The external battery should I do to be safe

Do not smoke. Or perform any sparks near the battery.Checked the battery voltage. The battery 6v. Or 24v. Not a trailer with a 12 v. battery will explode.Make sure the car does not start.To check the battery. By looking at the battery. Or use the measured specific gravity (HYDROMETER) by measuring the color of light to charge the battery.If it is green, the power capacity during the fullIf it is brown or black, indicating that the battery runs out. Should charge the battery.If it's yellow. Show whether or not to replace it.Make sure that both positive and negative battery terminals clean. If you want to pour hot water to clean the battery terminals.Do not let the battery trailer collideFirst, the battery cables attached to the red or positive terminal of the battery to the trailer before. Then connect to the battery positive.The tow line is connected to the battery or remove the black negative terminal of good battery. The last line of black trailer with a removable battery cathode.The engine is a good battery. Idling while to go.Do not open fire in the engine. The power will fall. Cause damage to your car using the computer.Start the engine, the battery is not good. When the load line, remove the battery. In reverse order to the next.Set the battery on the trailer, you should accelerate to around 2000 and then make sure the battery.