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DPDT high-current contactor needed

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jmcburney(at)pobox.com
Guest

Posted: Sun Mar 16, 2008 6:05 pm Post subject: DPDT high-current contactor needed

Hi, Listers,



I need a manually operated double pole double throw contactor that will

carry (not make or break) up to 400 amps.  I'm building a 14v system, but my

engine requires 24v to spin the starter.  My plan is to install 2 batteries.

Normal configuration will be parallel for charging and normal running, but

switching one battery into a series configuration for starting.  Actual

starting will be with a starter contactor, so the dpdt contactor won't make

or break the starting current.  Any thoughts on where I could find such a

contactor?



Blue skies and tailwinds



Jim

CH-801

DeltaHawk diesel

Augusta GA

90% done, 90% left

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nuckolls.bob(at)cox.net
Guest

Posted: Mon Mar 17, 2008 6:00 pm Post subject: DPDT high-current contactor needed

At 10:02 PM 3/16/2008 -0500, you wrote:



 	  Quote: 	
		  



Hi, Listers,



I need a manually operated double pole double throw contactor that will

carry (not make or break) up to 400 amps.  I'm building a 14v system, but my

engine requires 24v to spin the starter.  My plan is to install 2 batteries.

Normal configuration will be parallel for charging and normal running, but

switching one battery into a series configuration for starting.  Actual

starting will be with a starter contactor, so the dpdt contactor won't make

or break the starting current.  Any thoughts on where I could find such a

contactor?


	


   The last time I saw a series-parallel battery controller

   it was a about half the size of a breadbox, weighed about

   10 pounds and cost a couple of grand. Of course, this was

   an electrically engaged/disengaged device. It was a WWII

   era design. I think a Hartman product. Not part of their

   current bag of tricks that I could see . . .



http://relays.tycoelectronics.com/hartman.asp



   I'm unaware of any manually operated device for this

   purpose. On the TC side of the house, we go to a LOT

   of effort to avoid a need for such agility in battery

   management.



   Here's a drawing I did for a client some years ago

   to address a similar requirement. He didn't need 400A

   so the Stancore/White-Rogers contactors would suffice.

   If this approach works for you, you'll need to consider

   some heavier devices. Perhaps Type 124?



http://www.stancor.com/wrdstc/pdfs/Catalog_2006/Pg_054_55.pdf



   Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

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jmcburney(at)pobox.com
Guest

Posted: Tue Mar 18, 2008 7:05 am Post subject: DPDT high-current contactor needed

Hi, Bob,



I miswrote in my original post, and was graciously corrected off-list by

bakerocb(at)cox.net.  I should have used the term "switch" instead of

"contactor", as what I envision is a dpdt switch, manually operated, that is

heavy enough to carry the ~400 amps that the starter might pull when

engaged.  Normal operating current would be much less, just battery charge

current.  I would throw the switch to "start" before energizing the starter

contactor, giving me 24v at the starter, then go back to "run" position when

starting is complete.  0 amps make and break on the "start" side, few amps

make and break on "run" side, must carry the heavy current when starter is

energized.

bakerocb(at)cox.net gave me a link to Blue Sea Systems, which may have what I

need.  Other suggestions are welcome, though.

Oh, and DO NOT ARCHIVE.  (I forgot that last post.)



Blue skies and tailwinds



Jim

CH-801

DeltaHawk diesel

Augusta GA

90% done, 90% left

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nuckolls.bob(at)cox.net
Guest

Posted: Tue Mar 18, 2008 11:22 am Post subject: DPDT high-current contactor needed

At 10:54 AM 3/18/2008 -0500, you wrote:



 	  Quote: 	
		  



Hi, Bob,



I miswrote in my original post, and was graciously corrected off-list by

bakerocb(at)cox.net.  I should have used the term "switch" instead of

"contactor", as what I envision is a dpdt switch, manually operated, that is

heavy enough to carry the ~400 amps that the starter might pull when

engaged.  Normal operating current would be much less, just battery charge

current.  I would throw the switch to "start" before energizing the starter

contactor, giving me 24v at the starter, then go back to "run" position when

starting is complete.  0 amps make and break on the "start" side, few amps

make and break on "run" side, must carry the heavy current when starter is

energized.

bakerocb(at)cox.net gave me a link to Blue Sea Systems, which may have what I

need.  Other suggestions are welcome, though.

Oh, and DO NOT ARCHIVE.  (I forgot that last post.)


	


   That's what I understood you to mean . . . and the only

   products I've seen to address that design goal were not

   manual devices . . . but custom electro-mechanical

   constructs.



   You can emulate this activity with a series of single

   pole, battery switches that are readily available through

   speed shops. Battery disconnect switches are required

   on most competition vehicles. As long as you throw

   them in the proper sequence, you won't blow any fat

   fuses. My best recommendation is that you use the contactor

   array described . . .



   Perhaps someone on the List has a broader experience/

   knowledge than I and can make a recommendation.



   Bob . . .

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