How this fire happened
The battery pack was placed on charge at approximately 09:00 a.m. - on a workbench and the fire alarm sounded at 09:50 a.m.
The owner looked into the room in question and noticed flames and smoke coming from the area of where the battery pack was sited.
He entered the room and unplugged the charger unit from the mains, then dropped the battery and charger on the floor and stamped on them both.
He did however state that smoke was seen coming from the rubber matting on the table where the battery pack was sited.
He then vacated the building and waited for the arrival of the Fire and Rescue Service.
The owner of the battery pack had stated that the battery itself was totally discharged and had suffered impact damage on a number of occasions whilst being used.
Please always follow manufacturers advice to avoid fire risk and consider the following precautions:
Never charge the battery unattended
If you have a multifunction charger, thoroughly read the instructions and make sure it is in LiPo mode
Verify that the total voltage in the pack never exceeds the amount of cells the amount of cells in the pack may never exceed (5 x 4.20V =) 21.00V
Put the charger and battery on a non-flammable surface, like a ceramic tile, during charge and make sure no flammable objects are within a radius of 1m
If possible, put the battery inside a special LiPo bag or in a fireproof container during charge
Stop charging immediately if the battery gets warm or swells, disconnect the pack and put it in a safe place for observation for a few hours
Never charge or recover a battery pack that damaged/bad/swollen cells, or cells that are below 3.0V
Use properly insulated connectors and charge leads at all time
How this fire happened
This fire occurred in a ground floor shop selling historical finds and metal detecting equipment.
The fire was extinguished by firefighters wearing breathing apparatus using a high pressure hose reel.
The battery from an imported metal detector was left on charge overnight, the premises were vacated at approximately 2030 hours and the fire was discovered by a passer-by 7 hours later in the early hours of the morning.
LiPo batteries are currently the most efficient power sources available with the highest possible specific energy.
This means that you get more power and capacity from a smaller and lighter battery.
To accomplish this, a different technology is used compared to NiCd, NiMH, and Li-lon batteries; subsequently, slightly different handling and charging applies.
3.7V is the average voltage. LiPo can be charged up to 4.20V and discharged down to 3.0V per cell, any lower or higher in voltage and the cell will almost certainly be damaged and will become unstable which can be very dangerous (fire risk).
If the voltage of a single Lithium cell exceeds 4.20V, it will become unstable. When this happens the cell will over heat, swell up and rupture whereby the electrolyte can spill and catch fire! Because the technology of the LiPo batteries is different from other batteries, you must always use specialized LiPo charger. Under no circumstances attempt to charge a LiPo with a NiCd/NiMH charger.
The charger parameters must match the LiPo and must be verified each time before you start the charging process:
The programmed number of cells must be the same as the LiPo or the nominal voltage must be equivalent. A 3s must be charged with 3s or 11.1V setting etc.
The charge current must never exceed 1C (for a 1500 mAh battery: 1.5A)
A balancer must be used to balance the voltage of individual cells during charge. (See chapter: Balancing)