General Knowledge on Battery Use

1. Prevent overdischarge

After the battery is discharged to the termination voltage, any continued discharge is called overdischarge. Overdischarge can seriously damage the battery, which is extremely detrimental to the electrical performance and cycle life of battery.

The internal resistance is great when the battery is discharged to the termination voltage. The concentration of electrolyte is very thin, especially the hole internal and surface of the pole plate are almost neutral. The internal resistance has tendency to generate heat during overdischarge, and the volume expands. When the discharge current is great, the battery obviously generates heat (even heat deformation), the concentration of lead sulfate is particularly high at this time, and the possibility for existence of dendrite short-circuit increases. Moreover, lead sulfate will be crystallized into larger particles at such time point, in other words form into irreversible sulfate, which will further increase internal resistance. The battery has poor charging recovery ability and even may not be repaired.

Battery should be prevented from over-discharge during use, and "under-voltage protection" measure is very effective. In addition, because the "under-voltage protection" of electric vehicles is controlled by the controller, other devices such as voltmeters, indicator lights and other power-consuming appliances other than the controller are directly powered by the battery, and the power supply is generally not controlled by the controller. Electric vehicle starts to use electricity once the lock (switch) is turned on. Although the current is small, over-discharge may occur if discharged for a long time (1~2 weeks). Therefore, never turn on the lock for extended period of time, and immediately turn it off when not in use.

2. Prevent overcharging

The previous chapter has given description on overcharge. Overcharge can increase water loss of the battery, accelerate grid corrosion, soften the active material, and increase the possibility of battery deformation. Overcharge should be avoided as best as possible; the choice of charger parameters should be well matched with the battery, and the operating conditions of battery in hot seasons and the changes throughout the service life should be fully understood. Battery may not be placed in an overheating environment during use, and should be kept well away from heat sources especially during charging. After the battery is heated, cooling measures must be taken, and the battery may not be charged until the battery temperature returns to normal. The installation location of the battery should ensure good heat dissipation as much as possible, and charging is stopped when overheating is found. The charger and battery should be checked. When the battery discharge depth is shallow or the ambient temperature is high, the charging time should be shortened.

3. Prevent short circuit

When the battery is short-circuited, its short-circuit current can reach hundreds of amperes. The stronger the short-circuit contact, the greater the short-circuit current, so all the connected parts will generate substantial heat, and the heat generated at the weak links will be greater, which can fuse the connection and cause short-circuit phenomenon. Explosive gas (or explosive gas accumulated during charging) may be generated locally in the battery, and sparks generated when the connection is fused can cause battery explosion. If the battery short-circuit time is short or the current is not particularly great, the connection fuse phenomenon may not be caused, but short circuit still causes overheating, which will damage the adhesive around the connection bar, leaving hidden dangers such as fluid leakage. Therefore, the battery must not be short-circuited. Special care should be taken when installing or using the tools. Insulation measures should be taken for the tools. When wiring, first connect electrical appliances other than the battery. When short-circuit is not found from inspection, the final step is to connect the battery. Wiring should be standardized and well insulated to prevent cracks caused by overlapping pressure.

4. Prevent loose and unsecure connections

Loose contact but slight degree can cause poor conductivity, so that the contact parts of its line is heated up, the line loss is rather great, the output voltage is low, which will affect the motor power, reduce the driving mileage or prevent normal riding. Loose contact at the wiring terminal parts (most of the faults are at the terminals and connection joints), the terminals will generate excessive heat to impair combination of terminals and sealant, and the "acid creeping" of acid fluid will occur over time. If the contact becomes loose during driving or charging, open circuit may occur, and strong sparks will be generated during the open circuit, which may ignite the explosive gas inside battery (especially for battery just charged, as much explosive gas is present in the battery, and the battery has sufficient power, the spark is strong during open circuit, and the possibility of explosion is rather great.)