Double Spike Performance?

[jelloir]

I have been mucking around with my SSG's magnet spacing, wheel size, coil gap and base resistance, nothing very scientific or well recorded, just general fiddling and watching what happens to charge rates, RPM's etc.

One thing I have noticed is that my SSG "seems" to perform better when it's double spiking. The amp draw can be all over the place and I can usually alter the coil gap to smooth that out a little but in general, having a lower RPM, double spike means increased charge rate and lower amp draw!?

If I go single spike my wheel goes flat out and gives me the warm and fuzzies like it's pounding the charge battery but if I go to the slower "clunkity, clunk" double spike performance seems better.

I was just curious whether anyone uses the double spike all the time and whether JB's machine is single or double spike?

James

[jelloir]

Here is an example just now from my SSG (see pics)... I moved the coil away to get single spike then moved the coil gap to where it was previously and let it run for a few minutes in single, then slowed the wheel down to drop in to doubles again.

In single spike the wheel goes like the clappers and gets up to 505RPM 1.1A draw, so you think... that must be doing something, you test against slower 265 rpm double spikes and see 900ma draw and better charging! Just to be clear I am using a 20" wheel with 13 square magnets on it currently, this behavior happens on my "by the book" 26" 21 magnet wheel but this wheel is more apparent probably due to the higher RPM's.

[BobZilla]

Hi James,

Yes what you are observing is known to many of us and there are many different opinions on what spike to run at. My two coiler liked to run at 2 spikes, I have had other machines that did better at even three spikes but conversely I have had great tuning on one spike as well.

While you are experimenting with the tuning you should keep in mind the target battery size. What I mean is two spikes may do wonderful on a garden battery but just not good enough on a car battery, or a car battery may do well but a storage battery will not like it. Hopefully you get my meaning.

I have yammered on in many other posts about spike counts and trigger induction, current on time vs spike, so I don't want to go over it all again but you are on to something there so study it and tweak it.

When you think you have it perfect make sure and put a charged battery on the back end to check that it will be pushed all the way to low 15's. It is easy to sometimes get excited about a charge rate going really steep on like 300ma until you realize it will only push up to 14v,, I am not saying that is what you have it's only a hypothetical example. Tweak it so you can get the full voltage in the end.

*EDIT*
I wanted to add that looking at your chart there is a big clue there. Can you spot the impedance,, think about what it means.

[jelloir]

RE: the impedence... Let's see if I'm learning anything. The single spike is not necessarily poorer performing but the charge battery I'm using cannot handle the frequency and voltage from a single spike, the double spikes produce a lower voltage but more spikes in total which this particular charge battery can handle? Am I close ? So in theory if I have a battery that can cope with the single spike it may charge better than double (or triple) spike.

As always, thanks Bob (your an asset around here for sure), anyway I have done a site search on the forum and come across some of your posts about double/triple spikes so I will read them a few more times to get it into my head.

James

[jelloir]

Coil impedance! Yes? I tested putting a larger 65AH charge battery on and also tried the comparator and the same trend occurs so it's the impedance of the coil.

[BobZilla]

All of the above ;-)

I don't want to say yes this or not that etc.. It is all part of learning. Many of my older posts will contain errors, everyone's for that matter. We are all on a path of learning and experimenting so there are bound to be misinterpretations. The important thing is to think about all the aspects of what is going on and you are certainly doing that. You will learn little things along the way that will flip your brain over but as long as you keep both eyes open and really question what you see happening you will do better than most who build the machine.

Another thing to consider, (generally speaking here) is under different tuning points we will observe the voltage differently. The voltage rises as a result of the capacity of the battery and the current being pushed on it. What I am getting at is if we over drive a battery we can observe it climb up to 16+ volts when it levels but under a more reasonable charge it might level at 15 and a quarter. It is good to pay attention to that because if you are going to hard it will show up that way and it is because of to high a frequency or too much current. With mechanical wheels there are a ton of variables that can affect all of it but in short that is why people will use some sort of governor like a genny coil or a fan. Another thing I look at along the same lines is when you first start a charge how much does it jump up when you start, if your resting at 12v and you start the charge does it go up to 13v, or 12.7, or 13.5,,, get what I mean. How far it jumps is the effect of the current being pushed and the impedance of the battery. Does it jump up and then drift down at the start or is it a smooth climb, again thinking of pressure and impedance. And of course the condition of the battery effects all of it as well. All batteries will have some impedance but one that you are just starting to work on will have much more so don't let it throw you off.

I am really not the best at explaining this stuff. I try to find examples but a lot of this is something you just sort of learn and use intuitively after awhile. I will see something in a chart and adjust without even thinking about it anymore Lol.

James you are doing great my friend.

[Yaro1776]

BobZ,

Very eloquent on the topic.

Yaro