Connecting A123 20ah lithium prismatic cells

Some people on this forum have previously purchased A123 lithium pouch cells and used them for their PHEV projects.

I know that others are considering purchasing these cells for their own PHEV projects but are unsure of how to connect the cells since they have tabs rather than regular battery post terminals.

I wanted to start this thread so we could specifically talk about the connections.

Hopefully some of our experienced members will chime in and possibly share the pros and cons of how they did it. I'll also see about throwing in some info I've seen posted elsewhere on the web. No need to recreate the wheel.

 

Here is one example of connections done by member planetaire Can | PriusChat
His cells were a bit different only because they did not have full tabs to work with.
But you can still get a general idea of the connections.

He, and almost everyone I talk to, says buying cells with full tabs is recommended.
It is too much of a pain to work with the short/cutoff tabbed cells.

 

Here is a link to the tried and true clamping method.
Nuts bolts, and block of metal.
These pics are from evtv. They want $10 apiece for them.
A123 Prismatic pouch cell clamp pic1
A123 Prismatic pouch cell clamp Pic2
A123 Prismatic pouch cell clamp Pic3
A123 Prismatic pouch cell clamp Pic4

I may see if these could be made up by a local shop instead.

 

Exactly.

Another guy down at our shop is considering using an accordion fold to connect the tabs and then crimping a piece of metal over top of the accordion fold. Seems reasonable. Lots of surface area touching, reversible if necessary.

Other person here at the shop put holes through the tabs and bolted together.

I also have some specialty connectors I have been researching. Unfortunately they are a custom order item with a minimum order and they only make a run of them periodically. 6 week lead time. I have some samples and they look promising. I'm waiting to get some other engineering opinions on them before ordering any.

 

I have been researching some options for a while.

Here is a pre-made crimp connector for foil tabs
51943 Product Details - TE

It seems like a very easy solution for most of the needed connections for foil packs.
The current would be carried between the tabs by the crimp connection.
The spade connector could be used for balancing & monitoring.

Here is a link to the technical specs pdf I downloaded.
EV_Powers_Termifoil_51943_Connector.pdf - Google Docs

I still want some confirmation that they can handle the current that we will be drawing. Any engineers want to weigh in?

Downside is that there is a (6-week) lead time on ordering these plus a minimum order.

Depending on cost I'll probably be putting in a group buy/large order for these as well. That way we can get them into the hands of people who need them.

 

These are not a stocked item anywhere. The factory makes them only when there are orders for them. Minimum quantity I must order is 2,000.
They would probably cost something like $1.25.
Now they are saying 12-14 lead time.

 

Great pictures!!
How thick is the copper you are using to crimp around the tabs?

 

With the crimping method it is not too bad to replace a cell.

Just wanted to note that the hole in the pouch cells Jack showed is there from a previous connection method. The hols is not needed for the crimping method.
The old method involved a three nut/bolt combo. Plates on either side of the tabs, a nut/bolt combo through the center of the tabs, and two nut/bolt combos just past the edges of the tab.