[15A Lead Acide Battery Charger!]

Just thought it worth mentioning that Lead-Acid rechargable batteries like a raw recharging supply. In other words, rectified but unsmoothed. The battery itself will have a smoothing effect on the supplied voltage but that is irrelevant. Look at the battery recharging circuitry in a vehicle and you will find no smoothing components are used. I'll see if I can dig up some more info on this for you as it's a long time since I researched this. I do remember though, that a raw DC supply was more efficient at reversing the chemical process involved.

[Resistor wattage]

Of course, you could achieve the same result by connecting two 160 Ohms resistors in parallel. Just in case it's not obvious to everyone..

[led powered by a/c How To?]

It has nothing to do with the circuit operation. A polarised capacitor needs a net voltage applied in the correct polarity to maintain the electrolytic. This circuit is AC so a non-polarised capacitor is required.

[Outout of a transformer!]

The line-to-line voltage of a three-phase system is √3 times the line to neutral voltage. This quote is taken directly from the following website.
http://en.wikipedia.org/wiki/Three-phase_electric_power
Another interesting website is
http://www.federalpacific.com/university/transbasics/chapter3.html
So, contrary to what the expert tells you, the voltage is actually higher by approximately a factor of 1.732. Therefore I would expect the phase to phase voltage to be around 173 volts.

After all is said and done, though, Ante is right. It's the transformer ratio that determines the output voltage.