tabless A123 ?
Posted: Fri, 02 Dec 2011, 13:43
EClubman wrote: Can I suggest that these staples are great quick and dirty way to connect tabbed cells for testing on the workbench, but definitely NOT what you want in a pack for an electric vehicle.
These jobbies were designed to hold a wad of paper together in an office environment, not conduct up to 600A of current in a dirty, vibrating EV pack.
Conductivity, corrosion, area of contact patch, what happens if one should come loose inside the battery box.
I think that something like a braided cell interconnect folded over the two connecting tabs and then a bolt through the middle to hold it all toegether would be much more robust. (Though then you have the issue of how fat this connection is compared to the width of the cells to deal with)
not proposing that the clip conducts power , clip only holds the contact faces together.
there are medium and heavy duty versions of these clips , and while i will point out i have not tested any yet on the bench , if they are found to be too light then there is opportunity to have a few thousand heavier ones pressed up in your pick of the 500 sheet metal companies around the country who could do so
manufacture and cad plating might cost 8 - 20 cents per clip
there are many photos on the web of machined blocks used to clamp them together . they are too bulky and expensive IMHO , probably costing $ 6 - 15 per each.
i would not be drilling holes through the tab
my proposal was to use two clips per tab , have a copper bus bar plate at least 1mm thick under the clip on each side where the tabs are mated , and where a connector is fastened to a tab you would use a mini bus bar of around 1.2 - 1.6 mm thick ,and use conductive grease or bonding agent between each tab and bus bar joint
have you looked at the thickness of the tab material ?
whats the point in having an 8 mm conductor bolted to a 0.4 mm thick tab ? ( i am guessing btw - i didnt measure one yet )
there will be a more elegant solution to this.