Many individuals have the habit of leaving electric vehicle batteries connected to their cars even when not in use, failing to turn off the main power switch, and not riding their vehicles for several months. When they attempt to use their vehicles again after such a long period, they often find that the battery is completely drained and unable to charge properly. The charger remains green even after 24 hours of being plugged in due to the battery’s extremely low voltage. If there is a significant difference between the charger’s output voltage and the battery’s voltage, the charger will be unable to recharge the battery effectively.
This situation is commonly referred to as a “dead” or “discharged” battery. The voltage of such a battery cell typically drops to around 5.6V and does not exceed 6V. In most cases, replacing the battery is the only solution. However, given that a new set of batteries can cost hundreds of dollars, this can be quite disappointing, especially for batteries that have just expired their warranty period.
Fortunately, there are five effective methods to potentially revive most of these “discharged” batteries. Please note that these methods are not guaranteed to work 100% of the time.
1.Series Connection Method
Connect another fully charged 12V battery in series with the entire battery pack. For instance, if the original vehicle had a 48V-20AH battery, you can connect another 12V-20AH battery in series. A fully charged 12V battery has a voltage of approximately 13V. When connected in series, it increases the overall voltage of the battery pack, allowing it to be charged using the original charger. Once the charger turns red, indicating that charging has begun, allow it to complete the charging cycle. After the charger turns green, disconnect the additional battery that was connected in series and proceed with normal charging.
2.Parallel Connection Method
This method is slightly more complex. For example, if the vehicle originally had a 48V-20AH battery, you will need to connect another set of 48V-20AH batteries in parallel. In a parallel circuit, the voltage across each battery is equal, and the current will flow from the higher voltage to the lower voltage. This method is also employed by many battery dealers to test completely dead batteries. By connecting them in parallel, you can increase the overall voltage of the battery pack and achieve successful charging.
3.Low-Voltage Charging Method
Use a smaller charger for charging. For instance, if you have a set of 60V-20AH batteries, you can use a 48V-20AH charger. In many cases, this method can also be effective. The principle is similar to the series connection method, as it brings the charging voltage closer to the voltage of the battery terminals.
4.Single Battery Charging Method
Charging a single battery with a 12V motorcycle charger can activate the battery, but this process is relatively slow and can take more than seven hours before the battery voltage gradually returns to around 12V. If all batteries need individual charging, it can be quite time-consuming.
5.Special Charger Method
Some chargers, like the Tianneng charger, automatically recognize the battery’s voltage, regardless of its current state. This means that even if a 60V-20AH battery has dropped to less than 30V, it can still be charged. As the voltage increases, the charger adapts to higher voltage levels before fully charging the battery. Brands such as Tailing, Green Jia electric vehicles, and Jinpeng tricycles use chargers from this manufacturer.
Activating Lithium Batteries in Laptops or Mobile Phones
Battery activation in Lenovo’s power management software is referred to as “power scale calibration.” When using Everest to test a PC’s battery, you will see a “design capacity” followed by a “full charge capacity.” If these two values are the same, the “battery loss” will be 0%. Newly manufactured batteries or those that have not been maintained properly will often have a “full charge capacity” that is smaller than the “design capacity,” resulting in a 1% battery loss. This indicates that the battery is not fully charged, and it needs to undergo “full charge and discharge” (continuous charging for 12 hours or more after a full discharge) to fully unlock its potential. This process is known as “activating the battery.” Power management software like Lenovo Thinkpad’s has a “power scale calibration” feature that operates on a similar principle.
Personally, I believe that older technology batteries, such as NiMH, require activation. The theory behind lithium battery activation is that a protective layer of SEI needs to form on the negative electrode. However, this process is typically completed during the production and testing phases. I suspect that consumers’ misconceptions about batteries have led to such services being offered.
If your phone battery is completely discharged and cannot be turned on or charged, it needs to be activated. Firstly, “discharged” refers to a battery’s inability to recharge when it has very little or no remaining charge. There are currently two methods to activate it: one involves using universal charging for about 20 minutes, and the other involves using a professional power supply with a slightly higher voltage, such as 12 volts, at a mobile phone repair shop. Specifically, place the positive and negative terminals of the power supply on the corresponding terminals of the battery for several seconds or even minutes to fully charge it. After activation, you can charge the battery as usual. It is unclear whether this process will significantly affect the battery’s lifespan.
If the above methods do not work and the battery is not faulty, you may need to activate it using a “voltage regulator power supply.” Connect the black wire to the battery’s negative terminal and the red wire to the positive terminal. The charging voltage should reach 3.8V. For devices that use lithium batteries, there is no need to charge them for 12 hours the first time; this is unnecessary.
