Hi ParkingLotLust. May I join this interesting thread and share some insights in what you are trying to do. Silicon diodes drop .6 to .7 volts. That is true. the other fact is that when you parallel them, they may not share the current flow equally. When we parallel transistors in power supplies, we put a low resistance resistor in series which acts as the bottleneck and more or less allows the same current to each transistor. The same principle can be used on the diodes. I would have made 3 sets of 3S(3 in series) and parallel them but I would not have put the jumper across the anodes I saw in your circuit. I am not saying that it will be the correction as the uneven current distribution is still there. Of course I would series a resistor of the same value on each 3S. But we still have a problem when we parallel diodes. The reason why there is a drop is due to the diode acting as a resistor and when we parallel resistors, the sum value drops which is the opposit of what you were trying to do, i.e. when you series, you add up the internal resistance. Making a single 3S with higher capacity diodes will vanish the curernt distribution problem of course. You might want to use voltage regulators. Get a 7810 voltage regulator which can handle 1 amp easily. If you can find one that can handle higher current, better. The LM317 has a 3 amp version in a TO-3 package similar to the 2n3055 or the 2955. You need to google how to set it up. Shout if you need me on that. The 7810 is a three legged VR much like a regular transistor. Let pin is in, middle is ground, right pin is out. If it gets hot,series an appropriate resistor before the input and heatsink the VR too. We can put a bypass transistor to increase the amp capacity but it will be a little complex. The diode way is simpler
Hope this helps a bit.
BravoKilo.