Take the 2-minute tour ×
Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It's 100% free, no registration required.

I have just seen a diagram of the 787 Dreamliner's battery system. In it, the negative terminal is copper and the positive is aluminium.

In a DC system I understood that the current at the supply was equal to the current at the 'sink', i.e. the same amount of current must be passing through both terminals. Why, then are they made from different materials? The only reason I can think of is that it means they could make the copper terminal smaller due to it having less resistance, but I'm just guessing.

enter image description here

share|improve this question
    
I think it hast to do with potential corrosion, but I'm far from being an aviation specialist. –  jippie Feb 20 '13 at 14:46
    
@jippie - apparently the designers of this battery were not aviation specialists, either, given its failures to date. –  Pete Becker Feb 20 '13 at 14:54
    
The terminals are not necessarily the same size: the aluminium negative terminal may also be the body of the battery. –  pjc50 Feb 20 '13 at 15:04
add comment

1 Answer

up vote 1 down vote accepted

The Lithium Ion battery cathode is Aluminum coated with LiMn2O4, the anode is Copper coated with graphite. Here is a link to a mfgr's anodes.

The aluminum and copper are brought outside of the cell for connection. The dissimilar metals can be managed by cladding the aluminum. From the pics of the dreamliner cells, it looks like a triangular intermediate link is connected by rivets to two posts going into the cell.

I am gonna guess that the diagram is not exactly correct, and guess that those triangular links are copper, so the interconnect is not across dissimilar metals.

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.