Makita battery pack - accidental short- is the battery garbage or unsafe?

[multiback]

Hello all
I was testing the battery voltage of a Makita bl 1830 B battery pack. The pack is relatively new. the SoC was unknown. A very rough guess would have been 75%. While testing the voltage with a washer in the slots, I accidentally shorted the positive and negative terminals with a screwdriver For a split second. Yes I was Distracted and stupid. the screwdriver did not weld, but a very small discolouration of the superheated metal can be seen On the washer and screwdriver. no magic smoke.

In a bit of panic I measure the voltage again and could've sworn it was 0v, but I am not certain I got good contactBecause it was done so quickly. After about 5 minutesI then put it in the makita charger just to Confirm I did kill it, it started charging and the error code did not come. I took it off after about 10 seconds

I checked the voltage again after a few minutes and I got 19._ _ ( I forgot) V,. after half hour it settled at 19.17 V which makes approximately 3.83 V per cell. When pressing the state of charge button on the battery itself, I got 2 out of 4 LEDs. I then put the battery in an old makita tool, and the tool didn't die. is now sitting in an aluminum pot.

I was very surprised to find out it was not dead
questions

1. I would have thought the shorting would have taken it down to 0 V like a capacitor. Did I indeed only have a small amount discharge?
2. have I probably cause some damage To the battery?
3. Do you know what most likely happened?
4. Is this battery still safe to charge and use? I only use the Mikita slow charger to charge. I know this is a bit of a loaded question and understand those who would not like to answer.
5. is it safe to keep in my garage
6. What would you do?

 

[fill]

Battery if genuine is probably fine, dont know specifically but suspect a reasonable BMS (battery management system) is in the pack and has some short protection, a reseting thermal switch perhaps? which would account for the initial 0v test result and apparant battery recovery..

so
1) see above
2) The battery is probably ok due to said protection
3) see above
4) Yes again thanks to the protection, but keeping an 'extra' eye on if for the next couple of charges isnt a bad idea i would be giving it a touch temperature test
5) Yes
6) I would take care not to do the same again, and pat myself on the back for investing in quality kit to start with.. a budget battery may not include any bms or protection...

 

[marty]

garage

As in the place where you store cars full of gasoline? Me I try not to worry about stuff. With electricity. If it smokes, you got a problem. If battery runs a tool and charges, I would guess that everything is OK. But with spoiled food and questionable electronics. "When in doubt. Throw it out."

Bad things happen with fires and people sleeping. That's why we don't sleep in the garage or anywhere gasoline is stored. Do make sure garage has all the common sense fire protection stuff. Most important is a closed door between garage and living area.

 

[multiback]

Battery if genuine is probably fine, dont know specifically but suspect a reasonable BMS (battery management system) is in the pack and has some short protection, a reseting thermal switch perhaps? which would account for the initial 0v test result and apparant battery recovery..

so
1) see above
2) The battery is probably ok due to said protection
3) see above
4) Yes again thanks to the protection, but keeping an 'extra' eye on if for the next couple of charges isnt a bad idea i would be giving it a touch temperature test
5) Yes
6) I would take care not to do the same again, and pat myself on the back for investing in quality kit to start with.. a budget battery may not include any bms or protection...

Battery is genuine.I bought it at a reputable tool store in Toronto who is a dealer for most of the the major power tool brands.
I'm still a bit surprised about not discharging all the way. if the battery recovered, there is no way you could be at 50% in 10 seconds. there is something I would like to know about BMS,Would it prevent a discharge over a certain amp draw? in my mind I still think of any capacitor that drains immediately

As in the place where you store cars full of gasoline? Me I try not to worry about stuff. With electricity. If it smokes, you got a problem. If battery runs a tool and charges, I would guess that everything is OK. But with spoiled food and questionable electronics. "When in doubt. Throw it out."

Bad things happen with fires and people sleeping. That's why we don't sleep in the garage or anywhere gasoline is stored. Do make sure garage has all the common sense fire protection stuff. Most important is a closed door between garage and living area.

I do not store cars or gasoline in the garage. ever. that's a waste of space. also Jerry cans can stink. i do take note with what you said about the other stuff.

 

[docw009]

The short circuit tripped the BMS overcurrent circuitry, which immediately isolates the cells from the outputs. This is accomplished by a couple of transistors. That's why your next measurements showed 0 volts, When you plugged it into a charger, it reset the BMS.

 

[multiback]

The short circuit tripped the BMS overcurrent circuitry, which immediately isolates the cells from the outputs. This is accomplished by a couple of transistors. That's why your next measurements showed 0 volts, When you plugged it into a charger, it reset the BMS.

meaningProbably no damage?