2.How Do You Charge A Battery That Is Completely Dead?

There are two ways you can revive a dead lithium-ion battery. The first involves its original charger or other approved models, while the second consists of another battery of similar voltage and capacity.

Reviving a Dead Li-Ion Battery Using a Booster Charger

If the battery comes with a separate AC charger or charging dock, check with the manufacturer that it has a ‘boost’ function.

This is a feature where the charger checks the battery to see whether it is above nominal voltage. If not, it applies an appropriate voltage to restore it to acceptable levels.

Different manufacturers incorporate various functionalities in these chargers. They will typically display light to show if the battery is charging. For some, you might need to manually change between ‘normal’ and ‘boost’ charging.

Give the battery 3 hours in 'boost' charging and 2 hours in 'normal' charging. Then connect it to a high load such as a power tool or flashlight until it discharges fully, then charges it normally.

If the charger has an automatic boost mode, let the battery charge to halfway full, discharge it, then recharge it normally.

Reviving a Dead Li-Ion Battery Using Another Battery

You can also use a similar charged battery to ‘jumpstart’ the dead one. Here is what you should do.

●Find a similar battery with a matching voltage and almost similar charge capacity.

●Make sure the other battery has sufficient charge. It should have a higher voltage.

●Connect the two batteries with cables. The two positive terminals should match, same with the negative ones.

●Let them sit for 5-10 minutes, then disconnect the cables.

●Check that the previously depleted battery is now above minimum voltage, then charge it as usual.

What happens here is that as the batteries equalize their charges, the one with the higher voltage directly boosts the one with a lower one. Once the voltage is above the minimum, it can be recharged normally with a charger.

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