-06-18 by TimeTraveller
My DeWALT DCB181 18V 1.5Ah 27Wh has 9k68 on TH–B+ and 316R on ID–B-
2019-10-09 by Dwayne Baraka
Hey, I’ve got an old battery and want to use it with a 20V DC power supply. After I take the batteries out of the pack, will it be possible to fool the circuits into thinking that there is a battery present so that the tool works?
I’m guessing a few resistors to get the required 4, 8, 12, and 16 volts for the C1 C2 C3 and C4 terminals?
2019-10-09 by Dwayne Baraka
Hey, I’m planning on using an old battery case to make an AC adapter through a transformer.
I’m confident I’ve got enough juice, but unsure what will happen when I disconnect the batteries.
I’m guessing I need to do something like set up resistors to whisper 4, 8, 12 and 16 volts into C1-4’s ears. Is that right or is there more I will need?
Best Regards,
Dwayne.
2019-10-09 by Russell Graves
Sorry, I don’t understand what you’re trying to do enough to be able to offer advice.
2019-10-10 by Joe the Jerk
Hi, Dwayne. If you’re looking to power a tool (or whatever) with an AC adapter, you need not fuck with the C1-C4 terminals at all on the tool end, which are there for the charger to balance the cell groups. If it won’t work with just B+ and B-, try emulating the “TH” and “ID” terminals; “TH” is a standard NTC 10k-at-25-degrees-Celsius thermistor, and “ID” is a resistor whose value corresponds to DeWalt’s specified charge rate for the pack (e.g. 1 kOhm for the 21700-celled DCB230, ~800 Ohm for DCB204, ~316 Ohms for the wee DCB203; IOW, more resistance means a faster charge rate up to the charger’s limit). The newer DW brusless motored tools may need one or both of those terminals to work, but brushed ones (“20V Max” or any older ni-cad era tools) absolutely don’t; proof of the last one is that DeWalt’s so-called 18V-to-20V adapter (which in no way changes the voltage, of course) only spits out B+ and B-, no other terminals.
Hope that helps, comrade. Please feel free to reply with your results! Cheers.
2019-10-13 by Dwayne Baraka
Thanks, this is really useful.
I tried wiring the AC direct to the board (with the balance board still in place). B+ and B- reporting 19.8 volts
Using a brushless driver, it would connect so that the light on the driver would go on, but not operate the drill.
I suppose its possible I burnt out one of the components or the board when soldering the main terminals with new wires, but I can’t really see the heat transfer being high enough.
I’ll check the components you identified, try adjusting the voltage and get back to you! I also have one cordless that I can try.
Thanks again!
2019-10-15 by Dwayne Baraka
Thanks, I sourced a spare (empty) battery pack and started again. (Amazon.com) My first battery pack had no voltage indicator, whereas this one has it built-in. It’s a handy addition! No second guessing whether power is being delivered to the pack.
Same result - ie, enough to power the lights on Brushless driver and Brush Drill, but not enough to power it.
On looking at the terminals in the tools, the all have B+, B-, TH and C3 terminals. I should have realized this earlier. (Flexvolt uses way more)
Tim Medders noted above that the packs wont work if C3 is disconnected. I experimented slightly before removing the batteries and note that cutting the connection to C4 didn’t stop anything, and I assumed it therefore wouldn’t matter to cut the others. Shoulda checked the tools! Still a strange decision by DeWalt to check for dead cells 1-3?
I’m now surmising that I need to give the correct voltage to the C3 terminal. Looks like that will be at least 11.1 (3.7v per cell cut off) and up to 12.6. Anyone have any idea what resistor I should use? The current pulled through must be minimal, but not sure how to calculate. Alternatively I guess I just drop a few bucks on a step down converter or regulator - your thoughts appreciated!
I should also be able to use the same solution to fix my first battery pack, so I’ll have two - luckily I included two outputs on my AC to DC transformer!
Cheers!
2019-10-15 by Russell Graves
They might be checking for weird balance issues.
A note: TH is a 10k NTC thermistor going to the /positlve/ pack terminal - it’s weird.
Try it with TH connected, then see if you need C3 as well. They can’t be pulling much power from it or it would unbalance the pack, so I’d just try it with some 10kΩ class resistors first, then modify as needed once you get it working.
2019-10-26 by Dwayne Baraka
Thanks Russell, after thinking about it a bit more, and quite a bit of experimenting, I got it working with a buck an adjustable buck transformer feeding into the C3 probe.
Adjusted the buck to about 12V (I think 11.1 is the minimum, and 12.8 the maximum) and it is working really well. I haven’t tested under a huge load yet, but it is powering the 20V Max Brushless tools and Brushed. It needs the TH connected also.
A friend has already asked me to build one for him also and I’ll do a build video and post it here!
I didn’t have many of the parts, and tended to go bigger than what might be necessary, but total cost about $120 and now have mains powered DeWalt tools (I have 7 battery tools).
Cool!!
2019-10-29 by Russell Graves
Awesome! Glad you were able to work it out! Any chance you want to send me some details of what you’ve done, and/or photos? I’d be happy to do a writeup!
2019-11-19 by RDC
The small chip on the board in the battery is for OVP only, and only if the charger is monitoring the ID pin to detect it. It’s a BQ771803 or possibly CW1051 depending on the OVP style board in the pack. I’ve just started poking around in these, but didn’t see this info here.
Some mostly complete schematics of the OVP and LED boards I’ve messed with so far for those interested. Working off and on for one for the DCB118 charger now.
Vertical style OVP board, 4 layer PCB, (uses the BQ771803) - http://www.acidmods.com/RDC/DeWalt/DCB204%20Type%202.pdf
Flat style OVP board (seems to use a CW1051) - http://www.acidmods.com/RDC/DeWalt/DCB203%20Type%202.pdf
LED board - http://www.acidmods.com/RDC/DeWalt/DCB203-DCB204%20Type%202%20LED%20Board.pdf
2019-11-19 by Russell Graves
Hey, awesome! Thanks for sharing those details! Certainly more detail than I’ve put into my teardowns…
2019-11-19 by RDC
Welcome. It’s mainly for S&G, but figured may as well post it somewhere it could be useful. These were simple, now the 18v Ridgid packs, those things are a mess by comparison.
2019-11-22 by Greg
the c3 pin on the drill needs to see a voltage of 10v approx in order to run.
2019-12-07 by RDC
My schematic so far of the DCB118 20v Max Charger, for any interested or curious.
www.acidmods.com/RDC/DeWalt/DCB118.pdf
2019-12-12 by Joe the Jerk
I don’t own a 118, but I appreciate the work that went into the schematic. I downloaded it as a work of art. Thank you.
2019-12-12 by RDC
Welcome. The thing is a little more ‘busy’ than it really needs to be, but that’s because I left all of the jumper wires and jumper Resistors in it so I could redo the board virtually in the PCB software that I use here. That’s how I make sure I didn’t miss an connections and the schematic is as accurate as I can get it, by actually remaking the board based off the original.
Here’s some board scans and screenshots of a bit of that process, for any interested.
Index of /RDC/DeWalt/DCB118 Pics
2019-12-12 by Russell Graves
RDC, you’re insane, you know that. Ping me via the contact form if you want to chat - I enjoy getting to know insane people better, especially the kind who are good with PCB layout software!
2019-12-16 by RDC
Welcome, that wasn’t really too much of a chore though being a single sided board. The “BMS” in the DCB606 FlexVolt was a little more fun to do, as it was encased in a couple different materials to get at it first, and then being a 4 layer board.
Not the greatest screenshots as the detail gets lost, but you can see the mess a schematic made from a board usually is, then after it’s cleaned up and the PCB ‘remade’ to check things.
Index of /RDC/DeWalt/DCB606
Sent you a message also.
2019-12-16 by Rob Greenwalt
I can’t believe I found you guys. Just today I wired a AC/DC 20 amp transformer to my 20v Dewalt driver but all I use was B+/B- terminals.
The LED light would come on momentarily but no sign of power to motor. I presume I need to hook resistors as stated by Dwayn Baraka to the C3 and TH terminals? Any more specifics would be greatly appreciated. I am running a 40’ 12 ga extension cord from the transformer and hardwiring to battery shell. Can anyone foresee any other problems I might encounter? Thanks everyone in advance. I will post pictures of transformer, storage box and wiring if I get it working correctly.
2019-12-16 by Russell Graves
Sounds like that should work!
This is definitely a weird little backwaters of the internet. I’m quite surprised by just how much work some other people have put into reverse engineering this sort of pack…
2019-12-16 by Rob Greenwalt
I can’t believe I found this blog and you guys. I hooked up a 110v/20v 20 amp converter to my 20v Dewalt driver using a 40’ 12 ga extension cord. I thought I just needed power to the B+/B- terminals. I see Dwayne Baraka and Russell Graves mentions I need some voltage to C3 and TH. That’s about all I know LOL. Any details would be greatly appreciated.
2019-12-17 by Dwayne Baraka
Rob - I abandoned trying to find the right resistor combination, after having the same problem as you. It might be as simple as that (although I doubt it), but it was easier to order a battery ‘blank’ with related PCBs and components whispering “I’m a DeWalt battery” to the tools and rewire that with a buck transformer to make the tools work.
Battery pack: $16 Amazon.com
The PCBs and components in the blank battery pack, along with the buck transformer allow you to send the relevant
voltages to the terminals.
I plan to make a video about how to do what I have done (transformer with two leads that will power two tools simultaneously) over the holiday break. I’ll post it when I have it done, and the owner of this blog has graciously undertaken to post a new thread about it.
Sorry I am not more immediately giving you a fix, but I’d rather be comprehensive than pithy!
Dwayne.
2019-12-17 by Dwayne Baraka
Oh yeah, and I think I initally used 14ga, but 12ga should be enough and is what I will use for the video…
2019-12-17 by RDC
I home there’s quite a bit more than just a transformer in that box?
It depends on the tool. I’ve only had the DCD780 apart here, and some of them use the TH pin while others don’t have it, but it needs to have voltage on C3 and TH to work if it has both of those pins in the tool.
For the TH pin, put a 12k Resistor from B+ to TH and you’re done there. A 10k will also work, but may throttle the tool a bit as that would be the same as the pack being installed and a bit warm. If you don’t have a 12k, a 10k and then two 1k in series is the same thing, 10 + 1 + 1 = 12.
For that C3 pin, you need 3/5 of the pack voltage there, around 12v, which can also be done with a couple of Resistors to make a voltage divider off of the B+ and B- lines to get that 12v.
There are plenty of Voltage Divider Calculators online to work that out, just make sure you get the divider ends connected to the B+ and B- correctly and then the middle of it will go to C3, and do check it with a meter, couple times, before plugging it into the tool.
Plug in any 3 values here to find out the last one you need - http://www.ohmslawcalculator.com/voltage-divider-calculator
Source Voltage is the battery pack voltage, ~20v
Output Voltage is the 12v you want.
R1 = for example sake here, say you have a 10k Resistor.
Plug all of those in and hit Calculate, and you’ll get 15k for the R2 value.
C3 is not a current source, at least not in the DCD780 anyway, so you should be able to get away with 10k/15K there, or 1k/1.5k, anything that gives you that 3/5 value on C3.
Likewise there if you don’t have any 15k and only have 10k and 1k you can do a 10k + five 1k in series to get the 15k, or use three 10k to make the 15k up, series/parallel, oh what fun. Two 10k in parallel make 5k, then you do the third 10k + those two 10k in parallel that are 5k and there you are at 15k again. 
2019-12-18 by RDC
“C3 is not a current source” should be, C3 doesn’t seem to need any real current for that pin.
2020-01-06 by Unknown
Thank you for all the work you put into sharing this info. I’m building a portable kit for ice fishing using a Garmin Echomap + 9sv and a Panoptics livesope transducer (live sonar). Hoping to power it using Dewalt 20vlt / 5 Amp hour battery platform since that is what I use to run the drill for the ice auger already. I have installed a Drok step down module to bring my voltage down to 17.5 vlts as the maximum range on the head unit is 18vlts. My question for you is at what low voltage should I swap out batteries as to not permanently damage them? I can configure the Garmin head unit to warn me and shut down at specified voltages. What would you recommend?
2020-01-14 by Joe the Jerk
The thing about setting the voltage cutoff in the Garmin is that your buck converter’s output voltage is, I’m assuming, constant at 17.5V (a synonym for buck converter is “voltage regulator”). IOW, the Garmin will never see a voltage decrease, so can’t shut down on that basis. You’ll need another approach.
If you’re able to have a voltmeter (either a digital multimeter or hobby-type mini voltmeter+LCD) on your battery while it’s being drawn down, you could take it to 3.0V/cell (so, 15V total from B+ to B-) pretty safely, or 3.3V for longest life/utmost caution. Failing that, I think Russell Graves lays out somewhere on the blog the voltages that correspond to the lights on the 3-bar battery indicator; IIRC, when it drops from “two bars” to “one bar”, it’s 15.x volts (I don’t remember the tenths). If that’s all you have to go by, defo stop at “one bar”. “Zero bars” is 2.xV/cell…and that’s bad! I dunno how warm an ice fishing hut typically is, but closer to room temp is better, and I know you guys have propane heaters nowadays, so…yeah! 
All that said, I’ve recently had this thought of building a Frankenpack for the DW “slidey battery” platform (I still hate calling it “20 Volt”). So, in a nutshell, neither the DW tools nor chargers give a flying fuck what the capacity (amp-hours) of a pack is. This being the case, you could make a single pack by parallelling as many packs as you wanted – let’s say four 5Ah packs, as those are the cheapest per-amp-hour in Canada right now – in order to get an 18V “slidey battery” with 20Ah capacity. The key for ease of use would be to leave the top pack’s battery board intact, to connect to a DW charger like it ever did (except perhaps with the charger slid over the pack upside-down as a hat, rather than the usual way).
This honestly may not be the way to go if keeping the battery warm is an issue, but then, a custom battery case could be insulated! Also, with a large-by-huge battery, there’s the option of adding a tiny heating pad that turns on and off at temperatures chosen by you to keep your electrons nice and toasty…but not toasted!
I did something similar last summer to make an ebike pack, buying 4 Ryobi 9Ah packs at Home De Pot (Cdn.$100 apiece = 33% cheaper per-Ah than DW, which is otherwise always the cheapest), removing the BMSes and making a 2-bricks parallel/2-bricks-in-series configuration (6P10S, cellularly, or…er, 3P10S2P?). In my case, I’m contemplating actually decoupling it back to two 18V packs, adding DeWalt battery board/charger interfaces and charging as I outline above. The board doesn’t give a fuck who made the cells, or even their capacity. Neither does the charger, except for the resistance on the ID terminal – which you may want to bodge to full current with a 1MOhm resistor anyway if you have a large pack. Even without the DW board installed, I do in fact use two DeWalt “slidey” chargers to charge my Frankenpack.
I have to connectorize it though, so as to avoid any more “glowing orange wire” incidents. On the bright side, I learned a lesson about using sketchy “temporary” wiring in conjunction with lithium-ion batteries!
P.S. I certainly wouldn’t suggest anyone try this with anything they care about, but…input voltages are sometimes understated on things. For example, I recently converted a Zoom recorder that uses two AA batts (~3.3V) to a single 18650 (~4.1V), and it works a treat. Again, such things are experimental, so don’t try unless you can really afford to lose a thing or the money to replace it. Needless to say, I’d be less positive about the experience if I had cooked the thing! lol
Happy New Year, electro-weirdos one and all!
2020-01-14 by RDC
You don’t want to run the pack down any lower than 15v really, 3v per cell.
What converter are you using exactly? If it’s purely a step-down type, it will die before the battery hits the 15v mark, as you’re not going to get 17.5v from anything under 18v or so. If it’s a buck/boost type of converter, then it would drain the battery down well past the 15v and the Garmin would never know because the regulator will try and maintain that 17.5v for as long as it can. Unless it is connected directly to the battery voltage to monitor it?
2020-01-14 by Russell Graves
Joe - depending on the buck converter, things may actually work as Unknown hopes. Most of the buck converters I’ve met will just go to passthrough if the input voltage is lower than the regulated voltage. So, if you have a battery ranging from 15V to 20V, and regulate to 17.5V, anything above 17.5V will be regulated down, but anything lower will be just passed through - since the buck topology can’t boost the voltage, there’s nothing else it can do (except shut down - some nicer ones might do that, most cheap ones won’t).
If that’s how the converter works, then you could still use the head unit to shut the system down.
I’d set the shutdown around 15.0V - there’s just no good reason to run the cells lower than 3.0V/cell. All you do is trash longevity for a tiny bit more energy.
2020-01-14 by Joe the Jerk
Sincere thanks for the correction, Russell. That makes perfect sense, and is surely more welcome as news than my ignorant scaremongering. If you can choose any voltage <17.5V tho, why not 16.5V (3.3V/cell)? Perhaps that’s overly cautious, but >90% of the pack’s energy is released between 3.6V and 4.2V anyway, so not much incentive to go a lot further.
2020-01-14 by Dwayne Baraka
I’ve seen low voltage recommendations from 2.7 to 3.1 V per cell. Anyone know about the particular cells DeWalt uses? Or indeed what the Tools shut off at? Seems that might be the safe limit!
2020-01-14 by Russell Graves
I generally consider 3.0V a good compromise between capacity available and cycle life. You could set it higher if you wanted, but especially in the cold, the batteries will sag a bit on the output side, so…
It really doesn’t matter. Just don’t run the cells down to 2.5V as a matter of course, and they’ll be fine.
2020-01-14 by Russell Graves
The cells are typically cycled to 2.5V for capacity testing, though I don’t know where the tool actually shuts off. I swap packs when mine start feeling saggy, which is typically around 1 LED, but I don’t carry a voltmeter with me when I’m working on stuff. I just carry spare packs.
2020-01-14 by RDC
The cells are most likely Samsung, though you’d have to open the pack and see exactly which ones they were.
Just a quick check here, and the drill I have cuts out around 16.5v, or 3.3v per cell, but I’ll guarantee that’s dipping down lower than that before the tool is cutting off. I just have other projects on the bench currently to get deeper into setting all of that up to measure it more accurately, but sticking with anything from 3.3v to 3v minimum per cell would fine.
The DeWalt pack indicator will show 1 LED from around 17.8v (3.56v per cell) on down until around 15v (3v per cell) or so. The FlexVolt indicator will show 1 LED down to around 12v, but at that point the tool has long since cutoff.
2020-07-05 by Unknown
Hi Russell,
Many thanks for your in depth explanation. Very welll done and informative.
I attempted 3 dewalt batteries this morning; 1 x original 4amp/h and 2 x copies 4/h. Igot to say that the build quality of the copies is fantastic and it look lik ethe moudling are identical. Any way the copies only needed the thermistor to be resoldered. Both had come adrift using my multitool and I think that it was just due to vibration. The good thing is that the thermistors are located on one of the cells. Bit fiddly but hey ho all done and repaired. The dewalt battery had been dropped and the connection to the 4th pin on the tool was missing. I stripped off the whole thing and reconnected it and once again success. Wouldn’t have tried this without your blog so ManY Thanks
Gary
2020-08-20 by rzwinston
Well guys thats to much for me:)
I have question if I can replace cells at Dewalt battery with some similar cells without problems.
Lets say 18V 5Ah bat. has LGHE2 2500 mah cells so can I replace it eg with Samsung 18650 30Q or BSM will allowe to work just exactly same battery.I replaced my old Hitachi 1.5ah batteries with Samsung 20Q and 20R but there wasnt any board and its workiing nicely over 2 years now.Regards
2020-08-22 by Joe the Jerk
BMS doesn’t care about capacity. Happy spot welding!
2020-09-01 by DefToneR
Incredible awesome article! I was searchjing for one to make a “big battery” for the leaf blower or the mowder, there is an adapter to make the battery huge: Dewalt 20v max upgrade spacer 5 cell to 15 cell by rwaudio - Thingiverse that I’m going to be printing and I have a lot of 18650 that Used for another project.
2020-09-01 by rzwinston
well any better alternative cell to HB4 at this time as I need to rebuild 5ah battery,I am not sure if Samsung 30Q will make it?)
2020-09-11 by Hanz
Hi Russell, thanks for the great explanation. I’m stumped with something, maybe you or someone can help me figure it out: due to missing wiring inside the house, I decided to run the doorbell off a battery pack (DCB207, DeWalt 20Vmax, similar to yours). The circuit is open except when pressing the doorbell, and it works fine. But the pack gets discharged to zero in a few days, even when the bell isn’t pressed at all in that period. I checked for possible leaks but current was zero (down to the microamps setting) when the doorbell button is not pressed. I’m using the B+ and B- to feed the doorbell solenoids, with the doorbell button as a normally open switch. I took out the LED that permanently illuminated the button to avoid drains. But still, the battery discharges to zero. When I leave the same pack on the drill, it lasts for a very long time, it doesn’t self discharge.
Any hints would be appreciated.
2020-10-04 by Jacob
Do any of you know how to get a replacement clip for the BMS board? It’s the clip from the battery to the drill.
2020-11-25 by Unknown
Hello Russell,
The info you shared here are so helpful, I really learned a lot from it, thanks a lot!
I have a question you may know the answer. For the Dewalt drill using 20V Max battery, if I have other DC power supply(enough for the drill, e.g. 20v 10A), do you think the drill will work if I just connect the B+ and B- on the drill(ignore the other pins)?
Norman
2020-12-27 by Bill
I have 2 Home Despot shelves on a hoist system that raise/lower up to my garage ceiling. It does come with a tool to connect to a drill, otherwise you are using the hand crank for eons. I wanted to connect power window motors to the crank and feed power from a 6-AH battery via a momentary contact bidirectional switch that I would mount to the wall. Your pinout, and the detailed information, will help me in that design. Many thanks!
2020-12-27 by Bill
I don’t know about your doorbell system, but mine operates off an AC transformer. My transformer is mounted on my furnace, and brings the house 120v down to 20v for the doorbell. I understand you don’t have wire available to your system, but this might be something to get you heading in the right direction. Maybe the impedance of your doorbell chime is low enough when a DC source is applied that it heavily drains current from your battery. Also consider some doorbells have an illuminated light in the switch, and that might also be draining your battery faster when a DC source is attached to it when it is expecting AC.
) and 316 Ohm on the ID connector. Works perfectly fine, charger accepts the battery and takes care of the balancing.
You should be able to just use a decent resistor and bleed each group down. Below… oh, 3.3-3.4V/cell group, there’s not enough energy to let them be exciting, but if you’re draining it to scrap it, get it below 2.0 V/cell, and then mark it dead.