KYErik
Platinum Member
- Joined
- Dec 2, 2005
- Messages
- 904
- Location
- South central IL
- Tractor
- 1977 AC 7000, 1980 JD 2840, 1963 Case 930, 1963 Ford 4000, 1943 Case SC, Case 530CK backhoe
Short version-
Taking proper safety precautions and anticipating a possible explosion, I used a 12 volt "dumb" charger to raise the voltage of three dead/non-chargeable 18-20 volt lithium drill batteries up to 3-4 volts, then placed them on the factory charger. Then the factory charger worked normally for all three batteries and there was no explosion.
Long version-
I had three lithium batteries that my chargers stopped working on over the last several years. 2 of them were 20 volt craftsman batts and 1 was an 18 volt hitachi. All three were at least 8 years old and had likely been sitting idle for at least 12 months when I noticed the problem (the factory charger would not charge them). Since then, they have been sitting for at least 1 year.
For the craftsman batteries, the charger did not light up or recognize them as attached- one had 0.1 volt, the other had 0.3 volts. For the hitachi battery, the charger showed it as fully charged while a voltmeter said it had only 0.2 volts.
From what I understand, lithium chargers must sense a small voltage before they will recognize/charge the battery- it seems like the cutoff is somewhere around 3-4 volts. So, you have to "wake up" the battery and get it above 3-4 volts. I used a "dumb" 12 volt battery charger set to 2 amps- this provided about 13 volts when attached to the drill battery. Knowing that lithium batteries can explode, to minimize property damage and the risk of personal injury I used a long extension cord and placed the battery in a 5 gallon bucket. I had 18 gauge wires stuck into the positive and negative terminals of the battery and then attached the charger's alligator clips to those wires.
Attached is a pic of the voltage when I began.
I plugged the extension cord in (from a safe distance) momentarily, then gradually worked my way up more and more seconds. The voltage would slowly drop after I unplugged the charger. Eventually after 5-6 minutes of plugging it in and unplugging it, the battery remained at about 4 volts even after the voltage dropped for a few seconds. The battery did not ever feel warm to the touch. I then plugged it into the factory charger- and the charger recognized it! This method worked for all three batteries! I am running the hitachi battery down right now in a work light and the capacity seems to be similar to battery that had never malfunctioned (I have 6 of these batteries and a variety of tools).
Taking proper safety precautions and anticipating a possible explosion, I used a 12 volt "dumb" charger to raise the voltage of three dead/non-chargeable 18-20 volt lithium drill batteries up to 3-4 volts, then placed them on the factory charger. Then the factory charger worked normally for all three batteries and there was no explosion.
Long version-
I had three lithium batteries that my chargers stopped working on over the last several years. 2 of them were 20 volt craftsman batts and 1 was an 18 volt hitachi. All three were at least 8 years old and had likely been sitting idle for at least 12 months when I noticed the problem (the factory charger would not charge them). Since then, they have been sitting for at least 1 year.
For the craftsman batteries, the charger did not light up or recognize them as attached- one had 0.1 volt, the other had 0.3 volts. For the hitachi battery, the charger showed it as fully charged while a voltmeter said it had only 0.2 volts.
From what I understand, lithium chargers must sense a small voltage before they will recognize/charge the battery- it seems like the cutoff is somewhere around 3-4 volts. So, you have to "wake up" the battery and get it above 3-4 volts. I used a "dumb" 12 volt battery charger set to 2 amps- this provided about 13 volts when attached to the drill battery. Knowing that lithium batteries can explode, to minimize property damage and the risk of personal injury I used a long extension cord and placed the battery in a 5 gallon bucket. I had 18 gauge wires stuck into the positive and negative terminals of the battery and then attached the charger's alligator clips to those wires.
Attached is a pic of the voltage when I began.
I plugged the extension cord in (from a safe distance) momentarily, then gradually worked my way up more and more seconds. The voltage would slowly drop after I unplugged the charger. Eventually after 5-6 minutes of plugging it in and unplugging it, the battery remained at about 4 volts even after the voltage dropped for a few seconds. The battery did not ever feel warm to the touch. I then plugged it into the factory charger- and the charger recognized it! This method worked for all three batteries! I am running the hitachi battery down right now in a work light and the capacity seems to be similar to battery that had never malfunctioned (I have 6 of these batteries and a variety of tools).
