Super Capacitor Installation Guidance Request

Scott,

It's easy:

• Disconnect and remove the 2.4 volt battery from the engine.
• Meter the battery's out put to determine positive and negative DC.
• Desolder, or cut off, close to the battery, the two wires wiring that are connected to the battery.
• Solder the wiring harness to the Supercap, observing the correct polarity. Use heat shrink tubing to insulate the connections.
• Place the Supercap into the engine in place of the battery.

Thanks Barry!   The band on the caps does not indicate polarity, but taking a closer look I see there is a mini circuit board connecting the caps that has the + and -.   Very nice.

The first engine I want to modify has a 9v rechargeable battery. Do I still use one super cap?

Did some more research and found instructions describing what is needed for a 9v application ~ different caps + zener diodes.  Looks like I will be limiting my current effort to 3v applications.

Scott, send me an email for more information on 9V applications.

For the 3V, I use the proper JST connector to plug directly into the PS/2 board, eliminates the whole charging harness.  Pull one plug, plug in the supercap.

You can use two in series to get your 9V cap.  G

Are zener diodes still required? 

Recommended, but it'll probably work without them.  You'd want 4.7v Zener diodes for the two 5V caps in series.

This is just an FYI ---

Don't know if this would affect your design, but be aware that caps in series are additive for voltage, but lowers effective capacitance. So if you are using two 5VDC 2 farad caps in series, the series pair can tolerate 10VDC, but the effective capacitance of this series pair would be 1 farad.

gunrunnerjohn posted:

Scott, send me an email for more information on 9V applications.

For the 3V, I use the proper JST connector to plug directly into the PS/2 board, eliminates the whole charging harness.  Pull one plug, plug in the supercap.

Hi John,

The cap pictured says 5.4V. Will it work on both 5V and 3V boards? Should I worry about my PS2 engines that don't get charged very often and replace the batteries with caps?

George

George S posted:

gunrunnerjohn posted:

Scott, send me an email for more information on 9V applications.

For the 3V, I use the proper JST connector to plug directly into the PS/2 board, eliminates the whole charging harness.  Pull one plug, plug in the supercap.

Hi John,

The cap pictured says 5.4V. Will it work on both 5V and 3V boards? Should I worry about my PS2 engines that don't get charged very often and replace the batteries with caps?

George

Hey George,

GGG says for the 9V battery system (AKA PS2 5V) you can "use two in series to get your 9V cap.  G".

GRJ adds his recommendation (seems optional) of using "4.7v Zener diodes for the two 5V caps in series."

Hope this helps!

George S posted:

The cap pictured says 5.4V. Will it work on both 5V and 3V boards? Should I worry about my PS2 engines that don't get charged very often and replace the batteries with caps?

NO!   The 5V board uses a 9V battery, and the charging circuit puts out close to 10 volts peak.  You actually need a cap (or caps) that have at least a 10V rating.  Since that's rare or unobtainable  EDLC capacitors (supercaps), they're used in series to attain the voltage rating.

The caps also have to have a ESR (Equivalent Series Resistance). 

gunrunnerjohn posted:

George S posted:

The cap pictured says 5.4V. Will it work on both 5V and 3V boards? Should I worry about my PS2 engines that don't get charged very often and replace the batteries with caps?

NO!   The 5V board uses a 9V battery, and the charging circuit puts out close to 10 volts peak.  You actually need a cap (or caps) that have at least a 10V rating.  Since that's rare or unobtainable  EDLC capacitors (supercaps), they're used in series to attain the voltage rating.

The caps also have to have a ESR (Equivalent Series Resistance). 

Now I get it. Thanks. I don't know if I have any 5V boards, but I might in my MTH 400e engines. They are older.

George

MED posted:

This is just an FYI ---

Don't know if this would affect your design, but be aware that caps in series are additive for voltage, but lowers effective capacitance. So if you are using two 5VDC 2 farad caps in series, the series pair can tolerate 10VDC, but the effective capacitance of this series pair would be 1 farad.

If i remember correctly,  the voltage applied to the caps (10v?), will divide between the two caps in proportion to the actual capacitance of the two capacitors.   So if you have two 1000mf 5v capacitors in series and each cap is truly 1000mf, then a 10v input will put 5v on each cap.  But if the actual capacitance is 900mf and 1100mf, then you will see about 4.5v on the 900mf cap and 5.5v on the 1100mf cap.  So in this case the zeners will be very handy.

In addition to the capacitance, the actual leakage of the caps, the ESR, will also affect which one sees the most voltage.  If you're going to do this, they should be evenly matched in characteristics.  I suspect why the Zener diodes appears is to make certain a mismatch didn't over charge one cap.  EDLC caps are VERY sensitive to over-voltage, and even a small amount over their ratings can damage or destroy them.  The Zener just establishes a "max" charge voltage for each cap.

gunrunnerjohn posted:

In addition to the capacitance, the actual leakage of the caps, the ESR, will also affect which one sees the most voltage.  If you're going to do this, they should be evenly matched in characteristics.  I suspect why the Zener diodes appears is to make certain a mismatch didn't over charge one cap.  EDLC caps are VERY sensitive to over-voltage, and even a small amount over their ratings can damage or destroy them.  The Zener just establishes a "max" charge voltage for each cap.

Hi guys,

Hope all is well my friends.

Just want to ask/clarify where the Zener will go? On the positive leg of the first EDLC? Or do you put one on the first EDLC and another between the two (negative of first EDLC and positive of Second)?

Thanks in advance for the help!

I am assuming 1 zener goes across the + & - of each "2 pack" of super caps, with the black band on the zener going to the negative. A total of 2 zeners and 2 super cap packs per 9v application.

I am also assuming the zeners are required for the 9v but optional for 3v. If so, what happens if the caps fail for the 3v?

Correction, the band goes to the positive pin of the cap.

The 3V caps are 5V or higher rated, no Zener required.

Thank you gunrunnerjohn! 

This topic appears to be quite popular and of interest to many.

Many years ago I read a technical article in the TCA magazine where a member successfully used a large electrolytic fuse capacitor to replace the D battery in P/W diesels with horns. He claimed that it worked perfectly. As to the values I do not recall what he used.

What's an electrolytic fuse capacitor?  Is that like a flux capacitor?