# dc-dc converter



## Tesseract (Sep 27, 2008)

That would be V_I_, not V1... and did you not even try Vicor's website?

http://www.vicr.com/cms/home/technical_resources/Data_Sheets

The -09 (-O9?) suffix doesn't seem to be current, but VI-251 means it has a 150VDC nominal input and a 12VDC output. Note that part number VI-25_P_ has a 13.8VDC output and therefore would be much better suited for use in an EV. All the VI converters have a provision for trimming the output voltage over a narrow range (+/- 10%) so you could get up to 13.2V on your 12V model but that still isn't enough to keep the 12V battery charged. I personally think relying on just a DC-DC converter for the 12V system in a vehicle is way too risky - at least use a small garden tractor battery so if/when the dc-dc finally blows up from the abuse you aren't stranded.


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## GerhardRP (Nov 17, 2009)

jehan12413 said:


> I just found some dc-dc converters on ebay, I'm looking at a Vicor V1-251-09 200v to 12v model and am wondering if anyone is familiar with this one. I sent a request to the seller for the datasheet but while I'm waiting I figured I would post it here .


Looks like an old numbering scheme...
http://cdn.vicorpower.com/documents/datasheets/ds_vi-200.pdf

Gerhard


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## jehan12413 (Feb 4, 2010)

Thanks for the link that's exactly what I needed. My main question was weather the output is isolated and I see it is. As far as the battery the one I'm using is the standard size for my vehicle (a honda) so the converter is just to keep it topped off.


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## dtbaker (Jan 5, 2008)

jehan12413 said:


> I just found some dc-dc converters on ebay, I'm looking at a Vicor V1-251-09 200v to 12v model and am wondering if anyone is familiar with this one. I sent a request to the seller for the datasheet but while I'm waiting I figured I would post it here .


least expensive ones I can fnd at the moment that look up to the job re the ones from chennic.com . The Vicors are reported to not last well. I have been happy with my Curtis, but it was 3x the cost of the chennic. i have ordered from chennic to try when I upgrade my pack from 96v to 120v.


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## dtbaker (Jan 5, 2008)

chennics arrived today.... box was pretty beat up, and fuse holder/fuse was broken on both units. looks like the box was really tossed around, but the units and heat sinks look ok. I won't be able to install the first one for another couple weeks as my new batteries have not arrived...


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## jehan12413 (Feb 4, 2010)

I ordered a vicor to try out but if you have a web adress I'll look into a chennic also. Thanks


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## dtbaker (Jan 5, 2008)

jehan12413 said:


> I ordered a vicor to try out but if you have a web adress I'll look into a chennic also. Thanks


chennic.com
they don't have prices published online, but it comes out to right around $99 shipped to US for the 500watt units.


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## JimDanielson (Oct 19, 2008)

I bought this vicor and am very unhappy. I ended up needing two so that the vacuum, lights, contactor, and potentially blower or windshield wipers could all be powered.

Since it only gives out 12 volts it does a fail job of charging the accessory battery. I need the accessory battery to turn on the contactor. I often use an extra charger to charge the accessory battery just because I don't trust the vicors will give me the required power.

I recommend against buying this, buy something that outputs 13.8 volts.

Jim


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## dtbaker (Jan 5, 2008)

my old curtis is only 300 watts, but is enough for everything including fan... 

In prep for my pack upgrade from 96v to 120v I did step up to 500 watt chennic, so should be more than enough. I got the 13.5v output in case I ever charge a 12v battery, but for now I just go direct with no aux battery. I ordered one voltage step down from my 'nominal' to avoid low end brownout when batteries are at full load/sag...


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## frodus (Apr 12, 2008)

jimbo12d said:


> I bought this vicor and am very unhappy. I ended up needing two so that the vacuum, lights, contactor, and potentially blower or windshield wipers could all be powered.
> 
> Since it only gives out 12 volts it does a fail job of charging the accessory battery. I need the accessory battery to turn on the contactor. I often use an extra charger to charge the accessory battery just because I don't trust the vicors will give me the required power.
> 
> ...


its only ~250W, of course you'd need two for a car.... at 12V, thats 20A, I'd use at least that on my motorcycle. I think a MINIMUM for a car/truck is 3-400W.

Did you trim it up with resistors to get 13.2V?


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## TomA (Mar 26, 2009)

jehan12413 said:


> I just found some dc-dc converters on ebay, I'm looking at a Vicor V1-251-09 200v to 12v model and am wondering if anyone is familiar with this one. I sent a request to the seller for the datasheet but while I'm waiting I figured I would post it here .


I have these exact Vicor DC-DC units, and I got them on ebay from Troy Gaud at Azure Dynamics. He does not have a data sheet for them; he will send you the generic VI 200-Series Vicor data sheet, which does not in fact have this part number listed anywhere on it. 

The -09 suffix signifies that these converters were a from a custom run by Vicor for Solectria/Azure made around 2007. They vary a little in spec from a standard VI-251-xx converter, as they are listed at 200V nominal input voltage, and the part# call-out would normally be 150V. Vicor will not discuss the specs of these units with anyone not from Azure, (ask me how I know...) but Troy told me that according to the Azure engineers, they are good down to about 130V, and up to a little over 250V input. They are also in fact "IU" suffix-class, which means -40 to 85 degrees C operating range, and 200W max output. I also have the -09 series matching Booster units, which allow you to run several booster bricks off of one 200 Series control unit. I haven't installed them yet, but I'll be using 4 or 5 boosters and a control unit, for either 75 or 90 amps of max current at 13.2V. Just what a late-model car needs.

These DC-DC converters can be trimmed up to 13.2V output by installing a trim resistor. If you only have 200-Series units, and no boosters, you can match them in trim and still use them together, as Jack Rickard has documented. His implementation, complete with a schematic and some thoughtful instruction, is here:

http://jackrickard.blogspot.com/2009/10/this-week-on-mini-cooper.html

Don't use Jack's resistor values on the VI-251-09! The correct one is 422K, from Section 5 of the Vicor Manual. You could also put in a pot and trim the output manually. In any case, it is instructive to just RTFM:

http://cdn.vicorpower.com/documents/applications_manual/DesignGuideAppsManual_200J00.pdf

I actually think this unit and the matching booster are superb quality equipment, particularly for the price, and the ones I got from Troy were brand new. They are in fact the very units you will find if you open up the Azure Dynamics DC-DC converter, and at $50 versus the hundreds they cost new, you really can't go very wrong. My understanding is Azure has "hundreds" of them to sell...

TomA

Not a shill for Vicor or Azure Dynamics, though both have been nice to me on the telephone...


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## Dave Koller (Nov 15, 2008)

dtbaker said:


> chennics arrived today.... box was pretty beat up, and fuse holder/fuse was broken on both units. looks like the box was really tossed around, but the units and heat sinks look ok. I won't be able to install the first one for another couple weeks as my new batteries have not arrived...


So Dan, do you think they test them with a baseball bat before shipping . That is three for three shipped lol ...
Let me know before I get mine "field tested" with a bat.......


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## JRP3 (Mar 7, 2008)

Let them know the packing is inadequate. I told Sharon the same thing, maybe they'll get the message if they get enough complaints.


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## JimDanielson (Oct 19, 2008)

TomA said:


> These DC-DC converters can be trimmed up to 13.2V output by installing a trim resistor. If you only have 200-Series units, and no boosters, you can match them in trim and still use them together, as Jack Rickard has documented. His implementation, complete with a schematic and some thoughtful instruction, is here:
> 
> http://jackrickard.blogspot.com/2009/10/this-week-on-mini-cooper.html
> 
> ...


Wow, thanks! I never knew that. I will be trying this first thing when I get home from school for the summer.


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## jehan12413 (Feb 4, 2010)

So if I'm only using one vicor what do I do with the two gate connections?


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## frodus (Apr 12, 2008)

read the application manual....

http://cdn.vicorpower.com/documents/applications_manual/DesignGuideAppsManual_200J00.pdf

Gate IN is for disabling/enabling the DC-DC. Gate out is for driving Booster modules.


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## Woodsmith (Jun 5, 2008)

Can I pose some questions here also?

I am going to get converters for both my compact tractor and my MR2. 

For the MR2 I will wait until I know what voltage I am going to run at and then get an isolated 500W+ 13.8V converter. I figure that is the sort of thing I will need to run a car.

But for the tractor. I only have 48V. Can I use a golf buggy type non isolated 120W 12V converter?
I dont know if the 12V vs 13.8V and isolated vs non isolated will be an issue.
I am planning on running some lights and the reversing contactors.

Guidance will be much appreciated.
Thank you.


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## JRP3 (Mar 7, 2008)

How about just running a small 12 volt battery, charged separately when you charge your pack?


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## dtbaker (Jan 5, 2008)

there are lots of choices for 48->12v... most of the ev wholesalers also cover the golf cart world...


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## dtbaker (Jan 5, 2008)

JRP3 said:


> How about just running a small 12 volt battery, charged separately when you charge your pack?


dc-dc converter is smaller, lighter, and *never* has to be replaced....


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## brainzel (Jun 15, 2009)

As an alternative to the Vicor: Densei-Lambda (TDK-Lambda?)
Theses DC-converters (I got four of them) have although a great input range and a adjustable output.









300W (25A) per unit will be more than enough, so I can perhaps leave one out of the car.
Nice feature: If I wire them parallel, they will (hopefully) share the load.
I hope that this will hold the temperature down.
Everything theoretical, not tested yet.

TDK-Lambda:
http://us.tdk-lambda.com/lp/products/ph-series-ff.htm

documents:
http://us.tdk-lambda.com/lp/ftp/Specs/ph-ff.pdf
http://www.ic-on-line.cn/IOL/datasheet/ph300f280-_278821.pdf


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## Woodsmith (Jun 5, 2008)

JRP3 said:


> How about just running a small 12 volt battery, charged separately when you charge your pack?


On the tractor I'm already planning on charging each of the pack batteries individually with one 12V charger, it would just add to the charge time.
For summer use/play it isn't a problem but later on in the year I want to have lights on in the evening and I have worked out that I will need a larger battery then I want to give space for. I will have a small battery but want the converter to charge it from the pack.

Mainly I wanted to use one just to see what they are like to use before I get a bigger more costly one for the car.

So I have figured out that most automotive stuff expects 13.8V and that 12V may cause a slightly low voltage to be seen and can't charge a battery.

What effect does isolation and no isolation cause?


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## ElectriCar (Jun 15, 2008)

Wow just learned about these things. I'm planning to convert mine from an Iota before it craps out.


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## spdas (Nov 28, 2009)

I found some [email protected] vicor units for 20.00 each, so for the halibut I will put 2 in parrallel to make 200W as I rarely use headlights, only electric steering. Good experiment for $40.00

francis


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## ElectriCar (Jun 15, 2008)

Francis I don't think you're supposed to parallel these things like you do with batteries, if they're Vicor models anyway. They make a master and a slave unit for added watts. Just an FYI.


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## StanSimmons (Sep 3, 2011)

You can parallel the standard models, but putting a standard with a booster is more efficient.


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## spdas (Nov 28, 2009)

Delete

francis


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## spdas (Nov 28, 2009)

It will be a good test of these vicors. If no worky, then I will use one on my trike that SOMEDAY I will finish. 
BTW. If you have an Iota 55 (1000watt unit) and using 100 watts, will it use more or less overall watts compared to a Vicor 100 watt unit putting out 100 watts?

Theory to me is that a car with a big V-8 motor will use more gas than a moped, both traveling at 30mph.

francis


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## cruisin (Jun 3, 2009)

ElectriCar said:


> Francis I don't think you're supposed to parallel these things like you do with batteries, if they're Vicor models anyway. They make a master and a slave unit for added watts. Just an FYI.


Nice thing about putting them in parallel is doubling the ah and being able to increase voltage to about 14.5v which is what we should all be using. Is very simple, been doing it sice 2002 on Li-ion conversions as only 12v-15v source without any batteries for system source..


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## StanSimmons (Sep 3, 2011)

cruisin said:


> Nice thing about putting them in parallel is doubling the ah and being able to increase voltage to about 14.5v which is what we should all be using. Is very simple, been doing it sice 2002 on Li-ion conversions as only 12v-15v source without any batteries for system source..


Are you taking the 12v up to 14.5v? What value trim resistor are you using and have you seen any odd noise in the output?


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## favguy (May 2, 2008)

I've been following this thread with interest as I've been thinking about DC/DC converter options lately. I'd like an opinion on the following as an option.

Laptop computer power supplies are readily available that use a universal input of 100V to 240V AC @ 50 to 60Hz. With an output of 15V @ 8A. These can be bought for as little as £6, (around $9) each. I know that they will also work with a DC input of 144V/156V nominal. Obviously 8A is inadequate for a DC/DC coverter, but would it be feasible to run 3 or 4 in parallel to give a suitable power output?, and if so would they need a diode on each units output to avoid upsetting one another? 15V should be within tolerence for the 12V system if used with no battery (as it would see 14.4V with an ICE alternator anyway). If used with a small lead acid battery, would the battery cope with the slightly higher charge/float voltage of 15V? or possibly the supplies output could be trimmed down to 13.8V/14.4V by finding and changing out the right resistor?

Has anyone tried this yet and had any joy?


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## ElectriCar (Jun 15, 2008)

favguy said:


> I've been following this thread with interest as I've been thinking about DC/DC converter options lately. I'd like an opinion on the following as an option.
> 
> Laptop computer power supplies are readily available that use a universal input of 100V to 240V AC @ 50 to 60Hz. With an output of 15V @ 8A. These can be bought for as little as £6, (around $9) each. I know that they will also work with a DC input of 144V/156V nominal. Obviously 8A is inadequate for a DC/DC coverter, but would it be feasible to run 3 or 4 in parallel to give a suitable power output?, and if so would they need a diode on each units output to avoid upsetting one another? 15V should be within tolerence for the 12V system if used with no battery (as it would see 14.4V with an ICE alternator anyway). If used with a small lead acid battery, would the battery cope with the slightly higher charge/float voltage of 15V? or possibly the supplies output could be trimmed down to 13.8V/14.4V by finding and changing out the right resistor?
> 
> Has anyone tried this yet and had any joy?


With the way electronics are designed, connecting a device designed to work on AC input like the Iota and computer PS will likely not hold up at it's rated output amps because you're only using half of the rectifier diodes thus only 50% of the design power. Using only half will likely burn out in this application due to a doubling of it's design amps if you try and draw full capacity from it.


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## cruisin (Jun 3, 2009)

ElectriCar said:


> With the way electronics are designed, connecting a device designed to work on AC input like the Iota and computer PS will likely not hold up at it's rated output amps because you're only using half of the rectifier diodes thus only 50% of the design power. Using only half will likely burn out in this application due to a doubling of it's design amps if you try and draw full capacity from it.


Are they 100% isolated? Its all about money. Save a nickel and maybe loose your $9K pack.


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## ElectriCar (Jun 15, 2008)

cruisin said:


> Are they 100% isolated? Its all about money. Save a nickel and maybe loose your $9K pack.


You know it does appear that most of your posts are "all about money", that is steering it your way. What would be your professional suggestion?


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## favguy (May 2, 2008)

Thanks for the input so far guys, 

But... Electricar, although I appreciate your input, your understanding of bridge rectifiers appears to be flawed, during an AC cycle, power is first chanelled through 2 diodes of the bridge, then during the second half of the cycle the other two diodes. When applying DC, dependent on which way the polarity is, one set of 2 diodes or the other is solely used, power input is not halved. Also, as the supply voltage can be anything from 100V to 240V on this type of unit the DC battery voltage (at least at 144V/156V) is well within the design range the unit can cope with and is expecting from rectified from AC, DC input voltage. 

My concern isn't input, it's more about output and using these in parallel to achieve a suitable stable current supply, the point made about isolation is a good one. I will test my existing laptop supply for this, but as they can be used with up to 240V AC input, I'll be amazed if the output is not isolated.

As for saving a buck... I partly agree on this one, but controllers aside, a lot of "bespoke" EV components are often very overpriced due to the low volume demand, and are often only slightly rehashed from existing non EV equipment available for a fraction of the price due to economies of scale!


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## ElectriCar (Jun 15, 2008)

favguy said:


> Thanks for the input so far guys,
> 
> But... Electricar, although I appreciate your input, your understanding of bridge rectifiers appears to be flawed, during an AC cycle, power is first chanelled through 2 diodes of the bridge, then during the second half of the cycle the other two diodes. When applying DC, dependent on which way the polarity is, one set of 2 diodes or the other is solely used, power input is not halved...


I just realized the error of my thoughts on that.  You're right each set does take the full current through them. Rectifying power through one set continuously however doubles the average amps through them and really boosts the heat build up which is likely a contributor to the early failures. What was I thinking initially. Electronics class was way back in the early Reagan days...


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## cruisin (Jun 3, 2009)

ElectriCar said:


> You know it does appear that most of your posts are "all about money", that is steering it your way. What would be your professional suggestion?


My suggestion all along for a couple of years on this forum regarding DC converters is to use the 1/2 or whole brick Vicor or other brands. Not to use AC laptop 15v chargers which somebody just thought would be a good idea. Once again, the reason for all this off the wall stuff, like using non isolated 15v laptop chargers, is to save money. This could end to be very foolish. I cannot believe some of the things people want to use to circumvent the purchase of items proven and known to work. Maybe this is just a place for those who like to swim upstream to get some attention.


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## ElectriCar (Jun 15, 2008)

Yes I understand well why people want to save money. Building an EV I'd venture to say always is more expensive than first contemplated. I think we're all guilty of trying something apparently cheaper only to have it backfire on us and costs us more. I've done it a bunch doing my truck!


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## DJBecker (Nov 3, 2010)

cruisin said:


> Are they 100% isolated? Its all about money. Save a nickel and maybe loose your $9K pack.


What do you mean by "100% isolated"? Are you aware of a product that's "98% isolated"?

Essentially all consumer device power supplies are isolated. The usual safety standard is testing to 600 volts (category I for 120V circuits) or 1000 volts (category II).

Non-isolated supplies are used only for physically enclosed internal uses, such as the clock on a stove or LED lighting. Except for a Variac or sleazy travel voltage converters, you won't find non-isolated plug-in power conversion.

A laptop power brick is certainly isolated, and likely constructed to higher physical standards than low-volume parts. Their down-sides are that the cheap ones have optimistic power ratings, and their regulation feedback makes them less suitable for paralleling to share a load.


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## favguy (May 2, 2008)

Electricar,

Good point about the diodes, they could be the weak link, will have to keep an eye on that one.

Cruisin,

Having tested one, I can confirm laptop power supplies are isolated. Although I absolutely agree that safety must not be compromised to save money, If properly fused on the input and output, I see little risk to either the pack or the car in trying this. As for what you are saying about items proved to work and sold by EV suppliers, this isn't always true. Take the vacuum pump kits as an example, they are very expensive and although they work, make an awful racket in use, The OEM VW/Audi/Landrover etc. vacuum pumps are far cheaper and run almost silently, I presume you prefer the former?!

This is a technical discussion forum to discuss matters such as this topic and help one another, I think your comment about getting attention is inappropriate. I come here for help, if you can give me a valid technical reason why this is a bad idea, I'll happily throw it out! Also, if this is "off the wall" may I remind you what we are all doing here!! Most of the population probably think everything we discuss here is "off the wall", by your logic, we may as well all give up and go and buy a Leaf!

DJBecker,

Thanks for the input, can you elaborate on the possible effect of paralleling these, regarding power output, would diodes on the +ve of all units help, although I suspect they already have one internally?

For what they cost, I might just buy four of them, parallel them up and apply 10A/20A/30A loads and soak test them at each for a few hours.


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## cruisin (Jun 3, 2009)

favguy said:


> Electricar,
> 
> Good point about the diodes, they could be the weak link, will have to keep an eye on that one.
> 
> ...


 
You may be interested in the customer of mine who came in 2 weeks ago with a dead $9k pack. He was using a home designed charger (to save a buck) and it failed taking out the entire pack. Yes, he could have installed some safety devices to prevent it, but that costs too. Cant tell if the charger caused the problem or the defective IOTA which isnt designed for the purpose of a converter like they are being used for. And I might add, the amount of failures as witnessed on this forum.


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## Tesseract (Sep 27, 2008)

favguy said:


> ...
> Cruisin,
> 
> Having tested one, I can confirm laptop power supplies are isolated. Although I absolutely agree that safety must not be compromised to save money, If properly fused on the input and output, I see little risk to either the pack or the car in trying this....


The problem with laptop supplies (or the Iota, for that matter) is that they expect to receive relatively clean AC on their input and deliver DC to a well-behaved load on their output, expectations that can prove fatal in an EV.

As a consequence of the motor controller's normal operation there will be some level of AC ripple across the traction pack. This ripple, if not blocked/filtered by an LC network, can destroy the input capacitors on the Iota (etc.) being used as a DC/DC converter, or the output capacitors on a laptop adapter being used as a cell-level charger, because it will cause an excessive amount of current to flow through them. Note that an excessive amount of ripple current for electrolytic capacitors in these applications might be 3-6A, so well below the fuse rating. Ergo, you can cause the capacitors to expel their electrolyte all over the board (which, as the name suggests, conducts electricity very well) while the fuse remains intact.

Otherwise, as we say here at Evnetics all the time: What Could Possibly Go Wrong???


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## favguy (May 2, 2008)

Tesseract, thankyou, that is very useful feedback. Allowing for this effect, what would you recommend as a most suitable DC/DC converter to use?

Cruisin, I completely agree that it is not worth risking the pack with a badly designed charger, either home brew or cheaper commercial type.

I still however can't see how a failing/failed DC/DC converter of any sort can harm the battery if it has a correct input fuse as any current it is taking that is inadequate to blow the fuse would be far too low to harm the battery. That is unless it was left connected all the time (very bad practice, surely?) and drained the battery dead on developing a fault.


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## Tesseract (Sep 27, 2008)

favguy said:


> ...Allowing for this effect, what would you recommend as a most suitable DC/DC converter to use?


I don't recommend anything as none of the commonly used products are close to ideal for the job, including the Vicor models. That said, if you put at least 100uH of inductance (rated for the maximum dc current expected) in series with the input of the dc/dc converter, or the output of the charger, then that will give them a fighting chance. For example, this inductor from DigiKey would be a good choice for protecting all but the largest dc/dc converters, and smaller chargers and/or ones connected to higher voltage traction packs.

And, yeah, leaving the dc/dc converter connected all the time (you know, so that you can sacrifice your traction pack to protect your 12V battery from overdischarge  ) is how a partially failed dc/dc converter can kill your pack. The device most likely to cause harm is the charger, however, as its output will likely be fused at a much higher current than the dc/dc converter's input.


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## JRP3 (Mar 7, 2008)

Isn't the current rating kind of low at 17.6A?
D'oh, input! Never mind.


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## favguy (May 2, 2008)

That's the most usefull advice I've heard all week!  Many thanks


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## Yukon_Shane (Jul 15, 2010)

Tesseract said:


> I don't recommend anything as none of the commonly used products are close to ideal for the job, ...QUOTE]
> 
> It's a bit of a mystery to my why no one is filling this gap in the market. By my count we have atleast 4 good quality DC controller products competing with each other but no company seems interested in developing a DC/DC converter or a charger specific to electric vehicle conversions.
> 
> ...


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## Tesseract (Sep 27, 2008)

Yukon_Shane said:


> It's a bit of a mystery to my why no one is filling this gap in the market. By my count we have atleast 4 good quality DC controller products competing with each other but no company seems interested in developing a DC/DC converter or a charger specific to electric vehicle conversions...


The solution to this mystery can be found by honestly answering how much you would pay for a good quality, properly engineered dc/dc converter and/or a programmable charger.


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## EVfun (Mar 14, 2010)

Tesseract said:


> The solution to this mystery can be found by honestly answering how much you would pay for a good quality, properly engineered dc/dc converter and/or a programmable charger.


$184 from Kelly Controls? (price with shipping to the west coast of the USA)


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## cruisin (Jun 3, 2009)

EVfun said:


> $184 from Kelly Controls? (price with shipping to the west coast of the USA)


I have replaced 3 of the Kelly's in customers cars, using Kelly products is wanting to have a problem, as time will tell.


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## Tesseract (Sep 27, 2008)

EVfun said:


> $184 from Kelly Controls? (price with shipping to the west coast of the USA)


And there's your answer...


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## EVfun (Mar 14, 2010)

cruisin said:


> I have replaced 3 of the Kelly's in customers cars, using Kelly products is wanting to have a problem, as time will tell.


Controllers or DC to DC converters? I've heard bad things about their controllers but bought my Kelly DC to DC based on the advice of another list member and it seems that neither of us have had any problems yet.

If you where replacing Kelly DC to DC converters was there any chance they where operated outside of their design voltage range? Most people understand that taking something over its maximum rated voltage is bad, but with DC to DC converters taking one under its minimum rated voltage can also lead to failure.


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## HYPRDRV (Aug 20, 2009)

How about these guys?
http://www.zahninc.com/

Steve with an Electric Boat...


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## Yukon_Shane (Jul 15, 2010)

Tesseract said:


> The solution to this mystery can be found by honestly answering how much you would pay for a good quality, properly engineered dc/dc converter and/or a programmable charger.


It's a fair question. I'm not a big spender but I would happely save my pennies for a quality DC/DC converter in the range of $300-400. Anything over $500 and I'd probably start to consider sticking with the Iota.


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## Tesseract (Sep 27, 2008)

Yukon_Shane said:


> It's a fair question. I'm not a big spender but I would happely save my pennies for a quality DC/DC converter in the range of $300-400. Anything over $500 and I'd probably start to consider sticking with the Iota.


$300-$400 is reasonable; the aforementioned price of $184 is not. If you want a ~600W SMPS that is weatherproof, self-protecting and competently designed it's going to cost more than $184, especially if it is built in a country that does not enjoy the significant cost saving advantages from using slave/forced labor to build stuff (ahem).


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## JRP3 (Mar 7, 2008)

HYPRDRV said:


> How about these guys?
> http://www.zahninc.com/


Did you see the prices for 120V and above, and the wattage???


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## JRP3 (Mar 7, 2008)

Tesseract said:


> The solution to this mystery can be found by honestly answering how much you would pay for a good quality, properly engineered dc/dc converter and/or a programmable charger.


I spent $100 on a Chennic that died after one year and low mileage, and then spent about $160 on a Mean Well that is going strong so far. So to get it right the first time I'd say $260 is reasonable  Assuming the Mean Well holds up, if not then I guess the price goes up. There are a number of people using the Mean Well and I've yet to hear of any failures.


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## JRP3 (Mar 7, 2008)

Tesseract said:


> ...especially if it is built in a country that does not enjoy the significant cost saving advantages from using slave/forced labor to build stuff (ahem).


That was back on 07, I'm sure things are much better now,  and I need my cheap components


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## EVfun (Mar 14, 2010)

JRP3 said:


> That was back on 07, I'm sure things are much better now,  and I need my cheap components


If we really want to go there almost every one of us are using Chinese made batteries.


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## Tesseract (Sep 27, 2008)

JRP3 said:


> ...So to get it right the first time I'd say $260 is reasonable...


Not enough to get me interested, especially since most people will buy a MeanWell instead anyway.


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## Yukon_Shane (Jul 15, 2010)

JRP3 said:


> I spent $100 on a Chennic that died after one year and low mileage, and then spent about $160 on a Mean Well that is going strong so far. So to get it right the first time I'd say $260 is reasonable  Assuming the Mean Well holds up, if not then I guess the price goes up. There are a number of people using the Mean Well and I've yet to hear of any failures.


It depends on what Mean Well you look at. The Mean Well AC/DC converter that I think I'd want for my conversion is the SP-750 (125-370V input, 50 amp) which EV-Propulsion is listing for $389. The SP-500 may work for most but it's still listed at $300 so I think my estimated competitive price point of $300-$400 isn't bad. 

From all accounts the Mean Well is a good products but it's still designed as an AC/DC converter and (like all the DC/DC options) looks like it belongs inside a computer case in an air conditioned room rather then under the hood of a car. I'd happily pay a $50 premium for a product that had a nice sealed case that gave me some confidence that it would survive a season of: mud, snow, salt, dust, etc. 

Then again not everyone lives in sticks


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## JRP3 (Mar 7, 2008)

Don't buy non-EV specific products from EV dealers 
600 watts, $150 not including shipping:
https://www.jameco.com/webapp/wcs/s...-1&catalogId=10001&pa=374222&productId=374222


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## Yukon_Shane (Jul 15, 2010)

JRP3 said:


> Don't buy non-EV specific products from EV dealers
> 600 watts, $150 not including shipping:
> https://www.jameco.com/webapp/wcs/s...-1&catalogId=10001&pa=374222&productId=374222


Wow, you're not kidding!

lesson learned, thanks.

Shane


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## notailpipe (May 25, 2010)

I got the ACME DC/DC from evolveelectrics.com and so far I'm very pleased with it. I've thrown all I can, hitting brights and brake pump at the same time with full blower fan on and loud stereo... not a problem. Has a trimmable battery float voltage too and price wasn't unreasonable.


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## JRP3 (Mar 7, 2008)

Is there a part number on yours? It looks like another AC/DC converter that might be found for less money from a non EV vendor, though that price is not bad.


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## notailpipe (May 25, 2010)

No, indeed EvolveElectrics put their sticker on it so I don't know who actually made it. The price/performance did seem reasonable so I haven't spent any time figuring it out. 

I am running it full-time with a backup aux 12V battery. It takes so little power to just be on, it's below the 100mV resolution of my voltmeter when I look at how the pack voltage changed over a couple days. And MTBF is rated to about 16 years always on.


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## cruisin (Jun 3, 2009)

JRP3 said:


> Is there a part number on yours? It looks like another AC/DC converter that might be found for less money from a non EV vendor, though that price is not bad.


 
Its a Samplex SD 350D-12 you can take a look see here http://www.samlexamerica.com/products/meanwellspecs/SD-350spec.pdf


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## JRP3 (Mar 7, 2008)

Looks different, and the amps aren't as high. The samlex you linked is a Mean Well anyway. https://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2107207_-1
https://www.jameco.com/webapp/wcs/s...1bCzcQi&ddkey=https:StoreCatalogDrillDownView


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## JRP3 (Mar 7, 2008)

I think I found it, Mean Well HRPG-600-12 
https://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2094961_-1
Actually slightly higher priced at Jameco so Evolve does not appear to be overcharging for it.


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## cruisin (Jun 3, 2009)

JRP3 said:


> Looks different, and the amps aren't as high. The samlex you linked is a Mean Well anyway. https://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2107207_-1


All the same, some private label. Buy one, take it apart, and repost your info with realistic data. I have been working on these for years. Medoacre at best.


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## notailpipe (May 25, 2010)

Fits the specs at a good price point, and they warranty their product for 2 years. I'm not happy with how Evolve hides who made it, but it seems like all the EV suppliers are doing that. Other than that, what exactly is your problem with it? 

I haven't been running it even a month yet, so I can't promise you it will make it to the 16 years it's spec'd at, but so far it is taking everything I throw at it.


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## JRP3 (Mar 7, 2008)

cruisin said:


> All the same, some private label. Buy one, take it apart, and repost your info with realistic data. I have been working on these for years. Medoacre at best.


Not sure what you are talking about. The second one I linked matches the specs of the Evolve unit, the one you posted did not, and they are both made by Mean Well.


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## Tesseract (Sep 27, 2008)

Mean Well makes a decent, though not terribly robust, power supply. We use a bank of them to charge each AGM battery in our dyno. Every so often one blows up, and not because of abuse via the dyno, so we have learned to keep 4-5 on hand at all times. That said, at only $35 each for a 13.8V/11A power supply unit ("psu) *including* PFC, well... even my pride takes a back seat and just orders the damn things, rather than try to roll my own.

But let's be perfectly clear here: we installed the Mean Well psus inside a NEMA cabinet with filtration and fans to keep them clean and cool. The pc boards are not even remotely humidity resistant - CEM-4, which is literally a sandwich of paper and phenolic resin - and they run hot at rated load (not much safety factor in the design. They require a minimum load to prevent the output voltage from skyrocketing - and said load is provided by some power resistors on the pcb. These resistors continue to drain your battery (around 1-1.5A) whether the supply is on or not. A different topology choice and/or control scheme would have sidestepped this issue. There is also not a proper precharge circuit for handling DC supply voltage - just the usual NTC resistor. Cycling power to the unit before the NTC resistor has a chance to cool down again will blow something up sooner rather than later.

Etc... and so on. But hey, you can get 350W for $120 so who cares, right?


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## JRP3 (Mar 7, 2008)

I'll start to care when this one dies, each one I have to replace means I'd be willing to spend that much more on a better one in the first place. Maybe after a few years you'll have a market for a $400 DC/DC for those of us who have to learn the hard way  It sounds as if the Mean Well design could be made better with some relatively simple fixes.

I've been trying to deal with some of the issues you brought up by disconnecting the input and output when the vehicle is off but I didn't consider the startup issue with the hot NTC resistor. Maybe I should add more cooling to help avoid that, what sort of times are we talking about for it to cool down, one minute, 10 minutes, more? Also is there a preferred timing of connection, output first, input first, or same time? I've been switching on the output first then the input, and disconnecting in reverse.


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## Spyder.ev (Sep 6, 2011)

Hi just been reading with interest can I ask silly question.
Can you put 2 in parrellel to give you bigger output at same voltage . Plus if 1 fails you still have other to run emergency stuff to get you home. Am thinking of buying this unit so need clarification (the unit in question was the acme from evolve or evsource or whoever ) 

Cheers


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## cruisin (Jun 3, 2009)

Spyder.ev said:


> Hi just been reading with interest can I ask silly question.
> Can you put 2 in parrellel to give you bigger output at same voltage . Plus if 1 fails you still have other to run emergency stuff to get you home. Am thinking of buying this unit so need clarification (the unit in question was the acme from evolve or evsource or whoever )
> 
> Cheers


You may consider doing what I did for a customer who wanted the following and it has proven to work as intended. A Mean Well SD 100D-12 ($40) was installed to operate all the time keeping a 14.25v nominal 50ah Li-ion battery, made up from 18650 cells, charged. The Mean Well requires very little standby power, has no noisy fan, and if it fails, the battery is in parallel. The total 14.25v system is about 60ah which is more that what most people need. Less cells would lower the cost of the battery for a smaller system. The real advantage here is being able to use 14.25v for the system instead of 12v. I will let others add to this post to outline those advantages. It should be noted that the Mean Well has a voltage adjustment that could be used to increase the voltage to around 15v to keep the battery charged.


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## favguy (May 2, 2008)

Cruisin,

A few posts ago on this thread you told of a customer of yours who had a $9000 battery ruined by a DC/DC converter. Therefore can I clarify your last post, you are now advocating leaving a small DC/DC converter permanently switched on?

I hope I've misunderstood, my advice to Spyder is to only have whatever DC/DC he chooses turned on when the ignition is on, sized appropriately to keep the auxillery battery topped up whilst using the expected loads as the car is in use.


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## StanSimmons (Sep 3, 2011)

What do you guys think of the Mean Well SD-1000H-12? 

It is US$300 from JameCo 72-144vdc in, 11-15vdc, 60A out. It has a couple of interesting features; remote on/off, and 12V 0.25A auxiliary output. It has a 3 yr warranty, and lists a MTBF of 32k hours (3.65 yrs).

If the Aux 12v out is always on, it would be ideal for running the EV Works ZEVA Fuel Gauge Driver Plus, which requires an always on 12v, 35mA source.


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## JRP3 (Mar 7, 2008)

The Aux 12V is a nice feature, would also keep an EV Display powered up.


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## Coulomb (Apr 22, 2009)

StanSimmons said:


> What do you guys think of the Mean Well SD-1000H-12?


I like the 11-15 V output voltage range.

I don't like how they describe the overload protection: "Constant current limiting," (good) "unit will shut down output voltage after about 5 seconds." (not so good) "Re-power on to recover" (bad!)

I mean, if it's constant current limiting, it can withstand an "overload" indefinitely, right? It has separate overvoltage and overtemperature protections. Those I don't mind needing to restart to recover; in fact, I think it's a good idea for overvoltage.

I think it's just poor wording on the datasheet, but I don't like having to buy one to find out.


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## cruisin (Jun 3, 2009)

favguy said:


> Cruisin,
> 
> A few posts ago on this thread you told of a customer of yours who had a $9000 battery ruined by a DC/DC converter. Therefore can I clarify your last post, you are now advocating leaving a small DC/DC converter permanently switched on?
> 
> I hope I've misunderstood, my advice to Spyder is to only have whatever DC/DC he chooses turned on when the ignition is on, sized appropriately to keep the auxillery battery topped up whilst using the expected loads as the car is in use.


Because a car with a BMS and/or SOC draws 12v from the battery, some source needs to keep the battery charged while the car is not being used. My statement was that using the IOTA, which appears to have a high failure rate, one could have a problem if it fails. The samr problem exists with the Mean Well, but have not seen the failures as other DC/DC converters have experienced. Using the smallest available (100watt) will not put a big load on the pack while idle like the IOTA does. Using a seperate 12v charger to charge the 12v battery is useful but not part of a good design for many reasons.


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## favguy (May 2, 2008)

Hi cruisin,

OK, I understand your logic, but I think it's flawed. You are arguing that the 12v battery needs to be kept topped up whilst the car isn't in use or over time will need charging seperately via 12v charger. So in order avoid this you suggest leaving a parasitic load running off the main pack.

Lets take an example to show why this is such a bad idea. You can slate me for this later if I'm wrong! I'm always happy to have my thinking proven incorrect if it actually is. 

Assuming a conversion has a typical 160Ah lifepo4 battery and you have your small DC/DC on it all the time, and lets assume you have a 2A fuse on the input to protect the main battery. Now lets say that the DC/DC develops a fault over a long weekend whilst the car is parked up and starts to drag a couple of amps constantly as a result from the main battery. We'll also take it the car has been charged and the charger subsequently unplugged for the safety of the pack. 

Now 2A doesn't sound much does it?, but if left for only 3 1/2 days in that state the main battery that probably cost as much as the rest of the conversion put together is probably permanently dead! 

Would it not be more correct to build using a correctly sized 12v battery that could last a couple of weeks minimum with the expected parasitic loads, as current ICE designs do and have a larger, suitably sized DC/DC converter capable of maintaining the necessary running loads and topping off the 12v battery whilst the car is in use only? 

That way, there is no risk to the main pack, (at least from the DC/DC converter, as for a BMS left connected.... well that's an arguament for another time )


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## cruisin (Jun 3, 2009)

favguy said:


> Hi cruisin,
> 
> OK, I understand your logic, but I think it's flawed. You are arguing that the 12v battery needs to be kept topped up whilst the car isn't in use or over time will need charging seperately via 12v charger. So in order avoid this you suggest leaving a parasitic load running off the main pack.
> 
> ...


Your argument is valid, but I have not experienced a failure like you have used in your example. Of the 50 something conversions we have done, most use DC/DC 1/2 bricks as they are SS and the most dependable of all DC converters. Most people want to get away from heavy batteries and dont want to spend the money on Li-ion. We use 50ah Li-ion 14.25v nominal for for our cars. The charge does need to be mantained or a gradual discharge will take place when using a BMS and a SOC. If you have not used these in conversions, then you may not understand their use. By the way, hybrids use traction power to the inverter to provide static power for most uses other than lights, etc which is used by a small 12v battery. Also, using your example, you are stuck with 12v, which really doesnt do much for lights etc. How long do you think a properly sized battery will last with a 2amp draw at 12v? Figure it out.


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## favguy (May 2, 2008)

I take your point that such failures as in my example may be rare, I just don't like the thought of any risk to such a large investment as a main battery.

I understand the use of BMS and SOC. Personally I don't like BMS and will not be using one, but I know that's another can of worms! (not BMS as in management anyway, monitoring, yes)

The 2A draw was an example of a fault condition, nothing like that will be taken from the 12V battery under normal parasitic loads, so a correctly sized battery should be fine for a while at least. If you meant a fault drawing power out from the 12v battery and killing it, well, better that than the main pack!! lol!!

As for the extra weight of a properly sized 12v battery, so another 10Kg to 15Kg tops, it's negligible in the scheme of things. 

I also don't know why you keep referring to only having 12v, a properly sized DC/DC should be putting out 14.4v or so to maintain the running loads and charge the battery. (as an ICE alternator would).

At the end of the day, I suppose everything is subjective and there is more than one competent way of achieving the end result.


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## cruisin (Jun 3, 2009)

favguy said:


> I take your point that such failures as in my example may be rare, I just don't like the thought of any risk to such a large investment as a main battery.
> 
> I understand the use of BMS and SOC. Personally I don't like BMS and will not be using one, but I know that's another can of worms! (not BMS as in management anyway, monitoring, yes)
> 
> ...


I dont think there is a for sure solution to this problem as long as we have devices that have static drain on the 12v battery when unattended. I have tried various designs to lessen the possibility of a disaster, so far all my conversion customers have been happy. Does this mean it will never happen, NO. I did prevent all of them from ever having a DC/DC failure that could have stranded them or worse, damage the traction power pack. I keep refering to 12v because the standard car works on 12v, or about 13.5v with the altenator running. With a adjustable voltage output on the DC/DC converter, it is practical to boost it to about 14.25v. You cannot do that with a lead acid battery. I use Li-ion since 2p4s gives us 14.25v nominal with 5.4ah. Savings of a lot of weight as well. You are wrong if you think the weight savings is not important in a conversion. Its all about money and weight as to the outcome. Dont want to get into a debate on BMS here, but you are dead wrong on that issue. After building the first street legal Li-ion conversion in 2002, I have seen it all and would not drive a conversion with out a BMS or SOC, period.


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## bjfreeman (Dec 7, 2011)

favguy said:


> I take your point that such failures as in my example may be rare, I just don't like the thought of any risk to such a large investment as a main battery.


A properly designed dc-dc for EV will have short protection,and should have a cut off when the source drops below the prescribe voltage, that leaves enough to limp to a charging stations.


> I understand the use of BMS and SOC. Personally I don't like BMS and will not be using one, but I know that's another can of worms! (not BMS as in management anyway, monitoring, yes)


Li have a different charge and discharge curve that lead acid so as long as what you use (charger, controller) understand that curve then you fine.


> The 2A draw was an example of a fault condition, nothing like that will be taken from the 12V battery under normal parasitic loads, so a correctly sized battery should be fine for a while at least. If you meant a fault drawing power out from the 12v battery and killing it, well, better that than the main pack!! lol!!


per my previous comment about sensing the LI pack voltage for cut off.
The best test of this is to leave you headlights on, like many do on a foggy morning. atleast with a properly designed Dc-DC it wiil shut off till the voltage is restored through charger.


> As for the extra weight of a properly sized 12v battery, so another 10Kg to 15Kg tops, it's negligible in the scheme of things.


it is ball park 0.12-0.18 HP per 10kg.



> I also don't know why you keep referring to only having 12v, a properly sized DC/DC should be putting out 14.4v or so to maintain the running loads and charge the battery. (as an ICE alternator would).


Note sure if you in the USA or not but top charge is 14.1 and needs a temperature sensor, unless you have a staged charger or regulator. otherwise you boil and blow the seal on the sealed batteries and/or buckle plates..


> At the end of the day, I suppose everything is subjective and there is more than one competent way of achieving the end result.


Yes as long as you put murphy's law into to the equation.


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## cruisin (Jun 3, 2009)

bjfreeman said:


> A properly designed dc-dc for EV will have short protection,and should have a cut off when the source drops below the prescribe voltage, that leaves enough to limp to a charging stations.
> Li have a different charge and discharge curve that lead acid so as long as what you use (charger, controller) understand that curve then you fine.
> per my previous comment about sensing the LI pack voltage for cut off.
> The best test of this is to leave you headlights on, like many do on a foggy morning. atleast with a properly designed Dc-DC it wiil shut off till the voltage is restored through charger.
> ...


What are you talking about? Top charge is what? Go back and read my ENGLISH about what size the battery is.


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## bjfreeman (Dec 7, 2011)

cruisin said:


> What are you talking about? Top charge is what? Go back and read my ENGLISH about what size the battery is.


Whoa Cool your jets, this was not to you but someone else.

There is a discussion about using LI against lead-acid. unless I missed something.
Also the difference between using the Traction Batteries with a DC-DC for supply the "12" volts requirements, as compared to using a LI pack and lead-acid at "12" volts.
BTW using larger volt Battery packs with a Dc-DC has been around for Decades in RV conversions.

Yes I saw you LI equivalent for a lead acid "12" volt. and I understand that LI "12" volt pack is 80% discharge to lead-acid 55%.

I use "12" as a way to say the vehicle requirements, because lead-acid 12 volt is different than LI 12 volt. they should not be mixed since it caused the confusion, without some clarification.
In a 12v lead acid system the top (max)charge voltage is 14.1. I am aware that some LI top (max) charge is 14.4 volts.


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## rwaudio (May 22, 2008)

bjfreeman said:


> Whoa Cool your jets, this was not to you but someone else.
> 
> There is a discussion about using LI against lead-acid. unless I missed something.
> Also the difference between using the Traction Batteries with a DC-DC for supply the "12" volts requirements, as compared to using a LI pack and lead-acid at "12" volts.
> ...


I'm not getting into the whole thing here, but automotive alternators are designed to put out 14.4V and there is a tolerance, some will put out 14.5 or so. This is RPM and load dependant, my '01 F150 has minimal electrical extras and at idle the voltage sits at 14.45V, rev it up and it's about 14.5v with lights/wipers/ac on it's around 14.2V.... also the term LI as a battery type is much more misleading than saying "12 volt" system. LiFePO4 in a 4S pack would be nicely charged at 14.4V however what about LI-PO, LI-ion etc....
I think cruisin is on the right track for a simple reliable system with minimal chance of pack destroying failure. I have some mean well power supplies and every one that I've blown up fails short circuit and blows the input fuse, sure there could be other failure modes, but having one fail at a constant current just below the fuse rating is unfounded speculation at best.


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## JRP3 (Mar 7, 2008)

How are you using the Mean Well's that blow up? Do you switch them off with the car? I've been trying to decide what the best way to switch them off is, input power off first, then output, reverse, doesn't matter? Tesseract says switching them off and then back on before the resistor cools down enough causes voltage spikes.


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## rwaudio (May 22, 2008)

JRP3 said:


> How are you using the Mean Well's that blow up? Do you switch them off with the car? I've been trying to decide what the best way to switch them off is, input power off first, then output, reverse, doesn't matter? Tesseract says switching them off and then back on before the resistor cools down enough causes voltage spikes.


Killed them on the bench, not in the car. One I had running without enough cooling, the other was overloaded significantly. They work well but can be a bit fragile. I do have one that might make it in the car, and if I do it will stay on all the time. I have some bricks that might be used to power the stereo or other optional loads but they have a nice remote turn on that you can switch with a normal relay vs switching pack voltage.


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## bjfreeman (Dec 7, 2011)

rwaudio said:


> but automotive alternators are designed to put out 14.4V and there is a tolerance, some will put out 14.5 .


My point is the USA standard for Vehicles is 14.1 max. I just went out and check my two alternators that charge my vehicle Starter battery and my House Batteries. My Traction Pack is charged off the separate generator and is at 450 Volts. BTW the alternators were installed in 2005
I believe from other posts that the Canadian, and European charging rate is 14.4
That was what I was trying to point out. 
Correct me if I am wrong.


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## bjfreeman (Dec 7, 2011)

the ouput of an alternator is determine by the regulator. My regulators are external.
if you take the regulator out of the circuit, the Alternator will run at about 3,000 volts but less current.
This is not possible where the regulator is built in the Alternator.


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## Tesseract (Sep 27, 2008)

JRP3 said:


> ... Tesseract says switching them off and then back on before the resistor cools down enough causes voltage spikes.


Sort of... Cycling power to a SMPS too quickly causes a current spike from unhindered charging of the input capacitor. That current spike resonates with stray inductance and capacitance in the input wiring to cause a voltage spike that Blows ..err.. _Stuff_ Up.

The cure can take the form of many different kludges, such as a lockout timer if power is even briefly lost on the "AC" side, to a total redesign of the input stage of the SMPS.

As for what order to turn stuff on and off, how the hell should I know? Ask the guy that designed the SMPS!


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## rwaudio (May 22, 2008)

bjfreeman said:


> My point is the USA standard for Vehicles is 14.1 max. I just went out and check my two alternators that charge my vehicle Starter battery and my House Batteries. My Traction Pack is charged off the separate generator and is at 450 Volts. BTW the alternators were installed in 2005
> I believe from other posts that the Canadian, and European charging rate is 14.4
> That was what I was trying to point out.
> Correct me if I am wrong.


Two of my cars are from the USA (not made in, but sold in) and the '07 Infiniti charges at 14.3 at least, that was after a dead battery so at idle with a big load on the alternator. The '83 Porsche charges at 14.4v which is exactly the same as the '86 Porsche which is an actual Canadian car.

14.1v would not be uncommon when measuring a running vehicle with some electrical stuff turned on while it's topping up the starting battery. However there are no cars that I am aware of that are designed to peak at 14.1V...

Search some Car audio forums, everything I am aware of is designed to charge at 14.4v, they are picky about voltage because ever tenth of a volt helps during SPL competitions. Car audio amplifiers are rated at either 14.4v or if they are nice, both 14.4 and 12 or 12.5v to represent the ideal engine on/engine off conditions.

There are of course exceptions based on poor designs or old worn out parts, a '79 VW I had years ago would only charge at 13.5V and that was the no load voltage it would never exceed that.


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## JRP3 (Mar 7, 2008)

Tesseract said:


> As for what order to turn stuff on and off, how the hell should I know? Ask the guy that designed the SMPS!


He probably speaks Chinese. I just thought there might be a basic rule. I'm going with the assumption that it's better to turn on the output side before input, and to turn off the input before the output, so there is never power going into the unit without a load on the output. Yes, no, maybe?


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## Tesseract (Sep 27, 2008)

JRP3 said:


> He probably speaks Chinese. I just thought there might be a basic rule. I'm going with the assumption that it's better to turn on the output side before input, and to turn off the input before the output, so there is never power going into the unit without a load on the output. Yes, no, maybe?


A competently designed, modern SMPS won't care - it will be stable at all loads. When I see a minimum load resistor hardwired across an SMPS these days I just shake my head because it couldn't scream "I'm from the 80s" any louder if it wore leg-warmers...

The answer to your question depends on how the control loop is compensated, how heavy the output is loaded on startup and what form of current limiting (constant or foldback) is used. I don't know the answer to those questions so I can't advise you. Almost all SMPS are (or should be) designed to start up with the full load already connected.


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## bjfreeman (Dec 7, 2011)

rwaudio;278040
There are of course exceptions based on poor designs or old worn out parts said:


> *Table 4-5: Effects of charge voltage on a small lead acid battery (SLA)
> 
> http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery
> *


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## rwaudio (May 22, 2008)

bjfreeman said:


> *Table 4-5: Effects of charge voltage on a small lead acid battery (SLA)
> 
> http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery
> *


Ideal charging schemes and how cars are built are two unrelated subjects. I'm just telling you how it is, not how it could be.


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## bjfreeman (Dec 7, 2011)

rwaudio said:


> Ideal charging schemes and how cars are built are two unrelated subjects. I'm just telling you how it is, not how it could be.


Then we agree to disagree about the real world.
my view is USA has it standard.
I work part time as a car mechanic. so I see charging system daily.
I am willing to say there are two standards.
I am also saying that chemistry does not change.
if you read the table.


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## dladd (Jun 1, 2011)

bjfreeman said:


> Then we agree to disagree


sounds familiar...


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## rwaudio (May 22, 2008)

bjfreeman said:


> Then we agree to disagree about the real world.
> my view is USA has it standard.
> I work part time as a car mechanic. so I see charging system daily.
> I am willing to say there are two standards.
> ...


Fair enough, you are welcome to believe what you want.
I spent over a decade in car audio industry along with designing and building signal processors to work with automotive electrical systems. I can only pass along what I saw, what I learned and the 100's of vehicles that I worked on.

If you can show me one credible place where it shows USA alternators only charge to 14.1V I would happily agree with you.
But I'm sure you will find thousands of places that say 13.5 -14.4 (or 14.5v) is the common measurable output depending on what electrical loads are on the alternator. Turn everything off that you can while the battery is fully charged and you should be in the 14.2-14.5v range, turn everything on and you will probably be in the 13.5-14.2v range.

If I am wrong please prove it so that I don't continue going around telling people incorrect information about common ICE electrical systems.


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## EVfun (Mar 14, 2010)

My old Dodge had a mechanical regulator and I adjusted it so the peak voltage didn't exceed 15.0 volts.

I just checked 2 late model Toyotas in my driveway. One reads 14.29 volts at idle with everything off. The other reads 14.35 volts with everything off. These are factory stock, no charging system parts have been replaced. They even have the factory original 12 volt batteries.


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## rwaudio (May 22, 2008)

EVfun said:


> My old Dodge had a mechanical regulator and I adjusted it so the peak voltage didn't exceed 15.0 volts.
> 
> I just checked 2 late model Toyotas in my driveway. One reads 14.29 volts at idle with everything off. The other reads 14.35 volts with everything off. These are factory stock, no charging system parts have been replaced. They even have the factory original 12 volt batteries.


Exactly as expected


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## bjfreeman (Dec 7, 2011)

rwaudio said:


> Fair enough, you are welcome to believe what you want.
> If you can show me one credible place where it shows USA alternators only charge to 14.1V
> I would happily agree with you.
> If I am wrong please prove it so that I don't continue going around telling people incorrect information about common ICE electrical systems.


http://www.progressivedyn.com/prod_details/rv_conv/rv_converter_pd9160a_2.html 13.6 output.
this has a remote button that when pushed set the output ton 14.1.

sorry a quick search of the net did not give me my outputs of my alternators.
So do it get a half point 
I can tell by your disertation you did not read the link I gave.


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## rwaudio (May 22, 2008)

bjfreeman said:


> http://www.progressivedyn.com/prod_details/rv_conv/rv_converter_pd9160a_2.html 13.6 output.
> this has a remote button that when pushed set the output ton 14.1.
> 
> sorry a quick search of the net did not give me my outputs of my alternators.
> ...


I did read the link, but it has nothing to do with automotive alternators.
Neither does that link. Are you trying to prove that cars *shouldn't* charge to 14.4v or that cars *don't* charge to 14.4v

The only thing that I am saying is that common OEM alternators on all late model cars/trucks/suv's that I have ever encountered and are in proper operating condition will put out 14.4v +/- 0.1v. That's all I'm saying, nothing more nothing less.


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## bjfreeman (Dec 7, 2011)

EVfun said:


> My old Dodge had a mechanical regulator and I adjusted it so the peak voltage didn't exceed 15.0 volts.
> 
> I just checked 2 late model Toyotas in my driveway. One reads 14.29 volts at idle with everything off. The other reads 14.35 volts with everything off. These are factory stock, no charging system parts have been replaced. They even have the factory original 12 volt batteries.


Now we have an other variable of the accracy of the meter.

the newer Cars may have the higher voltage. however how many are going to strip out a new car they just paid $18K to 40K for, to put in and EV.
no, you will used a older Car.
my 1988 Toyota truck charges at 13.1 volts using a Fluke meter that has been calibrated last summer. it is ECU controlled Alternator.


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## rwaudio (May 22, 2008)

bjfreeman said:


> Now we have an other variable of the accracy of the meter.
> 
> the newer Cars may have the higher voltage. however how many are going to strip out a new car they just paid $18K to 40K for, to put in and EV.
> no, you will used a older Car.
> my 1988 Toyota truck charges at 13.1 volts using a Fluke meter that has been calibrated last summer. it is ECU controlled Alternator.


Ok.... so newer cars charge at 14.4v that's all I said... now in an EV and related to this topic of dc/dc converters those who use a lead acid battery can benifit from having one that puts out 14.4v and it will not harm a lead acid (or Lifepo4) "12v" system battery..

period.


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## bjfreeman (Dec 7, 2011)

rwaudio said:


> I did read the link, but it has nothing to do with automotive alternators.
> Neither does that link. Are you trying to prove that cars *shouldn't* charge to 14.4v or that cars *don't* charge to 14.4v
> 
> .


the first link is about charging and the pros and cons.
like I said you did not read the link.
the second one shows what the industry considers as proper charging of lead acid batteries.
the first link explains why


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## bjfreeman (Dec 7, 2011)

rwaudio said:


> those who use a lead acid battery can benifit from having one that puts out 14.4v and it will not harm a lead acid (or Lifepo4) "12v" system battery..
> 
> period.


the link I gave explains 14.4 pros and cons. because of the cons I would not use 14.4 as a constant charge voltage more as a equalizing charge.
(or Lifepo4) I agree.


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## EVfun (Mar 14, 2010)

rwaudio said:


> Ok.... so newer cars charge at 14.4v that's all I said... now in an EV and related to this topic of dc/dc converters those who use a lead acid battery can benifit from having one that puts out 14.4v and it will not harm a lead acid (or Lifepo4) "12v" system battery..
> 
> period.


Well... If the DC to DC converter is being used like an alternator it will not harm a lead acid or LiFePO4 "12v" system battery. 

If a constantly on DC to DC converter is used the voltage should not be over 13.8 volts. That is the upper "float" voltage for lead acid and 3.45 vpc for LiFePO4. I would recommend the voltage not be over 13.6 volts for better "12v" battery life.


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## madmike8 (Jun 16, 2011)

I have 4 16ah Headways that I plan to use in series for my 12v battery. So, if my dc2dc is set at 13.6v I should be ok?


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## dougingraham (Jul 26, 2011)

madmike8 said:


> I have 4 16ah Headways that I plan to use in series for my 12v battery. So, if my dc2dc is set at 13.6v I should be ok?


If the cells are top balanced then yes. This should be fine.


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## cruisin (Jun 3, 2009)

madmike8 said:


> I have 4 16ah Headways that I plan to use in series for my 12v battery. So, if my dc2dc is set at 13.6v I should be ok?


Your DC/DC converter should be about 1 1/2v more than the nominal voltage of your batteries.


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## bjfreeman (Dec 7, 2011)

cruisin said:


> Your DC/DC converter should be about 1 1/2v more than the nominal voltage of your batteries.


could you explain this?
Nominal, for 4s, as the rest volts or Float?
LI discharge is 12.8, rest/float is 13.6-14.0 and charge is 14.4
1.5 volts would be any where from, based on discharge, 14.3 to based on rest 15.5


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## cruisin (Jun 3, 2009)

bjfreeman said:


> could you explain this?
> Nominal, for 4s, as the rest volts or Float?
> LI discharge is 12.8, rest/float is 13.6-14.0 and charge is 14.4
> 1.5 volts would be any where from, based on discharge, 14.3 to based on rest 15.5


What is the manufacturers nominal voltage?


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## dougingraham (Jul 26, 2011)

cruisin said:


> Your DC/DC converter should be about 1 1/2v more than the nominal voltage of your batteries.


This would be 14.3v and would mean a float voltage of 3.575v per cell which is too high.

3.45v per cell is generally considered to be the safe float voltage for LiFePo4 cells. It is actually documented in A123's literature. Going to a little less than this would certainly be ok. He was thinking 13.6v which is 3.4v per cell. This would result in a battery that never gets to full charge but also would be safe, probably even good for the batteries.


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## bjfreeman (Dec 7, 2011)

this is my understanding of the characteristics of a LiFePo4


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## bjfreeman (Dec 7, 2011)

cruisin said:


> What is the manufacturers nominal voltage?


your orginal statment was 1.5 volts above Nomial.
Nominal cell voltage 3.3 V for *LiFePO4 *regardless of manufacturers.
so your 1.5 for a 4s would be 13.2 + 1.5= 14.7v

So I am asking how you arrived at 1.5 volts?


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## frodus (Apr 12, 2008)

BJ,

Cruisin gets it from Experience.... He's converted cars for various customers.

Generally speaking, lets say you have a 3.3V cell, 4 of those is 13.2V. Now, lets say this cell has a HVC of about 3.7V from the datasheet. That would yeild an upper charge limit of about 14.8V. 13.2V - 14.8V is.... ~1.6V.

So he's saying to charge at just under that limit.... which I'd agree with, mostly. For me I'd charge a little under that.... mostly because it depends on the size of aux pack, lets say it's a 2C charge limit 10Ah pack). That's 20A. Lots of DC-DC's I see used are higher than that. So if the cell is discharged, it could potentially charge at a current higher than that recommended by the manufacturer. It's also a bit safer, but it shouldn't really hurt anything if you go about 1.5V. It'l keep that battery topped off pretty well. 

He was just giving a ballpark figure. In the end, just keep it somewhere between "just above nominal" to "just below HVC". The closer to HVC you get, the more fully your pack charges, but some people like to float at lower voltages (i.e. 3.45V a cell would be a good example, I use 3.5V a cell).

NOTE: nominal cell voltage is not "regardless"... some are 3.2, some are 3.3-3.4. It all depends on what manufacturer, but it's somewhere in the range of 3.2-3.3 from the cells I've tested. It's what is on the sheet for your cell.


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## bjfreeman (Dec 7, 2011)

frodus said:


> BJ,
> Cruisin gets it from Experience.... He's converted cars for various customers.


Yes I know he has experience, and I was asking instead of telling, because I wanted to know what he did.
thanks for the explanation.
I also find that some manufactures are using a different chemical compostion that is on the cells, sometimes. and this changes the standard curves. Like they are now using 4.0 volts as max for charging.
I was hoping to get info in a way that everyone could figure out how things work.


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## Agust Sigurdsson (Oct 25, 2009)

You will never get a 12 Volts battery carged from a 12 Volts supply - no matter how long you wait. You need approximately 14 volts +/- 0.5, depending upon battery type, temperature etc. In order to run an automobile safely you must have a well charged battery to supply current for all the lights, motors and other accessories.
Do not forget that DC motors and incandescent lamps have inrush current which can be up to several times their steady state current.
You can figure the worst case load scenario - every conciveable lamp lit, the blower running at max, wipers on and whatever you have *except* the vacuum pump or some other large 12 V motor. The the vacuum pump kicks in - demandig perhaps 50 Amps in addition to the previous load. Unless you have a well charged battery to supply the load transient you can easily overload your DC/DC converter which will probably protect itself by switching off automatically. Now the 12V system is suddenly down and you may find yourself in a very dangerous traffic situation.

I would not put the blame on the 12 Volts DC/DC converter. You seem to have a design issue by selecting a DC/DC with too low voltage. Charging the battery manually is a workaround.


Agust


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## cruisin (Jun 3, 2009)

frodus said:


> BJ,
> 
> Cruisin gets it from Experience.... He's converted cars for various customers.
> 
> ...


Travis, you do a much better job of explaining than I do. In my example I stated that I was using 18650 cells of 14.4v which is 3.6v nominal. I use at least 15v to keep the pack charged, but that will depend on how many amps the converter is capable of. I guess one could use a large ah pack with a small DC converter full time just to keep it charged, but using a small pack will require a larger DC converter due to the current needed when using the lights etc.


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## octagondd (Jan 27, 2010)

I purchased my kit over a year ago and it contains an IOTA DLS-55 DC-DC Converter. I just saw on Evolve Electrics page that the DLS-55 had a design change and can no longer be used as a DC-DC converter.

When did this design change occur? Was it due to failures I had heard about in the last year? Is my unit basically useless to me?

What is the latest ideas on DC-DC convertors. I like the idea of a converter and aux battery system as a backup if DC-DC dies. Are people just wiring the DLS-55 to AC power and using it to charge the Aux battery while the car is charging? (I have a LA aux battery)


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## Coulomb (Apr 22, 2009)

octagondd said:


> Was it due to failures I had heard about in the last year?


I don't think so. As far as I know, Iota don't make this for DC/DC work, it just happened to be a cheap solution for a time. Now, new units are no longer a cheap DC/DC solution.



> Is my unit basically useless to me?


No, this merely means if it fails, you can't get another one the same size and shape and part number to replace it. Your Iota continues to be a medium quality AC to DC power supply, not designed for EV use, but which can be adapted to be more suitable by making half a dozen moderately easy modifications. Search for Lee Hart's EVDL post in this, if you haven't already seen it.



> What is the latest ideas on DC-DC convertors. I like the idea of a converter and aux battery system as a backup if DC-DC dies.


As far as I know, that's still the most popular configuration. After all, it lets you run hazard lights, headlights, and wipers if you need them even if the DC/DC happens to fail, or its fuse blows, etc. In some jurisdictions, you have to be able to provide say 20 minutes of hazard flasher use even if the high voltage battery fails, so then the "backup" auxiliary battery becomes required, not optional / recommended.



> Are people just wiring the DLS-55 to AC power and using it to charge the Aux battery while the car is charging? (I have a LA aux battery)


I suppose some might, but I believe that most simply feed fused traction battery (120 V nominal minimum) to L1 and N input leads, any orientation. If you bypass the bridge rectifier inside (I believe that this is one of Lee's recommendations), then it does become polarity sensitive. The 13.8 V output goes via a separate fuse to the 12 V auxiliary battery.

Most switch the DC/DC off when the main contactor is off; some run the DC/DC all the time. It's a matter of preference. I would not like to have a device like the IOTA, which is not designed for continuous DC use, across my pack at all times, so that the quiescent drain of the auxiliary system (radio memory, all sorts of quiescent loads) doesn't drain the main pack. Granted, the main pack has a lot more energy storage than the auxiliary battery, but the consequences of draining the main pack are far worse then draining the auxiliary pack (e.g. if left unattended for extended periods of time).


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## octagondd (Jan 27, 2010)

Thanks for the excellent response. I will look into the Lee Hart thing and see if I want to go down that road.

What DC-DC are people using now?


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## bjfreeman (Dec 7, 2011)

A dc to DC, unless Isolated, is dropping the higher voltage to a lower voltage with enough current to do the job.
The is the same function that most Chargers use, except you don't have the conversion from AC to DC front end.
The open source power supply would provide you all the parts you need to build a nice 60 amp converter.


Since it uses a micro to control the voltage and current, you can program you final voltage an current.
The other advantage is that if the micro is not running you have no DC to DC.
You might want to talk to the author of the thread to see if he wants to seperate the parts and code his stuff for just DC to DC.


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## JRP3 (Mar 7, 2008)

A number of us have been trying the Mean Well brand, though they are also actually AC/DC units.  MeanWell


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## Yabert (Feb 7, 2010)

JRP3 said:


> A number of us have been trying the Mean Well brand,


My SP-320-13.5 (65$) working great for my 154v (48s) set-up.


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## octagondd (Jan 27, 2010)

JRP3 said:


> A number of us have been trying the Mean Well brand, though they are also actually AC/DC units.  MeanWell


Anyone doing the Lee Hart Mod to them, or just using as is?


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## JRP3 (Mar 7, 2008)

I'm not aware of anyone doing the mod.


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## DIYguy (Sep 18, 2008)

I didn't read every post (got cross-eyed reading the alternator thing... lol) but what about the Vicor bricks? I run an Iota and it has worked flawlessly however, I don't like the open vent nature (even though I have driven in torrential rain storms) plus I am making a list of all items possible to lighten my ride . . this is a smaller item but the $/lb return is a favorable number if you find the right one used. They are sealed, light and you can trim the output. I think JR has been using them. I have bought one and have it sitting in my "upgrade" pile.  Be careful with the ouput voltage though, as the 12V MAxi only can be trimmed up to 13.2 I think. You may need the 15 volt version. . . and trim it down.


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## JRP3 (Mar 7, 2008)

I think Jack has killed a few of those as well.


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## DIYguy (Sep 18, 2008)

JRP3 said:


> I think Jack has killed a few of those as well.


Really? Crap. . Does that make them better than the Meanwell's . . . or worse? lol 
Did he give any hints as to why/how?


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## dougingraham (Jul 26, 2011)

DIYguy said:


> I didn't read every post (got cross-eyed reading the alternator thing... lol) but what about the Vicor bricks?


I bought 3 of the Vicor MegaPac's off of Ebay and put together an 80A DC/DC converter. Downside is the fan runs all the time and it isn't weatherproof. So I am going to put it in a box that will protect the air intake from possible water and dust ingestion. I am also probably going to turn it off when the key is turned off. I will provide an unswitched 12v to keep the clock running and the J1772 device active. I don't know if this will be a battery or a standalone Vicor brick. Maybe both....

I used three 5V modules trimmed down to 4.6v paired with three 5V booster modules. Actual output current is a little over 87a at 13.8v. The voltage starts to sag when you load it more than that. I have it wired into the car with 4ga wire. This is capable of doing 1200 watts and 6ga would have been questionable at full output current. Since I don't have the traction pack in the car yet I have an AC cord on it so I can plug it in and use the car stereo in the garage while I work.

I just looked and none of the reasonably priced units for sale have the 5v boosters. So if a 40 plus amp unit would work for you then you just need a MegaPac with three of the 5v 40a modules (M5V/40A is the module designation). The booster modules are M5V/40AB and cannot be used unless slaved to the A module. MegaPac's have PFC front ends which means they can operate on AC from 110-240 VAC from 47-400hz and DC from 110 to 300 VDC. Kind of universal input.

At EVCCon Jack told me he had a bad booster module that just didn't work at all. He didn't mention any other problems. These devices seem to be pretty bulletproof in that if wired up correctly they seem to protect themselves pretty well.


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## DIYguy (Sep 18, 2008)

dougingraham said:


> I bought 3 of the Vicor MegaPac's off of Ebay and put together an 80A DC/DC converter. Downside is the fan runs all the time and it isn't weatherproof. So I am going to put it in a box that will protect the air intake from possible water and dust ingestion. I am also probably going to turn it off when the key is turned off. I will provide an unswitched 12v to keep the clock running and the J1772 device active. I don't know if this will be a battery or a standalone Vicor brick. Maybe both....
> 
> I used three 5V modules trimmed down to 4.6v paired with three 5V booster modules. Actual output current is a little over 87a at 13.8v. The voltage starts to sag when you load it more than that. I have it wired into the car with 4ga wire. This is capable of doing 1200 watts and 6ga would have been questionable at full output current. Since I don't have the traction pack in the car yet I have an AC cord on it so I can plug it in and use the car stereo in the garage while I work.
> 
> ...


Thanks Doug. Kinda what I was thinking. On a side note, if you don't need more than about 40 amps (which I don't), you can just go with one 15 volt by 600 watt brick. This would be weatherproof and no fan. . . although u may need to mnt it on a bit of a heat sink.


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## Dave Koller (Nov 15, 2008)

octagondd said:


> Anyone doing the Lee Hart Mod to them, or just using as is?


http://www.diyelectriccar.com/forums...2&postcount=73
thought I posted this here but guess not. I used this supply with DC input to charge a battery used for Robotics as a test.. worked good.....


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## rfhendrix (Jan 24, 2011)

I was thinking about buying this: http://kellycontroller.com/hwz-series-dcdc-converter-144v-to-135v-25a-p-186.html

The only problem is I have a 30 amp 12v heater. But I am using a standard LA deep cycle battery. Would that battery and converter combination present any problems? Other accessories include a power brake vacuum pump.


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## favguy (May 2, 2008)

13.5 volts is a bit low, so your battery (if included) won't ever get fully charged and may fail prematurely. Other than that, it looks to be very good value (assuming it lasts a while!)


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## rfhendrix (Jan 24, 2011)

favguy said:


> 13.5 volts is a bit low, so your battery (if included) won't ever get fully charged and may fail prematurely. Other than that, it looks to be very good value (assuming it lasts a while!)


Thanks! I can't understand why they would set it at 13.5v. But you are saying that the battery will absorb the extra amps without affecting the 25amp output of the converter right? That is my main concern.


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## favguy (May 2, 2008)

Hi,

It might be worth talking to them, the 13.5v figure could be at full load, 25A and the output at small/no load is actually higher as the voltage will usually drop a little under load.

13.5 volts will certainly not harm the battery from overcharging! but you'd need to manually charge it from time to time to maximise its life. The DC/DC will only provide up to the maximum current when it's needed, with a small, or no load, it will just maintain the battery as needed (although, not adequately if it really is only 13.5v at low/no load)


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