# A nice DC-DC converter



## jaspersk (Jun 26, 2008)

I have gone through several DC-DC's over the years. I had the old Iota before they converted to a model that doesn't work with DC input. I have used the ones that a lot of the EV parts stores are selling now that is basically a rebranded Meanwell. I found a new one that I recently installed and it seems to be about the same price but a lot better for the task so I wanted to share it here.

I purchased the Meanwell HEP-600C-12.
http://www.meanwell.com/search/HEP-600C/HEP-600C-spec.pdf

It cost $195 before shipping at Sager Power. It works off both AC and DC input. I found it better than the normal offerings for the following reasons:
1. It has no fan. (I hate how loud my old DC-DC and the internal electronics got exposed to any dust in the air).
2. It is built for harsh environments including high vibration according to the spec sheet.
3. It manages my 12V battery better than other DC-DC's. It will ramp up to 14V when there is a load. It will ramp down to float voltage when there is minimal load on the 12V system.

I have no relationship with Meanwell or Sager. Just wanted to share a good experience since I haven't seen this product discussed here before. I think it might be new. I have only had it in my car for a month now so can't confirm it will last longer but it seems like it should. I know my 12V battery is happier and I have more confidence that it won't burn out like my old DC-DC's did.


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## PThompson509 (Jul 9, 2009)

I've also been quite happy with the Meanwell DC-DC boxes. I have the SP-750-15 box in my 914.


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## jaspersk (Jun 26, 2008)

PThompson509 said:


> I've also been quite happy with the Meanwell DC-DC boxes. I have the SP-750-15 box in my 914.


Is that the same one sold at many of the ev parts stores?
http://www.evsource.com/tls_dcdc.php

I had that one and didn't like it. Mine was in the trunk and the fan was really loud. I had the one from EVSource and it was the one that died last month. I opened it up to see if I could figure out what failed. It had quite a bit of dust built up as well. For the same cost, I prefer the fanless design and the improved battery management of HEP.


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## SWF (Nov 23, 2007)

jaspersk said:


> I purchased the Meanwell HEP-600C-12.


I will be needing to purchase a DC-DC converter soon for my project and was wondering if this unit is still working well for you. Also curious if you have installed it with a precharge circuit and inductor on the input.


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## jaspersk (Jun 26, 2008)

SWF said:


> I will be needing to purchase a DC-DC converter soon for my project and was wondering if this unit is still working well for you. Also curious if you have installed it with a precharge circuit and inductor on the input.


Yes. I love it. I stopped replacing my 12V batteries now that I have a DC-DC that works more like a battery charger. It is actually designed for this job. If these are still available, I can't imagine why anyone would recommend anything else for a DC-DC.


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## Moltenmetal (Mar 20, 2014)

If I had to do my project again, I'd skip my SurePower DC/DC, which is reliable but cost a lot of $$$. I'd simply stick with my U1 battery and parallel a separate charger off the AC input to my main pack charger. That way, you're not worried about isolation between your 12V and high voltage systems at all- they're perfectly isolated. You'll also likely save a few bucks, though I guess $195 for a MeanWell is pretty brainless. Have heard of people blowing these up though, so I'm not sure how reliable they are long term.


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## SWF (Nov 23, 2007)

Moltenmetal said:


> If I had to do my project again, I'd skip my SurePower DC/DC, which is reliable but cost a lot of $$$. I'd simply stick with my U1 battery and parallel a separate charger off the AC input to my main pack charger. That way, you're not worried about isolation between your 12V and high voltage systems at all- they're perfectly isolated. You'll also likely save a few bucks, though I guess $195 for a MeanWell is pretty brainless. Have heard of people blowing these up though, so I'm not sure how reliable they are long term.


I agree it would be simpler, but I would have to size the 12V battery to handle all my consumption between charges. I will have two D5 cooling pumps (battery + controller) likely running continuously while driving, potentially 4 LED headlights, vacuum pump for power brakes, fan for heating as needed, plus of course a kick-ass stereo.


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## onegreenev (May 18, 2012)

SWF said:


> I agree it would be simpler, but I would have to size the 12V battery to handle all my consumption between charges. I will have two D5 cooling pumps (battery + controller) likely running continuously while driving, potentially 4 LED headlights, vacuum pump for power brakes, fan for heating as needed, plus of course a kick-ass stereo.


Installing an alternator sounds about right then for your situation. Its about the only other choice you have.


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## Tony Bogs (Apr 12, 2014)

Why not both DC/DC and a 12V battery? Seriously improves overall reliability. 

DC/DC for the high loads. Connect the input(s) behind a DC relay. 
Preferably with a precharge circuit for those low cost DC/DC converters with very high inrush currents. 
Without it, don't be surprised when a very nice shiny DC/DC fails when the warranty has expired.
Otherwise hook one up permanently and hope it really meets the specified MTBF.

The battery can act as a backup system and the DC/DC converters can charge the 12V battery.


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## CivicEV (Aug 1, 2015)

Hi Folks, has anyone modified the DLS-55 (build date April 2015) or later to accept a DC input? I bought one to replace a 2009 model but as they say it cann't work with DC input. It does deliver a 14V output but drops voltage the moment you put load on it. There are minor differences on the board, but it seems to my novice understanding that there wouldn't be much needed to kick this into play.


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