# IOTA vs MW DC-DC



## sabahtom (Mar 1, 2011)

Any comments on why these have similar amp ratings but MW is half the price? Any suggestions on a good DC-DC also welcome. My pack is 312v nominal and I need about 700w peak, 300w continuous.


http://www.evolveelectrics.com/DC-DC%20Converters.html

http://evworks.com.au/index.php?product=DCD-DLS-55-220


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## Nabla_Operator (Aug 5, 2011)

I (also) hope on a knowledgable recommendation, mr.Sabathom, cause I have to decide equally. 
By the way: Your 1st link should contain:

http://www.evolveelectrics.com/DC-DC Converters.html


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## sabahtom (Mar 1, 2011)

Nabla_Operator said:


> I (also) hope on a knowledgable recommendation, mr.Sabathom, cause I have to decide equally.
> By the way: Your 1st link should contain:
> 
> http://www.evolveelectrics.com/DC-DC%20Converters.html



Hi Nabla

Thanks I fixed the link.

The Vicor Megapac is supposed to be good and scaleable.

I'd like to get one off ebay but none suitable there right now. I saw one that was $500, untested and no return/no refund. I'll keep looking though.


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## zeva (Nov 4, 2013)

In my experience the IOTAs are a decent unit for the money. I have one in my EV. The catch is that they are/were actually a reappropriated AC-DC converter, and the new version (released a couple of years back) apparently doesn't work with DC input. The old design just had a simple diode bridge input so was "too dumb" to know if you were actually running it off DC, perhaps the new one uses some kind of PFC front end.

Back when I was with EV Works we stocked Meanwell DC/DC converters for a while and I'm sorry to say we saw a rather high failure rate. Also many require a (big) diode on their output to avoid back-feeding from the 12V battery, or they will flatten it if left off and idle for a long time. That was a few years ago now so YMMV. Just make sure it comes with a warranty 

The Vicors are really nice products. I used some of the 300W Maxi modules on an engineering project earlier this year. Very compact, totally weatherproof, seemed to be robust. Their output voltage is adjustable about +/-10% so in automotive applications where you want 13.8V, you have to use the 15V one and adjust it down, rather than a 12V one which can only go to 13.2V (not really high enough). Also they do need to be mounted to an external heatsink for cooling. If you think 600W might cut it, you could look at something like this: http://www.digikey.com.au/product-detail/en/V375A15C600BL/1102-1362-ND/2851253

EV Source also appear to carry one that'll support high enough voltages (and Ryan is good to deal with), but I haven't used them so can't speak for the quality/reliability: http://www.evsource.com/tls_dcdc.php


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## TEV (Nov 25, 2011)

sabahtom said:


> Any comments on why these have similar amp ratings but MW is half the price? Any suggestions on a good DC-DC also welcome. My pack is 312v nominal and I need about 700w peak, 300w continuous.
> 
> 
> http://www.evolveelectrics.com/DC-DC%20Converters.html
> ...



http://www.diyelectriccar.com/forum...onverter-82902.html?highlight=dc/dc+converter


http://www.diyelectriccar.com/forums/showthread.php/cheapest-dc-dc-converters-650w-100-13924.html

Enjoy your reading


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## sabahtom (Mar 1, 2011)

*Vicor + cooling DMOC*

Thanks TEV. Conclusion is that the IOTA can be unreliable. The PC based one seems to handle DC input max 150v so not good for me.

While testing my DMOC (drive wheels jacked up) the heatsink temp went from 30 to 32 degrees in 10 min. Then the fan came on. I stopped using it, and I waited 10 minutes, still no drop in temp.

So I think the cooling fans will have to run all the time and I may need another cooling fan as well, but I'll see how much the wind helps when I drive first.

I'd like to put the DMOC where it is in the photo, but there is only room for a pair of girly sunglasses before the engine cover. Manual says it needs about 4.5 times the headroom that I have available.

The forced air from the fans on the DMOC comes out of both sides of the heatsink. I'm thinking if I get the Vicor I can put it near the DMOC so it'll get the airflow from the DMOC fans. I can only do this with the Vicor because it is weatherproof. Other DC-DC seem to need a dry spot.

The Vicor has max 40A. If I get rich later I could add another one and have enough amps to power a steering pump like this:

http://www.evsource.com/tls_steering.php


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## TEV (Nov 25, 2011)

*Re: Vicor + cooling DMOC*



sabahtom said:


> Thanks TEV. Conclusion is that the IOTA can be unreliable. The PC based one seems to handle DC input max 150v so not good for me.
> 
> While testing my DMOC (drive wheels jacked up) the heatsink temp went from 30 to 32 degrees in 10 min. Then the fan came on. I stopped using it, and I waited 10 minutes, still no drop in temp.
> 
> ...


Actually you need one of those 
http://www.diyelectriccar.com/forums/showthread.php?t=19505&highlight=toyota+steering

I got it from eBay for ~ $500 it's a very good and intelligent pump , this is a video I made 

http://www.youtube.com/watch?v=UlTxX9Ed2sI


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## TEV (Nov 25, 2011)

Regarding DMOC temperature you should re RT.. and check the specification about temperatures, you may worry for nothing, also I believe it's smart enough to cut back in power output and finely to turn off if the temperature is too high.


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## sabahtom (Mar 1, 2011)

zeva said:


> The Vicors are really nice products. I used some of the 300W Maxi modules on an engineering project earlier this year. Very compact, totally weatherproof, seemed to be robust. Their output voltage is adjustable about +/-10% so in automotive applications where you want 13.8V, you have to use the 15V one and adjust it down, rather than a 12V one which can only go to 13.2V (not really high enough). Also they do need to be mounted to an external heatsink for cooling. If you think 600W might cut it, you could look at something like this: http://www.digikey.com.au/product-detail/en/V375A15C600BL/1102-1362-ND/2851253


Thanks zeva. They've got free shipping on the vicor too. seems to be the best option for me, since I might end up with electric power steering so I would need something tough, and the Vicor can be paralelled.


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## sabahtom (Mar 1, 2011)

*Re: Vicor + cooling DMOC*



TEV said:


> Actually you need one of those
> http://www.diyelectriccar.com/forums/showthread.php?t=19505&highlight=toyota+steering
> 
> I got it from eBay for ~ $500 it's a very good and intelligent pump , this is a video I made


I like that it only uses 40A with the big tyres, probably similar on my van.

EVWorks in Australia have this, new for AUD$525.

http://evworks.com.au/store/datasheets/TRW_2012_Steering_EPHS_eng.pdf

Any idea how much those toyota parts would cost?


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## sabahtom (Mar 1, 2011)

TEV said:


> Regarding DMOC temperature you should re RT.. and check the specification about temperatures, you may worry for nothing, also I believe it's smart enough to cut back in power output and finely to turn off if the temperature is too high.


You're right, it can be set to turn off and when to turn on the fans, max operating temp 60 C. I knew that......but only because I saw the parameter on CCShell


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## sabahtom (Mar 1, 2011)

*Used Vicor Maxi*

http://www.ebay.com/itm/V375A12C600...403?pt=LH_DefaultDomain_0&hash=item1e7666b51b

$133, means I can just get two. Less work for the modules to do, probably last longer? Comes with a 14 day warranty.

Any thoughts?


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## TEV (Nov 25, 2011)

*Re: Used Vicor Maxi*



sabahtom said:


> http://www.ebay.com/itm/V375A12C600...403?pt=LH_DefaultDomain_0&hash=item1e7666b51b
> 
> $133, means I can just get two. Less work for the modules to do, probably last longer? Comes with a 14 day warranty.
> 
> Any thoughts?


I didn't read all this tread but from the first post is obviously that you need modules with 15V output, not the 12V.

http://www.diyelectriccar.com/forums/showthread.php?t=83507&highlight=vicor


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## sabahtom (Mar 1, 2011)

*Re: Used Vicor Maxi*



TEV said:


> I didn't read all this tread but from the first post is obviously that you need modules with 15V output, not the 12V.
> 
> http://www.diyelectriccar.com/forums/showthread.php?t=83507&highlight=vicor


Thanks for noticing the different model number and saving me money TEV. The 15v one is $220 unused so might get that.


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## sabahtom (Mar 1, 2011)

*Vicor DC DC factory version*

Can't find what I need on ebay, so I guess I'll have to take the plunge. Vicor is very helpful and they do customised once-offs via their website, no extra charge. Great for newbies like myself.

Looks like I'll end up with this, for $470 odd before shipping.


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