DC-DC FAILURES what is cause?

classic Classic list List threaded Threaded
7 messages Options
Reply | Threaded
Open this post in threaded view
|

DC-DC FAILURES what is cause?

Ruckus
Hi everybody,
Jack Rickard and perhaps others are suffering constant dc-dc 12v failures.  Those who watch EVTV will have noted that Jack uses no stabilizing 12v batt and has suffered very many dc-dc 12v failures.  Is it the lack of a 12v batt that is the cause, or is it current ripple or voltage sag due to main pack sag under heavy use?  He has used a diode to isolate the dc-dc from this sag and is still having problems with them blowing.

I am using the same Chennic dc-dc (without any isolation) and the Zilla at 1000 Amps.  The one difference is the 37 Jag uses 4 Headways as a 12v buffer.  Is it the 12v batt that is saving the Jag's dc-dc or something else?  The Jag does use 260AH Thundersky's which might sag a bit less.

Pretty much it seems to be a voltage sag issue or a 12v aux battery issue.

Anyone care to weigh in ??
Reply | Threaded
Open this post in threaded view
|

Re: DC-DC FAILURES what is cause?

Cruisin
After trying all kinds of DC converters for over 10 years with failures, I have found the best solution is a 14.5v Li-ion battery pack with enough ah for a couple of hours of use should the dc converter fail, being charged with a full time dc converter of about 150w or so. All bulbs should be changed to LED and headlights changed to Halogen. Since I have started to use these on all customers cars, no more failures. Be careful when selecting a DC converter that it functions during your voltage range from full charge to bottom sag. Don't use PC power supplies to save money. The 14.5v will work real nice on a 12v car that really wants at least 13.5v. Use a power supply that has a adjustable output to achieve this voltage.
Reply | Threaded
Open this post in threaded view
|

Re: DC-DC FAILURES what is cause?

Robert Johnston
On 2012-08-26 5:00 PM, Cruisin wrote:

> After trying all kinds of DC converters for over 10 years with failures, I
> have found the best solution is a 14.5v Li-ion battery pack with enough ah
> for a couple of hours of use should the dc converter fail, being charged
> with a full time dc converter of about 150w or so. All bulbs should be
> changed to LED and headlights changed to Halogen. Since I have started to
> use these on all customers cars, no more failures. Be careful when selecting
> a DC converter that it functions during your voltage range from full charge
> to bottom sag. Don't use PC power supplies to save money. The 14.5v will
> work real nice on a 12v car that really wants at least 13.5v. Use a power
> supply that has a adjustable output to achieve this voltage.

Switching to LED and Halogen is good (Though HID/Projector would
probably be better for headlights, as Halogen bulbs use as much power as
regular bulbs), but 14.5v is kinda high. I was under the impression that
vehicle power was supposed to be 12v direct from battery, and 13.8v from
the ICE's alternator. I have a feeling if you're going as high as 14.5v,
you might start overloading fuses and the like.

Just a thought.

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply | Threaded
Open this post in threaded view
|

Re: DC-DC FAILURES what is cause?

Mike Nickerson
In reply to this post by Ruckus
I'm using an Elcon DC-DC with an auxiliary 12V lead-acid battery.  I think
this has the most benefits:

  -  The auxiliary battery is available for heavier spike loads than the
DC-DC might be able to provide.  Since my DC-DC is only 300W, that could
happen.
  -  The DC-DC is only active when the ignition is on.  Therefore, I'm not
risking exceeding the duty cycle of the converter.
  -  I have in-rush limiters on the DC-DC to limit any inrush current that
might exceed the ratings of the converter.
  -  The Elcon has a wide input voltage range so it doesn't seem to be
susceptible to sag in my traction pack.
  -  The Elcon is a sealed unit which appears to be made for this purpose
(it isn't a repurposed PC power supply, for example).
  -  I haven't noticed any problems with ripple from the controller (Kelly).
Either it doesn't create much, or the DC-DC isn't sensitive to it.

I have two years on this unit without any issues.  My only concern is that
my BMS and AC relay can drain my 12V battery if it isn't recharged every 2-3
weeks.  I have to watch for that.  I have a very small 12V battery (12 Ah)
because that is all I have room for.  When I had the standard battery that
came with the ICE, the auxiliary battery lasted for much more than a month.

If Jack has no auxiliary battery, he has to keep his DC-DC converter powered
all the time.  I only have my DC-DC converter on about an hour a day.
Unless the converter was designed for 24/7 duty cycle, that alone could
cause a problem.  I'm pretty sure my Elcon would not last long-term if it
were on 24/7.

Mike
www.evalbum.com/2778


> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On
> Behalf Of Ruckus
> Sent: Sunday, August 26, 2012 4:08 PM
> To: [hidden email]
> Subject: [EVDL] DC-DC FAILURES what is cause?
>
> Hi everybody,
> Jack Rickard and perhaps others are suffering constant dc-dc 12v failures.
> Those who watch EVTV will have noted that Jack uses no stabilizing 12v
batt
> and has suffered very many dc-dc 12v failures.  Is it the lack of a 12v
batt that
> is the cause, or is it current ripple or voltage sag due to main pack sag
under
> heavy use?  He has used a diode to isolate the dc-dc from this sag and is
still
> having problems with them blowing.
>
> I am using the same Chennic dc-dc (without any isolation) and the Zilla at
> 1000 Amps.  The one difference is the 37 Jag uses 4 Headways as a 12v
> buffer.  Is it the 12v batt that is saving the Jag's dc-dc or something
else?  The

> Jag does use 260AH Thundersky's which might sag a bit less.
>
> Pretty much it seems to be a voltage sag issue or a 12v aux battery issue.
>
> Anyone care to weigh in ??
>
>
>
> --
> View this message in context: http://electric-vehicle-discussion-
> list.413529.n4.nabble.com/DC-DC-FAILURES-what-is-cause-tp4657516.html
> Sent from the Electric Vehicle Discussion List mailing list archive at
> Nabble.com.
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere.  Thanks.
> |
> | REPLYING: address your message to [hidden email] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply | Threaded
Open this post in threaded view
|

Re: DC-DC FAILURES what is cause?

Roland Wiench
In reply to this post by Ruckus
I am been using a bank of Iota's-45 since 2002 with no problems.  They come
on with the ignition switch and/or dash switch that turns on two contactors
that provide the main 180v battery voltage to the input of the converters.

Even though they are rated for 45 amps, each one has a output fuse for 30
amp or 66% of the rating which we call the demand factor. Each input fuse is
set at 3 amps which are a Busman Fustron type.

These units are in a air cool compartment in the rear of the vehicle that a
Dayton 150 CFM fan brings outside air through a air filter cooling the
converters plus the battery charger that is in another enclose compartment.
Each one has it own exhaust outlet venting to the outside.

These DC-DC converters are set for 14.5 volts which use two AWG No. 6
stranded copper wires parallel per 14.5 volt line that has a run of 25 feet
to a 12 volt 135 ah deep cycle accessory battery.

I am running a electric power steering and braking hydraulic pump that pulls
15 to 50 amps depending on the demand of these units.  The voltage drop is
normally to 13.0 to 13.8 volt.  If I turn on all 12 volt loads which was
done as a test, the ampere has increase to about 80 amps with the volt drop
to the 12 volt range.

I also added a 145 amp alternator that is design to charge a deep cycle
battery.  The DC-DC converters are in parallel with the alternator.  The
alternator is mainly use to provide regenerative braking that is use on are
very steep hills.  The alternator is also set for 14.5 volts.

As the rpm of the motor is between 0 and 1100 rpm, the alternator is not
excited where there is no generation.  At this time the DC-DC converters
provides the current as shown on two separate meters.  When the alternator
reaches the excitation rpm and reaches 14.5 volts providing the current, the
DC-DC converters start to drop the current close to 0 amps.

As the EV goes up hill, I can choose to select a lower output voltage of the
alternator lower than the DC-DC converters.  This lowers the demand and the
load on the motor while going up a hill.  At 25 mph, my main battery ampere
is between 60 to 70 amps at this time.  Going down hill the main battery
ampere drops to 0 amps and the alternator can provide up to 100 amps while
holding the EV like engine compression on a ICE.

Roland


----- Original Message -----
From: "Ruckus" <[hidden email]>
To: <[hidden email]>
Sent: Sunday, August 26, 2012 4:08 PM
Subject: [EVDL] DC-DC FAILURES what is cause?


> Hi everybody,
> Jack Rickard and perhaps others are suffering constant dc-dc 12v failures.
> Those who watch EVTV will have noted that Jack uses no stabilizing 12v
> batt
> and has suffered very many dc-dc 12v failures.  Is it the lack of a 12v
> batt
> that is the cause, or is it current ripple or voltage sag due to main pack
> sag under heavy use?  He has used a diode to isolate the dc-dc from this
> sag
> and is still having problems with them blowing.
>
> I am using the same Chennic dc-dc (without any isolation) and the Zilla at
> 1000 Amps.  The one difference is the 37 Jag uses 4 Headways as a 12v
> buffer.  Is it the 12v batt that is saving the Jag's dc-dc or something
> else?  The Jag does use 260AH Thundersky's which might sag a bit less.
>
> Pretty much it seems to be a voltage sag issue or a 12v aux battery issue.
>
> Anyone care to weigh in ??
>
>
>
> --
> View this message in context:
> http://electric-vehicle-discussion-list.413529.n4.nabble.com/DC-DC-FAILURES-what-is-cause-tp4657516.html
> Sent from the Electric Vehicle Discussion List mailing list archive at
> Nabble.com.
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere.  Thanks.
> |
> | REPLYING: address your message to [hidden email] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
>

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply | Threaded
Open this post in threaded view
|

Re: DC-DC FAILURES what is cause?

David Nelson-5
In reply to this post by Ruckus
On Sun, Aug 26, 2012 at 3:08 PM, Ruckus <[hidden email]> wrote:
> Hi everybody,
> Jack Rickard and perhaps others are suffering constant dc-dc 12v failures.
> Those who watch EVTV will have noted that Jack uses no stabilizing 12v batt
> and has suffered very many dc-dc 12v failures.  Is it the lack of a 12v batt
> that is the cause, or is it current ripple or voltage sag due to main pack
> sag under heavy use?  He has used a diode to isolate the dc-dc from this sag
> and is still having problems with them blowing.
>

Just a correction to that last statement. On the eCobra with a 1400A
Netgain controller there was not a diode. Here is Jacks reply to my
request for confirmation:

"Jack Rickard replied:

The eCobra did NOT have the diode and inductor treatment. So I’m
fairly confident it will provide a fix. Again – 1300 amps is a lot of
amps. Those power levels are actually a new thing for us here at EVTV.
And it sags a battery pack dramatically."

That is why he is adding the inductor and diode to the replacement he
is/will be installing.

--
David D. Nelson
http://evalbum.com/1328
http://2003gizmo.blogspot.com
http://www.levforum.com

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply | Threaded
Open this post in threaded view
|

Re: DC-DC FAILURES what is cause?

Ruckus
Thanks for your informative reply.  Guess we'll have to wait and see.
Hopefully he will be testing it hard at EVCCON for our viewing pleasure.
Cheers
On Aug 28, 2012 11:49 AM, "David Nelson" <[hidden email]> wrote:

> On Sun, Aug 26, 2012 at 3:08 PM, Ruckus <[hidden email]> wrote:
> > Hi everybody,
> > Jack Rickard and perhaps others are suffering constant dc-dc 12v
> failures.
> > Those who watch EVTV will have noted that Jack uses no stabilizing 12v
> batt
> > and has suffered very many dc-dc 12v failures.  Is it the lack of a 12v
> batt
> > that is the cause, or is it current ripple or voltage sag due to main
> pack
> > sag under heavy use?  He has used a diode to isolate the dc-dc from this
> sag
> > and is still having problems with them blowing.
> >
>
> Just a correction to that last statement. On the eCobra with a 1400A
> Netgain controller there was not a diode. Here is Jacks reply to my
> request for confirmation:
>
> "Jack Rickard replied:
>
> The eCobra did NOT have the diode and inductor treatment. So I’m
> fairly confident it will provide a fix. Again – 1300 amps is a lot of
> amps. Those power levels are actually a new thing for us here at EVTV.
> And it sags a battery pack dramatically."
>
> That is why he is adding the inductor and diode to the replacement he
> is/will be installing.
>
> --
> David D. Nelson
> http://evalbum.com/1328
> http://2003gizmo.blogspot.com
> http://www.levforum.com
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere.  Thanks.
> |
> | REPLYING: address your message to [hidden email] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.sjsu.edu/mailman/private/ev/attachments/20120828/390af73a/attachment.html 
_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere.  Thanks.
|
| REPLYING: address your message to [hidden email] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev