[Stoves] TEG great idea / Li ION recup small idea

Fri Feb 3 05:57:40 CST 2012

Dear Frans

Great sets of information. If a stove generates power then it would have to
be above 4.2 volts, plus 0.6 or so for the zener to clip it at 4.2. That
means 4.8 so let’s say 5 VDC from the TEG, yes? Reasonable?

That will charge single cells which is the most likely circumstance on a
recycled battery approach.

I used to play with Jones Choppers (saturating core + SCR) back when I
wanted to make electronically controlled wheel chairs with DC permanent
magnet motors. Extremely efficient. It was ahead of its time. Oh well.  Now
everything is like that.

So it gets simple now. Bolt a TEG on the stove, draw 5+ volts, limit the
voltage to 4.2 and away it goes. I think most TEG’s will not give
over-current if the thing can take 2 amps. Getting a 5 watt module is not so
cheap. Like solar electric, best to have a system that can run wide open on
the charge cycle without damaging the batteries. There I a guy in Paal, near
Cape Town who designs and sells converters who used that approach to avoid
having a voltage regulator on the batteries. The excess heat generated when
fully charged was able to be dissipated by the battery pack design. It works
on very simple systems. Thus the stove TEG should be matched on the max
current the battery can tolerate.

Thanks

Crispin

From: stoves-bounces at lists.bioenergylists.org
[mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Frans Peeters
Sent: Friday, February 03, 2012 6:29 AM
To: 'Discussion of biomass cooking stoves'
Subject: Re: [Stoves] TEG great idea / Li ION recup small idea

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

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