Hi Guys,
I found the following link
http://cds.linear.com/docs/en/datasheet/4000fb.pdf
See Page 36. What do you think? I have no idea how does his circuit work.
melissa
Hi!
This group need some information about what your purpose with the
isolation/charger is e.g.:
* fun
* learn
* save money
* design a professional charger
* safer charging
Please note that standard li-ion cells are potentially very unstable if
you do not follow some security rules. They can explode and catch fire
instantly - or sometimes long after they have been mishandled.
So do not start with standard li-ion chemistry cells.
-
Instead start with LiFePO4 li-ion - or LSD-NiMH.
LiFePO4 - please note the pdf-papers. This accumulator very robust, but
still needs care when used. Can under optimally circumstances be fully
cycled more than 7000 times. Will not catch fire even if shot with a nail:
http://www.buya123batteries.com/ANR26650_Lithium_Ion_Cylindrical_Cell_p/anr26650m1b.htm
-
LSD-NiMH:
https://en.wikipedia.org/wiki/Nickel–metal_hydride_battery#Low_self-discharge_cells
These might work 5 years and/or up to 1800 cycles under optimally
circumstances. An unloaded LSD-NiMH can keep the charge for more than a
year:
https://en.wikipedia.org/wiki/Eneloop
Generally:
https://en.wikipedia.org/wiki/Category:Battery_charging
-
Test of another LiFePO4 (LFP) accumulator:
SANDIA REPORT
SAND2008-5583
Unlimited Release
Printed September 2008
Selected Test Results from the LiFeBatt
Iron Phosphate Li-ion Battery
Thomas D. Hund and David Ingersoll
Prepared by
Sandia National Laboratories
Albuquerque, New Mexico 87185 and Livermore, California
http://www.lifebatt.com/sandiareport.pdf
Citat: "...
Test results have indicated that the LiFeBatt battery technology can
function up to a 10C discharge rate with minimal energy loss compared to
the 1 h discharged rate (1C).
.....
The majority of the capacity loss occurred during the initial [!] 2,000
cycles, so it is projected that the LiFeBatt should PSOC cycle well
beyond 8,394 cycles with less than 20% capacity loss.
.....
[See graph pdf-page 23]
[ Read: 48% capacity available at -30°C. ] [ very useable! ]
[ Read: 65% capacity available at -20°C. ]
[ Read: 74% capacity available at 0°C. ]
.....
3.8 Over Voltage/Charge Abuse Test
In Figure 16 the events in an over charge/voltage abuse test are
documented. Initially, as expected, the cell voltage increases quickly
while being charged at 10 A, but then slowly increases after 4.7 V. The
cell voltage slowly increases for about 30 minutes while the cell
temperature continues to slowly rise to about 100 °C at which time cell
voltage spikes to the maximum value of 12 V. At about 110 °C the cell
vents liquid electrolyte without any fire or sparks and then
open-circuits at 116 °C. After open-circuiting and a loss of
electrolyte, the cell looses all voltage at 120 °C. The data acquisition
shuts down due to a no voltage condition, but temperature is manually
monitored until the cell reaches its maximum value at 160 °C about 20
minutes after the cell open-circuited.
...."
-
Test of LiFePO4-accumulator:
Nail penetration testing A123 Li-ion [ one of the best
LiFePO4-accumulators ]:
-*-
Comparison with other Li-ion chemistries (non-LiFePO4):
Exploding Laptops on Good Morning America:
Nail penetration testing Standard Li-ion:
World's Most Dangerous Battery!:
Modify Li-Po Battery Nail Penetration Test:
Glenn
