To be deleted...

[nul-points]

...I'm having good indications with mine as well.
However, had to use 2 warm white top hat leds in series, not enough voltage for the 120 volt led bulb.
I think a secondary coil with more turns and then use the 120 volt led bulb as diode to charge lithium cell might work.
Not sure how well that would charge the single lithium ion cell, considering the voltage will be higher, whereas the 2 leds in series probably drops the voltage down from the primary flyback.
I also have mine, for now, with the 2 leds off the collector into positive of charge cell and negative of cell to common of circuit.
The voltages seem to be tracking very closely, as far as the loss on input and gain on charging cell.
The lithium cells seem to take the charge fine, of course they are larger capacity and take about 2 hours at the 20 milliamp input to go from 3.93 to 3.94 volts.
...

You've given yourself some interesting challenges there, SW, right off the bat!  :-)

But it will be a nice piece of kit when it all comes together.

I suspect that if you can get the intended lamp drive sorted first, to your own satisfaction,  then the Li-ion charging will sort of fall into place

Some useful comparative discussion by Maxim chip co. in the following link about relative pros & cons of charging Li-ion by switched, linear & pulsed methods - might be some useful pointers or confirmation there if you haven't seen it already (just for the issues, i mean, not that you might use their chips!)
  https://www.maximintegrated.com/en/app-notes/index.mvp/id/913#

The high-from-low voltage requirement sounds like a job for the old auto spark generator arrangement of coupled coils (aka 'auto-transformer'?) , looks like a transformer, but is driven by flyback action (might be similar to Tesla coil behaviour?)

Your system is going to have a good energy density!  ...looking forward to hearing how it develops


Thanks for comments, TK - appreciated!

np

[fritz]

There is a charge / discharge graph for NiMH chemistry, fig5

http://www.cobasys.com/pdf/tutorial/InsideNimhBattery/inside_nimh_battery_technology.html


Between 50% and 80%, the figures are parallel, 70mV spacing.

[SkyWatcher123]

Hi nul-points, oh and i just realized you were quoting crocodile dundee, lol.
Well, i swiped the tv flyback coil/core i had in one of my lamps for testing, as it lighted the led bulb in question to good brightness, though it uses a 30awg. secondary coil.
As i suspected and you must have suspected as well, i need a separate step down transformer in line with the led bulb/secondary coil, since the lithium is not taking the higher voltage charge well, compared to the setup more like yours.
Maybe i will try nimh cells and see how they charge with the higher voltage.
peace love light

[nul-points]

Thanks for the link, fritz - interesting to step back in time and see what wonderful things a 'New Technology' was about to achieve.  Useful background info about the Chemistry of these cells, too, although i always get funny looks these days when i finally manage to include the word 'stoichiometry' into the conversation!  ;-)

I guess you noticed that my graph above is equivalent to a small section of Fig 5 from your link (albeit my data represents 2 seperate cells, not the same one)

Hi nul-points, oh and i just realized you were quoting crocodile dundee, lol.
Well, i swiped the tv flyback coil/core i had in one of my lamps for testing, as it lighted the led bulb in question to good brightness, though it uses a 30awg. secondary coil.
As i suspected and you must have suspected as well, i need a separate step down transformer in line with the led bulb/secondary coil, since the lithium is not taking the higher voltage charge well, compared to the setup more like yours.
Maybe i will try nimh cells and see how they charge with the higher voltage.
peace love light

Lol, my boys used to love that film - CD: "what day is it Wal?".... Wal: "doesn't know, doesn't care!"

Anyway, where were we?  ...oh yeah - saving the world....

Luke Skywatcher, you be careful with them high voltages! 

I'm not sure that NiMHs would be any more forgiving than Li-ion -  it's all stoichiometry in the end

...hmmm - you see?  'stoichiometry' - conversation killer!

If you think of voltage as 'head of pressure', then you can usefully lose some across the LED stack, just have to make sure you leave around the necessary headroom for pulsing the battery - a series inductor might be your friend here

Alternatively, you could flyback charge, via your LED, the smallest cap which will still store a suitable packet of energy for transfer to the Li-ion and switch a transformer primary across the cap to get turns ratio less volts through some diodes (Schottky) as a charge pulse

Just thinking out loud - i think you're way ahead of me! 

I'm currently going for a clean run on a charge/discharge graph - 23 hours down and if this rate continues it'll be around another day & a half before i can swap the 2 cells.  Meanwhile my LED continues to light up a circle on my ceiling.

...it's at times like these that i wish i'd paid more attention at my hand-shadow puppetry classes

np

[SkyWatcher123]

Hi nul-points, goo-day mate, hehe.
No, i actually think i'm getting too far ahead of myself.
Carry on with your version, as it seemed to work the best, as far as my tests have shown.
I'll have to give more thought to the step back down idea.
In the meantime, i ventured back to the Rene re-emf charger idea.
So in my case, 2 lithium cells in series charging directly another lithium cell, with transistor and primary of blocking oscillator in line and of course lighting the led bulb off secondary.
I am swapping the single lithium charging cell periodically with one of the input series cells, it seems to be working well so far.
Anyway, carry on, i don't want to distract further from what you are doing.
peace love light