Can the 12.6 volt lithium battery charger with 2.6 volts be reduced to new: No
When a 9v charger charges a battery 12.6v lithium battery, it is easy to cause the capacity to become unrecoverable. The problem is that the battery capacity decreases when charging. If the charger is designed according to the normal method, the transformer with an output voltage of 9V AC cannot meet the requirements and cannot be charged normally. Even if it is a power transformer, if the output voltage is only 9V, the output voltage is too low. and it still cannot charge the 12.6V battery.
The 9V transformer produces alternating current, which cannot charge the battery directly. If full-wave rectification is used, the highest voltage is around 12.69 V. In fact, this voltage cannot fully charge the battery. the only way is to use a circooked voltage doubler and voltage regulator.