How to step down 110V DC to 46V DC?

Little about the beast:
This is a home build rectifier made of x6 KBPC3506 which comes out to total capable throughput  of 210Amp
This THING connects to an outlet via thick power cable. I measured the output when plugged and it is 110V DC.

So this got me thinking is there an easy way to step down 110V DC to like 46V or 60V?

WHY?
Well I have an electric e-bike and just as a fun project I wanted to see if it is possible to replace the battery with portable gasoline generator and then AC 110V from generator turn it to DC and step it down to a little more than 46V. Of course I will have little baggie at the back of the bike :-)


Picture of How to step down 110V DC to 46V DC?
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No, there's not an "easy " way to convert DC to DC. Use your engine RPM to control the output voltage of the alternator, or, if you get really, really clever, get a separately excited alternator, and control the output volts by adjusting the field current in the alternator.
Redion (author)  steveastrouk5 years ago
Hi Steve
"engine RPM to control the output voltage" - But isn't that going to also decrease amps?
"get a separately excited alternator" - I attached an image of the generator that I have. Not sure if it is possible with this type of the alternator but I will take it apart to see how exactly alternator get exited.

I was thinking... Once the alternator taken apart I could tap in to the coil for lover voltage?
Image2.jpg
No, amps are determined by the LOAD your generator is driving.
If you;re using something like this, you could use a transformer to convert AC-AC and then turn that to DC.
Redion (author)  steveastrouk5 years ago
That is going to be hell of a transformer ;-)
Any ideas where to source out transformer like that?
How many watts is your motor ? It must be less than 1000 I'd guess.
Redion (author)  steveastrouk5 years ago
I believe it is somewhere between 500W and 700W running on 46V.
I could get a custom controller board to increase torque and the voltage little over 60V.

Perhaps install 2 motor on the bike and 2 separate controllers connected to the same throttle while being connected in series maybe then I could get away with using 110VDC ? :-) 
my bike.jpg
1000VA autotransformer ? lighter than the generator !
Redion (author)  steveastrouk5 years ago
actually I happen to have 1 sitting around! :-)
Mine is 110V to 220V

So then I connect:
110V to the 220V output
and
the 110V input to the rectifier?

Does that in theory makes an output equal to half of the 110V?
Yep. That should do it. You'll need to be careful about the current you pull.