Dear Crispin,
Charging any battery needs OVERVOLTAGE A car battery of 12V needs 14,5V in the car to charge it and well controled: max 15,5 till the First H2 bubbel apears . In labtop Li ION is used in FAST mode !And for safety each couple so 4 controls are done also one or 3 temperature sensors ! and some times a pressure switch inside a cell! Not resetable ! Exemple : 4cells in paralel =3,7 V .Empty is 2,9 V .Charging must be 4,2V exact ! no more. Current limited to 0,5 A otherwise it takes 3,5 A After 10 minutes no current limmited takes 1,5 A for 2 hours Stop at O,9 amp . No heat ! Use 24 LED Hüfner lampset with regulator for 4,5 V . For other LED combinations 3,2 V you substract 0,6 V with any Si diode zener-effect like 1N 1002 1Amp 3,7-0,6 V=3,1 V Or Ge diode is minus 0,4 V like OA100 . You must not charge and licht the same time! Is high power 100 000 candela or 1watt or 40 watt ? It exist . But 24 leds for 480 mA is all you need to work at night in the garden . Labtop uses no chopper in the battery ! It only NEEDED OVERTENSION to charge . Battery 14,8 V is charger 20 V and 8cells ,4serie couple . 6cells in serie 6x3,7 =22,2 V battery but charger 4,2x6=25,2V switched power supply at 40 KHz to make it light weight end cheaper than a transformer of 100 Watt and less losses .. LED controler Chips use puls wide regulation.and tension adaption . A dead battery pack can be new in the cells and broken in the chips inside the pack !! Or 1cell bad and 7 new for Africa ..= 100$ from the waste bin !!! (Even a dead cell in a new envelope gave tension again !! Only by pressure switch off,inside the cell !.MIND NERVE GAS under pression ) Regards Frans _____ Van: [email protected] [mailto:[email protected]] Namens Frans Peeters Verzonden: vrijdag 3 februari 2012 3:04 Aan: 'Discussion of biomass cooking stoves' Onderwerp: Re: [Stoves] TEG geat idea / Li ION recup small idea Dear Crispin, Indeed a labtop charger is 20V DC 3,5 A charging current for 3,8 Ah ,but the battery is14,8 Volt . But between charger and cells you have 20 cm2 chips inside the battery and and 30 cm2 in the PC .So supper uPcontrol and secret design ! DELL P/N75UYF contains 8 cells=4 times 2 paralel so 14,8:4=3,7 volt. Put all 8 in paralel and 3,7 V will run your ideal 24 LEDs licht like HÜffner Germany with regulator inside ,intended for 3X1,5=4,5 volt Charging was indended in Africa with 1 sun cell of 3$ limited with zener to 4,2 volt PC controler use 4,28 V charging / cell .Puls only at the end . An emty cell needs soft start charging 0,5 A for 10 minutes .followed by 2h at 1,5 A . LEDs design current is important,less the voltage !! Can be adapted with a serie resistor like 56 ohm for 6 leds . Find the value with a current meter and potentiometer . Regars Frans _____ Van: [email protected] [mailto:[email protected]] Namens Crispin Pemberton-Pigott Verzonden: donderdag 2 februari 2012 16:54 Aan: Stoves Onderwerp: Re: [Stoves] TEG geat idea / Li ION recup small idea Dear Frans The charging voltage for a great many laptops is 19-21 volts for a 6 cell Li-Ion battery. Is it fair to say that it is safe to charge one cell with 4.2 volts, with an operating voltage of 3.2? 3.2 is enough to fire most HE-LEDs though many of the packaged units use 3.5 (for full brightness of white HE-LEDs). 19/6 = 3.2 (only) so perhaps 4.2 is a bit high. Are they using a pulse width modulated chopper to increase it to 25.2 as the charging voltage, or something else? I recall some battery packs are charged as 2 parallel sets of 3 in series, but power is drawn as 6 in series. Those were 12 VDC input. Now they are all 19.2 or so. The one I use has a 9-cell and it is probably 3 sets of 3 in series when charging. Breaking out the cells from an old laptop is a safe thing to do and probably some cells are better than others. In previous discussions here we have noted that an old (almost dead) cell phone battery can run 3 LEDs for a couple of weeks. Dead to a phone or laptop is not at all dead to a light, especially the newest high efficiency small white ones. Thanks for your continuing advice and enthusiasm. Regards Crispin From: Frans Peeters [mailto:[email protected]] Sent: Thursday, February 02, 2012 9:03 AM To: Stoves Subject: TEG geat idea / Li ION recup small idea Dear RON LARSON , With KNOW HOW ., a smal idea can become a geat idea for Africa ! The World is over full with LAPTOPS and weak powerpacks ! DELL :It contains 8 Li ION cells of 3,7 volt 3,5Ah And regulator prints inside -------> secret !! 80% of this broken or wasted packs can be used for head lichts and home lichting , with 24 LEDS; you get one week lichted evenings ! You put all the cells in paralel . And charge by sun with a 10x5 cm sun panel end limit the voltage on 4,2 Volt like ZX4,2 zener diode Not more, for explosion danger . It contaains Fluorinated ether !!! (For the laesy and fortunated . :www.CONRAD. de could sell rechargeable Lithium ION cells ! Not to find in a shop . ) Regards Frans .
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