Battery connection can cause fire if not done correctly
Do you know that a battery connection can cause fire if not done correctly? Many of us working with electrical equipment, and particularly with solar energy, are dealing with battery banks consisting of a large number of batteries. Generally, battery terminals will often be tightened after a piece of equipment has been tested and repaired and is now being finally fitted into the system. Also, there is generally an urge under such circumstances to “finish with it” and move on to another emergency. As a result, a terminal may be left slightly loose. To learn about proper battery wiring click here
To understand why a loose fitting of battery terminals is dangerous, think of a bolt of lightning. How dangerous is a lightning strike? It can burn to death humans and animals. It can turn buildings to ashes. It can burn out anything that it strikes. It is a huge spark of electric current. A spark must produce heat, may be light and sound. Lightning does all those three things. We see the light, we hear the thunder, and we see the damage caused by the heat. A spark in a power circuit is a smaller version of a lightning bolt.
A spark will be produced whenever two conductors at different potentials lie so close that the potential difference between them can ionize the air in between. In dry air 3 KV is required to ionize an air gap of 1mm. If the gap is lesser much less voltage will produce a spark. How much voltage will ionize an airgap of 1μm? Just three volts. A loose connection on a battery terminal is one situation where such gaps can occur. The voltage is low, but any gaps that may occur will also be in micrometers. The slightest vibrations on a loose connection can cause such gaps to occur many times in a second.
And now use the basics of electrical engineering to calculate the power of a spark in a 12 V circuit carrying 200 A. The power is product of voltage and current which in this case comes out to be 2.4 KW! All that power converts to localized heat. What do you think will happen if the sparking continues? Temperature will keep rising. The insulation on the cable and the terminal will melt and possibly catch fire. Part of the terminal and some strands of the cable near the terminal will burn away. Reduced conductance of the path in this region will increase the local resistance and increase the heat generation due to the sparking. Let it continue and you will surely have a fire.
There is another way in which a loose terminal can cause problems. The mating surfaces of the clamp and the battery terminal acquire some rough spots. In case the terminals are not tightened properly, the circuit may still be completed but not all the available surface is in contact. That means increased resistance, and again, localized heating possibly leading to fire.
Have you got a fire alarm and fire protection arrangement in place?