Branch's SSG Build

[Tom C]

Getting ready to start run #9 tonight. Really seeing some nice changes in my charge curve. Here is a chart showing how the curve is changing.

[ATTACH=CONFIG]2657[/ATTACH]

I'm expecting to hit a COP of 1+ here in the next 5 runs.

classic SG charge curves!! nice work Branch. you are already at a cop over 1 if you include the mechanical. your next step is to run the SG in branch mode charging circuits. desolder the output diodes from the charge battery positive trace and solder a wire to each one on the output side. then run a wire to the positive of 4 batteries. those batteries will have a common negative.

then try it in generator mode...

Tom C

[Branch Gordon]

Thanks Tom!

There is one point though that I'm concerned with until I feel like I can move onto a more advanced build....hopefully you can shed some light...

I am not getting 1:1 charging for the full capacity of my battery. I can only pull around 3AH out of the charge battery...any more than that and the primary battery dips below 12V to charge it back up. This is a 10AH battery. I would think I need to figure out how to reduce my primary amp draw first and get 1:1 charging.

Is this correct? Any suggestions?

classic SG charge curves!! nice work Branch. you are already at a cop over 1 if you include the mechanical. your next step is to run the SG in branch mode charging circuits. desolder the output diodes from the charge battery positive trace and solder a wire to each one on the output side. then run a wire to the positive of 4 batteries. those batteries will have a common negative.

then try it in generator mode...

Tom C

[Tom C]

alright let me see if I understand. you have 2 purchased new 10 amp batteries, one for charging on the SG, one for running the primary. after each run you charge the primary fully on a standard charger, and discharge your charge battery at C20 on your CBA... your primary battery is discharging into your SG at the C20 rate for that battery or perhaps higher say C30.... you are logging the primary batteries starting and ending voltages as part of your calculations. anything I missed here?

Tom C

[Branch Gordon]

All correct except i havent been logging the primary battery voltages every time. I did at run #1 and #7.

Is the primary battery voltage supposed to improve through the runs?

alright let me see if I understand. you have 2 purchased new 10 amp batteries, one for charging on the SG, one for running the primary. after each run you charge the primary fully on a standard charger, and discharge your charge battery at C20 on your CBA... your primary battery is discharging into your SG at the C20 rate for that battery or perhaps higher say C30.... you are logging the primary batteries starting and ending voltages as part of your calculations. anything I missed here?

Tom C

[Tom C]

how do you know if your primary battery is fully charged each time? it should come off your standard charger, it will take your battery to 14.5 then should be floating it at 13.2 or so and when it is at rest it should be around 12.7... so if your primary is degrading that could be a problem.... its not a 10 amp battery if you can only transfer 3 amps out of it.... what is the primary current draw again? Tom C

[Branch Gordon]

The charger stops automatically at around 15v and goes into a slow trickle state at which point the primary floats around 13.6

After i remove the charger and let the primary rest for an hour it is usually sitting around 13.38.

Im pulling 680mA from the primary to run the SG. If I charge up the charge battery after using the CBA to take out 2AH, the primary is sitting at around 12.38. But for some reason if I take 3AH out, it takes considerably longer to charge back up and the primary drains to 12.01V.

Primary amp draw: 680mA
Charge input amps: 220mA

So just over three times as much to run vs charging.

how do you know if your primary battery is fully charged each time? it should come off your standard charger, it will take your battery to 14.5 then should be floating it at 13.2 or so and when it is at rest it should be around 12.7... so if your primary is degrading that could be a problem.... its not a 10 amp battery if you can only transfer 3 amps out of it.... what is the primary current draw again? Tom C

[Tom C]

how long is it taking to do a charge run? do a load test on your primary battery and see what the true capacity is, also do one on your charge battery. 680 milliamps is hi you are below C20 if these batteries were brand new, you may find that your charge battery was not fully formed internally. what are you charging to on your wheel?

[Branch Gordon]

It's taking about 8 hours to do a charge run.

I will do a load test on both of them and post the results...will take a couple days to run both curves.

I am charging up to around 15.6 where the curve flattens out. I have been recording the time it takes to get to 15.3 though on my COP spreadsheet.

how long is it taking to do a charge run? do a load test on your primary battery and see what the true capacity is, also do one on your charge battery. 680 milliamps is hi you are below C20 if these batteries were brand new, you may find that your charge battery was not fully formed internally. what are you charging to on your wheel?

[Branch Gordon]

I have completed load tests on both of my batteries, and the results are terrible. It's no wonder I am having issues.

The longer curve is my primary battery (8.5AH), and shorter curve is my charge battery (3AH).



I actually looked this model battery up, and it's supposed to be a 20AH battery. But they have terrible review online. So it looks like I need to buy some new batteries.

Specifications
Chemistry Conventional (Wet Cell)
Voltage 12.0 V
Capacity 20 Ah
Rating 240 Whr
CCA 300
Cell 6 cells
Connector Flag Nut & Bolt

[Tom C]

before you do that run your charge battery several times on your standard hot charger see if it comes up.... the cell may not have been formed from the factory. a new battery needs current to form the plates.

Tom C

[Branch Gordon]

Good news is that these batteries have a free 6-month replacement guarantee. I just called the hardware store and they are going to give me two brand-new ones.

I will run a few cycles first on those with the standard charger, and then run baselines on both. Stay tuned...anxious to see how my charging is impacted by having new batteries now that my SG is setup correctly.

before you do that run your charge battery several times on your standard hot charger see if it comes up.... the cell may not have been formed from the factory. a new battery needs current to form the plates.

Tom C

[Branch Gordon]

Ok I have my new batteries, and am going through the process of charging them with a standard charger, and discharging them while charting some baseline curves.

While that's going on, I have a question. From my understanding there are a few ways of trimming down the primary amp draw. One is making sure the bike wheel has very little friction, and a high free spin time. The other is of course the base resistance in the circuit, but this affects charging amps as well.

The other I'm not sure on is adding a load to the wheel. If I remember correctly, you can load down the wheel to use mechanical energy up to 30%, and it doesn't cause the primary amp draw to go up. Does the amp draw decrease at all? Do the charging amps decrease as well? Should you tune the SG without the load first and THEN add it, or vice-versa?

[Tom C]

Branch,

the mechanical load will cause the machine to slow down, which will lower current draw, because these are not motors the draw does not go up as you load it. charging will also slow down sometimes, and sometimes it gets better. it just depends on how the speed change affects the coils resonance with the charge battery. try a fan like JB does, or a genny coil in phase or out of phase with the coil pulse,, you can use a cap to dump to the primary "back pop" it.

Tom C

[Branch Gordon]

Is it best to maximize the possible mechanical load for the SG?

Let's say I get my current best charging at 352 RPMs, drawing 680mA. Then I add a fan, and my max RPMs drop to 330, drawing 500mA. I guess I don't understand the principles behind the coil resonance with the charge battery... If a different RPM will still resonate, with the mechanical load added, then there is another factor in play that changes where that window of resonance is...

Branch

Branch,

the mechanical load will cause the machine to slow down, which will lower current draw, because these are not motors the draw does not go up as you load it. charging will also slow down sometimes, and sometimes it gets better. it just depends on how the speed change affects the coils resonance with the charge battery. try a fan like JB does, or a genny coil in phase or out of phase with the coil pulse,, you can use a cap to dump to the primary "back pop" it.

Tom C

[Tom C]

there are frequencies that are additive in a circuit, its like a LCR circuit or an LC circuit. feed back in an amp can cause it to runaway and blow itself up..... same thing in an SG circuit, it was much more obvious in repulsion mode, where there were 2 or 3 sweet spots in the tuning curve, this was resonance with the coil and the wheels rpm in the bloch wall of the coil core. much less noticable with attraction mode.

Tom C