General builder query

[sm0ky2]

The math is a bit complicated but in your example
You would expect something like 7v @ 1.5A
round abouts


Because the current is double, i would think that
connecting them in series would give you


15v and 1 &1/3 amps or closer to your 20 watts


You wont get 3 amps like you would if they had the same voltage.
The drop in current becomes lower as the proportional difference decreases
meaning at 100V, a 5v difference wont change the current much


Also, at higher currents, the drop is less.

[onepower]

captainpecan

The point is, wondering if it is a viable option for a generator to have both high voltage low amp coils as well as low voltage high amp coils. That way at very slow speeds, a battery would get enough voltage to at least catch a small charge from the high voltage coils. But as speeds increase, the high amperage coils reach a high enough voltage to start dumping higher amps into it as well. Or are we kind of stuck choosing one or another, or switching between coils dependant on speed of rotor.

In the past this was done however a better option is boost/buck or cuk converters. For example inverter generators don't run at 60hz they run at 600hz, rectify the output to DC then convert it to 60hz 120/220v power.

I have done similar experiments and ran a PM generator with low turn thus high amp/low voltage coils. The output was then rectified and sent to a boost converter which could vary the output voltage and amperage.

You may also want to look at MPPT (max power point tracking) which is all I use anymore. I use an Arduino to track voltage and current then calculate power. At some operating level the voltage and current produce the maximum power. The circuit basically continually hunts for the maximum power point (MPP) and tries to hold it.

Regards
AC