Branch's SSG Build

[Tom C]

I looked up the lawn & garden batteries I am using that I got from True Value. Looks like they are rated at 20AH.

Interstate SP-35 Lawn & Garden Battery 300 CCA

That still gonna be ok?

yes that is fine. its also good to see how resistance changes can produce a rise in rpm, that you can see the bell curve form on both sides if the resonant point.

Tom C

[Branch Gordon]

Excellent, thanks Tom. I've ordered some 110 ohm 1W resistors, so I can switch over to using a fixed resistor. Not that I have a tuning point, good batteries, and my baselines charted...I can confidently begin my test runs.

yes that is fine. its also good to see how resistance changes can produce a rise in rpm, that you can see the bell curve form on both sides if the resonant point.

Tom C

[Branch Gordon]

Ok I'll be working through test runs for the next 6 weeks I'm guessing. I'll post my results every 5 runs with comparisons against the original baseline.

[Branch Gordon]

Finished my first run and the charging time wasn't ideal. I realized that when I created my RPM's vs Resistance chart, I didn't factor in amp draw at all.

I ran through all the resistances again last night, and found two points which I believe are sweet spots. Here is what I found:

Sweet Spot 1

318.2 RPMS - 740mA - 51.2 ohms
317.4 RPMS - 750mA - 48.1 ohms
316.7 RPMS - 760mA - 46.1 ohms
316.7 RPMS - 760mA - 44.3 ohms
316.2 RPMS - 760mA - 42.1 ohms
315.8 RPMS - 780mA - 34.2 ohms
346.6 RPMS - 590mA - 32.4 ohms

Sweet Spot 2

291.0 RPMS - 380mA - 160 ohms
290.8 RPMS - 370mA - 163 ohms
288.8 RPMS - 360mA - 165 ohms
272.3 RPMS - 430mA - 167 ohms
271.5 RPMS - 430mA - 171 ohms

With the first sweet spot...if I move up to 34 ohms, the amp draw stays around 760mA, and doesn't shift down. At 32.4 ohms, the wheel speeds up to around 317 RPMS, hangs for a minute at 780mA, and then shifts down to 590mA and the wheel speeds up to 346 RPM's.

Does this sound like I've found the correct sweet spot?

I believe the amp meter and extra cable to hook it up in series is adding some resistance, so when it's removed...the sweet spot will shift. Should I just compensate by moving up slowly in ohms without the amp meter until I find the shift again?

[John_Koorn]

Branch, sweet spot number one is the way to go. Now remove the ammeter and put in a fixed resistor that will give you the 346 rpm you're looking for.

John K.

[Branch Gordon]

Thanks John. I am glad I'm on the right track.

When I ran the tests above to determine those sweet spots, the primary voltage was sitting at around 12.2V. However, after charging the primary...the RPM's are different at a higher voltage, as is the "shifting" point. It seems to be at around 50 ohms with a full charged primary battery.

Is this normal? Which spot is best? Is the sweet spot supposed to shift as primary voltage changes?

[Branch Gordon]

John-

Never mind...I looked through some older threads and see that you've told people before to tune the machine with a full primary battery.

Sticking with 50 ohms.

[Branch Gordon]

Heya. I think you may have posted in the wrong thread. I don't have a lab...and my SG runs great.

Cheers!

Branch

Sorry for your loss Mr. Bedin, I hope your lab. was insured and nobody was hurt. If your SSG don't start up as it should maybe you are not spinning the shaft fast enough manually . I've come to find out that is what I over looked for a few months.

[Branch Gordon]

There should be an option right below your post to "edit". Then you click delete.

I'm sure someone out there is charging car batteries...maybe create a thread on it and see who bites?

[Branch Gordon]

Getting ready for my 4th charge/discharge cycle. The past two curves have displayed gradual improvements, so all is looking good so far. The last discharge cycle I got about 2 1/2 amp hours more than where I started.

I'll post a screenshot of the curves once I get to 5 so everyone can see the improvement.

Branch

[Branch Gordon]

So it's currently taking me 5 charges of the primary to get the charging battery up to 15.x volts. As in...I run the primary down to 12V, stop the SG, recharge the primary, start the SG again, and continue charging. Does that sound normal for the first cycles?

Just to confirm...the expected result after a number of cycles is that it will only take 1 charge of the primary to charge the charging battery...correct?

Branch

[John_Koorn]

Branch, you could take just 1 or 2 amp hours out of the charge battery initially when you load it.
I would start off with taking just 1Ah out of it, while you're doing this re-charge the primary. Then next time charge the secondary to 15.3v. Note the voltage of the primary when you're done. If the primary is at 12.3v for example, take 2Ah out of the secondary next time. Keep doing this an increasing the amount you take out of the charge battery each time.

Ideally you want to charge the secondary without having to recharge the primary in between. New batteries take a few cycles to properly form the plates as they aren't formed properly in the factory anymore.

John K.

[Branch Gordon]

Hey John-

I'm not sure I follow...

What I've done the last three complete runs is that I don't load the charging battery at all until it's fully charged. So the charging battery is just sitting...resting...until my primary fills back up, and then I continue to charge to 15.3v.

As they are 20AH batteries, I've been using a 1 amp load with the CBAIII for the discharge.

So...to confirm..you are saying I shouldn't let the charging battery rest...that I should discharge it a bit...before continuing it's journey to 15.3v?

If it's still taking 5 recharges of the primary after 10 or so complete cycles of the charging battery....would you think I have a tuning issue?

Thanks,

Branch

Branch, you could take just 1 or 2 amp hours out of the charge battery initially when you load it.
I would start off with taking just 1Ah out of it, while you're doing this re-charge the primary. Then next time charge the secondary to 15.3v. Note the voltage of the primary when you're done. If the primary is at 12.3v for example, take 2Ah out of the secondary next time. Keep doing this an increasing the amount you take out of the charge battery each time.

Ideally you want to charge the secondary without having to recharge the primary in between. New batteries take a few cycles to properly form the plates as they aren't formed properly in the factory anymore.

John K.

[Branch Gordon]

John,

Here's an example of my last charging cycle.



You can see I started at 12.34v....ran the primary all the way down...and the charge term voltage ended at 12.85v.
So I had to recharge the primary, and go again, and again. The last run I finally hit 15.00v.

After this I ran a discharge curve on the charging battery.

[John_Koorn]

Branch, what I'm suggesting is that once you have your charge battery charged up to 15.3v just take 1 amp out of it for 1 hour (1Ah). During the load time recharge your primary with a normal charger, such as a 2A12.
Then recharge your secondary back to 15.3v.
The idea is that you only load the secondary down so the primary can last long enough to charge it back up to 15.3v in one go on the next cycle.
If you find that you still have juice left in the primary after charging the secondary up to 15.3v, you can take a little more out of the secondary next time.

John K.