Archived from the Tools In Action forum (Bosch). This thread is read-only.
Hello.
I have just been given a used PSB 18 li-2 cordless drill and when I press the trigger a white light shows then the 3 led’s flash three times then the drill cuts out. ( I can do this over and over and over)
I have checked the battery on my multimeter and it is showing 15.8v (I don’t yet have a charger)
Do I take it there is a fault on the drill itself? brushes maybe?
appreciate help
thank you
PROTOOLNUT wrote:
Wait, hold on a second. You said the lights flashed three times to indicate a dead battery and went off, and you admit to not having a charger. I think the battery is dead dude, you need a charger. Charge that baby up and it will purr like a kitten on steroids. 😉
Does the flashing led’s mean the battery is dead?
If so why would multimeter show a nearly full charge
I have never had a bosch cordless before, I always used makita so I am unsure about Bosch “error messages”.
appreciate further advice please
That’s an 18v drill. Those cells are full charged at 4v and fully discharged at 3v
An 18v/20v has 5 cells in series. Fully charged you should get a reading of 20V. (That’s why DeWalt calls their batteries 20v)
If you are reading 15.8v with the battery not under load it’s dead. Lithium batteries do a great job of holding their voltage to the end of the cycle. Once they get to the end the voltage drops quickly. See the graph in the pictures. It’s tracking the individual voltage of each cell in one of my 2 cell Lithium LiFe packs (built from a cut up 36v DeWalt pack). I call it falling off the cliff.
Our newer lithium powered tools stop the discharge before it falls off the cliff to protect the battery. Your battery is at the edge of the cliff. When you pull the trigger the voltage drops and the tool cuts off to protect the battery.
Leaving lithium battery’s deeply discharged can damage them. I would recommend not trying to use the drill until you get a charger. It will just make the situation worse.
Yup. Li-ion have used up 95 % of it’s capacity when it reaches around 3-3,1V per cell (around 15-16v).
The last energy/voltage is needed to not destroy the battery. If the safety didn’t cut power you would have killed the battery going any further.
Which is why Li-Ion really needs its needed electronics.
Great answer C harris, that is some good info
Can I say thank you to you all
very informative.
I was stumped thinking that 3 lights may have been the drill rather than the battery, now I know better
And feel safe in buying a charger
cheers folks