# Cheap dc dc converter



## evmetro (Apr 9, 2012)

I am looking for a dc converter, and would like it to be able to handle up to 30 amps. I see an Iota and a Powermax for under 200 bucks, but was hoping to get some feedback first. If anybody can comment good or bad on these or suggest another for under 200, I would love to hear it. Also if there is a good reason to spend more? I understand the "you get what you pay for" wisdom.


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## frodus (Apr 12, 2008)

Voltage input?
voltage output (13.8V, 12V)?
Sealed?
Isolated?


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## evmetro (Apr 9, 2012)

Ahh, yes... the specifics! This will be for a 144 volt system, isolated. I suppose it would be nice to have it sealed so I don't have to make a shield.


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## evmetro (Apr 9, 2012)

I have been thinking that it would be nice to build some kind of consumer guide for all the EV components. Maybe some kind of poll for each product. The specifics for each one would probably make it really complicated, but for the diy EV industry, we can make more rapid progress if we can see what those who have gone before us have learned.


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## mora (Nov 11, 2009)

I'll throw in one more option. TCCharger (Elcon) 400W DC/DC, see http://www.hztiecheng.com/english/ProList/T16

Isolated, input voltages up to 192V nominal, output 12.5V or 13.8V, trickle charge for lead, fully sealed, passive cooling.

They were something like 110$ + shipping when I asked about prices last year. If you'd buy 20 its something like half of that. 1kW model was 380$.

The bad thing is one single unit doesn't accept 48-192V input.


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## favguy (May 2, 2008)

Then there is the Chennic 144v 480w converter:

http://www.ebay.co.uk/itm/110782179512?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

I've heard these are pretty good for a cheapie.

Also, don't forget with any of the cheaper DC/DC's the advice is to use an inductor on the input, especially if you're using a soliton controller to protect against ripple


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## favguy (May 2, 2008)

Had a look at the elcon specs. The soft start option switched via the ignition looks like a nice feature and should negate the need for a high voltage DC relay.


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## evmetro (Apr 9, 2012)

Mora and Favguy, thanks for the replies. I will look into these as well.


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## EVfun (Mar 14, 2010)

I've been using the Kelly Controls HWZ DC to DC converter for my 120 volt EV. They have a 144 volt model too. http://kellycontroller.com/hwz-series-dcdc-converter-144v-to-135v-25a-p-186.html


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## corbin (Apr 6, 2010)

evmetro said:


> I am looking for a dc converter, and would like it to be able to handle up to 30 amps. I see an Iota and a Powermax for under 200 bucks, but was hoping to get some feedback first. If anybody can comment good or bad on these or suggest another for under 200, I would love to hear it. Also if there is a good reason to spend more? I understand the "you get what you pay for" wisdom.


I had the IOTA fail twice on me. I upgraded to the Belktronix and it has been solid. It is around $300. I recommend that one, and don't buy a cheap one.

corbin


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## dtbaker (Jan 5, 2008)

favguy said:


> Then there is the Chennic 144v 480w converter:
> 
> http://www.ebay.co.uk/itm/110782179512?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
> 
> ...



I have had BAD luck with Chennic.... two died both within 12 months. Using a ACME now.... no problems so far or $200-ish 500watt+ output, but open chassis design, not sealed.


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## TEV (Nov 25, 2011)

evmetro said:


> I am looking for a dc converter, and would like it to be able to handle up to 30 amps. I see an Iota and a Powermax for under 200 bucks, but was hoping to get some feedback first. If anybody can comment good or bad on these or suggest another for under 200, I would love to hear it. Also if there is a good reason to spend more? I understand the "you get what you pay for" wisdom.


Enjoy your next project 

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


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## Joey (Oct 12, 2007)

dtbaker said:


> I have had BAD luck with Chennic.... two died both within 12 months. Using a ACME now.... no problems so far or $200-ish 500watt+ output, but open chassis design, not sealed.


Dan, is your DC-DC still working? I picked up an ACME from evolve and it died after 24 hours. The output just keeps cycling on and off every 3 seconds. I think thermal protection is kicking in, but the unit is not hot. I'm working on getting a replacement unit.


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## EVfun (Mar 14, 2010)

I've had good luck with HWZ series DC to DC converters from Kelly Controller. 

One thing that can cause problems for some DC to DC converters is letting the input voltage go below the listed minimum when accelerating. The Kelly DC to DC converters come in a range of input voltage ratings so I pick one where that won't happen. I don't know if the Kelly would be prone to failure in an under voltage condition. I know the old Todd converters where notorious for this failure mode.


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## dtbaker (Jan 5, 2008)

Joey said:


> Dan, is your DC-DC still working? I picked up an ACME from evolve and it died after 24 hours. The output just keeps cycling on and off every 3 seconds. I think thermal protection is kicking in, but the unit is not hot. I'm working on getting a replacement unit.



I have ACME in both cars now.... no problems.

what voltage input are you running?

what controller do you have? you may need an inductor to protect charger + dc-dc?


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## Joey (Oct 12, 2007)

dtbaker said:


> I have ACME in both cars now.... no problems.
> 
> what voltage input are you running?
> 
> what controller do you have? you may need an inductor to protect charger + dc-dc?


The spec input range on the DC-DC is huge: 110 to 370 V. My pack is 192 nominal and would absolutely be between 150 and 216. This converter in the 24 hours it worked only saw 184 to 204 volts (I've logged all my driving time so far). And when the green light is on it is outputting the correct voltage. Every 2 seconds I hear a relay click and the unit cycles on and off, which is why I think there is an issue with the internal thermal cutoff.

I'm running the Soliton1 and I have the inductor (recommended by EVnetics) and the fuse (recommended by Evolve) on the DC-DC input. I'm also protected from all moisture.


Sounds like I just have a faulty unit, and all I need is a replacement. Waiting to hear back from their service group at evolve. Good to know they are still working well for you.


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## ElectriCar (Jun 15, 2008)

I ran a 144V lead pack for 9000 miles and now run a 169V lithium pack with 11000 miles on it. SO that's 20,000 miles on my Iota DLS-55. It's rated at 55A but it will sag pretty bad under a good load. Just put an air core coil of about 12uh in line with the power leads for insurance. Only one lead needs a coil. I made one on a 1.25" dia PVC pipe and rolled about 20 turns or so of 14 ga wire. That supposedly keeps controller spikes out of it.

I don't know about the ACME Dan runs but I wouldn't want one that wasn't enclosed some what because I'd drop a wrench or screw in it and blow it up!


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## dtbaker (Jan 5, 2008)

ElectriCar said:


> I don't know about the ACME Dan runs but I wouldn't want one that wasn't enclosed some what because I'd drop a wrench or screw in it and blow it up!


The ACME does have an enclosure... its vented and has an internal fan versus the Curtis and Belktronix that are sealed and just have fins for cooling. dropping screwdrivers is ok, powerwash with hose probably not.


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