# DC-DC converter



## cruisin (Jun 3, 2009)

jehan12413 said:


> If anyone is interested there are some more VICOR DC-DC converters for sale on e-bay. Item # 190520444458 $24.99 for one with free shipping and there are also lots of 5, 10 or 20 for sale ( only $200 for 20!) The model is a VI-251-09 which is the model I use (200V 250W). I talked to VICOR a while back and was told that the 09 was a special production unit with a wider input range (150-250v). I have tested mine down to almost 100v and they seem to work ok. They are also very easy to parallel.


 
The problem with these DC converters is that they are only 12v output. That is not enough as a car is uaually around 13.4v. There is a Vicor with a 15v output but rather hard to find.


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## major (Apr 4, 2008)

cruisin said:


> The problem with these DC converters is that they are only 12v output. That is not enough as a car is uaually around 13.4v. There is a Vicor with a 15v output but rather hard to find.


You can trim the output voltage to 110% for 13.2V, IMMIC (If My Math Is Correct)  Is that like turning it up to 11


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## frodus (Apr 12, 2008)

That's correct. They go to 110% with just a trim resistor, so It's not an issue Cruisin.

And anyway, car electronics are made to operate between like 11 volts up to like 15, so it would run just fine on 12V.



jehan12413, is the input range 150-250? I was under the impression that it'd work at ~115V (251 is 100-200V from the datasheet), which is why I bought it. Would it work at 115VDC?


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## cruisin (Jun 3, 2009)

frodus said:


> That's correct. They go to 110% with just a trim resistor, so It's not an issue Cruisin.
> 
> And anyway, car electronics are made to operate between like 11 volts up to like 15, so it would run just fine on 12V.
> 
> ...


I guess I just like a little more voltage for brighter LED's and Haligen headlights at around 15v. Is it possible to connect 2- 48v Vicor 1/2 brick DC converters in series on the input using a 120v battery pack?


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## frodus (Apr 12, 2008)

cruisin said:


> I guess I just like a little more voltage for brighter LED's and Haligen headlights at around 15v. Is it possible to connect 2- 48v Vicor 1/2 brick DC converters in series on the input using a 120v battery pack?


Yeah, true, but it'l still work 

Vicor are isolated, so it shouldn't be a problem. I'd put one DC-DC one the top half and the other on the bottom and then parallel the outputs.

The only problem is, is that without extra circuitry, they don't equally share the load current, so it is possible that it could cause an unbalanced pack.


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## cruisin (Jun 3, 2009)

frodus said:


> Yeah, true, but it'l still work
> 
> Vicor are isolated, so it shouldn't be a problem. I'd put one DC-DC one the top half and the other on the bottom and then parallel the outputs.
> 
> The only problem is, is that without extra circuitry, they don't equally share the load current, so it is possible that it could cause an unbalanced pack.


I didnt mean one Vicor on 1/2 pack and one on the other half, I mean wiring the inputs in series off the whole pack.


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## frodus (Apr 12, 2008)

cruisin said:


> I didnt mean one Vicor on 1/2 pack and one on the other half, I mean wiring the inputs in series off the whole pack.


I know what you asked Cruisin, I just said what I'd do.


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## cruisin (Jun 3, 2009)

frodus said:


> I know what you asked Cruisin, I just said what I'd do.


That is the way I have been doing it for years, just want to avoid creating a unbalanced battery pack.


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## frodus (Apr 12, 2008)

There are other DC-DC converters that Vicor makes that are a little easier to have power share. I think you should be fine, we're only talking a couple hundred watts.


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## Newbiee (Feb 16, 2011)

So just to make sure before i go ahead and get one, the 200vdc 200watt vicor dc-dc VI-251-09 on ebay will work on a 100vdc traction pack too? well.. i think i will be at 96v though.


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## frodus (Apr 12, 2008)

he said its a wide input range 150-250V.... so I wouldn't risk it. Call vicor and ask about the Vi-251-09


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## TomA (Mar 26, 2009)

These Vicor bricks are from a Solectria (Azure Dynamics) inventory liquidation. I posted my investigation of them some time ago:

http://www.diyelectriccar.com/forums/showthread.php/dc-dc-converter-44048p2.html?highlight=Vicor

TomA


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## frodus (Apr 12, 2008)

Forgot about that Tom, thanks for posting....

looks like ~130-250V

Oh well, got a VI-2T1-EV today, should work better for me.


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