Rene/Meissner EMF Higher Voltage Charger Variant

[SkyWatcher123]

Hi all, I have been testing this charger variant and testing different voltages.
Have been finding using higher and higher voltage inputs is increasing efficiency of power flowing through oscillator circuit and into the 12 volt tractor battery.
Will copy and paste results so far from other forum.

I'm using all 11 strands in parallel as the oscillator primary in this latest test, with 2 diodes in parallel off the collector of transistor to 12 volt charge battery and using the ferrite tube core.
I am now using my 400 watt boost converter as the input power supply, so i can raise the voltage even further to test any efficiency increases.
When using an input voltage of 50.6 volts from power supply, the efficiency is 72.5 percent, of course not including flyback recovery, actual voltage shown flowing through oscillator is around 35 volts.
On this latest test, using 60.1 volts from power supply, the efficiency has increased to
77.5 percent, actual voltage shown flowing through oscillator is around 46 volts.
These tests are tuned to use close to the same input wattage, by adjusting resistor values in oscillator circuit.
I find these results promising, i will continue to raise the voltage by 10 volt increments and tune and share the data with you folks.
I think this boost converter can only reach around 90 volts though.

The results at 70.2 volts dc input, is showing increased efficiency.
The actual voltage through oscillator circuit is 57.2 volts at .07 amps.
That is 4 watts flowing through the circuit into the charge battery and 4.91 watts being input.
Efficiency is now 81.5 percent, not including flyback recovery.

Latest test using 80.2 volts dc input.
The efficiency of the circuit has increased further.
It has increased to 84 percent.
Actual voltage through oscillator is 67.4 volts.
Current flowing through circuit is .06 amps.
Also had to wire another neon in series with neon across transistor collector, because the higher voltage was causing it to conduct.
I also have a capacitor in parallel with each of the resistors shown in the circuit drawing, it helps to adjust frequency and lower input.
Also, I'm finding the circuit to charge very efficiently, have been using a 12 volt led bulb to discharge the 12 volt battery and observing watt hours used, then can compare to watt hours placed back in and so on.

Your thoughts on these results are very welcome, not much interest at the other forum apparently.
peace love light
Here is pic of coil on left and latest circuit drawing.

[gyulasun]

Hi Tyson,

You have been doing an excellent job on optimizing most component values in this circuit. Also, you use a relatively
good HV switching transistor, the only 'issue' I can mention would be its rather low h_FE, DC current gain of 8 to 10
at around 1 to 4A collector current range, from data sheet: http://www.wakamatsu.co.jp/waka/2sd1878.pdf

You wrote about currents flowing through the circuit in the range of 60-70 mA or so, I assume this is an average
value and the peak collector current for the transistor must be higher than this of course.

With a more modern switching transistor like ZTX857 for instance, the DC current gain ranges from 100 to 300
for around 0.5A or from 15 to 25 for 2A collector current, from data sheet:
https://www.diodes.com/assets/Datasheets/ZTX857.pdf   
This is a 300V, 3A (5A peak) switching transistor with very low collector-emitter saturation voltage:
50mV (max 100mV) at 500mA collector current, this is better than the 120-130mV at the 0.1 to 2A
collector current range for the 2SD1878.

Question is what benefits such a transistor would bring versus the presently used one? The 23 kOhm base bias
resistor could be in the 100-200 kOhm range or so and the 15 kOhm could be in the 50-100 kOhm range or so I think.
It is possible the DC pre-bias role of the 23 kOhm resistor would become obsolote i.e. there would be no need for
any resistor at that place, due to the much higher h_FE value.
Another advantage would be the lower dissipation in such transistor due to the much lower saturation voltage.

I think these two better parameters would bring a minimum of 3 to 4% increase in overall efficiency.

Price for this transistor is here and notice it has no integrated diode across the collector-emitter and while
you could use a fast diode there, maybe it would not be needed at all.  The 2SD1878 type has got a built-in diode
because of the intended task for horizontal line output stages in television receivers of the 80s and 90s.
https://www.digikey.com/product-detail/en/diodes-incorporated/ZTX857/ZTX857-ND/92594
Of course there are other switching transistor types with more or less similar parameters than the ZTX857.

Thanks for showing these results.
Gyula

[stiplanet]

hello good job I am interested in your tests but I would like to know what are the objectives you want to achieve and what are the advantages of this technique, I want to understand what it will serve, thank best regard

[SkyWatcher123]

Hi gyulasun, thanks for the positive words.
I am using the 2SD1878, because it's what i had on hand (salvaged) at the moment, since i fried my audio transistor i was using.
I will look at what transistors i can get, that are similar to what you describe, any improvements in efficiency is what i need.
I wonder if the built in diode is causing any loss of charging efficiency, i can't see how it would though, unless it somehow conducts when the transistor is not conducting.

Hi stiplanet, Thanks for the reply.
The main function of this circuit setup, is to pulse charge a battery using the current flowing through an oscillator coil.
Then, use the flyback recovery of the coil to try and increase efficiency further and also help to reduce sulphation of battery and increase capacity.
The objective is to charge the battery with the highest throughput efficiency.
Then if the recovery can exceed the power input, then when using a battery for input, we may be able to swap batteries and gain charge in both batteries, which is why the tests to gain the most efficiency with this type of split negative setup.
Though the main goal is an efficient charger that can make a battery last for many more cycles than a typical, off the shelf charger. Which limits the peak charging voltage and in far less cycles, will cause the battery to sulphate and die.
peace love light

Edit: I've just about maxed out my boost converter at 90 volts. Highest efficiency is 85% with this coil arrangement.

[gyulasun]

Hi SkyWatcher123,

Regarding other transistor types, you could look for types used in electronic ballast circuits in CFLs, in projector lamp
driving circuits  and the like and you may find such with gutted lamps but the electronic circuit inside may have
remained good. It is possible though that the older types will have a low value h_FE so you would need to pre-bias the base.

I do not think either that the built in diode would be an issue.  When the transistor is off, the built in diode between
the collector and emitter immediately becomes reverse biased from the DC supply voltage appearing across it and
the kickback pulse (flyback) coming from the coil will also appear in reverse direction.  In case the coil has conditions for
ringing like an LC circuit, then the diode may have a chance to conduct, this is not the likely case in your circuit.

Gyula

Hi gyulasun, thanks for the positive words.
I am using the 2SD1878, because it's what i had on hand (salvaged) at the moment, since i fried my audio transistor
i was using.
I will look at what transistors i can get, that are similar to what you describe, any improvements in efficiency is what i need.
I wonder if the built in diode is causing any loss of charging efficiency, i can't see how it would though, unless it somehow conducts when the transistor is not conducting.
....

Edit: I've just about maxed out my boost converter at 90 volts. Highest efficiency is 85% with this coil arrangement.