STOP Throwing Away Dead Drill Batteries! Simple Fix with Laptop Charger, by Brain Inventor on YouTube. 2 min 59 s.
- Video length
- 2 min 59 s
- Time to do it
- 20 minutes
- Difficulty
- Medium
- Steps
- 9
What you need
Steps
Set the battery on a fire-safe surface and put on safety glasses. Check the pack for swelling, cracks or leaking. If you see any, stop and dispose of the battery properly instead of charging it.
Measure the battery voltage with the multimeter. Touch the red probe to the positive terminal and the black probe to the negative terminal and write the reading down.
Compare that reading with the charger output printed on its label. A 19V to 20V charger suits an 18V or 20V pack. Do not use a charger with a higher output voltage than the pack's nominal rating.
Find the polarity of the laptop charger plug with the multimeter, or read the polarity symbol on the label. Identify which wire is positive and which is negative before anything touches the battery.
Connect the charger's positive wire to the battery's positive terminal and the negative wire to the negative terminal. Keep the contact brief, a few seconds at a time, and watch the multimeter.
Stop as soon as the voltage climbs to roughly the pack's nominal rating, for example 18V on an 18V battery. Pull the leads off immediately and let the pack rest for a few minutes.
Feel the battery for heat after each short connection. If it gets warm, smells odd or the voltage does not rise, disconnect and stop. Do not keep pushing current into a pack that is not responding.
Place the revived pack on its own brand charger once it shows a normal voltage. The charger should now recognise it and finish the charge properly.
Test the battery in the drill and run it under light load. If it holds charge and the drill runs normally, the fix worked. If it dies within minutes, the cells are worn out and need replacing.
Tips and common mistakes
Never leave this setup unattended, and keep a fire extinguisher or a bucket of sand nearby.
Short touches of a few seconds are safer than one long connection, so watch the multimeter the whole time.
A pack that only wakes up briefly and drops again has failed cells, not a sleeping protection board.
Store revived packs at around half charge in a cool, dry place to slow further damage.
Questions
How long should I leave the laptop charger connected?
Only a few seconds at a time, checking the voltage between each touch. Stop once the pack reaches its nominal voltage and move it to its own charger.
Is this safe to do at home?
It carries real risk because you are charging lithium cells without their protection board. Work outdoors or in a well-ventilated space, wear safety glasses and stop at the first sign of heat or swelling.
What if the battery will not hold charge afterwards?
Then the cells are worn out rather than merely shut down, and no charger trick will fix that. Replace the pack or have it rebuilt by a professional.
This guide was drafted from the video's details and general task knowledge. It has not been checked against the full video. Check the video and relevant product instructions before following a procedure. Report a correction.
