# [EVDL] DC to DC converter...



## EVDL List (Jul 27, 2007)

Hello John,

The 25 amp rating is only going to be able to run just the contactors and 
controller circuit.

I end up using four 45 amp Iota DC-DC converters which are really only power 
supplies. These converters are really power supplies that either have a 
output of 13.5 or 14.5 volts.

Each contactor takes 5 amps, the controller is 4 amps, cooling fans is 
another 8 amps, heater fans is 6 amps plus all the instruments panels, 
lighting and etc.

Its either a minimum average of 50 amps or run a 13.5 to 15 V alternator 
which I do now to keep a 12 volt deep cycle battery charge up to 14.8 volts. 
I now only use the converters to run separate isolated devices.

You can get a 55 amp DC-DC converter from evsource.com for the same cost of 
the item you are showing.

Roland


----- Original Message ----- 
From: "John Nln" <[email protected]>
To: <[email protected]>
Sent: Sunday, December 28, 2008 6:37 PM
Subject: [EVDL] DC to DC converter...


>
> I have 12 12 volt (144 volts) AGM batteries (C&D Technologies UPS12-475FR) 
> and a 12 volt AGM auxiliary battery (C&D Technologies UPS12-370FR).
> I am thinking of buying this DC to DC converter for $189:
>
> http://www.cloudelectric.com/inc/sdetail/5005
>
> Any advice or better option?
>
> Thanks,
> John
>
>
>
>
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> 

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## EVDL List (Jul 27, 2007)

John, most of us don't have Roland's auxiliary loads and only run one converter. You could probably get by with a 25 amp unit but it would be more stressed than a larger unit. The DC loads on my 120 volt conversion typically draw from .5 A to 2 A at pack voltage, depending on conditions but can go higher when running the heater blower, etc. I use a 45 A DC-DC.




________________________________
From: John Nln <[email protected]>
To: [email protected]
Sent: Sunday, December 28, 2008 9:37:17 PM
Subject: [EVDL] DC to DC converter...


I have 12 12 volt (144 volts) AGM batteries (C&D Technologies UPS12-475FR) and a 12 volt AGM auxiliary battery (C&D Technologies UPS12-370FR).
I am thinking of buying this DC to DC converter for $189:

http://www.cloudelectric.com/inc/sdetail/5005

Any advice or better option?

Thanks,
John




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## EVDL List (Jul 27, 2007)

Right now I'm driving with no DC-DC, just a 12v SLI battery, and it's
working fine. I can drive my 15 mile round trip with no issues, but I think
I'm on the edge. If I had to use all my electric loads, I'm not sure what
would happen. So my next step is a low wattage Vicor power supply that I
picked up for a very reasonable price. Vicor is a good brand and should be a
robust unit. I don't know how it will like the automtive environment yet.
This is an incremental improvement, but probably not the final solution. I'm
one of those "price sensitive" EV owners, but I listen to the list and do
the best I can. I'm working my way to a solid solution, but I'm not there
yet.

A good battery will buffer a low wattage DC-DC, but there's no replacement
for a bigger supply. And don't forget to cool it. If your DC-DC is working
hard, keep it cool or you'll let the smoke out.

Dave Cover, 944 EV in CT



> Frank John <[email protected]> wrote:
> 
> > John, most of us don't have Roland's auxiliary loads and only run one
> > converter. You could probably get by with a 25 amp unit but it would be
> ...


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## EVDL List (Jul 27, 2007)

> dave cover wrote:
> > Right now I'm driving with no DC-DC, just a 12v SLI battery, and it's
> > working fine.
> 
> ...


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## EVDL List (Jul 27, 2007)

Last try to post here - registered and logged in...

I posted: 03 Sept: "Question on DC to DC converter..." but was not
properly registered.

I have the car: http://www.evalbum.com/2589

I have a DC to DC converter - 120 volt to 12 volt (13.5)
Two questions:
1) Suppose the 120 volt end is hooked up, but the 12 volt end has no load. 
If one puts a voltmeter across the terminals, will there be a voltage, or
does the electronics zero out if no load? I know this is how a charger
works, just wondered if DC to DC converters have the same type of "shut off"
electronics.
2) Can anyone give a recommendation as to a new DC to DC converter? Note,
my car is NOT high end and am looking for a reliable, but reasonable priced
component.

Thanks,
John



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## EVDL List (Jul 27, 2007)

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> 
> It's your cheap option at $ 105, but it has a few downsides and I 
> would recommend paying an extra $30 for the 2nd option I outline
> below...
> 
> 
> If my DC/DC ever dies, I think I would pay a few extra bucks to 
> replace it with this guy, which has an input range of 88-265 volts
> for $135 
> https://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10001&langId=-1&catalogId=10001&pa=374222&productId=374222
>
> 
> 

BTW- Note that this is a 15 volt supply, not a 12 volt supply.
However, the Meanwel supplies have a "trim knob" that you can turn to
reduce the voltage to 13.5 volts, which is about right for float
charging a 12 volt battery, or 14 volts to pretend to be an alternator
that only runs when the auto is being driven.

On my 12 volt supply I turn the knob up, on a 15 volt supply you'd
turn it down.

Jay
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## EVDL List (Jul 27, 2007)

> John K wrote:
> 
> > 2) Can anyone give a recommendation as to a new DC to DC converter? Note,
> > my car is NOT high end and am looking for a reliable, but reasonable priced
> ...


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## EVDL List (Jul 27, 2007)

Another option is the Elcon DC-DC converter line. I have one in my del Sol
conversion. It was about $250 and puts out 30A which is enough for my
small car. It looks like they are about $300 now. They come in various
voltage ranges, but cover a wide range. Mine for example, covers 132 -
168VDC as the input voltage. They have a regulated output which puts out
around 14.5V for the first 1/2 hour then drop back to a float voltage.

They are also sealed units with no ventilation holes for water to enter. 

They claim they have an inrush limiter internally, but I still put one on
the inputs myself, just in case. I see that claim on the new ones, but I'm
not sure I recall seeing that in the literature when I bought mine.

I've had mine for two years with no problems. I only run it when the key is
on and there is an auxiliary 12V battery.

Units like the one on this page:

http://www.evamerica.com/evsafety.html

Mike

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of Willie McKemie
> Sent: Saturday, September 15, 2012 11:32 AM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] DC to DC converter...
> 
>


> John K wrote:
> >
> > > 2) Can anyone give a recommendation as to a new DC to DC converter?
> > > Note, my car is NOT high end and am looking for a reliable, but
> ...


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## EVDL List (Jul 27, 2007)

I forgot to mention, there is no 12 volt auxiliary battery. I run the 12
volt items directly from the converter.

John




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## EVDL List (Jul 27, 2007)

That makes things harder for two reasons. First, the DC-DC has to be
running all the time so you have 12V to turn on the car. That means you
need to find one that can be on continuously. It may not last as long that
way. Second, it needs to be sized larger so it can supply your maximum
burst needs without dimming headlights. When a battery is present, it can
help handle the short-term burst needs.

My Elcon might not be big enough without a battery.

Personally, I would add the battery and switch the converter on with the
key. It can and has been done the other way, though.

Mike

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of John K
> Sent: Saturday, September 15, 2012 11:55 PM
> To: [email protected]
> Subject: Re: [EVDL] DC to DC converter...
> 
> 
> I forgot to mention, there is no 12 volt auxiliary battery. I run the 12
volt
> items directly from the converter.
> 
> John
> 
> 
> 
> 
> --
> View this message in context: http://electric-vehicle-discussion-
> list.413529.n4.nabble.com/DC-to-DC-converter-tp4657972p4657994.html
> Sent from the Electric Vehicle Discussion List mailing list archive at
> Nabble.com.
> 
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
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## EVDL List (Jul 27, 2007)

Hi Jay,

The PDF shows a minimum DC input of 124V (max 370V) which is too low for a 120V pack but would probably work well with 144V. Otherwise it does look very good value and a nice robust looking/sounding design.

MW




> Jay Summet wrote:
> 
> > -
> >
> ...


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## EVDL List (Jul 27, 2007)

I agree - my DC/DC-cum-charger worked without issues with a stable output until I removed it following the accident that wrote off my van last year. It'll be going into my next EV.

MW




> Willie McKemie wrote:
> 
> > On Fri, Sep 14, 2012 at 04:41:49PM -0700, John K wrote:
> >
> ...


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## EVDL List (Jul 27, 2007)

I agree, Mike. Having the aux 12V battery makes the whole thing much more flexible in my view. Also, don't forget, John, that you only need a relatively small aux battery - a motorcycle one would do. Much smaller and cheaper than one designed for a car.

MW




> Mike Nickerson wrote:
> 
> > That makes things harder for two reasons. First, the DC-DC has to be
> > running all the time so you have 12V to turn on the car. That means you
> ...


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## EVDL List (Jul 27, 2007)

> John K <[email protected]> wrote:
> 
> >
> > I forgot to mention, there is no 12 volt auxiliary battery. I run the 12
> ...


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## EVDL List (Jul 27, 2007)

While a redundant system is certainly possible and for a hobbyist
doing his own conversion, it is not a problem to spend the extra time
and effort and money to make a redundant system , it should not be
required if the DC/DC has normal reliability.
Think about it - no other part of your vehicle is redundant.
If a battery fails, you stop. If the controller fails or the motor
or a wheel or any part of the drivetrain - you stop.
Why would the DC/DC suddenly be unique that you need a redundant system?
Granted, the problems due to failure rate on alternators is somewhat 
helped by the fact that you can drive some distance without the
alternator working, but it is not a true redundant system either.

BTW, in my EV a different choice was made - I have 20 golf cart
batteries as pack and two "spare" batteries as aux.
That gives a huge capacity aux battery and the result is that
I only need to charge it occasionally (I am planning to use a
14V 5A current limited power supply that will charge the aux
whenever the pack charger is plugged in).
My dash still has the original battery meter, so I have a
feedback as to how the aux battery is doing.

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water Tel: +1 408 383 7626


-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Chris Tromley
Sent: Sunday, September 16, 2012 7:33 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] DC to DC converter...



> John K <[email protected]> wrote:
> 
> >
> > I forgot to mention, there is no 12 volt auxiliary battery. I run the
> ...


----------



## EVDL List (Jul 27, 2007)

> On 16 Sep 2012 at 23:52, Cor van de Water wrote:
> 
> > Why would the DC/DC suddenly be unique that you need a redundant system?
> 
> ...


----------



## EVDL List (Jul 27, 2007)

Hi Cor,

With respect, I think Chris has a valid point that stems from the average DC/DC converters poor record of reliability - DIY EV'ers ones at least. Generally, ICEV engines and drivetrains, batteries etc are very reliable and in failure mode are relatively benign. As Chris says, if your headlights fail halfway through a junction or doing 60mph on an unlit road in the dead of night, it could a different matter entirely (I know - it happened to me once in my Triumph Spitfire crossing Dartmoor at 2am back in the '80s!).

The alternative you suggest for doing away with the DC/DC converter altogether ie a large aux battery is a perfectly sound one tho I think as most people are drifting away from lead-acid packs in preference of Li(?), there is a natural reluctance to cling on to lead for the 12V supply. For those who want to stick with lead tho, having an extra lump in the the form of an aux battery would be fine. Personally, I'd wire it up so that whenever the EV was plugged into the mains that the aux got charged as well via a dedicated charger.

I still think that if you want to do things properly a good DC/DC converter with a relatively small lead acid battery is the best mix of practicality, reliability and cost - tho I could have my arm twisted to agree to forgo the DC/DC converter for the donor's alternator.

Regards, Martin Winlow
Herts, UK
http://www.evalbum.com/2092
www.winlow.co.uk




> Cor van de Water wrote:
> 
> > While a redundant system is certainly possible and for a hobbyist
> > doing his own conversion, it is not a problem to spend the extra time
> ...


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## EVDL List (Jul 27, 2007)

Even pricier @ $500, but my Zivan NG1 DC/DC has been working reliably for 3=
.5 years.
Purchased it from KTA.

Thanks;
Dennis=
=

Elsberry, MO=
=

http://www.evalbum.com/1366
http://www.evalbum.com/3715=
=
=




-----Original Message-----
From: Willie McKemie [mailto:[email protected]] =

Sent: Saturday, September 15, 2012 12:32 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] DC to DC converter...



> John K wrote:
> 
> > 2) Can anyone give a recommendation as to a new DC to DC converter? Note,
> > my car is NOT high end and am looking for a reliable, but reasonable pric=
> ...


----------



## EVDL List (Jul 27, 2007)

Hi John,
Here's my take on DC-DC converters:

http://www.corbinstreehouse.com/blog/2011/04/plug-bug-dc-dc-converters/

I compared them and eventually went with the Belktronixs one. It has been working great for ~17k miles.

corbin



> John K <[email protected]> wrote:
> 
> > Last try to post here - registered and logged in...
> >
> ...


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## EVDL List (Jul 27, 2007)

> Why would the DC/DC suddenly be unique that you need a redundant system?

Well, normal cars *do* have redundant 12v systems. The alternator, and 
the battery. As long as at least one of them works, you have 12v power.

Many hobby EVs also skimp on the quality of their DC/DC converter. 
Instead of something actually built for automotive use, they often use 
some cheap AC power supply that's intended for indoor use in a dry, 
clean, temperature-controlled environment. When used in a car, they 
often have a high failure rate.

Thus, I think having two redundant DC/DC converters is a good idea.

-- 
If we knew what we were doing, it wouldn't be called research, would it?
-- Albert Einstein
--
Lee A. Hart http://www.sunrise-ev.com/LeesEVs [email protected]

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## EVDL List (Jul 27, 2007)

You know, the Leaf has a separate 12v battery. I always wondered why they
did that - the official answer is "to power the auxiliary devices" - which
didn't really answer anything. But, thanks to the contributors of this
thread, I think the question is answered.

Peri

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Martin WINLOW
Sent: 17 September, 2012 1:56 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] DC to DC converter...

Hi Cor,

With respect, I think Chris has a valid point that stems from the average
DC/DC converters poor record of reliability - DIY EV'ers ones at least.
Generally, ICEV engines and drivetrains, batteries etc are very reliable and
in failure mode are relatively benign. As Chris says, if your headlights
fail halfway through a junction or doing 60mph on an unlit road in the dead
of night, it could a different matter entirely (I know - it happened to me
once in my Triumph Spitfire crossing Dartmoor at 2am back in the '80s!).

The alternative you suggest for doing away with the DC/DC converter
altogether ie a large aux battery is a perfectly sound one tho I think as
most people are drifting away from lead-acid packs in preference of Li(?),
there is a natural reluctance to cling on to lead for the 12V supply. For
those who want to stick with lead tho, having an extra lump in the the form
of an aux battery would be fine. Personally, I'd wire it up so that
whenever the EV was plugged into the mains that the aux got charged as well
via a dedicated charger.

I still think that if you want to do things properly a good DC/DC converter
with a relatively small lead acid battery is the best mix of practicality,
reliability and cost - tho I could have my arm twisted to agree to forgo the
DC/DC converter for the donor's alternator.

Regards, Martin Winlow
Herts, UK
http://www.evalbum.com/2092
www.winlow.co.uk




> Cor van de Water wrote:
> 
> > While a redundant system is certainly possible and for a hobbyist
> > doing his own conversion, it is not a problem to spend the extra time
> ...


----------

