Thank you to this forum for the help on my previous thread. Taking to heart the suggestions made there I have started a new circuit simulation.
please find attached the result of how I interpreted what was suggested.

This 555 circuit uses the discharge and not the output, which I found interesting.
the frequency was in the 200-200 hz range, is that a good operating point for the 555?
I would be open to suggestions on the NPN transistor for SMD solutions, also the FET is just what I grabbed. I assume a lower on resistance is ideal for this application.
have a great day

 

PS, I am still open to suggestions on White LEDs in the 1-3watt range.
directional distribution is preferred to flood, but that is a minor point right now.
I think the LTspice library was showing discontinued LEDs, but I think they are OK for simulation.

 

Hello,

Could you post a schematic?
This could be a screendump of the LTspice screen.

Bertus

 

 

is 0.1 ohms a good internal battery resistance for a deep cycle marine battery?

 

I have started a new circuit simulation.

Your previous circuit can be made to work.

For the one you are working on, look for 555-based smps circuits and you can easily repurpose them as a constant current led driver. It is much more efficient than that you have here.

 

View attachment 102019

I kind of like it.
If you put 3 three watt watt LEDs in series the efficiency would not be to bad at a nominal battery voltage and at charge voltages you probably don't care.
Just change the emitter resistor to .75 or 1 ohm to limit the current.
The internal resistance of the battery is probably in the milliohms.

 

Thank you Ronv, I will actually have (3) 12V batteries and I hope to make my LED string operate at around 36V.
I agree with your opinion, the losses of one FET vs 10-11 LEDs will be minimal. I just need to get through about 6 hours of night fishing.
33w of LED and lets say 3w loss of this circuit, is doing about 90% efficiency.
and I figure using 6AH to run this for a fishing run.

 

ps. In my family it is spelled tang yew, as in Tang yew berry mulch.

ak