High voltage low amp controller + battery... thoughts?

Currently I have my eZip running overvolted with a 42v 8ah battery (2 42v 4ah lico's in parallel). The motor never struggled with the higher voltage and speed even at full throttle. It definitely got hot but not hot enough to not keep your hand on it. I think this is due to the fact that I only run thin 14 gauge wires from the batteries to the controller so the voltage increase is definitely there and noticeable but the thin wires help from pulling too many amps at once and cooking the motor. I'm assuming its the wires that are bottlenecking the controller which is basically a crude way to limit amps. The battery wire never gets too hot either so its not like its pulling high amps through thin wire. Right now this setup is on a 24v brushed controller with no HVC and 50v caps. I get a decent range, 10-15 miles depending how hard i run it. I want to up my speed more without more amps or overheating.

Recently I've had an idea in mind after coming across this thread finding out that it is possible to run 120vAC power supplies directly on high voltage DC perfectly fine to use them as sort of "high voltage dc-dc converters". I needed a way to get a high amperage 12v output directly from my battery pack of higher voltage to feed an audio amplifier. I looked into voltage reducers, buck converters, inverters, but anything with an output above 10-15 amps gets expensive quick. Once i saw most laptop power supplies and such can be plugged into DC, i rewired my pack in series for 84v 4ah and started testing supplies. I found basically all of them worked fine off DC, only difference between supplies was the voltage it cut off at. Some ran off a single 36v battery fine while some needed 90 or more. I quickly searched for 12v psus and ran into the Dell DA-2. 12v 18ah output for about 220watts. It wouldnt run off 84v, so i added another 42v in series for 126v. The power supply ran fine over 119v, but shut down completely once the battery went below that. If i add another 40v battery in series this will equal 160v fully charged and be perfect for the 118-120v LVC when all the batteries are fully dead (3.0v/cell).

What I want to do now is replace my 24v 500w DC motor controller for one of these: http://www.ebay.com/itm/HX-PWM-AC110V-Input-DC0-110V-Output-4A-500W-DC-Motor-Speed-Controller-Driver-/191171913543?pt=LH_DefaultDomain_0&hash=item2c82bbe747

Then run it off my high voltage battery directly just like the power supply. This is the equivalent to an ebike controller (a PWM speed controller) but runs off high voltage correct? The only difference clearly is it only puts out 4 amps of current, but at upto the voltage your putting in. My question is what would the performance be like with only 4 amps but 110v? Its still only about 300-500w so the motor shouldnt heat up any more than before. My question is will the high voltage make up for the low amperage in things like climbing hills or getting up to speed? I know torque comes from amps but i also know high rpms with low gearing can also make up for torque. I already geared my eZip down from a 20t to a 22t freewheel which made the 42v speed drop from 28mph to about 24mph so that may help slightly. How would a high voltage low amp setup feel? Watts are watts correct? So shouldnt it just feel a little more sluggish up hills requiring a little more pedaling but have a way higher max speed? Will this setup even work correctly? I would definitely monitor battery voltage manually instead of depending on any lvc in the system since i dont know if that controller stops at 120v like the Dell DA-2 or runs lower. Thoughts?

42V pushes you at 24mph = 30mph motor no-load speed, near 75% efficiency point ...
126V would be a motor no-load speed of 90mph, 400w limiting to <20mph but ... possibly 30% efficiency!

Also, high voltage produces excessive brush wear and 120V + might actually arc inside motor!

So 120v through a brushed motor isnt a good idea even with low amps? I want to keep my battery voltage at 120+ to keep the convenience of whats basically a portable wall outlet, is there any other kind of controller that would take high voltage input and output lower voltage but high amps like an ebike controller? Or, could I just power my existing ebike controller through another ac-dc converter that outputs 24v then connect that output to the controlller's DC input? I have a wall adaptor that works off dc fine, only needs about 60v versus 120v in the Dell DA-2 and has an adjustable output voltage from 12-24v at 5 amps. You can choose between 12,15,16,18,19,20, and 24v output. Maybe two of these in series for an on-the-fly adjustable output voltage which goes into the ebike controller? Or in parallel for more amps. But i would like to minimize voltage conversions and inefficiencies, i know just powering these 120v adaptors off dc wastes some energy at the rectifier, so if i can replace the old ebike controller being powered by adaptors with a controller that'll accept the high voltage directly, but better suited for my motor, that would be better.

120v DC can be very dangerous too. That's why most OEM ebikes are 48v or lower. Be careful!

Once small advantage I can see with this setup is now my speed should be constant throughout the entire battery's life. I plan on feeding the controller 48v (60v if i see this setup works well and upgrade my controller) but low amps maybe only 5 or 10. The DC controller will always see a constant voltage from the power supplies until the batteries fall below the power supplies operating voltage when theyre dead and the bike would just cut off. It wont see the voltage slowly decreasing from the battery as it drains since its being fed constant voltage, or suffer from voltage drop from the battery when pulling current (since its low amps there shouldnt be much voltage drop from the power supplies if im not mistaken)

Your controllers amp limiter, is what is limiting your power, not the thin wires. If it was the wires, they'd have melted by now.

Just get more 42v battery, so you have 16 ah. Then you will sag less, and less drop in speed until later in the ride.

Mine is a brushless hub motor, but I want to go on high voltage, just like you, because my current setup (18" wheels, 52V 33Ah Li-ion battery pack) gives me 38-43km/h, depends on the battery's voltage and around 80 km range (on full throttle). But I hate that the top speed really depends on the voltage and the power too, so I'll build another 52V 33Ah battery pack, so I'll have 104V. Higher voltage means greater top speed and more torque too and also less amps which will increase the range too and creates less heat. The small wheel at high voltage gives you great torque, speed and efficiency, while a large wheel will just heat up, because it's convinient RPM will never be reached. I already tried out how fast can I go with higher voltage, I bought a 108V 42A controller, and gave that 18" wheel 96V. I reached 70 km/h and it was so powerful, I had to be gentle with the throttle when I started from standstill, because the bike lifted up its front wheel. So the key for power, speed and efficiency is small wheel and high voltage. I also tried the 28" wheel on 84V, but it was so weak, but my top speed was 70km/h. So if you want to go fast and you are on a low budget, you can go with large wheels, but it will be weak and if you push it hard at low speeds it will heat up very fast. The smaller wheels can handle the power better.