New Cap-Dump Experiment

[BobZilla]

Greetings friends,

I have been experimenting with a new way to cap-dump and I wanted to share. I do not know how well this will hold up so keep in mind it is experimental. What I like about it so far is it is simple and there are no contacts to wear out or other mechanical wear.

The system is simple, it uses a flashing LED, a photo-resistor and the caps. What I am doing is using the LED in a closed dark chamber to light the photo-resistor as a sort of relay system. When dark the photo-resistor will produce about 2M ohm, when lit very brightly as I am doing it drops resistance to only a few hundred Ohm.

Here are some shots of those parts. The chamber is two LED holders taped with foil so that the LED faces the photo-resistor head on.





I have a bank of 180uf 330v Flash caps hooked up in parallel. These are fed by the ssg output (where normally you would connect the charge battery).

Coming out of the device I have the positive rail going through a diode (1n4007) to the charge battery. On the negative I have the photo-resistor in the path. One side is connecting to the negative side of the caps and the other side to the charge battery negative. What this does is switches the negative rail off and on when the LED blinks. The LED has integrated circuit to handle the blinking. You can vary the voltage a little to affect the frequency but it is best to just find one that blinks at the rate you want, mine is about 1 per second or so.

I also used copper magnesium cells to power my LED. Each puts out 1.5v and they are in series. This can be replaced by some AA batteries but I wanted to start putting all of my knowledge to work in this system. What I do like about it is that the trigger control does not cost anything in terms of energy. It is not pulling from the charge circuit or the primary battery. It is just self powered and does the job.

Here is a shot of the board I put this all together on.



Well that's the introduction to my latest experiment. I am in the process of doing some runs with it and I will post back with some data. It does look promising though ---Bob

[BobZilla]

Just a little update:

I have had to make some adjustments to the board.

First off when I was testing this prior to making the board I did not make such long runs. Sadly the crystal cells don't seem up to the task. I may revisit that but the focus of the experiment is the cap-dump and not what powers it. Still a bummer though.

One of the cells did a reversal, strangest thing! I have been playing with crystal cells for a long time now and I have never seen one do it until now. When I tested them individually one of them gave a negative reading of about 1/2 volt. I did take a 9v battery and tap it a few times to correct the polarity and it did fix it but I don't want that to happen again.

I darn near lost 4 transistors on my wheel because without the LED flashing the caps build up until the resistance is to high and neon's start glowing. Fortunately I caught this pretty quickly and the machine was fine but I decided not to risk it with those cells. They are fine for little LED lights but when the circuit depends on them it is to risky.

I really wonder if the proximity of the machine had anything to do with it. Going out on a limb but what I mean is perhaps the field from the coil had something to do with it. Who knows but I will experiment with that later on with a blinker that is not actually controlling a high voltage circuit.

I replaced the cells with a super cap 2.7v 400 farad. It seems to drive the LED just fine and I can charge it up before each run directly from the machine without the cap-dump in place. It likes radiant charging just fine.

The second thing I noticed and made an adjustment too is the capacity of my bank on the dump. Originally I had 6 in parallel and that did work but in looking at my graph it looked very sloppy. It was not clean steps along the charge curve, very spiked. I tried half of the bank by taking 3 of them out and jumping past them and the charts are looking very nice now. This may change with different size battery's but the 5AH I am testing with does much better with only 3 of the 180uf in parallel. When I move on to larger batteries I may hook the other 3 back into the circuit.

The last thing I changed was the photo-resistor. You will notice from the first picture that it was very small. I liked it because when I tested resistance I was getting about 250 Ohm when the LED was lit. When I started doing longer runs and really testing I noticed that the temps were about 15 deg higher on the photo-resistor than anywhere else. As we all know heat = energy loss so I have traded that out for a larger one. The larger one produces about the same resistance as the first one but I think it can handle more current. Kind of like the difference between a 100 Ohm 1/8th watt vs a 100 Ohm 1/4 watt normal resistor.

I am going to post some charts soon. I still think this project is on track. I have seen this circuit push a battery up to 14.5 V but my primary was getting low so I stopped that run. Another thing I am having to deal with that takes time is that all of my batteries are conditioned too radiant charging.

I think it is going to take several runs to get them accustomed to the new method, that is why I have not shared any charts yet. I want to properly represent how this circuit is running when it is not fighting itself within the battery.

Here are some pictures of the new photo-resistor and supply cap. It may be hard to tell in the picture but the diameter of the photo-resistor is about 1/2 inch or so, I didn't measure it before i put it in.

[BobZilla]

I have been tweaking this idea a bit as I go along. I tend to start these posts and bring you guys along with me as I go which sometimes results in flip-flops. I think it is valuable to see not only the finished setup but what was tried and failed along the way or at least different things that have been tried. By openly sharing my experience it may help someone else who wants to duplicate an experiment.

Ok with that said I have made another change. The last photo-resistor was changed because the original small one was getting hot and the idea was that a larger one could handle more current. To some extent this was correct but it did not completely solve the issue. I decided to make a parallel bank of smaller ones. These are about twice the size of the original.

By putting them in parallel I am distributing the load evenly which helps with the heating issue. It also helps them to drop to a lower resistance when they are lit. Resistors in parallel will reduce while in series increase resistance. This holds true for these photo-resistors as well. So with the four of these in parallel it has increased heat dissipation and reduced resistance in the lit stage.

Here is a picture of the new flash box. I made it from some cardboard that I covered in aluminum tape for maximum reflection inside. The LED fits in the front through a hole and the photo-resistors are mounted in the back, again four of them in parallel.



I am now comfortable with sharing some chart data. The battery being charged is a little 5AH glass mat from a computer UPS. It is a salvage battery that I did condition lightly with radiant charging but only to a point that it would start taking a decent charge. I did not want to fully condition it to a negative charge because initial testing indicates that it is hard to switch them back to normal once they are broken in with radiant. According to the data sheet on this battery when it was new it has a .25A C20 discharge rate to 10.5v

. I did this charge run at a relatively low rate for the wheel. 160ma draw. I wanted to see how well this cap-dump would work with a low input and if I could get it to take a full charge at such a low draw it would indicate that the system could be used with equal size batteries on the front and back. This particular SSG is designed to run anywhere between 70ma up to 500ma comfortably.

What I mean is if it were to take over .25A on the draw then I would have a problem trying to use this size as a primary which is really the whole purpose. I can already charge batteries directly from the SSG very well but I wanted to have a cap-dump to so that I could swap front to back. I chose to use 160ma consistently throughout this charge.

I do plan to try running at 220ma and then 250ma to see the performance but this run was intentionally done on “low”.

I put the original 6 caps in parallel. I think that was the right choice all along but I was getting confusing results from the other “negative” batteries I was testing with so it led me down the wrong path when I reduced the bank to three.

Again the specs on the cap bank is 960uf 330v total (6 flash caps) from disposable cameras. The SSG is running on 160ma from a large 12v battery. I wanted a good strong supply for this testing because it is the cap-dump circuit I am interested in; how well it can charge. The primary interest of the experiment was charging capability, not a one to one or better from the same size batteries. I do think that will be possible based on the current draw in this test though.

The charge battery started at 12.34v on the next run I will bring it down closer to 12v to start. While looking at this chart you notice three distinct dips in the chart. These points are where I shut off the SSG and connected it up directly to my supply caps for the cap-dumper LED supply. I did not have to adjust the pot at all so when I hooked the cap-dump back up and started the SSG again it comes back up at exactly the same draw and speed. If I had enough capacity to drive the LED all the way through the test this would not have been needed but it’s no big deal to me. I kind of like the fact that I can recharge the cap-dump supply directly from the ssg, no extra equipment needed.



And this is a text file of the chart data

https://files.secureserver.net/0sY6drZjGvdgZE



While running at least at this input (160ma) the cap-bank is charging to 30v and dumping. When it falls back it goes to about 18v and then the cycle repeats. This can be adjusted a bit by adjusting wheel speed, blinking frequency, and capacity of the bank. All of those factors can come into play on how this will operate.

Remember I designed this to be very simple so to make adjustments you need to work within the mechanical performance of the components. This is not a “smart” circuit like a 555. The logic in this has to be provided by the builder taking into account the machines capabilities and engineering it to produce the desired result. I am still tinkering with much of this but I can say that in its present form this WORKS. It is efficient and does fully charge batteries.

Here is a short video of this setup in operation. The SSG is built from an 8 inch wheel, with a TeslagenX motherboard and their small coil. The frame is not pretty; this is a unit I built for experimenting with so it is very basic looking and has had holes drilled to mount things etc. The video will show you the cap-dump voltage on the analogue meter and if you look close you can see the light blinking inside the box. It also shows a wide view of everything connected up and running.

https://files.secureserver.net/0sEHWlHZpa7Grm

I still have many things to try with this setup but I wanted to fill you in on this initial test and to confirm that the results do warrant more experimenting. I will be playing with different draw rates, larger batteries, larger capacitor banks, and also running it on a solid state setup. I have a ton of these recycle 5AH batteries so even if this cannot scale up I have something here already which is very useful for me.

More to come as I plug away with this, Thanks for reading! ----Bob