# Would a SMPS which upconverted be too lossy?



## chiques (Mar 9, 2009)

I really don't like the idea of having hundreds of volts along with hundreds of amps in my car; it just doesn't seem safe. I'm looking into designing a switched mode power supply that will convert (in theory) 12-20VDC to 80- 160 VDC. There would probably be many parallel boards (due to the current requirements), but I'm just curious on what efficiency and loss I'm looking at here. I would appreciate any opinions.


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## Amberwolf (May 29, 2009)

You're probably going to lose a whole lot of power doing that kind of conversion.

That said, I've seen a Yahoo discussion group for a bicycle motor controller that does boost conversion as you want to do; you might be able to upscale it to higher power levels. 
I think this was it:
http://tech.groups.yahoo.com/group/switchmode/
________
Paxil lawyer


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## Gavin1977 (Sep 2, 2008)

Put simply. Yes.
For many reasons.

1st, for a performance car, you're looking at 1000A at 144v, so you are looking at >10,000A @ 12v. The weight of the cable alone would be considerable. Not to mention your IsquaredR losses.

As an electronic engineer, I would be looking to up the system voltage, not reduce it.

As long as the appropriate precautions are taken, such as fuses, circuit breakers, adequate insulation, I really dont see a problem with high voltages on cars.


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## jockepocke (Nov 24, 2009)

Gavin1977 said:


> Put simply. Yes.
> For many reasons.
> 
> 1st, for a performance car, you're looking at 1000A at 144v, so you are looking at >10,000A @ 12v. The weight of the cable alone would be considerable. Not to mention your IsquaredR losses.
> ...


I agree, also it is not the voltage that is dangerous, (you can have an electrostatic shock of several thousand volts with no harm whatsoever), it is the current, however, with electric cars, the power is high enough to cause harm, yes. 

A higher voltage system will theoretically have less losses due to heat in conductors and cables, and also require much smaller cables.


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## Sunking (Aug 10, 2009)

chiques said:


> I really don't like the idea of having hundreds of volts along with hundreds of amps in my car; it just doesn't seem safe.


Besides the points others have made, I don't understand your logic. The whole point of using higher voltage is lower amperage and higher efficiency. To go from a low voltage at extremely high current, to higher voltage at lower currents is just not logical. You would have to give up most of the benefits of an EV going that route.


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## chiques (Mar 9, 2009)

Thanks everyone. I really appreciate the feedback.


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