voltage doubler (diode/capacitor method)

[ejonesss]

http://en.wikipedia.org/wiki/Voltage_doubler

i know that using transformers and dc to dc converters there is a volt/amp tradeoff just like there is a resistance/wattage tradeoff when seriesing/paralleling resistors


i was wondering if you take 3 volts 15 amps ac then feed it into a diode/capacitor multiplier network is there any tradeoffs there meaning is there a loss of amps on each diode/capacitor multiple?

i am thinking about building a battery charger to charge lithium batteries based on a microwave transformer i have cut off the high voltage side and re wound it with 3 turns of 3 conductor 12g household wire that will make 3 3 volt ac at 15 amp and then using diodes and capacitors make it to 3 6 volts or even more and then use dc to dc converters to do the regulation of the power to the cells?

 

[heathyoung]

Its very lossy, especially at low frequencies.

I'd be winding more turns onto the transformer.

 

[ejonesss]

i was thinking the trade off where to get 1 amp at 110vac you have to draw 10 or even 100 amp on the input.

because the ac is being converted to dc and make a + and - voltage a split power supply sort of like you see in many sound systems where there are 2 large capacitors

i know the dc to dc converter is going to be lossy but my main question is if there is any trade offs by seriesing a bunch of transformers if there would be the same loss idea like you see in seriesing capacitors?

 

[Punx0r]

Watch out for microwave oven transformers. They're only designed to run at full load and will overheat otherwise:

http://sound.westhost.com/xfmr2.htm#s16

 

[fechter]

Voltage doublers don't perform well at high currents. With more multiplication, you get a very high ripple on the output.

I'm not sure I follow about series transformers. The old fashioned way is to use multiple secondary windings or a tapped secondary. If this is all running at 60hz, you need a big chunk of iron to make it efficient.