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Fab Man 01-23-2009 01:50 AM

Electric motor boost?
I don't own an EV but am always thinking about new design technology...maybe some day when EV's can achieve 200+ mile range I may build one myself.

My question is one I am not sure anyone has ever thought about.

Do you think it could be possible to boost the battery output with a kick up transformer...if say, your running a 48 volt battery system, couldn't you get a further range by using a transformer?...the ideal is to boost the voltage output which would require less battery drain...or am I hoovering somewhere in la la land? :confused:

Just wanted an answer from the pros :thumbup:

captainslug 01-23-2009 02:14 AM

A transformer doesn't magically increase the wattage. It remains the same.
The point of going to higher voltages is essentially to increase the maximum wattage you can supply to the motor, while still using reasonable sizes of batteries and wires.

1,000 watts is 1,000 watts. 1,000 watts at 12 Volts is 83.3 amps, but 1,000 watts at 60 Volts is only 16.666 amps.
Higher volts and fewer amps will always result in more efficient power transmission.

Originally Posted by Fab Man (Post 84628)
maybe some day when EV's can achieve 200+ mile range I may build one myself.

They can, but the cost of the batteries to do so is still exorbitant.

Fab Man 01-23-2009 09:51 AM

Then if I understand you, using a coil would be a better choice...similar to an ignition coil that takes a 12 volt source and jumps it up to 30,000v at a smaller amperage.

Daox 01-23-2009 10:23 AM

Except that no normal controller could handle 30,000V, and ignition coils can't handle any usable amperage (they'd burn out).

Ryland 01-23-2009 11:46 AM

Also remember that every step you put your electricity through you lose something, so if you want a 120 volt or a 30,000 volt car you are best off configuring the batteries to that instead of converting it to a/c so you can run it through a step up transformer, the main reason that home made electric vehicles run at lower voltage is fewer batteries and safer electrical systems, I can bump my 48 volt pack with my hand and not get burnt to bad, I can grab on to half the pack (24 volts) and feel a slight tingle, a 72 volt or higher voltage car could kill me if I was not careful, but the lower voltage also requires larger wires to get the same wattage.

bennelson 01-23-2009 02:32 PM

I believe that hybrids such as the Prius DO bump up the voltage internal to the system.

For example the battery pack may be 144V, but goes up to 300 some for actual use in the motor. I am not sure of the exact reason why this is done.

I think it has something to do with how AC motors work, and possibly have to do with the regen braking as well.

Dagoberto 06-07-2014 12:29 AM

Electric boost
I was considering the idea of an electric motor that you could pair up to an existing under-powered gas engine for some 'grass roots' power when needed, say when pulling out on the freeway at the press of a button or switch. Something that wouldn't necessarily void a warranty. The idea came from my Dad's 2012 Tacoma, which of whom's 4 cylinder engine is more of a work horse than a high revver. Any ideas? Thoughts?

Also, the use of super capacitors to charge the battery pack needed to run this electric boost motor, in a full power and or full charge configuration. Any experience out there?

TexasCotton 06-07-2014 11:20 AM

You may want to go to Green Car Congress. There is a section there on 48 Volt. The car industry/mfg have future plans on mild hybrid vehicles which use a 48 volt alternator/generator for improved power.. ... kinda along your line of thinking.....

Cobb 06-07-2014 01:34 PM

First off you will never come out ahead. If you have a thousand watts its just going down from there from countless electrical losses. Its best to build the battery bank to match the operating voltage you need or find a different motor for your needs vs power supply.

Second, batteries have a limited voltage for their operating range and the more depth you use of that the short their lives will be. Sure you can use a transformer or puck converter to suck em to zero voltage, but it will never hold a charge again. :eek:

Astro 06-08-2014 08:10 PM

Using a boost circuit to boost a pack voltage up to a higher voltage to drive a higher voltage motor does introduce some electrical losses.
So using a battery pack with a higher voltage would be a better idea to avoid those losses.
However there may be other factors that make the boost circuit better even with its losses.
For example by using a boost circuit and keeping the battery pack voltage low you can use lower voltage chargers that are normally cheaper. The battery wiring is safer if it is a lower voltage, handy for DIY builders that may not use a sealed battery pack module.
Contactors, fuses, etc may be cheaper when using a lower voltage.
So there may be designs where using a boost circuit has advantages that outweigh the electrical loss disadvantage.

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