I left my flashlight battery on the charger all night and it still is dead, what’s the deal? Was I given a faulty battery? Is my charger bad? Or in the case of the Touch 1K charging, is my light bad? I paid a lot of money for this.
If this is familiar to you, you are in luck or could be in luck. To explain further I will cover some basics on lithium battery charging. There are several different battery chemistries but I’ll be covering just Lithium-ion and Lithium-polymer.
In the rechargeable lithium-ion batteries they will usually have a voltage rating at 3.6, 3.7, and 3.8 but if the voltage is checked on them they will read in a range from 3 volts on up to 4.2 volts depending on the charge level. The voltage rating is the nominal voltage not the actual voltage of the battery. When a lithium-ion battery is charged it is charged up to 4.2 volts. Once the battery reaches that voltage the battery is fully charged and you have a full tank ready to go. The battery when in use will dip a little and then deplete at the rate it is used. Most devices will stop or shut off when the voltage hits around 3.0 volts or somewhere close to it. Then the cycle starts all over again, the battery is placed back on the charger until it reaches 4.2 volts again.
Now that this has been explained we can discuss what happens when the battery doesn’t charge. When devices shut off when the battery reaches that 3ish volts, the charging presents no issues. What can happen and does happen is batteries in devices when left alone will drain slowly beyond that 3 volt point and depending on how low it drops is where the charging stops working. 3 volts has a buffer to allow the battery to drain some past that point. When it becomes a problem is when the voltage gets down to 2.5 or lower and depending on the charger the battery wont charge. Actually it not that the battery wont charge but that the charger will recognize it as a damaged battery and not charge it. Some batteries will even have circuits to prevent it from charging after dropping too low.
With that being said, there is a way to resurrect a battery that drops too low assuming it is not entirely bad
This is how to resurrect a battery from the dead
When a battery isn’t charging start by checking the voltage. It will likely be lower than 2.5 volts. Once you check the battery voltage there are two ways that I use to do the resurrecting.
- 1: Using a programmable power supply (as shown). Set the voltage to 4.19-4.2 and the Amps to .5 on up to 2 Amps. The lower amperage is safer but takes longer. When resurrecting a battery, I like to use 2 amps. I sort of feel like I’m using a defibrillator ready to restart someone’s heart at the point when holding two probes pressed on the battery. Place the positive lead to the positive of the battery and the negative to negative. The amps will typically show that it is using the full amount that it was set to, and the volts will only be as high as the battery accepts. Hold the leads to the battery until the voltage reaches around 3.6 and then immediately put in a charger. At this point you wait to see if the charger accepts the battery. If it doesn’t just repeat the process of holding the power supply to the battery a little longer.
2: Using another battery to resurrect is another option. I feel a little blind doing it this way but is much more simple way. To use this method, you’ll need to fully charge another lithium battery of the same size or larger. Once you have the charged battery, rest them next to each other with both positive ends face the same direction and contact the positive to the positive and negative to negative. After a minute or two place the batteries on a charger to see if the dead battery is alive again
On the Touch 1K lights I have seen this as the number one reason for them not working. Usually it is caused by the light being turned on and left on until the battery was dead and then left to sit for a week. This has happened during shipping and in backpacks. There is one setback to this happening in the Touch 1K where the battery is glued in. We are coming out with our own battery that will be safer and allow access to the battery. There was a blog post that talks about some ways to access the battery if you want to gain access to the battery.