Use for the Tesla Switch

[Sobakin]

Sobakin what size batteries are you using and are they the regular flooded lead acid batteries? The sealed gel cell type batteries do not work well with the TS. Also your load has to be matched to the size of the batteries and the size of the transformer. I don't remember seeing anywhere what batteries or size of transformer you are using. I do know you can go too large with your load and then you will get charging on the top but drain the bottom batteries at a much faster rate so your total run time will be shorter. About 12 watts or so seems to be working for most people with the rewound Radio Shack transformer. Another thing to remember is that the best run times and charging will probably not be at the same tuning spot as the place with the most output. You may have to make a compromise.

Carroll

Hi Carroll,
I'm using two battery sets - 4x 1.3 A-h 12V SLA and 4x 4 A-h 12V flooded lead-acid for scooters.
Transformer is like Matt recommended, originally ~30W, rewired with ~90 turns each of primary and ~110 turns of secondary 20AWG.
Loads 6W bulb or 21W bulb.
Now I continue tests for different conditions and combinations.
Looks like I found something, need to repeat for confirm.

[Sobakin]

After my second phase of testing I had good results. Attached is an pdf file of my data. I am more comfortable with this data, and also I have an explanation of my previous anomalous "charging".

Reading your pdf I don't understand how batteries in parallel can have different voltages.

I ran a 20 watt load (halogen bulb) for 8.5 hours for this test. The batteries were very close in initial charge (average of 12.465 vs 12.46). The total loss after 8.5 hours for the tesla switch was .2025 volts vs .425 for batts in parallel. So again I got 2 times better run time for the TS.

Two times less in voltage drop didn't mean two times better run as voltage drop is non-linear for time. Also your measurements under load in 2-switch TS shows that batteries that befor swap under load had 12.0V and after swap shows 12.2V, they're really may be not charged after that, only stopped to discharge and load like charge-discharge is closer to simply no load, what's why their voltage 12.2 instead 12.0 under load, in parallel all batteries are under load, so this is my explanations of difference:
Before last swap You have:
12.06 12.34 12.16 12.24
and after 8:30 You have
12.38 11.95 12.36 11.97
if You swap batteries after 8:30 and connect load, Yoy could see what batteries which had 12.06 and 12.16 before last swap remain about the same charge, same like batteries before first swap and after second swap (12.02 became 12.04 and 12.05 became 12.04) - their voltages the same, because they didn't discharge.
lets combine this results:
12.06 11.95 12.16 11.97
With 4 in parallel after 8:30 You have:
11.84 12.04 11.88 12.06 - not so big difference, but looks like it has something, including some loss in transformer.

I noticed I regained some of the lost charge after letting the batteries rest for a short period of time. I think this is what happened in my last test. I did a battery swap before hour 4 in my last test, so the batteries were diconnected for perhaps long enough to regain some charge. Also my voltage drop for the last test was so small (.04 volts total) that it didn't take much to make it appear the batts were charging.

It will really good if after resting and voltage gain You could load it and without returning voltage to state just before of stop load in one minute, measure voltage w/o load has ho practical sence.

All what I write is my thinking about, it may be wrong, of course.

[dnewkirk]

Hey Jpolakow,
Good job. Thanks for posting your results so we can all have more data to compare as we strive for making our own setup better.
You say,” I got 2 times better run time for the TS.” From your posted results, I see a runtime almost seven times greater as compared to the paralleled batteries supplying the same load. You have to compare how much battery energy was expended in each configuration.
You start the clock ticking with the batts under load and you take the average voltage, which you clearly did in each case. In both situations, the starting average voltage was within millivolts of each other; good. This is a must so that you have meaningful comparisons for each configuration. Then you let the voltage drop to what you deem a safe level without killing your batteries, and you take the ending average reading. Charge the batts back up and then connect them to the TS configuration. Again, start your readings under load at the same point as when the batts were paralleled. Good, you did this. The difference between starting average voltages was about 20 millivolts. Then you ran it down for 8.5 hours, or 510 minutes. V_average reached about 12.165v.
When I look at your paralleled battery readings, I see the average voltage reached 12.163v at elapsed time 1:15, or 75 minutes. So, you clearly got 6.8 times more runtime on the TS config than on the batts alone supplying the same load, discharging to the same level. <Insert applause here!>
Folks have spent their lifetime studying about lead acid batteries and improving performances. Differences between gel cell, AGM, flooded ‘wet’ cells, Peukerts Law, state of charge, non linear discharge, plate size and spacing and type of material, electrolyte makeup, ion flow,etc;etc;etc. It’s baffling to me. But it wasn’t until I carved out the time to do a quick (superficial) study that I began to realize the importance in how you go about taking readings and understanding the care and feeding of your batteries. These lead acid workhorses have been used in industry for 150 years. They pack a lot of energy per pound. Tesla was able to utilize their potential without sapping their strength. Matt’s configuration seems to be leading us toward that goal. All I can say is that I hope soon that we can help each other make it to the prize.

[jpolakow]

Strange readings

Hi Carroll,
I started my switch up today to do some tuning and I got some very strange behavior. When I first started the switch up my halogen bulb lit up super bright and then died. I figured there was a bad connection somewhere so I took out my DMM and took a reading at the caps(no load). I got 44 volts DC! I figured something was amiss so I turned off the switch, checked my connections and restarted the switch- now I got 24 volts and it slowly climbs higher by .01 volts at a time until about 26.75 volts. If I hook up a bulb, it will drop to around 14 volts pretty rapidly. Then If I disconnect the load again the output will jump to 22 volts pretty quickly, and then climb to 26, 27, or 28 volts (by .01 increments) depending on how long I wait. I'm still getting 17 volts out AC (rms) at the transformer. Isn't the rms value supposed to be what the equivalent dc voltage is if it's rectified? Very strange.... especially that the dc out slowly rises.

Also I have a second question- I have more tuning to do, and did realize my bottom batteries dropped much more rapidly with the 20w load. If we find the ideal load size for a given switch, can we simulate that load size with a capacitor bank? Then have the cap bank disconnect from the rectifier and run the load while the rectifier charges cap bank #2. Have some switching so the load is always independent of the rectifier output, enabling you to run any load size independent of the best value for the switch? Just an idea.

Thanks!

[citfta]

Hi John,

Well to answer your first question, what you are seeing is one of the interesting things about this transformer setup. The caps would normally charge to the PEP value of the current if the current was a true sine wave and there was no load on the cap. You are driving the transformer with short pulses of DC that are close to a square wave and not a true AC sine wave. So you are seeing some strange things as shown by your meter. Another thing to remember is if you are using a digital mutimeter they are designed for a sine wave too and don't handle other signals too well. The DC voltage on the cap is probably pretty close to right but your RMS value shown on the meter may not be.

To answer your second question, what is going to keep your load running while you are recharging the cap? Also if you run some tests you will see when the cap is fully charged you have almost no current flowing on the primary side so you won't get any charging of your top batteries. It is something else for you to play with and see if you can find a way to dump the cap into your load and still keep everything else working the way you want it to. Have fun.

Carroll

[jpolakow]

Strange readings

Edit: I have been able to replicate my previous strange readings. What I did was connect a bulb in series with one of the transformer windings, to see how running a load in series with the transformer would influence output. Right now with a bulb in series with one of the primaries I am getting 70 VDC steady state out at the caps, but with only 13.6 VAC at the transformer. How the heck is it jumping from 13.6 to 70 just going through the rectifier??? I've checked the readings with two separate meters to verify.

Also if I short the dc output quicly it jumps right back up to 70!! Do you think some kind of resonance thing is going on?

In regards to my second question I was suggesting two cap banks. One to run the load from while the other cap bank charges. Then flip flopping them.

Thanks!

[jpolakow]

Readings

Here is a picture of what I'm claiming. In the lower left corner you can see the yellow wires with alligator clips. They are connecting the bulb in series with the green winding primary.In the lower right corner you see the meter reading 69.4 volts. This is connected to the green wires with alligator clips, which in turn are connected to the output at the caps. In the upper right corner you see the other meter with a reading of 13.6 vac. this meter is connected to the output of the trafo(red wires) with the white wires with alligator clips

[Sobakin]

Hi Carroll,
I started my switch up today to do some tuning and I got some very strange behavior. When I first started the switch up my halogen bulb lit up super bright and then died. I figured there was a bad connection somewhere so I took out my DMM and took a reading at the caps(no load). I got 44 volts DC! I figured something was amiss so I turned off the switch, checked my connections and restarted the switch- now I got 24 volts and it slowly climbs higher by .01 volts at a time until about 26.75 volts. If I hook up a bulb, it will drop to around 14 volts pretty rapidly. Then If I disconnect the load again the output will jump to 22 volts pretty quickly, and then climb to 26, 27, or 28 volts (by .01 increments) depending on how long I wait.

It's a back-EMF spikes between pulses when transformer has no load, they are relatively high-voltage and very short in time, caps after rectifer can absorb them, and you can see a voltage gain in caps. Lower capacipy caps rises voltage faster.
Try not to exceed cap's maximum voltage, because it could explode.

[gtmbiz]

i need help

Hi Peter,
A big hello to all members i am new here and would be glad if any one that have an ultimate knowledge on the innovative idea on how to build tesla coil to power a bulb light.Please if you can help i need help for Tesla coil electric bulb my contact is gtmplace@yahoo.com Hoping to hear from you soonest

[jpolakow]

Back EMF

So I've got a question... can we harness the inductive kickback of the coil? I mean we pulse the coil, then we get a high voltage kickback. Why not harness this kickback in a cap and use it to either charge the batts -or pulse it back into the coil to get an even higher kickback/power out of the secondary. Is this feasible?

[Sobakin]

So I've got a question... can we harness the inductive kickback of the coil? I mean we pulse the coil, then we get a high voltage kickback. Why not harness this kickback in a cap and use it to either charge the batts -or pulse it back into the coil to get an even higher kickback/power out of the secondary. Is this feasible?

I think charging caps by this spikes is not effective, energy is very small, maybe it's better to direct them back to batteries.

[dnewkirk]

Look at the attached drawing on nvisser's post, #3797.
You'll see diodes D3 & D4 added to capture the inductive kickback energy and apply it to the charging batteries (+) buss.

[jpolakow]

Thankyou dnewkirk!

[shadowless]

I want to ask about doing the baseline 4 battery parallel discharge test.

Say if with the TS switch, you can generate a output of 10.5v max when loading it down with a 12v 100ma bulb, when you discharge the 4 batteries in parallel do you add a pot to adjust down the voltage of the bulb to the same 10.5v draw (so that it glows at a similar brightness as the TS test)in order to make a comparable test.

[Sobakin]

I want to ask about doing the baseline 4 battery parallel discharge test.

Say if with the TS switch, you can generate a output of 10.5v max when loading it down with a 12v 100amp bulb, when you discharge the 4 batteries in parallel do you add a pot to adjust down the voltage of the bulb to the same 10.5v draw (so that it glows at a similar brightness as the TS test)in order to make a comparable test.

What's why I did another baseline test with same transformer, for this I built H-bridge inverter, which powered by 4 batteries in parallel, so they are only discharged simultaneously to transformer and load.
I didn't found any advantage in TS against inverter with both types of batteries (I have 4x 12V 1.3 A-h SLA and 4x 12V 4 A-h flood acid batteries), and different loads (6W bulb and 21W bulb), time was the same as with inverter.
Tried different TS: Matt's 2-switch with mosfets, another with bipolar MJLs and symmetric 6-switch with mosfets, different loads, different batteries, different frequencies, different transformers (two iron, two ferrite) have done about 30 tests - result the same, +/- 5%.
W/o transformer I got discharge time even better, no transformer loss due primary's current consumption gain because of voltage gain in secondary.
6W bulb consumes 0.45A itself but transformer's input current about 0.55A.
Don't know how Matt managed to get up to 8x discharge time, for me it's a big secret