Matronics Email Lists :: View topic - 12V batteries in series

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

12V batteries in series

Matronics Email Lists Forum Index -> AeroElectric-List

View previous topic :: View next topic

Author Message

rtitsworth

Joined: 16 Jan 2006
Posts: 76
Location: Detroit, Mi

Posted: Tue Apr 03, 2007 7:10 pm Post subject: 12V batteries in series

Bob, etal



I'm wiring two 12v batteries in series (to make a 24 volt battery).  The

batteries I'm using (Panasonic) have threaded posts as terminals.  The

(+)and (-) terminals are symmetric, so placing the batteries back-to-back,

places the intermediate terminals close to each other (~1.5" apart).  The

batteries will be physically clamped together in the mount and are in the

tail (relatively low vibration).



Question:  How to best "wire" the intermediate (+) and (-) terminals

together?



1. I can make short leads from welding cable (like the other main battery

connections).  But, this uses much more material than necessary and creates

a space/routing problem in the battery mount/box.



2. I can make a short connection strap from some bar stock (assume approx 1"

x 2.5" x 1/8" or 3/16" thick) with two holes to mate with the threaded

terminal posts.  What to make the strap from???



Copper - good conductivity but eventually corrodes

Aluminum - lighter, but corrosion (al oxide) in not very conductive

Steel - ??? Most vibration resistant?



What about plating any of the above?  i.e. Copper with Tin or Nickel

plating.  (I have access to a professional plating shop).



Rick Titsworth

Lancair ES - building.

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

BobsV35B(at)aol.com
Guest

Posted: Tue Apr 03, 2007 7:23 pm Post subject: 12V batteries in series

Good Evening Rick,   

 Way out of my area, but what would you think about using a soft copper  strap with a U shaped excursion to absorb any vibration or temperature caused  movement? 

  

 I would use a strap about 3/4 of an inch wide, one sixteenth of an inch  thick and with the U shape about an inch high (or low!). I would make it by  making a ninety degree bend, go up (or down) about three quarters of an inch to  one inch, make a one eighty back to where the U started, another ninety and  off to the other battery.

  

 Nickel plating sounds like a great idea.

  

 Your thoughts?

  

 Happy  Skies,



Old Bob

AKA

Bob Siegfried

Ancient Aviator

Stearman  N3977A

Brookeridge Air Park LL22

Downers Grove, IL 60516

630  985-8503



  

 In a message dated 4/3/2007 10:11:49 P.M. Central Daylight Time,  rtitsworth(at)mindspring.com writes:

  	  Quote: 	
		  Bob,    etal



I'm wiring two 12v batteries in series (to make a 24 volt    battery).  The

batteries I'm using (Panasonic) have threaded posts as    terminals.  The

(+)and (-) terminals are symmetric, so placing the    batteries back-to-back,

places the intermediate terminals close to each    other (~1.5" apart).  The

batteries will be physically clamped    together in the mount and are in the

tail (relatively low    vibration).



Question:  How to best "wire" the intermediate (+) and    (-) terminals

together?



1. I can make short leads from welding cable    (like the other main battery

connections).  But, this uses much more    material than necessary and creates

a space/routing problem in the battery    mount/box.



2. I can make a short connection strap from some bar stock    (assume approx 1"

x 2.5" x 1/8" or 3/16" thick) with two holes to mate with    the threaded

terminal posts.  What to make the strap    from???



Copper - good conductivity but eventually corrodes

Aluminum    - lighter, but corrosion (al oxide) in not very conductive

Steel - ??? Most    vibration resistant?



What about plating any of the above?  i.e.    Copper with Tin or Nickel

plating.  (I have access to a professional    plating shop).



Rick Titsworth

Lancair ES -  building.



	


 





See what's free at AOL.com. 

  [quote][b]

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

nuckollsr(at)cox.net
Guest

Posted: Wed Apr 04, 2007 6:25 am Post subject: 12V batteries in series

At 11:09 PM 4/3/2007 -0400, you wrote:



 	  Quote: 	
		  

<rtitsworth(at)mindspring.com>



Bob, etal



I'm wiring two 12v batteries in series (to make a 24 volt battery).  The

batteries I'm using (Panasonic) have threaded posts as terminals.  The

(+)and (-) terminals are symmetric, so placing the batteries back-to-back,

places the intermediate terminals close to each other (~1.5" apart).  The

batteries will be physically clamped together in the mount and are in the

tail (relatively low vibration).


	


     But not zero vibration. Battery terminals are designed

     with limited structural integrity to mount conductors . .

     the lighter and more flexible the better. With lead posted

     batteries, there's real risk of stress cracks taking the

     post of entirely. Batteries with molded in threads are

     at risk for loosing the hermetic seal around the posts.

 	  Quote: 	
		  Question:  How to best "wire" the intermediate (+) and (-) terminals

together?



1. I can make short leads from welding cable (like the other main battery

connections).  But, this uses much more material than necessary and creates

a space/routing problem in the battery mount/box.


	


     A 3" piece of 4AWG with a couple of soldered or crimped terminals

     represents a space problem?



 	  Quote: 	
		  2. I can make a short connection strap from some bar stock (assume approx 1"

x 2.5" x 1/8" or 3/16" thick) with two holes to mate with the threaded

terminal posts.  What to make the strap from???


	


     Be wary of connections having considerable stiffness at

     right angles to the terminal. 0.064 sheet brass from a hobby

     shop is thick enough. These displays from K-S Engineering

     are found in many hobby, craft and hardware stores. They

     have small pieces of sheet brass.



http://tinyurl.com/286hsn

http://tinyurl.com/2638yx



     Their p/n 248 is an .064 x 1 brass strip that is highly

     suited to jumpers between robust studs like the pictures

     shown here:



http://www.aeroelectric.com/Pictures/Wiring_Technique/Contactor_Interconnect



     But to avoid having the sheet stiffness bear against the

     battery terminal, you'd want to make an "omega shaped"

     jumper that stands up 1/2 to 1" above the surface so that

     motion between the two terminals does not induce stress

     due to the relative stiffness of the jumper.

 	  Quote: 	
		  Copper - good conductivity but eventually corrodes

Aluminum - lighter, but corrosion (al oxide) in not very conductive

Steel - ??? Most vibration resistant?


	


     It's not the jumper that's at risk . . . but the

     battery terminals. Conductivity for so short a connection

     is not a serious issue but ability of the material to

     "give" under pressure of the threaded fasteners is what

     works toward a gas-tight joint. When the joint is good,

     the plating becomes a minor concern for longevity. If

     you used a 4AWG jumper and tin plated copper terminals,

     you will have selected a combination of materials designed

     and proven to meet design goals for connective integrity.

     If these are RG batteries, why a battery box? Adding an

     enclosure around an RG battery has offers no mechanical

     or operational advantages over simply strapping open

     batteries into a tray that captures the footprint.



 	  Quote: 	
		  What about plating any of the above?  i.e. Copper with Tin or Nickel

plating.  (I have access to a professional plating shop).


	


     Sound's like a good way to spend a lot of $time$ to

     work around a $2 jumper that you can build up in about

     ten minutes with a small torch and some house wire for

     "wedges" . . . see:



http://aeroelectric.com/articles/big_term.pdf



     A 3-4" piece of welding cable would be fine for

     the conductor. I need to update this article. Bernzomatic

     has a really nice ST-100T, $10 butane torch

     offered at places like Home Depot. I demonstrate

     these and give them away at my weekend seminars. VERY

     nicely built and the price is right. See:



http://tinyurl.com/37qyxf

http://tinyurl.com/3a933o



     Bob . . .

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

rtitsworth

Joined: 16 Jan 2006
Posts: 76
Location: Detroit, Mi

Posted: Wed Apr 04, 2007 9:31 am Post subject: 12V batteries in series

BobN,   

Thanks for the reply.  Some follow-up comments/questions...  

   

I'm not against #4AWG and crimped/soldered ends, but when placed face-to-face, the battery terminals are only 1.5" apart.  The top terminals are in a recessed area (below the top battery surface) and thus really only accessible from the sides (see attached photos.)  

   

The short side of the batteries are nearly flush with a bulkhead (~.25” gap), so the terminals are then really only accessible from the long side.  

   

If I tried to make a #4 AWG wire to connect the face-to-face pair, them the crimped/soldered ends would been less than 1/4” apart (essential the ends would just be soldered together, stiff).  

   

I could make a vertical "omega" strap, but if the paired batteries are secured together, I'm not sure I see how the two posts vibrate relative to each other?  Rather, I was thinking that the terminals are only exposed to the load(s) due to attempting to accelerate (vibrate) anything connected to them.  The direct connecting strap would be relatively light and so little load would be imposed to the terminals.  Furthermore, I’m thinking that connecting something solid to both terminals cuts the force imparted to each in half. ???  

   

The K&S suggestion is helpful.  I was thinking that I needed something thicker (i.e. 1/8")  

   

As an alternative, I could arrange the batteries back-to-back, but then the connecting wire would need to run around the outside perimeter (> 18”).  Perhaps that is best???  

   

Additional thoughts/comments???  

   

Rick  

   

   

--

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

Panasonic.jpg

Description:

Filesize:

30.98 KB

Viewed:

114 Time(s)

Arrangement.jpg

Description:

Filesize:

27.11 KB

Viewed:

119 Time(s)

nuckollsr(at)cox.net
Guest

Posted: Wed Apr 04, 2007 3:10 pm Post subject: 12V batteries in series

 	  Quote: 	
		  



I could make a vertical "omega" strap, but if the paired batteries are 

secured together, I'm not sure I see how the two posts vibrate relative to 

each other?  Rather, I was thinking that the terminals are only exposed to 

the load(s) due to attempting to accelerate (vibrate) anything connected 

to them.  The direct connecting strap would be relatively light and so 

little load would be imposed to the terminals.  Furthermore, I m thinking 

that connecting something solid to both terminals cuts the force imparted 

to each in half. ???


	


     When you have two chunks of lead like these

     you only 'think' you have them strapped together.

     It's not the weight of the strap but the weights

     of the two batteries and the inability to make them

     absolutely immobile to each other for all modes of

     vibration.



 	  Quote: 	
		  



The K&S suggestion is helpful.  I was thinking that I needed something 

thicker (i.e. 1/8")


	


     No, nothing nearly that thick. All I can do is

     give you best practices based on having torn a lot

     of stuff up in qualification testing that I thought

     was pretty robust. Give it a try. What you've proposed

     will probably be okay.



     Bob . . .

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

Display posts from previous:

	Matronics Email Lists Forum Index -> AeroElectric-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum