# High Input Voltage DC-DC Converter



## electricmini (Oct 21, 2008)

sailfish11 said:


> Hi all - I need a converter for my 320V system. I've looked around and there aren't that many that can accept such high voltage input. I have found a few, but before I shell out the cash, I wanted to hear from all you experts out there!
> 
> I've found the MES-DEA 400-1000 ($1500 from Metric Mind) and the CC Power 400 watt ($650 from Electric Vehicles USA). MM also has some nice Brusa controllers, but I think those are out of my price range. I'm not sure why there's such a price difference between the MES and the CC Power.
> 
> Any advice and/or experience?


 Try looking on Fleabay for Vicor Megapac converters, especially the Power Factor Corrected ones - they can accept DC input, from 100V to 380V. If you're lucky you'll get one with 12V or 15V output modules installed, or you can do like I'm doing and take the thing apart, swapping in some suitable Vicor modules (not a pleasant task, but possible) 
Or, most universal input PSUs (those with active PFC circuitry for the EU) will accept around 300 V dc.
hth Richard


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## sailfish11 (Sep 15, 2007)

Thanks for the tip, but I'm not an EE and wouldn't feel comfortable hacking something like that. I'll keep my eyes open on Ebay for the Vicor ones you mentioned, but so far no luck.

Any other suggestions?


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## iruraz (Sep 4, 2012)

@sailfish11 what is the result? Could you share your expreince about dc-dc if you bought a dc-dc converter which you mentioned above?

Regards.


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## onegreenev (May 18, 2012)

sailfish11 said:


> Thanks for the tip, but I'm not an EE and wouldn't feel comfortable hacking something like that. I'll keep my eyes open on Ebay for the Vicor ones you mentioned, but so far no luck.
> 
> Any other suggestions?


NO NO, its not a hack. These suckers work great. You can take three 5 volt 40 amp modules and parallel them or series them for what ever your needs are. I use one for my DC DC. I also use one for charging my A123 Cells with a high amperage fast charge. Works great. These modules are designed to be manipulated like this. I am not an EE either and its simple. I guess I have a video to do now. I can show you with my setups. 

If after that you still don't want to use one, you can buy some used lithium cells and make yourself a 4 cell 12 volt battery for your cars system. I have a 4 cell 100ah 12 volt battery with my DC DC. I used to only use the DC DC but I really need the battery too. Works great and lasts a long long time. Way better than the 12 volt lead acid batteries. 

I'll do a quickie on the Vicor MegaPac tomorrow and Thursday and then post it for you and others. 

It is really that easy. 

Pete


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## iruraz (Sep 4, 2012)

@onegreenev I need 1000 watt dc-dc converter. I have searched for a few of days. I have 320V battery pack and I want to convert 320V to 12V for my 12V accessories. If I install small capacity dc-dc converter parallel are there any disadvantages for battery pack or 12V accessories? 

(Consider this info : I am going to use 12V auxiliary battery in my system)

And what should I concern about dc-dc converter? For example should it be isolated or non-isolated, directional or bi-directional, single output or dual or more output?

Regards.


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## onegreenev (May 18, 2012)

The Vicor MegaPack is multi output depending upon the modules you have in the unit. If you use a battery you need a way to keep it charged up so you still need a DC DC connected to the battery. Then the only job the DC DC has to do is keep the battery charged. Using only an Aux batter you will find it drains rather rapidly unless you have one like mine. I have a 15 volt triple module set up for power for my controller and a 12 volt module to power the contactors. 

You always want your Aux system to have a healthy power supply. If not your Aux battery could drain enough and at the inopportune time your controller will power off due to inadequate power. Been there, done that. It's no fun driving and your system just turns off.


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## dougingraham (Jul 26, 2011)

electricmini said:


> Try looking on Fleabay for Vicor Megapac converters, especially the Power Factor Corrected ones - they can accept DC input, from 100V to 380V. If you're lucky you'll get one with 12V or 15V output modules installed, or you can do like I'm doing and take the thing apart, swapping in some suitable Vicor modules (not a pleasant task, but possible)
> Or, most universal input PSUs (those with active PFC circuitry for the EU) will accept around 300 V dc.
> hth Richard


I am using a Vicor Megapac as my DC-DC. I use 3 of the 5V 40A modules in series. I trimmed them down to 4.533V so the output voltage is 13.6V which I use to float a 4S4P pack of the A123 26650 cells. If I was going to go without a standby battery I would add three of the 5V 40A slave booster modules. The 5V 40A modules when trimmed down will do 44A and with the booster modules paralleled in the Vicor will do 88 amps (1200 watts total). An alternative would be to parallel a bunch of the 12v modules. The only ones I have are only 100 watts but if you put 8 of these in a chassis it would give you 66 amps and if a single modules fails you still have a working DC-DC although at a reduced output current. I purchased five megapacs with a mix of modules each for about $60 so a considerable savings over even the least expensive products being offered. And I have a lot of stuff left over for bench supplies.

The downsides of the Megapac's is they have a rather noisy fan and they aren't weather resistant. I am going to replace the fan with a larger diameter lower velocity fan one of these days. I try to fool myself by saying the sound is the pedestrian alert. And it is not in a place where it should get much weather but I have avoided driving in the rain so far (because it pretty much has not rained since I got the car rolling).


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## onegreenev (May 18, 2012)

I have my fan disconnected so I can turn it on manually when under load. I intend to connect up a temp switch so I can let that turn the fan on and off as needed. That avoids the noisy fan much of the time. If I am driving with lights on and such I will need that fan but while driving the road noise will drown it out. Keep it in a safe dry area.


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## dougingraham (Jul 26, 2011)

iruraz said:


> @onegreenev I need 1000 watt dc-dc converter. I have searched for a few of days. I have 320V battery pack and I want to convert 320V to 12V for my 12V accessories. If I install small capacity dc-dc converter parallel are there any disadvantages for battery pack or 12V accessories?
> 
> (Consider this info : I am going to use 12V auxiliary battery in my system)
> 
> ...


1000 watts is a lot of power for the 12V systems. What have you added that needs that much power (about 80 amps at 12 volts)? You can probably get by with less than half that and a small aux battery.

You want isolated. I don't know what you mean by directional. A single output should be fine. I can't think of a reason why you would need a dual output. I suppose you could use several lower power units and split the loads up. Put the essential only systems on the output with an aux battery. Car Stereo on its own if you go a little overboard in that area.


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## smpavlik (Mar 28, 2011)

sailfish11 said:


> I need a converter for my 320V system. I've looked around and there aren't that many that can accept such high voltage input. I have found a few, but before I shell out the cash, I wanted to hear from all you experts out there!


As a temporary solution you can use a regular PC power supply. It can accept input up to 350V DC. Vibration and moisture can be a problem, therefore I put mine inside my car to protect at least from water. I grab the supply from old PC so it costed me zero bucks


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## rwaudio (May 22, 2008)

Just like the Vicor megapac the Power One 2kw series can run off DC.

I'm using the HPF chassis in my car, however a pair of the power supplies in this link would give you 15v @ 150A plus an extra 5V @ 150A if you wanted unlimited USB power.

http://www.ebay.com/itm/Power-One-Switching-Supply-150A-2000W-Teradyne-PN-405-097-00-HPMA2A2KS234-/400360984856?pt=LH_DefaultDomain_0&hash=item5d375fd118

You should confirm the HPM is the same as the HPF and works off DC.


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## iruraz (Sep 4, 2012)

dougingraham said:


> 1000 watts is a lot of power for the 12V systems. What have you added that needs that much power (about 80 amps at 12 volts)? You can probably get by with less than half that and a small aux battery.
> 
> You want isolated. I don't know what you mean by directional. A single output should be fine. I can't think of a reason why you would need a dual output. I suppose you could use several lower power units and split the loads up. Put the essential only systems on the output with an aux battery. Car Stereo on its own if you go a little overboard in that area.


@dougingraham, I know 1000W is more than enough. But I haven't chosen and specified 12V accessories so I can't calculate the exact power needs. But according to previous recommendations in the forum I need ~500-600W for 12V accessories. And I want to buy high capacity converter against needs arise subsequent (maybe I add different accessories later).

I agree with you single output will be fine. When I asked about Directional, bi-directional, single or dual output, I wanted to learn certain technical details about dc/dc converter.

There are many useful info in the forum. But I haven't encountered technical details about dc/dc converter.

Regards.


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## onegreenev (May 18, 2012)

Here is the little video I did with the MegaPac. You might consider using one. 

Pete


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