Milwaukee and Dewalt do not have protection in the batteries because the liion batteries and tools were all designed together from the ground up and its more cost effective to have the protection circuitry in the tool. Ryobi 18V and Ridgid 18v maintained backwards compatibility with older non-li-ion tools. The older tools did not have protection because the old battery pack chemistry did not require protection. To maintain backwards compatibility, the new Ryobi and Ridgid li-ion packs needed protection. The giveaway when looking at the circuit boards is the large mosfets and heatsinks needed in the battery to act as the switch to turn the voltage off for low voltage and short circuit protection.
Things I've used battery packs for..... Forced air respirator Work lighting Soldering rig Charging for USB devices - phones, tablets, etc Echo Dot with Amazon music outdoors Fans Occasionally a cordless drill 😁 That's not everything and the planned list goes on a long way. I use Einhell and they have voltage control built into the batteries which makes like very easy 👍👍👍👍
You got to be careful, that relay draws a small amount power just to monitor the voltage. If you leave it connected for days / weeks, it will continue to trickle drain the battery until damaged.
I used these for Bluetooth amplifier speaker builds. I set the low voltage shut off at 17v so I’m able to charge the battery again also the lcd draws 25 milli amps if you don’t shut of the power that’s why I don’t set it to 15v Incase I forget to shut the radio off all day it won’t draw to much and damage the battery I have used this almost everyday for a work radio on a construction site for 6 months and hasn’t failed it’s in a plastic ammo box it doesn’t get hot at all and I would recommend mounting it on some abs plastic with stand-offs
Ya it drains 25milli amps with the led on so if you have a 20vdc battery 16.5-17 vdc would be a safe zone in case you don’t shut it off I would like to figure out to put a small buzzer on it when it gets low sometimes when I’m working it’s nice to know when to put a fresh battery on a 5amp dewalt battery will last me about 7-8 hours of run time on a single battery running to 17vdc running them down to nothing 15.5 has given me problems in the past like not charging
This is exactly what I was looking for 👍 Thank you for explaining what these do and why. It was precisely the question I had when I found adapters on Amazon that came with these low voltage protection adapters.
I used them to make security lighting, with a LBC and a wireless remote, and automotive Fog lights. I can place them about anywhere, on the chicken coop, driveway, shed, new project site. With a small plastic container to keep everything dry. Everything was great till my wife fond out I used some of her kitchen boles . Lol.
So you asked for projects, I sleep with a cpap machine. When I camp I have two 12v sealed lead batteries in a case to power my unit. I get 2-3 nights out of the unit. I am going to make a new setup using my dewalt 6A batteries since my unit can run on 12 or 24 volt input. So I am going to try out a battery first. If that works then I will parallel 3 batt together. It will be much lighter carrying drill batteties to a wall charger when on a long trip. Thanks for your video.
Note that if the voltage does drop too low, the built in BMS disconnects the cells and won’t allow them to charge again, but you can take the pack apart and manually bring the cells up enough to allow the charger to work again. My boss bought a huge truckload of Milwaukee and Milwaukee Fuel tools and none would charge, so I did them all. Keep in mind these were all new old stock and none of the cells were swollen or damaged. Also, this was done outdoors just in case. Matthias Wandel has a video showing how it’s common for the flexible voltage batteries have certain quirks as well.
ty for the video. I bought an adapter that plugs into the Dewalt battery's and it has two USB outputs and one 12 volt output. The only thing is that it will not shut off and will drain the battery to empty other then that it works great as a phone/iPad power source.
My capacity tester doesn’t cut off and just alarms on low voltage, which means I have to babysit it while testing. Used your link to purchase. Thank you
These do work, but this doesn't mean you can leave your battery plugged into the system when not in use. It will actually drain the battery until it's no good. I should have known this, but found out the hard way. Dewalt 6AH battery toast because life with kids is hectic and you sometimes forget to take the batter out of that free Gator you got sitting on the side of the road and converted to take your power tool batteries. A better option is to find the tool companies that put their low voltage protection in the battery instead of the tools. Then you will never have to worry about running them low. Dewalt's low voltage protection is in their tools, not the battery.
I power a projector for summer out door movie night for the family. I found the low voltage cut out only after I screwed up a couple of batteries. (If the family movie is over and the rest of the family goes to bed, you then switch to a baseball game then fall asleep it will fry a battery if you don’t have low voltage protection)
So I feel the need to say that the cells inside these batteries are capable of being brought down to 2.5v per cell but that is extremely low and I definitely recommend 3v minimum so that would be 15v off of this pack. Also I can say with certainty that just because the charger starts blinking doesnt mean it will charge necessarily I recently killed one of my 5ah bt battery packs due to not having a protection circuit in line with an older dealt 18v drill. Dealt has battery protection inside the drill not that battery which is why you can use them thus way. On a side note I think this is the longest comment ive ever made on a video.
Used my ridgid 18v 4ah batteries for my sons 12v powerwheels and it hauls ass. I use a 30a inline fuse but i do check the battery ever 10 mins before it gets too low. This would help a lot.
Thank you for an excellent video! Have you ever phoned someone and when they answered there was a radio or tv in their background? That's what music does to your video. I clicked on your video to learn something. It's not a commercial.
Great video. I use battery pack to power my chicken coop light. My goal was to have them charged using my solar panels but I haven't gotten to that yet.
2 years later but.... Aside from jumping the work truck.... and the occasional power source for 24vdc controls at work (18 is close enough).... my big project is an electric mountainboard running on (2) milwaukee M18 high output 6.0s. Low voltage cutoff is in the VESC and I use three phase AC motors. This helped fill in some missing knowledge I had. Thanks man.
So i recently bought my first house and due to the yard, i had to buy a mower that had to meet some odd requirements. Because of this i ended up buying the EGO mowers and blowers which i love bit since I now had a ton of their batteries now (i have slowly collected half their set with each coming with 1 or 2 batteries) and nothing to use them on but once every week or two. I was wondering how i can use them in other projects and i think that was the last part i was missing. I'm planning on using them to make a portable back up battery with power outlet to power small devices in case of a power outage as a proof of concept but i can't wait to see what you come up with as well.
I got an adapter on amazon for my milwaukee packs (not really necessary but it allows for both mounting the pack and a secure connection) and I use it to power my kayak lights, fish finder, etc...
I used this in a surebonder M18 to Ryobi battery adapter. It just barely fits in the disassembled adapter. Let's me use that odball Ryobi tool without needing to invest in a separate platform.
Thank you for putting this information out there. Does that little module you were using also limit the voltage that you can send out? Does it limit the voltage you can send out to your projects? To be more clear many of the things we are using out here are based on 12 V but we’re looking at batteries that are 20 V. Is there anything you could speak to about that scenario where we wanna make sure that we’re not burning out at 12 V application with a 20 V battery?
Please explain how you changed the 14 volt factory setting to the 15.3 volt of your choice. Did you press and hold the button? The amazon site does not explain that either.
I've been looking at these same low voltage shutoff circuits, and without much luck, have been trying to find an answer to "Will they retain their Low/High settings when disconnected from the power for an extended period of time? Or do they need resetting every time you use them?" I would like to be able to set them to x V low & y V high, and not have to reset again next time I decide to use the device. Is this the case? Thanks in advance.
The question is how to determine my battery's minimum voltage? let's say I have a scooter battery which is 36 volts and has nothing written on it, so how to know for sure the voltage that the battery should stop at?
Depends on the cell chemistry, assuming lithium ion cells which are typically rated for 3.7v that means 10 cells in series will make about ~36 volt pack. Li-ions can be safely discharged to 3.0v so simply cutoff at 30v but its better for the cell life to have more buffer like 3.3v * 10 series = 33v cutoff. In the video he sets the cutoff at 15.3v so divided by 5 series = 3.03v minimum per cell which is going for as much runtime as possible with a tiny buffer
@@kwitmeh3 its weird that you can only take .7 volts from those batteries before risking damage! there's so much power left in them. Now i understand why some of my devices still crank with the 3.7 and some shut down, the latter must have the safety shut off built into the device.
Can we chain multiple together to get more power? Could they ever be strong enough to run homemade shop tools, e.g. a belt grinder or small homemade metal saw?
I'm making a portable Bee vacuum using a 12v DC cooling fan, DC motor speed controller and 20v Dewalt batteries. Would I need to use a volt converter to drop the voltage from 20v to 12 v or will the speed controller do this for me.
Looks like I bought the same one and for some reason I’m not able to change the settings following the manufactures steps. Did you have a similar issue?
Yes, you would want to use a 12V battery rather than the 18V and then set the low voltage cut-off to 9.3 volts rather than 15.3 volts shown in the video. Although he has already given a good explanation in the video, I will try to go into a little more detail. Nominal voltage is the default, resting voltage of a battery pack. This is how the battery industry has decided to discuss and compare batteries. Nominal voltage for a lipo is 3.7 volts per cell and a fully charged lipo battery has 4.2 volts per cell. Examples are...nominal voltage of a 2 cell lipo is 7.4 volts but its charged state is 8.4 volts. Nominal voltage for a 3 cell lipo is 11.1 volts but fully charged is 12.6 volts. This is why the advertised difference between Milwaukee 18V and Dewalt 20V while in fact, they both have a 5 cell battery. 5 cell=18.5 Nominal voltage and 21 volts fully charged. Low voltage cut-off for a lipo battery is 3 volts per cell. As a precaution, most people like to stay a little higher than that to avoid a dead cell. Buy a 12 V battery and follow the same instructions from this video with but change the low voltage cutoff to 9.3 volts or higher. Some things, like the DC motor shown in the video are safe with slightly higher voltage increase. The result will be the motor spinning at a higher RPM. However, your GPS is will probably end up in smoke if you wire it up to the bigger battery. Hope that helps.
But the battery keeps getting discharged by the circuit! it does not turn off.. Sure if you are there to unplug you are good, but if you left it on walked away, and forgot.. well your battery will go to ZERO, I tested this using a variable power supply and found you still drawing 20mA when the circuit switches the load off. Phantom power. I need true power off! full disconnect.
buy batteries and put them in the case! or do what i do, everytime someone breaks a rechargeable vacuum, laptop ,bubble gun or anything else that takes the super common 3.7 volt lithium battery , you tear it apart and save those batteries LOL i have at least 20 of those things ready for random projects.
Why doesn't Dewalt build the circuitry into their battery packs like Milwaukee?? AND 14 volts is too low for that pack.. Should be at 16 volts to be safe.. 5 X 3.2....
The protection board's relay says it's good to 20A at 14VDC, and I'd extrapolate that to 14A at 20VDC. And running it at max might be a bad idea, so maybe put a 10A or 12A fuse on the circuit. Not sure if that's the continuous rating or the breaking rating.
Don't parallel two lithium batteries unless they're permanently connected and charged/discharged together. If they're "hot swappable" and you accidentally have one at full charge and the other at near empty you can easily overcurrent them as one charges the other. Bang!
Why would you build your own Low Voltage Disconnect (LVD)? These power tool batteries have built in Battery Management System (BMS) which has both Low Voltage Protection(LVP) and Over Voltage Protection(OVP). You're simply "re-inventing the wheel".
Some brands need to have the tool telling the battery when it has to cut off. Therefore most likely your(or my) application/project wasn't maybe built that way. I have Bosch 18V packs ans use them to power synthesizers and small PA set and I can say the protection does not activate while I am just connecting my audio devices to + and - terminals of the battery pack. This circuitry is highly recommended for any DIY projects.
![[006] Do Makita LXT batteries have low-voltage protection?](http://i.ytimg.com/vi/r1tQwoaCdBA/mqdefault.jpg)
Milwaukee and Dewalt do not have protection in the batteries because the liion batteries and tools were all designed together from the ground up and its more cost effective to have the protection circuitry in the tool. Ryobi 18V and Ridgid 18v maintained backwards compatibility with older non-li-ion tools. The older tools did not have protection because the old battery pack chemistry did not require protection. To maintain backwards compatibility, the new Ryobi and Ridgid li-ion packs needed protection. The giveaway when looking at the circuit boards is the large mosfets and heatsinks needed in the battery to act as the switch to turn the voltage off for low voltage and short circuit protection.
This is actually hard to find and incredibly useful information, dude… I subbed, I REALLY hope this channel really grows…
Things I've used battery packs for.....
Forced air respirator
Work lighting
Soldering rig
Charging for USB devices - phones, tablets, etc
Echo Dot with Amazon music outdoors
Fans
Occasionally a cordless drill 😁
That's not everything and the planned list goes on a long way.
I use Einhell and they have voltage control built into the batteries which makes like very easy 👍👍👍👍
Good point about using batteries that have a built in cut off, unfortunately all I have are Dewalt.
i love einhell batteries got ozito rebranded ones, cheap, use em for everything, even got one in my glovebox as a ghetto jumpstarter
You got to be careful, that relay draws a small amount power just to monitor the voltage. If you leave it connected for days / weeks, it will continue to trickle drain the battery until damaged.
This should be pinned
it's true and the small relay does drain the voltage.
I used these for Bluetooth amplifier speaker builds.
I set the low voltage shut off at 17v so I’m able to charge the battery again also the lcd draws 25 milli amps if you don’t shut of the power that’s why I don’t set it to 15v Incase I forget to shut the radio off all day it won’t draw to much and damage the battery I have used this almost everyday for a work radio on a construction site for 6 months and hasn’t failed it’s in a plastic ammo box it doesn’t get hot at all and I would recommend mounting it on some abs plastic with stand-offs
Ya it drains 25milli amps with the led on so if you have a 20vdc battery 16.5-17 vdc would be a safe zone in case you don’t shut it off
I would like to figure out to put a small buzzer on it when it gets low sometimes when I’m working it’s nice to know when to put a fresh battery on a 5amp dewalt battery will last me about 7-8 hours of run time on a single battery running to 17vdc running them down to nothing 15.5 has given me problems in the past like not charging
Great to know. Thank you for sharing!
This is exactly what I was looking for 👍 Thank you for explaining what these do and why. It was precisely the question I had when I found adapters on Amazon that came with these low voltage protection adapters.
This is exactly what I was looking for
I used them to make security lighting, with a LBC and a wireless remote, and automotive Fog lights. I can place them about anywhere, on the chicken coop, driveway, shed, new project site. With a small plastic container to keep everything dry. Everything was great till my wife fond out I used some of her kitchen boles . Lol.
So you asked for projects, I sleep with a cpap machine. When I camp I have two 12v sealed lead batteries in a case to power my unit. I get 2-3 nights out of the unit. I am going to make a new setup using my dewalt 6A batteries since my unit can run on 12 or 24 volt input. So I am going to try out a battery first. If that works then I will parallel 3 batt together. It will be much lighter carrying drill batteties to a wall charger when on a long trip. Thanks for your video.
Note that if the voltage does drop too low, the built in BMS disconnects the cells and won’t allow them to charge again, but you can take the pack apart and manually bring the cells up enough to allow the charger to work again. My boss bought a huge truckload of Milwaukee and Milwaukee Fuel tools and none would charge, so I did them all. Keep in mind these were all new old stock and none of the cells were swollen or damaged. Also, this was done outdoors just in case. Matthias Wandel has a video showing how it’s common for the flexible voltage batteries have certain quirks as well.
A couple of weeks ago I saw my friend Jumpstart his car with a Dewalt battery pack. I thought that was kind of cool
ty for the video. I bought an adapter that plugs into the Dewalt battery's and it has two USB outputs and one 12 volt output. The only thing is that it will not shut off and will drain the battery to empty other then that it works great as a phone/iPad power source.
Well explained, exactly what i was looking for! Thanks
My capacity tester doesn’t cut off and just alarms on low voltage, which means I have to babysit it while testing. Used your link to purchase. Thank you
These do work, but this doesn't mean you can leave your battery plugged into the system when not in use. It will actually drain the battery until it's no good.
I should have known this, but found out the hard way. Dewalt 6AH battery toast because life with kids is hectic and you sometimes forget to take the batter out of that free Gator you got sitting on the side of the road and converted to take your power tool batteries.
A better option is to find the tool companies that put their low voltage protection in the battery instead of the tools. Then you will never have to worry about running them low. Dewalt's low voltage protection is in their tools, not the battery.
I power a projector for summer out door movie night for the family. I found the low voltage cut out only after I screwed up a couple of batteries. (If the family movie is over and the rest of the family goes to bed, you then switch to a baseball game then fall asleep it will fry a battery if you don’t have low voltage protection)
So I feel the need to say that the cells inside these batteries are capable of being brought down to 2.5v per cell but that is extremely low and I definitely recommend 3v minimum so that would be 15v off of this pack. Also I can say with certainty that just because the charger starts blinking doesnt mean it will charge necessarily I recently killed one of my 5ah bt battery packs due to not having a protection circuit in line with an older dealt 18v drill. Dealt has battery protection inside the drill not that battery which is why you can use them thus way.
On a side note I think this is the longest comment ive ever made on a video.
We appreciate your time, longer comments are always welcome.
Used my ridgid 18v 4ah batteries for my sons 12v powerwheels and it hauls ass. I use a 30a inline fuse but i do check the battery ever 10 mins before it gets too low. This would help a lot.
Thank you for an excellent video! Have you ever phoned someone and when they answered there was a radio or tv in their background? That's what music does to your video. I clicked on your video to learn something. It's not a commercial.
Great video. I use battery pack to power my chicken coop light. My goal was to have them charged using my solar panels but I haven't gotten to that yet.
2 years later but....
Aside from jumping the work truck.... and the occasional power source for 24vdc controls at work (18 is close enough).... my big project is an electric mountainboard running on (2) milwaukee M18 high output 6.0s. Low voltage cutoff is in the VESC and I use three phase AC motors. This helped fill in some missing knowledge I had. Thanks man.
Did you wire both batteries to the one voltage protector?
@@PaigeSaucedo both batteries in series together for a 36v nominal system. Low voltage cutoff is somewhere around 32 if I remember.
Outstanding channel! I’ve shared your burn barrel design with 2 friends.
So i recently bought my first house and due to the yard, i had to buy a mower that had to meet some odd requirements. Because of this i ended up buying the EGO mowers and blowers which i love bit since I now had a ton of their batteries now (i have slowly collected half their set with each coming with 1 or 2 batteries) and nothing to use them on but once every week or two. I was wondering how i can use them in other projects and i think that was the last part i was missing.
I'm planning on using them to make a portable back up battery with power outlet to power small devices in case of a power outage as a proof of concept but i can't wait to see what you come up with as well.
Immediately Liking the video because your brain went where mine did and tried to put the pack on the chicken.
Very nice presentation !!!👌
My son-in-law runs them on a harbor freight winch which is used on his home built boat moving dolly. Gota let him know about these cutoffs...thanks.
I got an adapter on amazon for my milwaukee packs (not really necessary but it allows for both mounting the pack and a secure connection) and I use it to power my kayak lights, fish finder, etc...
I couldn't help but to say thank you.
I used this in a surebonder M18 to Ryobi battery adapter. It just barely fits in the disassembled adapter. Let's me use that odball Ryobi tool without needing to invest in a separate platform.
it fits way better if you cut the pcb corners
great video - very inspirational - thank you for your work
Good review, I like this module.
Would I use two when wiring in series?
How would you do thid with 2 dewalt batteries? We are trying to power a 24v power wheels and 1 20v is not enough.
Thank you for putting this information out there. Does that little module you were using also limit the voltage that you can send out? Does it limit the voltage you can send out to your projects? To be more clear many of the things we are using out here are based on 12 V but we’re looking at batteries that are 20 V. Is there anything you could speak to about that scenario where we wanna make sure that we’re not burning out at 12 V application with a 20 V battery?
you will need a DC Buck device for this, they are readily available on ebay for low current applications
This is exactly what I was looking for. So on a 20V Dewalt Battery, 15.3V is the minimum recommended.
Don’t go past 16.5 min voltage Incase you don’t shut off the power to the battery the lcd will drain the battery until it’s no good
@jimcatanzaro7808 so you're saying the device which is supposed to save the battery will actually drain the battery?
Please explain how you changed the 14 volt factory setting to the 15.3 volt of your choice. Did you press and hold the button? The amazon site does not explain that either.
just hold both buttons down then you press one to go up or the other to go down and wait for it to stop
I've been looking at these same low voltage shutoff circuits, and without much luck, have been trying to find an answer to "Will they retain their Low/High settings when disconnected from the power for an extended period of time? Or do they need resetting every time you use them?"
I would like to be able to set them to x V low & y V high, and not have to reset again next time I decide to use the device. Is this the case?
Thanks in advance.
According to the comments from the mfg most of these boards will hold the settings no problem.
The question is how to determine my battery's minimum voltage? let's say I have a scooter battery which is 36 volts and has nothing written on it, so how to know for sure the voltage that the battery should stop at?
Depends on the cell chemistry, assuming lithium ion cells which are typically rated for 3.7v that means 10 cells in series will make about ~36 volt pack. Li-ions can be safely discharged to 3.0v so simply cutoff at 30v but its better for the cell life to have more buffer like 3.3v * 10 series = 33v cutoff. In the video he sets the cutoff at 15.3v so divided by 5 series = 3.03v minimum per cell which is going for as much runtime as possible with a tiny buffer
@@kwitmeh3 its weird that you can only take .7 volts from those batteries before risking damage! there's so much power left in them. Now i understand why some of my devices still crank with the 3.7 and some shut down, the latter must have the safety shut off built into the device.
Your the man!
Can we chain multiple together to get more power? Could they ever be strong enough to run homemade shop tools, e.g. a belt grinder or small homemade metal saw?
I'm making a portable Bee vacuum using a 12v DC cooling fan, DC motor speed controller and 20v Dewalt batteries. Would I need to use a volt converter to drop the voltage from 20v to 12 v or will the speed controller do this for me.
Looks like I bought the same one and for some reason I’m not able to change the settings following the manufactures steps. Did you have a similar issue?
So the low voltage disconnect has to be hooked up every time ?
Hello. Please protection board have a memory? or must when change battery again setup?
would i need something like this for a 1S lipo?
Great video thanks
Could you use it to power a GPS if you don't have a charging port in a vehicle?
Yes, you would want to use a 12V battery rather than the 18V and then set the low voltage cut-off to 9.3 volts rather than 15.3 volts shown in the video.
Although he has already given a good explanation in the video, I will try to go into a little more detail.
Nominal voltage is the default, resting voltage of a battery pack. This is how the battery industry has decided to discuss and compare batteries.
Nominal voltage for a lipo is 3.7 volts per cell and a fully charged lipo battery has 4.2 volts per cell.
Examples are...nominal voltage of a 2 cell lipo is 7.4 volts but its charged state is 8.4 volts. Nominal voltage for a 3 cell lipo is 11.1 volts but fully charged is 12.6 volts. This is why the advertised difference between Milwaukee 18V and Dewalt 20V while in fact, they both have a 5 cell battery. 5 cell=18.5 Nominal voltage and 21 volts fully charged.
Low voltage cut-off for a lipo battery is 3 volts per cell. As a precaution, most people like to stay a little higher than that to avoid a dead cell.
Buy a 12 V battery and follow the same instructions from this video with but change the low voltage cutoff to 9.3 volts or higher.
Some things, like the DC motor shown in the video are safe with slightly higher voltage increase. The result will be the motor spinning at a higher RPM. However, your GPS is will probably end up in smoke if you wire it up to the bigger battery.
Hope that helps.
But the battery keeps getting discharged by the circuit! it does not turn off.. Sure if you are there to unplug you are good, but if you left it on walked away, and forgot.. well your battery will go to ZERO, I tested this using a variable power supply and found you still drawing 20mA when the circuit switches the load off. Phantom power. I need true power off! full disconnect.
Do you have to get 2 of the units if your running 2 batteries in Parallel ?
No, but you should have both batteries fully charged
I would like to learn how to rebuild a battery pack.
buy batteries and put them in the case! or do what i do, everytime someone breaks a rechargeable vacuum, laptop ,bubble gun or anything else that takes the super common 3.7 volt lithium battery , you tear it apart and save those batteries LOL i have at least 20 of those things ready for random projects.
Why doesn't Dewalt build the circuitry into their battery packs like Milwaukee?? AND 14 volts is too low for that pack.. Should be at 16 volts to be safe.. 5 X 3.2....
do Milwaukee packs have a bms?
@@Fatcode1 no they dont. Same as dewalt. BMS is built into their tools not batteries.
How to use it while it's powering the tool?
Very clear
The protection board's relay says it's good to 20A at 14VDC, and I'd extrapolate that to 14A at 20VDC. And running it at max might be a bad idea, so maybe put a 10A or 12A fuse on the circuit. Not sure if that's the continuous rating or the breaking rating.
Can you go thru programming the cutoff?
What’s the best way to figure out what setting I should set for an 18v Ryobi battery?
you dont need to they have everything built in
Just use Ryobi batteries. It's built in
Can you use it on two parallel batteries?
Don't parallel two lithium batteries unless they're permanently connected and charged/discharged together. If they're "hot swappable" and you accidentally have one at full charge and the other at near empty you can easily overcurrent them as one charges the other. Bang!
cool!
30 second like,,,
Thomas Thomas Brown Susan Rodriguez David
Couldn't tolerate the annoying background loop.
Why would you build your own Low Voltage Disconnect (LVD)? These power tool batteries have built in Battery Management System (BMS) which has both Low Voltage Protection(LVP) and Over Voltage Protection(OVP). You're simply "re-inventing the wheel".
Some brands need to have the tool telling the battery when it has to cut off. Therefore most likely your(or my) application/project wasn't maybe built that way. I have Bosch 18V packs ans use them to power synthesizers and small PA set and I can say the protection does not activate while I am just connecting my audio devices to + and - terminals of the battery pack. This circuitry is highly recommended for any DIY projects.
This is exactly what I was looking for