Dear Intellects
i am in a big spot of bother. we use li-ion batteries as source for our heated products. I was charging the battery with battery plugged to the heated product. I charged it for more than its actual charging time. After a precise period of time i heard a loud blast and i was terribly surprised to see my floor on fire and never in my wildest dreams i imagined this to happen.I had a complete faith in our product and its quality.
My analysis
* overcharging
* over heating
*failure of cells
* failure in charger
* protection circuit failed
*over discharging
COMPLETE SPEC
1.
Kind of Products specified：
2.1. Name
Lithium Ion Rechargeable Battery
2.2. Type
2S1P(7.4V-1500mAh)
2. Basic
Characteristics：
|
Item |
Description |
|
3.1. Rated Capacity |
2000mAh
(Discharge at 0.2C from 16.8V to 12.0V) |
|
3.2. Nominal Voltage |
14.8V |
|
3.3. Charge Voltage |
16.8V±0.10V |
|
3.4. Charge Method |
CC/CV |
|
3.5. Max. Charge Current |
0.5C(1000mA) |
|
3.6. Cut-off Voltage |
12.0V |
|
3.7. Max. Continuous Discharge Current |
0.75C(1500mA) |
|
3.8.Operating Temperature |
Charge |
0 ～ +45℃ |
|
Discharge |
-20～ +60℃ |
|
3.9. Storage Temperature |
1 month |
3 months |
6 months |
|
-20～+60℃ |
-20 ～
+45℃ |
-20 ～
+25℃ |
|
3.10.Environmental Humidity |
65±20% |
|
3.11.Dimensions(mm): L ×W ×H |
145×
37.0× 37.0 |
|
3.12.Weight |
405g(Approx.) |
4．Appearance
Defects,
such as scratches, flaws, dirty spots, rust, leakage, etc., which damage commercial
values shall not be presented.
5. Specification：
5.1.Electrical Characteristics
|
Items |
Performances |
Conditions |
|
5.1.1.
Complete Charge |
/ |
Charging the battery with 0.5C of constant current
and 16.8V of constant voltage for 4h. |
|
5.1.2.
Internal Impedance |
R≤500
mΩ |
Measured at 1KHZ after complete charge |
|
5.1.3.
Initial capacity |
> 2000mAh |
Measured with discharge current 0.2C to 11.0V
cut-off within 1h after complete charge. |
|
5.1.4.
Cycle Life |
500cycles
( Capacity≥70%
of initial capacity) |
Charge / discharge at 0.5C to 12.0V |
|
5.1.5.
Discharge at -20℃ |
Capacity≥70% |
After complete charge, Stored the battery at -20℃
for 20hrs and then discharge at 0.5C to 12.0V. |
|
5.1.6.
Discharge at 55℃ |
Capacity≥90% |
After complete charge, Stored the battery at 55℃
for 2hrs and then discharge at 0.5C to 12.0V. |
|
5.1.7.
Storage |
Retention capacity
≥85% |
Capacity after 28days storage at 20±5℃
from complete charge. |
|
Recovery capacity
≥75% |
Capacity after 7days storage at 55±2℃
from complete charge. |
5.2. Mechanical Characteristics:
|
Items |
Performances |
Test Methods |
|
5.2.1. Vibration |
No leakage, no venting, no explosion and no fire |
The battery is to be subjected to simple harmonic
motion with amplitude of 0.8mm.The frequency is to be varied at the rate of
1Hz per minute between limits of 10 and 55Hz. The cell is to be tested in
three mutually perpendicular directions. |
|
5.2.2. Drop test |
No leakage, no venting, no explosion and no fire |
The cell is to be dropped from a height of 1m with
3cycles. |
5.3. Safety Characteristics:
|
Items |
Performances |
Test conditions |
|
5.3.1.
Heavy Impact |
No explosion and no fire |
Use 10kg hammer fall free on the battery from 1m
height |
|
5.3.2. Overcharge |
No explosion and no fire |
Continue to Charge the battery at 0.5C/16.8V after
complete charge |
|
5.3.3.
Over-discharge |
No explosion and no fire |
Discharged
at a constant current of 0.2C to 11.0V, then discharge with external load of
50Ω for 24hrs. |
|
5.3.4.
Short-circuit |
No explosion and no fire |
The battery
is to be short-circuited by connecting the positive and negative
terminals with load of 0.1Ω for 1h |
|
5.3.5.
Heat Impact |
No explosion and no fire |
The charged cell shall be placed in an oven. The
oven temperature shall be increased at a rate of 5℃±2℃
per minute to 150℃±2℃
and maintained at 150℃±2℃
for 30min. |
6. Required Protection Functions：
To
insure safety, the charger and the protection circuit shall satisfy the
following conditions. As an additional safety feature, please use in
combination with the temperature fuse or polyswitch. The standard charge method
is CC/CV(Constant current/ Constant voltage).
|
Charger |
|
No. |
Items |
Parameter |
|
1 |
Charge Termination
Voltage |
4.20V ±
0.05V |
|
Protection function（for
reference only） |
|
2 |
Excess Charge Detection Voltage |
4.35V ±
0.025V |
|
3 |
Excess Charge Release Voltage |
4.175V ±
0.05V |
|
4 |
Discharge Termination Voltage |
2.75V ±
0.10V |
|
5 |
Excess Discharge Detection Voltage |
2.30V ±
0.08V |
|
6 |
Excess Discharge Release Voltage |
2.40V ±
0.10V |
|
7 |
Excess Current Detection Value |
3 A ±
0.2A |
7.
Storage and Warranty period
7.1. Standard storage condition:
Pre-charge 20-30%; Temperature:20℃±5℃;
Humidity：65±20%
7.2. Warranty period:
12months from manufacture code.
8.
Usage indications:
Please read and follow the handing
instructions for the cell before use. Improper use of the cell may cause heat,
fire explosion or capacity deterioration of the cell.
8.1. WARNING：
● Do not put the cell into a fire, or heat the cell, do
not store the cell in high temperature environment.
● Do
not connect the cell reversed in positive and negative terminals in the charger
or equipment.
● Do
not let the cell terminals contact a wire or any metal with which it carried or
stored together, may cause short-circuit.
● Do
not submerge the cell in water, do not wet the cell when store the cell.
● Do
not drive a nail in, hit with a hammer, or stamp on the cell , do not strike
the cell in other ways.
● Do
not disassemble or alter the cell's outside structure.
9. NOTICE：
● The cell shall be charged and discharged with proper
charger, in compliance with correct operation contents.
● Do not use the cell with other brand's cells,
different types and or models of cells such as primary cells, nickel-metal hydride
cells, or nickel-cadmium cells, or new and old lithium ion cells together.
● Do not leave
the cell in a charger or equipment if it generates an older and/ or heat,
changes color and/or shape, leaks electrolyte, or cause any other abnormality.
● Do not discharge the cell continuously when it is
not charged.
9.1. CAUTION：
● In case young children use the cell, instruct them on
the contents of the instructions and ensure the cell is correctly is correctly
used by them at all times.
● The cell was
inspected carefully by QA before shipment to confirm with the specifications.
However, in the case any abnormality of bad smell or heat, etc., arise after
purchase, bring it and communicate with us.
● For long-term storage, please charge at 0.5C for
about one hour in advance.
● Do not use the cell in other than the following
conditions , otherwise, the cell might cause heat generation, damage, or
deterioration of its performance.
Operating environment：
Charge： 0℃ ～ 45℃
Discharge：-20℃ ～ +60℃
Store less than 1 month：-20℃ ～ +60℃
Store less than 3 months：-20℃ ～ +45℃
Store less than 6 months：-20℃ ～ +25℃
THIS EVEN HAS BECOME A WORRYING POINT OF CONCERN.COULD SOMEONE SUGGEST A RELIABLE SOURCE TO TEST THESE DAMAGED BATTERIES TO PERFECTION HENCE THIS DO NOT HAPPENS AGAIN.
MANY THANKS TO ALL
2
Li-Ion Battery-Blast
Re: LI-ION BATTERY-BLAST
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