Dead DeWalt Battery Mystery

[bk2drvr]

I bought the Dewalt 12v drill and impact driver about 8 months ago and recently bought the compatible 12v flashlight to go along with the batteries. For some reason if I leave a battery in the flashlight (flashlight turned off of course) for a week or so the battery becomes completely dead and no longer useable. If I put the battery in the charger its as if the battery is not attached to the charger, nothing happens, no LED comes on. I'm down two batteries, what the heck is going on?

 

[rickym20]

Search YouTube video for dewalt battery jump. You can use wires to Shock it to work again . Never tried myself but might be worth a shot. You do need 1 good battery to do it with.

 

[Flying_Lavey]

Do

I bought the Dewalt 12v drill and impact driver about 8 months ago and recently bought the compatible 12v flashlight to go along with the batteries. For some reason if I leave a battery in the flashlight (flashlight turned off of course) for a week or so the battery becomes completely dead and no longer useable. If I put the battery in the charger its as if the battery is not attached to the charger, nothing happens, no LED comes on. I'm down two batteries, what the heck is going on?

Don't leave it in the flashlight as im sure the switch is a digital switch and doesn't eliminate all draw from the battery. There is likely a constant parasitic draw due to the electronic controls.

 

[Outdrive1]

Tool batteries are such a scam. Batteries usually cost more than a tool and battery. . I have so many old tools with dead batteries that are obsolete, but the tools are still perfect.

 

[JUSTWANNARACE]

They go into a "sleep mode" if they drop below lik 3v. Hit it with some jumper cables off your car or from a good battery charger. Do that for a couple min and the dewalt charger should detect it then.

 

[bk2drvr]

Do
Don't leave it in the flashlight as im sure the switch is a digital switch and doesn't eliminate all draw from the battery. There is likely a constant parasitic draw due to the electronic controls.

Pretty lame design. Why is the tool different than the flash light? I can leave the battery in the tool for weeks and no issue. Thanks!

 

[Nordie]

What these guys are saying, you have to jump the lithium battery above the low voltage threshold and the charger will register it again.

If you're a makita guy take note that they have a board in the batteries. If they drop below the threshold 3 times you will never be able to recharge them. That is even jumping them using a nimh charger, they have the smart wazoo system to shut down when the voltage gets low.

I'm not sure if any of the other tool lines do it, but makita does.

 

[Flying_Lavey]

Pretty lame design. Why is the tool different than the flash light? I can leave the battery in the tool for weeks and no issue. Thanks!

Most all LED flashlights use this same concept. There are some that don't but many do. Usually they have the various output levels.

 

[ka0tyk]

What these guys are saying, you have to jump the lithium battery above the low voltage threshold and the charger will register it again.

If you're a makita guy take note that they have a board in the batteries. If they drop below the threshold 3 times you will never be able to recharge them. That is even jumping them using a nimh charger, they have the smart wazoo system to shut down when the voltage gets low.

I'm not sure if any of the other tool lines do it, but makita does.

Most lithium batteries without built in bms will do this. I see people wiring stuff to their expensive tool batteries and doing deep discharges, basically ruining them all the time. I have a little usb charger with alligator clips that I use to manually charge each cell back up and then they’re usually good to go.

 

[Nordie]

Most lithium batteries without built in bms will do this. I see people wiring stuff to their expensive tool batteries and doing deep discharges, basically ruining them all the time. I have a little usb charger with alligator clips that I use to manually charge each cell back up and then they’re usually good to go.

Oh yeah I know exactly what you're saying, but why let a lithium battery get that low, most tools now have a lipo cut off.

Unless you're using them for cool shit like hopped up hot wheels, but you know how to bring them back

 

[hman442]

Pretty lame design. Why is the tool different than the flash light? I can leave the battery in the tool for weeks and no issue. Thanks!

Maybe the Dewalt flashlight is defective. It would seem like Dewalt would make a light that you could leave the battery on ? Maybe contact Dewalt ? Then we'll probably have a thread about Dewalt Customer Service located in Budapest or such...

 

[ka0tyk]

Oh yeah I know exactly what you're saying, but why let a lithium battery get that low, most tools now have a lipo cut off.

Unless you're using them for cool shit like hopped up hot wheels, but you know how to bring them back

I stopped using tool batteries and switched to 42v scooter packs. Once in a while the cell packs will get out of balance when the kid drives it hard.

 

[mesquito_creek]

I stopped using tool batteries and switched to 48v scooter packs. Once in a while the cell packs will get out of balance when the kid drives it hard.

View attachment 1083177

Those look like LG 18650 3.7v 2400 mah batteries? Does an individual cell consistently go out of balance or does it randomly happen to different cells? I am going to build some 24v batteries out of LG 18650s I salvaged from 2 of my ebike batteries and I am curious. I have a 5 out of 50 failure rate where the cell is zero volts in the pack and am not sure if I should jumper those 5 and try to recondition them or trash em.

 

[ka0tyk]

Those look like LG 18650 3.7v 2400 mah batteries? Does an individual cell consistently go out of balance or does it randomly happen to different cells? I am going to build some 24v batteries out of LG 18650s I salvaged from 2 of my ebike batteries and I am curious. I have a 5 out of 50 failure rate where the cell is zero volts in the pack and am not sure if I should jumper those 5 and try to recondition them or trash em.
View attachment 1083201

they're LG's. the problem ive seen is when i have em in the kids power wheels they'll like drive up a hill, or get stuck and theres a BIG power draw. they'll discharge faster than the bms can balance them and one "group" will get out of sync with the others. when I go to charge it the bms will see that pack lower than the others by a % margin and treat it as damaged or whatever and then not charge it. basically cutting the whole packs power by like 15%. only way to get em back in sync at that point is to charge the pack full, and then find out which groups arent charged and manually charge em. ill keep a log of which groups in which packs (i have 4 packs total) in case theres a group thats consistently failing. but it seems pretty random so far.

 

[mesquito_creek]

they're LG's. the problem ive seen is when i have em in the kids power wheels they'll like drive up a hill, or get stuck and theres a BIG power draw. they'll discharge faster than the bms can balance them and one "group" will get out of sync with the others. when I go to charge it the bms will see that pack lower than the others by a % margin and treat it as damaged or whatever and then not charge it. basically cutting the whole packs power by like 15%. only way to get em back in sync at that point is to charge the pack full, and then find out which groups arent charged and manually charge em. ill keep a log of which groups in which packs (i have 4 packs total) in case theres a group thats consistently failing. but it seems pretty random so far.

Thanks for this information it is very helpful. I wondered how the BMS handles the 18650 wired in series to achieve the higher voltage. Based on what you are saying, the bms treats all the individual cylinders wired in series as a single cell. The bms does not monitor each individual 18650 cylinder.

Am I correct that your picture shows 15 cylinders per side wired in series to 55.5v (ie 48v) and your bms must have 2 leads that monitors all 15 as a single "cell"?

BTW, I went ahead and tried to jump my deal 0.0 cylinders with zero success, so they are going into the trash.

 

[ka0tyk]

Thanks for this information it is very helpful. I wondered how the BMS handles the 18650 wired in series to achieve the higher voltage. Based on what you are saying, the bms treats all the individual cylinders wired in series as a single cell. The bms does not monitor each individual 18650 cylinder.

Am I correct that your picture shows 15 cylinders per side wired in series to 55.5v (ie 48v) and your bms must have 2 leads that monitors all 15 as a single "cell"?

BTW, I went ahead and tried to jump my deal 0.0 cylinders with zero success, so they are going into the trash.

its a umm 3p10s battery configuration? its been a while since ive read about the batteries. they're the original 10a cells so i think 30a continuous? 36v, max 42v after update to max charge. they're relatively cheap to get on ebay, $50 with free shipping. i was paying like $25 for a sealed agm 8ah battery and using 4 at a time. these seem to do much better. but they are a bit more work.

 

[RogerThat99]

Tool batteries are such a scam. Batteries usually cost more than a tool and battery. . I have so many old tools with dead batteries that are obsolete, but the tools are still perfect.

I had the same problem. I had Batteries Plus rebuild some Makita batteries for me about 7 years ago. It was about $50 per battery, but they didn't sell that style battery any longer.

Today I have a mix of new style and old style Milwaukee. They sell converters on Amazon to make a new battery work on an old style tool.

 

[Taboma]

I had the same problem. I had Batteries Plus rebuild some Makita batteries for me about 7 years ago. It was about $50 per battery, but they didn't sell that style battery any longer.

Today I have a mix of new style and old style Milwaukee. They sell converters on Amazon to make a new battery work on an old style tool.

Is it a physical restriction ? I ask because I have some 18V 1.5AH and a 3.0AH that are originals from 2007. I also have a mix of newer yard tools using the new 18V 5.0AH. If I recall, some hand tools wouldn't accept the older 1.5AH, or 3.0AH, until I filed off a piece of plastic that was preventing them from sliding on properly. Once removed, I can use any battery in any tool. Although I have no intention of using a 1.5AH in my chain saw or lawn trimmer, would exhaust them to rapidly. Going back to 07' I've yet to have a battery fail. I do know the new yard tools are much smarter, they'll run wonky to let me know the batt or batts are done before stopping. I think the new battery electronics keeps them from completely discharging.