SSG Update

[faramog]

HAd to have have break. Hacked up a wooden frame and stuck my 25" bike wheel on it. Interesting how it is not balanced (I read some note about wheel rotation due to imbalance). Anyway. Very crude setup with the coil just held under it by taping it to a block - no point in doing more until I know it works.

And he presto .. after blowing a trani as my load was not connected (need to get some 80V neons !!) it chunters along great. Pretty steady 85rpm. The suprising thing is that I needed min restsitance (ie max input current) to keep it going when horizontal, Now, max input slows it down, and the sweat spot (very crudely) is about 600 ohms. My induction current meter (not accurate I know but a good indicator) says 120-160ma (whereas before is was 800-950ma).

One battery is well bad so I gave it a soak charge and am using that as the source. The other larger on (65AH I stuck some lights on for an hour to load it a bit at the c20 rate) and its charging fine. Been running 8 hours now. Plan to run most of the day, then a long discharge at c20 and do that a few times to desulphate.

My pack of the beasts arrived ... MJL21154 so going for a more meaty setup in a couple of weeks after some testing with this....

[Mark]

Everything sound good to me, looks like your on your way!

[faramog]

Some Pics finally... and some advice needed

First crude pass with a bike wheel in a vice (LOL) and finally on a bit of knocked up wooden frame (very untidy corner !!).

The bit I am slightly confused by are the waveforms. Zoom in on the scope and I get lots of high V spikes and ringing (that seems to be popular). The bit I am less straight about is that each pass over a magnet seems to generate 4 pulses. This changes to 2 or so if I modify the base drive (shown on the dual trace pic). Voltage peaks are about right - up to about 70V I have seen depending on my loading. The battery is well dead and old and in need of resurrection - a fair old test I think !

Any views ?

[Bill H]

The difference in current draw between horizontal mount and vertical mount is likely due to a decrease in rolling resistance.
A good thing for you to try right now would be to remove your coil and give your wheel a good spin by hand, then time it's free spin time. Stop your timer as soon as the wheel stops moving in the direction of the spin...do not count rocking motion.
You want to have a free spin time of at least lets say 10 minutes, more is better, with your wheel I would aim for about 15 to 18 minutes, it is possible to get over 20 minutes. If you haven't already done so, take apart your bearings and clean out all of the grease, then lubricate it with a light oil, I use super lube (3 in 1 oil will work as well). Adjust your bearings just on the loose side so there is no preload drag.
You may find that just doing this will drop you down a couple of pulses per magnet pass, if not the decrease your resistance a little at a time and monitor.
Hope this helps.
Bill H.

[faramog]

I cleaned the bearings but just used motor grease. I might try light low friction lubes bit the bearing housing is not one that will seal easily so cant use a liquid I think. The free rotation was a little more (I already tried), circa 3 mins instead on 2.5. Difficult to see it getting to 10mins... maybe time to buy a new wheel. But other things to try first, like a bigger coil and a tri-filar with the same setups.

Does not explain the multiple pulses per magnet though ??

Thanks for the advice however - added to the plans :-)

[Zooty]

Multiple pulses per magnet can happen when the base resistance is high. Try 2K and higher and it will probably oscillate without the wheel turning.

[faramog]

I kind of thought of that so I wired it to enable me to take the resistance down to lest than 10 ohms .. still getting 2 pulses.

Is it likely to be a function of the battery - being poor the impedances are probably quite high ?

[phishy]

please try degreasing and applying a light oil or whatever you have... bike wheels are not made to run on their sides, run it properly.
get the mechanical part sorted, then try all the different electronic configs.
it´s worth it
cheers,
phishy

[Bill H]

Yes you have to get the free spin time up..3 minutes will not cut it. Hve to use light oil, don't worry about seals enough will stay on the bearings, grease slows it down too much.
Put it this way..If you don't get at least 8 minutes spin time and I think that is a bare minimum...more is much better, in fact HUGE and very important, it won't work right.
Do what you have to to ge that wheel spinning freely...very very important.
Bill H.

P.S. To Quote Guy Bradley aka Batman, "He who has the best spin time wins"
Not sure he said it first, but he says it alot, and it holds alot of truth.

[faramog]

Batman.... love it... reminds me that when faced with a problem the correct course of action is to ask "what would the lone ranger do ?"

LOL

[faramog]

Thanks Bill H & Phishy ... cleaned the bearing and housing - stuck it back together and put some 3 in 1 oil in. Had it a tad looser than before. Free spin time went from circa 2.5 mins to 7.5 mins !!! (and I could hear the bearings as they are so old !!

Powered up with no change from the setup last run. Instead of a heavy hand start to near 70rpm, just a gentle push and it was away accelerating to 112rpm (was doing 82).

There is now bearing noise... might end up with a new wheel or if I can get it to fit (its so old) new bearings and axle.

Need to keep a cycle going to clean the battery.

Just as a crude whatever, I filled in the spreadsheet from the yahoo groups monopole3 ... very crude but a battery cop of 0.47. I'll use the same criteria and see what happens

[Bill H]

Great stuff!!!!! 7.5 minutes is still too low a free spin time but you are getting the idea...it makes HUGE difference.
I spent alot of time trying different bearings and balancing my wheel till I got a free spin of 18 minutes before I ever put a coil under it. This is one area that causes alot of failures. Keep at it and let us know your progress...one step at a time, there are more tricks to come.
Bill H.

[citfta]

Spin time

Hi faramog.

Congratulations on getting the SSG to run. If you are getting 7.5 minutes with the coil still under the wheel that is pretty good. The coil causes a lot of drag. If the coil is not under the wheel then I have to agree it still needs some improvement. If you have the bearings adjusted for the best running (loose but not real sloppy) then you will hear the bearings making noise. If you are using a bike wheel and you don't hear the bearings then the bearings are too tight. Now that you have it freed up some see if you can find the sweet spots. There should be at least a few. Look for the one that gives you the highest rpm for the least amount of current coming from the run battery. You have to make the adjustments real slow to find the sweet spots. Adjust the pot and wait at least 5 to 10 minutes until the speed stabilizes. Enjoy your SSG. It is a great learning tool. Hope this info helps some.

Carroll

[faramog]

The 7.5 minutes was without the coil. I played around with the bearing - very light oil, looseness et, but could not get any real improvement. I spent some time with a bike expert and came to the conclusion that even with a very modern expensive wheel I would not get a huge improvement.

So this variable is now fixed on this incarnation of SSG.

[Bill H]

If you double stack your magnets the extra weight will increase your free spin time.
There is always room for improvement.
Bill H.