Lithium battery for starting in an gasoline car - in cold weather
Our tests of a LP12V/60AH battery in a Chrysler Voyager. The battery was installed in 9/2012. Now it has two winters usage and about 20000 km of driving. We do not see any change in performace. The car was able to start car in -20*C last year (about 1 week of cold waether) and in -13*C this year.
The test diagram shows the performace in cold weather (around 0*C). In cold weather the voltage during the start impulse will drop as low as 8.4V. After the engine starts working, the charge voltage will increase as high as 14.6V.
The short-circuit of Winston LiFePO4 cell (see from 4:23)
Video shows the short circuit with a direct cable connection over 8 mm bolts in the terminals.
Due to the high current and the relative high resistance of the terminal bolts, the bolts will get extremely hot with temperatures above 1000*C. This high temperature of the terminals will cause the over heating of the plastic around the terminal.
After some time, the plastic around the terminal starts melting and burning with a small fire. This fire is not caused by the battery failure but by the over heating of the terminal.
As the over heating continues, the temperature of the terminal increases and the meting and burning of the plastic case continues. However there is not any smoke and not an explosion.
Conclusion: at the short circuit, the cell does not emit any smoke from inside, does not burn, and does not explode. Due to the high currents the terminals will be overheated and the plastic case will burn as a result. The LiFePO4 is a safe technology.
TEST: The Winston LiFePO4 cell 160AH short-circuit at 1000Amp for 13 minutes
This test proves the safety of the LiFePO4 technology: no fire, no uncontrolled explosion into in fire, no sparking, no burning, no fire smoke (black).
The short circuit on an over-charged cell. This video shows the extremely high speed discharge (nearing the short circuit) of the Winston 160AH cell. To intensify the abuse conditions, the Winston cell was overcharged and become swollen before the short circuit discharge.
The over charged cell has already damaged internal structure (higher internal resistance). Thus the cell will release more heat than a healthy, regular cell with no overcharge.
After 3 minutes of short circuit the temperature of the terminal connectors increases. Due to the high temperature of the terminals, there is a small smoke coming from the plastics case around the terminals.
After 10 minutes the internal temperature of the cell has increased too high. The high temperature causes the gassing of the chemical substances inside the cell and as a result the cell has become severely swollen. More and more gasses start to be released from the safety valve on the top of the cell.
After 12:30 minutes the internal gassing is so high that the gasses start to be released from the safety valve. At this moment the temperature of the cells is around 180 *C and the internal structure if the cell is collapsing. The cell is no more releasing any energy, but most of the energy is burnt inside as a heat.
At 12:40 the release of the gasses from the cell is so high than the cell makes a „trumpet like sound“. At this moment the internal pressure increases to the maximum.
At 12:56 plastic case will no longer withstand the internal pressure and the plastic case breaks out making an „explosion like sound“, with a lot of smoke. At this moment all gasses inside the cell are released at one moment. The cell continues to generate the smoke.
During the short circuit test there was not any smoke with heat and fire (black color smoke). The cell did not set itself on fire, the cell did not burn, the cell did not explode because of fire.
The „explosion“, or rather burst opening, of the cell was because the case (outside shell) of the cell did not withstand the internal pressure. If the cell was in a battery pack, or tightly located in a proper battery case, the cell would keep the shape, as the neighboring cell would not allow the cell to become swollen. In a battery case, the cell would not most likely „burst open“: it would continue to resale the gasses thru the safety vent much longer.
The regular capacity of the cell is 160 Ah at 3.2V. The charging capacity is 160AH at 4V. This makes 640Wh of energy. With some overcharge, it can be estimated that the cell was holding of 700Wh of energy. This energy was released at some 13 minutes of short-circuit discharge. This corresponds of 3250W of immediate power. At 3.2V the short circuit current was about 1000Amp.
Inside the EVBike battery: the graph shows the results of EVBike battery balancing - with CellLog 8 used for monitoring. As seen from the graph, the cells are balanced to the same voltage level at the end of the charge.
We suggest avoiding the usage of such Li-ON cells for any serious applications.
Please think about this: if the TOP manufacturer Samsung gives „confidential“ information with such a low cycle life span, how much lower will be the life span of the identical cells produced by some no-name Chinese manufacturers? Well we even do not wish to try to guess what the reality may be.
The test data prove quite some difference in the performance of LiFePO4 cells from various manufactures. This test shows the difference between discharge results of GBS 100AH and WINA 100AH.
The discharge times at 1C (105Amp) from full charge to 12V are: 3000 seconds for GBS100AH, 3790 seconds for WINA100AH. The difference is 26%. When calculating the total energy, it is obvious the performance of the WINA100AH cell is 20% to 30% higher.
Download and check the latest test reports for the CALB CA100 and CA180 series. The tests show the results of full cell abuse, including short-circuit, cell crushing, braking and nailing. The cells show that no fire or explosion occured.
The graphs show the test results of cold temperature discharge tests for the CALB SE100AHA and CA100AHA cells. The performance is compared with tests at 31*C (88F) versus cold temperature -18*C (0F) to -4*C (25F) (the cells keep warming-up as they are discharged).
The original Winston LP12V80AH battery - after 3 years at 98AH!
The photo shows the LP12V 80AH battery produced by Winston (ThunderSky) in 2010. After 3 years of continueous use it gives 98 AH (!) of real capacity. After the warranty period, the battery was modified by the user to get access to each cell and to monitor the voltage of the cells, using the CellLog8.
What can be said? It seems better than “ideal dream”. But it is not a dream, it is the reality of the LFP technology. With LFP cells energy storage is possible!
LiFePO4 Cell Test Data - abuse and extreme conditions
The abuse test data show the results of hazardous situations and lithium cell extreme conditions: Overcharge by 1C and 2C current, overdischarge test by 0.5C current, cell damage – short Circuit, cell crush Test (50% of the cell), nail penetration test (3 mm), high temperature (150*C and 175*C), temperature performance, cycle life (0.5C).
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