A few things you ought to know about repairing a ryobi battery
The batteries found in power tools can suffer from battery crystallization.The amount of material available to take a charge is reduced when batteries are discharged.The effect is known as battery memory.The crystals limit the amount of charge the battery can take and prevent it from charging fully.If the battery is the problem, it makes sense to try to fix it yourself, since replacement batteries can cost a third of the price of a new tool.Some power cells may need to be replaced if the discharge method fails to refresh the battery.
Put the battery in the charging unit.Allow the battery to charge fully.
Attach the battery to the power tool.Allow the tool to run until it discharges the battery and stops.
Once the power tool stops running, turn it off and allow the battery to cool.
Allow the power tool to run until it stops, then rest for another 10 minutes.The tool can't be turned on until the battery is strong.
Let the battery charge until it's full.Attach the battery to the power tool.You've fixed your battery if the tool lasts longer.Dead cells in the battery pack need to be replaced if there is no improvement.
The type of cells in the battery pack can be found on the label.Continue to fix your battery if it says nickel metal hydride.If it says "lithium ion", replace the entire battery or take it to a professional for repair.
Never attempt to repair the batteries.If your battery is tampered with, it could make it dangerous.
The battery should be charged in the charger.Remove the cover from the battery when the charge is complete.There are small screws on the bottom of the unit that hold the battery pack cover in place.
Lift the cells out of the battery compartment with a screwdriver.Put the cells on the work surface.
Use a voltmeter to check the cell's voltage.Good cells keep their charge while bad cells discharge quickly.Keep the cells that read between 1.1 and 1.2 volts.
Unwanted battery cells should be thrown away.There are strict laws on how to recycle and dispose of batteries.