Replace old Ni-Cd Batteries of Boschmann Impact Wrench with LiitoKala Li-Ion Cells

[ercaneverything]

[DIYer]

Thanks ercaneverything! We've added your Cordless Battery Pack Repair to our Power Supplies category,
as well as to your builder page: ercaneverything's Homemade Tools. Your receipt:

Cordless Battery Pack Repair by ercaneverything

tags: battery

[RetiredFAE]

I take it ( I hope) that the circuit board alters the charging current and time so that it is safe to drop the replacement batter pack into the original ni cad battery charger?
Otherwise, that's a firebomb waiting to happen when the cells get charged at a ni cad rate, thermal runaway is in store.

[tlnixon]

My understanding is that Lithium-Ion batteries must be charged differently than NiCad, or Nickel Metal Hydride. The charge must be pulsed on and off. That is why visially looking at a LI-Ion charger, you will see it blinking. Continous charging can cause overheating and an explosion/fire. Also from having had several Craftsman batteries apart, I noticed that the charge is applied to each battery individually. They are not charged in series as other tytes are.

[RetiredFAE]

I believe Lithium-Ion batteries require a constant VOLTAGE charge until they reach full capacity, where Ni Cad batteries require a constant CURRENT charge until they reach full capacity. Also the Lithium Ion batters require a higher voltage during charging than the Ni Cads.
The individual Ni Cad cell has a voltage of around 1.2 VDC, while the lithium one is 3.6 VDC.

[tlnixon]

The pulsing charging has to do with preventing them from getting too hot and exploding. Yes the 3.6 volt cells require more volatage to charge, but it cannot be constant. It has to turn on and off to regulate the temperature.

[RetiredFAE]

I seem to recall that the pulsing runs, depending on the manufacturer, from 13 Khz to over 200 MHZ, with duty cycles running 25%to as much as 75%, not sure how much cooling effect that is going to have, but if that's the way they do it, it must work, although all my Dewalt lithium batteries for power tools , charged in the DeWalt charger that came with them, do get slightly warm after being recharged.

I never leave them in the charger unattended, and it sits in the middle of a large concrete floor, with nothing closer than 10 feet in any direction, and with a 20 foot ceiling, just to be safe.
We had quite a lithium battery fire near where I live a couple of weeks ago, shut down I15 into Vegas for 2 days.
I don't want one of those batteries going off in my shop, hence the charging location and only when I am present.