Rene/Meissner EMF Higher Voltage Charger Variant

[SkyWatcher123]

Hi gyulasun, thanks for sharing.
It is not clear to me, what components of groundloops circuit, are for adjusting the duty cycle and frequency.
Do you think that circuit with a mosfet can outperform this 1% duty cycle circuit I'm now using?
I have the normal 555 timer on hand, so i can try it with that and many salvaged mosfets i can choose from.

I finished the charge/load test, the efficiency is higher, around 88% charge transfer efficiency, though i'm sure its +or- a couple precent accuracy with this meter connection, new meter needed.
I'm not sure what the claimed charging efficiency is for 12 volt tractor batteries, though I'm thinking this result is good so far.
peace love light

[gyulasun]

I edited Groundloop's drawing, see attachment.  He indicated two 200 kOhm potmeters as J3 and J4 male 3 pin connectors
and I included both in the upper right corner again together with the potmeter connections and which controls frequency and which controls duty cycle.  Of course you can use other than 200 kOhm potmeters, say 100 kOhm etc. Of course the 1 - 2 hundred kOhm values insure the higher range frequency coverage versus say a 10 or 22 kOhm , the same reasoning is valid for the duty cycle adjust potmeter where the resolution is at stake.

Whether this circuit outperforms the 1% duty cycle circuit you have just built: I do not know.  It depends on:
1) whether the MOSFET has less voltage drop across its ON resistance than the C-E saturation voltage across your present bipolar transistor
2) using variable frequency pulses (together with variable duty at any set frequency) the coil + core may operate at a more optimum frequency than the present fixed frequency circuit.  Mainly it is the core characteristics that define this: what frequency range the manufacturer assigned to those cores etc.   

To estimate MOSFET loss, let's say your type has 0.1 Ohm ON resistance and the drain current is say 200 mA, then the voltage drop is 20 mV and confront this with your bipolar power transistor saturation voltage, say at least 120 - 150 mV at 200 mA collector current, see also data sheets I referred to in my earlier posts on your transistor types, with some comments too on possible dissipation due to actual duty cycle. 
OF course there are better MOSFET types that have say 0.065 Ohm ON resistance (and 250V breakdown voltage) so the voltage drop would be only 13 mV at 200 mA drain current. This involves a 10V gate source control voltage so the 555 needs at least 10 V supply voltage to provide this.  for instance https://www.digikey.com/product-detail/en/rohm-semiconductor/RCX511N25/RCX511N25-ND/5042492

I am not familiar with charging efficiencies for the different types of batteries, perhaps you could ask this at the other forum (energaticforum.com) maybe someone cares to answer it.

Gyula

[SkyWatcher123]

Hi gyulasun, thanks for the clarifying circuit drawing, i will try the standard 555 timer with adjustable duty cycle at some point soon.

I finished another charge/load test, this time with the rene/aum circuit.
The efficiency was higher for this circuit, at slightly higher 33 volt input, at 95.7% charge transfer efficiency +or- 1-2% I'm sure.
Am going to try 40 volt input, for a new test using this rene/aum circuit and see if efficiency increases or lowers, will probably have to adjust component values to keep similar watt input draw.
peace love light

[SkyWatcher123]

Hi all, so i verified that my amp meter in these latest tests is accurate, i used a 1 ohm resistor (voltage drop over resistor, divided by resistor value) in-line with the boost converter output, to verify the amperage.
Currently testing the charge transfer efficiency of the rene/aum circuit at 40 volt input.
peace love light

[SkyWatcher123]

Hi all, The test finished at the 40 volt input, load test efficiency is 93.5 percent.
I think even the lower 33 volt input test was probably very similar in load test efficiency.

I do wonder what the load test efficiency would be, if just using the flyback recovery to charge the battery.
Think i will try that, out of curiosity, will test at 12 volts for first test.
peace love light