solderless power tubes  
View related threads: (in this forum | in all forums)

Tower Hobbies
Enter up to 4 keywords or Tower stock numbers
Logged in as Guest



Users viewing this topic: none
  Printable Version
       

All Forums >> Radios, Batteries, Clubhouse and more >> Batteries & Chargers >> A123Racing Support >> solderless power tubes
Page: [1]

Login
Message << Older Topic   Newer Topic >>
solderless power tubes - 8/1/2007 1:08:07 AM   
dcnpaulk


 

Posts: 10
Joined: 5/30/2007
From: New Milford, NJ, USA
Status: offline 		I have been looking at the "solderless power tubes" developed and sold by MEC, http://www.modelelectronicscorp.com/index.php . It uses a "silver power paste" to enhance electrical contact between cells placed end-to-end. The cells are placed in a tube which uses compression from threaded rods and nipples to keep the cells in close contact. They claim these work great for A123 cells and have the obvious advantage in that no soldering is required (no heat, cell replacement easy, etc.) Has anyone used these, any experience with them? Does this idea sound feasible? Is it too good tobe true? I worry about the "silver paste" migrating from the contact point toward the shell and shorting out. TIA for any thoughts on this.

Paul K
       Post #: 1

RE: solderless power tubes - 8/1/2007 1:14:36 AM   
Red Scholefield



Posts: 4779
Joined: 12/8/2001
From: Newberry, FL, USA
Status: offline 		I made up a couple of 4S packs with the Powertubes. I did not use the silver power paste however. The packs seem to perform just as good as my other ones with welded interconnecting straps.

_____________________________

Red S.
AMA 951 Leader Member

(in reply to dcnpaulk)
       Post #: 2

RE: solderless power tubes - 8/1/2007 2:26:08 AM   
dcnpaulk


 

Posts: 10
Joined: 5/30/2007
From: New Milford, NJ, USA
Status: offline 		Thanks, Red. I bought one of those DeWalt 36 Volt packs and am going to make up a few smaller packs. It occurred to me that with these "solderless power tubes", there is no practical way to bring out nodes for balancing, is there? I was planning on using the Cell Pro 4s or the Balance Pro 6s, so I would need these. My understanding is that the a123 cells will not destruct catastrophically like LiPos, but it is still best to balance them, correct?

Paul K

(in reply to Red Scholefield)
       Post #: 3

RE: solderless power tubes - 11/7/2007 1:50:58 AM   
Brad604


 

Posts: 2
Joined: 11/7/2007
From: Seffner, FL, USA
Status: offline 		"there is no practical way to bring out nodes for balancing, is there?"

It can be done.
I used some silver plated copper strips 0.01 x 1/2 inch, cut so the full width contacts the button top, and cut with a 1/8 wide x 1/4 inch solder tab bent at a 90 degree angle. I used a dremel cutoff wheel and #11 xacto and made narrow slits just wide enough to let the tab through. I inserted the tab, then a battery with silver paste, the next battery, etc., soldered the wires to the tabs (quickly). I dremeled a hole/channel in the end caps for the wires (so the wires wouldn't dangle outside), and also soldered to the end pieces. I used two layers of kapton tape to insulate the exposed solder joints on the the tabs. If you try this, make sure to remove all burrs from cutting the strips. I also cleaned the strips with steelwool and alcohol/paper towel before assembling.

I've also seen it done just by drilling some holes, and squeezing the balance wires in between the cells. But that method has less contact area than using 1/2 wide strips. A bit higher losses I'd think, but at 30 amps probably ok. My motor pulls 70 amps though, so I wanted to do it right.

Note about A123. The button part you normally think of as the top of a battery and the positive terminal is actually the negative terminal. The case is positive. Learned that the hard way and had to take it all apart to fix...

Anyone know of a source for good quality silver paste, that's less expensive than the stuff MEC sells?

(in reply to dcnpaulk)
       Post #: 4

RE: solderless power tubes - 11/8/2007 2:38:19 AM   
dcnpaulk


 

Posts: 10
Joined: 5/30/2007
From: New Milford, NJ, USA
Status: offline 		That is a very clever solution! Not being so creative (and also cheap!), I decided to do it on the cheap. I used the side-by-side cell configuration as in the DeWalt batteries, keeping the tabs in place whenever possible (good for 4 and 5 cell packs). When necessary, I used commercial bars to link cells (solder to the tabs, not thecell). I found that for my purpose the side-by-side configuration fit the bulkhead spaces in my planes just right! I would have had problems with long sticks. Not being able to find the right size shrink tubing for these packs, I used glass fiber strapping tape, the kind used for heavy duty pqckage sealing. This tape I found is extremely light and tough. It also has good dielectric insulating properties. Soldering balancing nodes to the tabs was no problem.

(in reply to Brad604)
       Post #: 5

Page:   [1]
All Forums >> Radios, Batteries, Clubhouse and more >> Batteries & Chargers >> A123Racing Support >> solderless power tubes
Page: [1]





Jump to:


Google 



Search | Marketplace | Event Calendar | Local Clubs | Magazine | Product Ratings | New Products | Discussion Forums

Photo Gallery | Member Video Posts | RCU Video Gallery | Instructor Search | Field|Track|Marina Search

Advertisers | Hobby Vendor Resources | Rate Manufacturers | Sign In/Sign Up

SITE MAP!   : :   FORUM RULES

© 2001 - 2007 24-7 RC, LLC, all rights reserved.

Charities we support that also need your help
Yorkie Rescue | Humane Society | ASPCA | Crohn's-Colitis America

Kaango.com Classifieds

0.578RCU1