24 volt cap pulser battery swapper

[ren]

Hey Troops, another vid uploaded on the tube.

YouTube - 24 volt Bedini Cap Pulser

running on 24 volts, 1 amp, capacitive discharge into second bank. Ive successfully swapped banks (on 12 volt) for 5 days, letting batteries rest at night. Resting voltage of both batteries has been above 12.40 every morning. I dont have enough good batteries to run it on 24 volts, but as you can see it really gets up to speed. Id recommend building the cap pulser for anyone interested in battery swapping

[Sephiroth]

sounds like an engine reving up! Great Work!

I finally got my cap pulser working today but not 5 minutes ago fried my last scr gonna have to buy some better ones online

It works fine pulsing the cap, but when I connect the cap to the battery it sparks and dies... perhaps I need a diode between the scr and the charging battery as well...

[ren]

Sep are you using the schematic with 555 and h11d1 opto isolator? Or are you just using an scr?

[theremart]

Running out of batteries for 24V.

Nice setup!


Ya, I can relate to that running out of batteries. One of my batteries died during test so I have to start all over So... I waiting for a replacement battery, in the mean time I am recharging all the batteries back up. (11 Batteries ) They don't have far to charge up, but I really wanted to see how long this would go. Kills me I had to stop this one.

I had my battery swapper running for over 60 hours, and here is the results as I logged them..

Starting group of 24 batteries.
Batteries set to swap at 11 hour intervals
Banks of 24V 8 Golf 4 Deep cycle.. Pulling 1.5 Amp
Using 6 transitors on 4 coils.

Bank1 Bank2 Bank3 Bank4
24.2 26.0 26.0 26.0 11:52 AM 5/24/2008
25.5 24.2 25.5 25.5 11:10 PM 5/24/2008
25.6 24.1 25.6 25.6 5:59 AM 5/25/2008
25.2 25.2 24.9 25.2 11:43 AM 5/25/2008
25.2 25.2 24.7 25.2 6:15 PM 5/25/2008
* Note found that bank 4 Deep cycle battery went down to 12 V
adjusting the amp draw to high speed. .6 amp for this bank at 5 hours in.
25.3 25.3 25.3 24.5 12:49 AM 5/26/2008
24.5 25.2 25.2 25.2 7:47 AM 5/26/2008
* Back to 1.5 amp
24.0 25.5 25.5 25.5 1:45 PM 5/26/2008
25.2 24.0 25.2 25.2 11:10 PM 5/26/2008
25.2 25.2 24.4 25.2 9:53 AM 5/27/2008
25.2 25.2 24.2 25.2 2:29 PM 5/27/2008

[Sephiroth]

using a neon triggered scr with a 220mf cap

[Sephiroth]

I killed all my SCRs so I thought I would give it a go with a 2N3055 transistor (always have a couple knocking around!)

Here is the schematic I am using

cappulser.jpg

using this on my modified computer fan...

It is running on 90ma and discharges the 220mf capacitor from around 80v to 30v every 5 seconds. not bad...

interestingly this is with multiple pulses per north pole pass... when using single pulses per pass it runs on 150ma (this fan was originally rated at about 380ma) but only discharges the capacitor every 16 seconds

[Sephiroth]

oh, I forgot to ask...

wouldn't a transistor be better for this than an SCR?

an SCR pulser would have a sharp switching on time though the switching off time would be gradual (voltage would drop until the battery and capacitor are at equal voltage)...

though with a transistor there would be a sharp switch on, and a sharp switch off... isn't this more desirable?

[ren]

Hi Sep, while I cant be sure whether a transistor would be better I can say I have no reason to doubt JB's schematics. And there is a transistor in there, it is the one that triggers the scr to fire. I believe the SCR is used because it has the lowest voltage drop across its terminals.

If the moderators dont have a problem with it Id be happy to do a CD pulser walk through for all those that want to build the 555 circuit. Its a handy one to have, you could modify it to serve many functions. If people are interested and its all good, I'll post some drawings up for those that may be a little unsure of how to compile it all.

[Sephiroth]

Hi Ren,

Yeah, I saw JBs schematic with the transistor and SCR. The only purpose for the transistor I could think of would be if the trigger voltage wasn't high enough to trigger the SCR he uses but would trigger the transistor ok which would then trigger the SCR. Like a darlington pair.

Though after testing this method of pulsing the cap I have found it doesn't work very well compared to charging the batteries directly. I think it may be because the voltage in the caps is too high when triggered with a neon.

I would appreciate a simple 555 schematic to try!

Cheers!

[ren]

Hey Sep, I think your right, the transistor/scr arrangement amplifies the signal much like a darlington pair would. The H11d1 opto isolator is there so there is no direct link to the 555, thus protecting it. You may notice some similarities to the 555 circuitry on this page here:

http://tacashi.tripod.com/elctrncs/555sstc/555sstc.htm

Ok, to start with, I have attached a drawing of Johns schematic with a couple of extras which arent necessary, but can help beginners such as myself. If moderators find this a breach of copyright then please remove with my apologies, I know of two places on the net where this schematic is posted in full so I saw no problem with it. Once again, it is Johns schematic not mine, I have only added a couple of things.

Get yourself a little PCB prototype board, preferably like the one in the picture below. It spaces out the pins and makes soldering and joining them SO much easier! Remember each pin on the 555 and the opto must be isolated from each other, important to note if you can only get a PCB prototype board with rows and not separate pin holes!

Also, in the interest of simplicity get a 555 cradle and a 6 pin optoisolator cradle (machined pins if possible) this will save you soldering directly to the components themselves, most likely destroying them if you arent careful. This way you can swap them in and out if you damage them too. Take note of the pin references of each component carefully, especially the opto isolator. There are heaps of places on the net if you want diagrams for specific components.

Pins 8 and 4 on the 555 are joined together, so are 2 and 6. I put an extra cap between 8 & 4 (+) and 1 (-) to smooth out the voltage going to the 555. I was told JB said this is a good idea. 10 uF cap should do fine. The 1 uF cap is specified at 600volts I think but mine worked with a 63 volt 1uF cap. Resistor between 8/4 and 7 and second resistor between 7 and 2/6. I found you could vary the dump speed by varying this resistor. Maybe use a 10k and a 150k pot. Pin 3 is the output and it loops through the H11d1 before returning to ground through another resistor. I put a small 12v LED between 3 and pin 1 of the opto to show the pulse frequency. It is also a good indicator of whether it is working and whether you have left it connected. It will pulse away as soon as your primary battery is connected and all switches are on, EVEN IF THE WHEEL ISNT ROTATING. Only draws about 40ma or so, but it will flatten the battery if left connected.

Pin 3 and pin 6 on the opto arent used. Take note of the way you install the cradle and make sure your opto goes in the right way, same goes for the 555. There is a little notch cut out of both which signifies the top. 1 and 2 on the opto are pretty self explanatory, same with 4 and 5. 5 goes directly to the negative of the charge battery, or to make things easier, just connect it to the anode of the SCR. The Collector of the transistor is also connected to the SCR's anode. The cathode of the SCR goes to the negative terminal of the cap.

For the triggering transistor I couldnt find the one specified so I just tried to match basic charateristics. The 2n3440 or the MJE340 have both worked for me, they are both 300v rated. You may even find a 2n3055 will work ok, if you use a larger capacitor, say in the 1000's of uF's. I believe Aaron has used others here successfully too.The collector of your transistor connects to the anode and the emitter connects to the SCR's gate. The base of the transistor is triggered by the opto, pin 4. It makes sense when you trace the lines on the diagram. Please note if you use the MJE 340 the pins are reversed. What ever transistor you use, google it for a spec sheet to make sure you got everything right.

Take your time, especially with the 555 and opto. The pins can be a little trickey but if you have a cradle for them both you can afford to be a little reckless when soldering Just make sure there are no shorts between the pins.

And as always, I must state that I am no pro, and if anyone else has info or deems some of the above unecessary or incorrect please dont hesitate to post. Enjoy


PS oh and by the way, the 555 is limited to 18 volts input, so if you want to run your front end higher than that then it needs a separate source. For the 24 volt cap pulser I posted above I used a 3 pin voltage regulator to automatically drop input voltage to 12 volts. The voltage regulator is good for 35 volts on the front I think, with a 1 amp output max. Thats heaps as the 555 only needs 40 ma or so.

[Sephiroth]

Great write up Ren, and thanks for the schematic!

I have everything I need to build it, except the opto isolater, and as I said, the scr ... though do you think would it be possible to omit the opto isolator if a relay was used instead of the scr?

[ren]

hmmm. You could have a go I guess. The output from the 555 pin 3 could go through the relays coil and back to ground. Probably wouldnt need the resistor as the relays coil would provide resistance, but I could be wrong. You could hear the relay click if it was working so you wouldnt need the LED light I put in there either.

Try it, at the very least you will get a feel for the 555 and get your hands dirty!

You will have to source the parts over the net otherwise. Farnell is a good spot to try, they post most places. Thats where I got my optos and 2n3440's.

Let us know how you go.

[Sephiroth]

lol! that was easy.... already put it together and it works.... haven't tried the relay yet but the led is flashing...

though it is flashing steadily. approx 1 second on then 1 second off... is that what it is supposed to do? I thought it would only pulse briefly... I used a potentiometer for the 150kohm resistor and fiddling with that adjusts the speed of the flashing, but how do you adjust the on time?

[ren]

Good work Sep, that was fast! Im not sure how to adjust on time, Im not sure its that important in this configuration. If you want to delve deeper into the 555 look here 555 Timer/Oscillator Tutorial

Mine will go from about that (1 sec on 1 sec off) to on/off so fast it just looks like its on when I vary resistance. Im guessing thats what its supposed to do.

Perhaps pin 7 and 6 come into play when considering on time. Let us know how you go.

[ren]

Hey Sep I think I figured out how to adjust pulse frequency. Check out this doc.

http://www.aquapulser.com/docs/D14.pdf

look for the 555 section and note the three different capacitances with the rotatry switch