Prevents loose connections and is not strong if contact is not strong, to a lesser extent, poor conductivity will happen to the line contact area, fever, line loss is large, the output voltage is low, the impact of electrical power, so that mileage can not be reduced or normal riding ; if the contact is not strong at the terminals parts (mostly the fault is in the terminal and connection joints), the terminal will be a lot of heat, combined with the impact of terminal and sealants, leakage occurs over time will "crawl acid" phenomenon. If there is not strong in contact with the process or the charging process, may produce circuit, will have a strong spark circuit, may point the internal battery explosion explosive gas (especially newly charged battery, the battery can explode due to gas more, and enough battery power, disconnect the spark more intense when the possibility of an explosion is quite big.) to bear more intense vibrations of electric vehicles in operation, therefore, to deal with all the connection reliability assessment, connectors should bring " Self-locking "function to prevent vibration and pull off, to connect with the battery connector lugs should be taken and used to weld solder, crimp connectors and wiring application mode (also available after crimp and solder welding again increase reliability). 5, to prevent exposure to the sun in the sun exposure will increase the battery temperature, the activity of each active substance in the battery increases, affecting battery life. Fourth, the lead-acid battery short circuit and cause of lead-acid batteries are lead-acid battery internal short circuit means connected to the positive and negative groups. Lead-acid batteries short circuit mainly in the following aspects: (1) open-circuit voltage is low, closed-circuit voltage (discharge) quickly reaches the termination voltage. (2) large current discharge, the terminal voltage rapidly drops to zero. (3) open, the electrolyte density is very low, at low temperatures the electrolyte will appear icing. (4) charging, the voltage rises very slowly, always remains low (sometimes zero). (5) During charging, the electrolyte temperature rises very rapidly. (6) charging, electrolyte density to rise very slowly or hardly changed. (7) does not take charge or take gas bubbles appear late. The main causes of internal short lead-acid batteries in the following areas: poor (1) partition quality or defect, so that through the electrode active material, resulting in positive and negative plates virtual contact or direct contact. (2) partition channeling bits resulting positive and negative plates are connected. (3) expansion of the plates active material shedding, shedding due to excessive deposition of the active substance, resulting in positive and negative plate edge or side of the lower edge of the sediment caused by contact with each other is connected to the positive and negative plates. Cause within (4) conductive objects fall into the battery positive and negative plates are connected. When the formation (5) welding electrode group "Lead flow" is not divisible, the "lead beans" between positive and negative plates in the presence or assembly, in the course of charging and discharging caused by positive and negative plate is connected to the separator damage.