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Thread: Bedini current difference between run and charge battery

  1. #11
    I appreciate your explanation on the Cap dump Bob. I like your idea of using the Opto switched SS Relay. Mine is a cheap Chinese version. But it works well though.

    Bob did you ever try using a fuse with a cap dump circuit ? I have a concern on what if the arduino fails and the capacitor overcharges.

  2. #12
    No i don't have one installed. I'm not sure where I would put a fuse to prevent that because the MC failure would not cause a surge. The cap would just build up and up.

    I do have an idea however. What if you used an normal-closed relay instead of normal-open. The timing would be reversed but if the MC failed it would just become a the battery.

  3. #13
    Bob, I think attaching the cap to NC Relay position may work. I need to try it out and see if it works. It is also possible that the Solid State Relay can also fail.

  4. #14
    Another safety feature could be to attach a load across the cap but it has to be something that will not activate until a certain voltage is obtained. Perhaps a string of neon's I think they generally activate at 65-85v. I have never tried it, just thinking out loud. The criteria would be that the load only activates at a voltage well above your normal dump voltage and can carry enough current off to keep the cap from popping or your transistors from overloading. With some trial and error this could work but I have not tried it so take it with a grain of salt.

  5. #15
    Senior Member John_Koorn's Avatar
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    Jul 2012
    Melbourne, Australia
    Hi guys,

    I think if you are using a Bedini SG to charge the cap you are at more danger of blowing the trannys on the SG if the Arduino fails and the cap can no longer take the charge. From my experience the Arduino would only fail if it lost power and if the SS relay failed that you're using to dump the cap, it would normally fail closed - meaning the cap is effectively bypassed.

    Personally I would go with the idea of a NO relay in the trigger of the SG that is closed whenever the Arduino has power. If the Arduino drops power (or fails otherwise) the relay opens and effectively disables the trigger circuit on the SG.

    John K.

  6. #16
    Hi John,

    Yea I'm with you on that. AS ironic as it can be I just blew my relay! Not sure what happened but I came in the room to check on things, arduino was still running so it was not a power problem there. I glanced at my volt meter I had across the caps and it was buried, a 50v meter at that. I switched off the machine and touched the relay, very hot, caps were quite warm too. So I grabbed a gator clip and a 100 ohm 2 watt resistor to drain those caps. Oh well this kind of thing happens but it is funny we were just talking about "what if".

    I was lucky because there was no damage to my bedini machine, it seems the aurduino is ok too but the relay had cooked. I had run this thing for days at a time in the past but I don't know, something went wrong. Blahh, oh well. My machine is much more efficient without the cap dump circuit anyway.

    Sorry guys I was going to take a video and show but now the dumper is busted and I am not in a big hurry to fix it.

  7. #17
    Bob, Sorry to hear about your event.. At least your machine is safe. I also had a "thermal event" a few months back when I used Arduino with a Voltage Divider circuit. I was trying to check the voltage on the charge battery in an older Bedini machine that I build sometime back. I used a wrong gauged wire that caught fire and melted - I was able to read the voltage into Arduino later on. But the numbers are very unreliable as a single value. I had to take the average list of readings to make a decision. It was still pretty unreliable at the end. I had used a relay to momentarily cut off the battery from the circuit before reading the value into Arduino, using the voltage divider circuit. All those decisions I was making from the Arduino. My thought was, if I get a voltage reading into Arduino, I can make decisions to stop the charge as I need. I could also make other useful decisions from Arduino. Then, I don't have to worry much about having an overcharging situation. Back then I tried it on a battery. I need to try it on a cap and see if it gives me a more stable reading.

    Also Bob I had a question on the efficiency of the machine that you have. I am just trying to figure out and compare and see what all I need to do to make my machine efficient and working reasonably well. You begin with, if you put an ammeter or a clamp meter on you positive or negative wire of your machine, what current reading do you get ? I was interested in knowing the readings for both the charge battery and the run battery. I am trying to compare the readings of an efficient machine that you have v/s what I am getting at this moment.. I appreciate your help..

  8. #18
    I know what you are getting at but I'm telling you that the current on the back end is not a good indicator as too how well things are working. It is more important to get your spike optimum. Many people use an O-scope to see, I do not have one. I have just learned to tune from the sound of the coil, a timing light and a lot of trial and error. With that said generally if you were to put an amp meter on both ends you are going to see about half the current on the back as you see in the front. This will vary from one machine to the next and from one tuning to the next but ballpark it's about half.

    The machine I am currently working with is not typical. It is a four coil setup 16 transistors total. I will be expanding that out to 8 coils with 32 transistors soon. Have you looked through my post about this machine? If not you can go look in the intermediate section for my post and see some video's and charts from some runs. This machine has two different wheels that I change out for different running conditions. One is a normal mono pole like most people run and the other is a super pole which mean sharp north magnets. I have found that the superpole runs best with 24v input while the normal pole runs better on 12v input.

  9. #19
    Thanks Bob as always. I checked some of the pictures of your design. Looks nice ! It's shape some how reminds me of the old Marconi Radio - I like your wiring design inside the unit. Looks neat. What's that software you are using on your xps system ?

    I bought a new Clamp Meter that has a separate setting for DC current. All these days I was using a clamp meter that was rated for AC current I think. I had a cheap one from lowes that I got sometime back. The box did say it measures DC current, but I am not sure now. This new clamp meter is giving me totally different readings on my machine, that currently has just one 8 filer spool in it. The primary run red wire shows 8.6 amps at the DC amp position of the meter. And the red wire on the charge battery is showing around 10.2 amps. It is showing reverse than what you said above. Also reverse of what my old clamp meter shows which used to show in milliamperes. I am not yet sure what is going on. I am still shopping for an analog ammeter. Found a nice site where they are selling some,in case anyone is interested.

    Thanks for your advice on the currently v/s voltage question. I am using a 12v deep cycle battery on the primary run side and a 12v capacitor bank on the charge side. Its actually a 16v bank, but I am only using around 12-13v max charge for now. I noticed that it is charging nicely. I see a sub digit change every 10 sec. I still need to add more coil spools to the system.
    Last edited by Dieselship; 05-09-2015 at 10:11 PM.

  10. #20
    Those charts are produced by software that came with my digital multimeter from Radio Shack. Unfortunately they do not have them for sale on the site, I think Radio Shack may be going out of business soon, I have seen three semi-local stores that I know of close up.

    Another choice if you are looking to chart on a computer is the west mountain CBA. This device can actually do charge monitoring and perform discharge tests at whatever current you set so that you can see your actual capacity on your battery.

    Your current seems way high too me but then again your machine is not the usual build so it's hard to say what it should run at. It does explain why that smaller battery dropped down so low, you were probably pulling on it with like a C1 rate.

    One thing to keep in mind is that capacitors are hungry beasts, not at all like a battery. They will suck in as much current as they can as quick as they can, same goes in reverse meaning they can discharge almost immediately if given the chance. You may want to experiment with batteries on both the front and the back until you get a little better feel for how the machine wants to operate. Caps have an ever changing impedance as they charge which is very hard to tune too. Anyway it's your experiment so do what you like and have fun ;-)

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