A123 20AHr Pouch Cell Battery Build & Info Thread

[potatorage]

The positive tab is always folded over the negative tab. I purchased some solder that contains flux advertised for soldering to aluminum, but the joints are extremely difficult to make and it takes forever. Not to mention they aren't very solid either.

[ohzee]

heck id get a small heavy duty whole punch and just attach some small bolt/nuts.

I think trying to solder is out of the question.

[megacycle]

To get around soldering if your having problems, a lot of us are , could put lead between tabs and clamp around tab with a u shape of say copper, and I'm not sure were you live but some countries use earthing clamps to bond items to earth they are a small C clamp with screws for clamping to thin guage items and usually have a ring lug for connection could make them if your your handy, bent copper and set screws.
Another way is a termi-foil crimp (the weapon of choice ) if you can get some, squeeze on tabs, secretions bite in.
Good luck.

[teklektik]

Another way is a termi-foil crimp (the weapon of choice ) ...

Termi-Foil crimp! Who knew?

termiFoilCrimp.jpg (6.35 KiB) Viewed 875 times

[docnjoj]

Another way is a termi-foil crimp (the weapon of choice ) ...

Termi-Foil crimp! Who knew?

termiFoilCrimp.jpg

They were in a thread (this one?) a while back when Peter Perkins posted about them. They ain't cheep and dont exaactly fit the tabs. Also the crimp tool is about 1000 USD. I believe there was some discussion about trying to make a proper crimp tool from locking pliers. Luckily agniusm came through before anyone got too serious about them, but the idea seems sound.
otherDoc

[teklektik]

They were in a thread (this one?) a while back when Peter Perkins posted about them.

Oops - caught as a casual tail-of-the-thread reader!
You are quite right - here's the post - Thanks!

[agniusm]

Why cant it be drilled 3mm and balance wire bolted through?

[megacycle]

If you did end up sourcing termi-foil, which are like $0.50 each or a sample, could be less than a bolt price and are made for foil connections, similar to this and can be pressed on in a vice, besides Agniusm is right about a bolt, termi-foil punctures the tab too, same as a bolt hole would, just won't look as sexy IMO.

[EVPowers]

I've been down the termifoil path guys, and they require a minimum 2,000 piece order.
Price to the consumer would be about $1.25-$1.50 per connector.
Also there is a 12-14 week lead time.

I'd do it, but I'm not sure I'd ever be able to recoup the money.
Anyone wanna' go in on it with me? (Half serious here.)

I have some at my shop and it can be a bit tricky to correctly crimp.
Their "official" crimping is $600+.

You can make a poor man's termifoil connector with some copper and a hammer and nail.
I have pics somewhere around here.

[megacycle]

http://www.futureelectronics.com/en/Tec ... ICS5513395

Go half, 1/3rds, sorry 1/5ths dont need that many yet, got $50 spare.

Because we're on balance leads it only has to take say 10 amps max.
So maybe could use copper foil and a meat tenderizer half

[EVPowers]

Butt splices you linked to are not the same as the one in teklektik's post.
Cost is much different.
I notice that even on the butt splices there is a 500 piece minimum order and they do not stock them.

[drutledge]

I realized I never finished my build posts and thought I'd add some shots of my finished project.

I used ''Garolite' (think thin fiberglas) along with some strips of spring steel in between to add rigidity when then plates are clamped together. I threaded each bolt through some thin tubing to reduce conductivity between the pouches and the bolts. I placed some very thin,somewhat rigid foam between the two end pouches and the plates to better keep everything in place.

I've used this pack for about 500 miles and 30 recharge cycles. So far so good.

IMG_2772 3.58.43 PM.JPG

(247.83 KiB) Downloaded 4 times

[ambroseliao]

Beautiful! Do you have any shots of your pack on your vehicle?

[megacycle]

Butt splices you linked to are not the same as the one in teklektik's post.
Cost is much different.
I notice that even on the butt splices there is a 500 piece minimum order and they do not stock them.

These are a different splice to those being considered on the Honda forum, as my set up was different and i did a fair amount of research on using them for a pack, in saying that the application considered in this thread is for balancing which is usually < 10A.
Its a shame they are not in stock,
I might bite the bullet in the near future and buy 500.

[999zip999]

I made one out of copper I forgot to heat it up and drop it in water befor folding. As you fold on it will harden and maybe crack.

[megacycle]

Yeh you can get annealing happening, which you dont want, not plumbing work
But if its just thin guage bar can just squeeze it in vice or pliers if you grunt

[999zip999]

Cut up a cheese grater like stuff made out of ? Only 2amp sense wire ?

[megacycle]

Yeh if you had a crimper that had cheese grater like die and it folded back peircing section, yippy yi yah.
I reckon Ive seen something like that, hmm wish i hadn't destroyed so many memory cells .

[999zip999]

Yes you want it to grip without tearing it up with holes ( the tab ).

[oatnet]

The positive tab is always folded over the negative tab.

Is this just your routine, or do you feel this adds something to the build?

I purchased some solder that contains flux advertised for soldering to aluminum, but the joints are extremely difficult to make and it takes forever. Not to mention they aren't very solid either.

You mention it "takes forever" so I have this picture of you holding a 100w soldering iron against the tab for entire minutes. Heat degrades your cells. How hot are you getting the cell, when you get the tabs hot enough to solder? Is the tab material brittle after you heat it? If you flex the tab, does the solder pop right off?

Also, from your pictures, I can't tell if you only fold the tabs over once, or perform the minimum of (2) folds required to lock the cells together. With two folds to hold the balance wires, there is no need for solder them in place, just jam them into the first fold and crimp them down. Here are some pictures/instructions I posted a few years ago:

http://www.endless-sphere.com/forums/viewtopic.php?f=6&t=12461&start=60#p281360

[flexy]

I am about to assemble a 24s 6p pack for my scooter,

I have been trying to come up with a method of connecting tabs from one 6p group of cells to the next
I need a low profile connection due to lack of space.

I have considered the following;

1.5 mm copper plate which I can bend and drill as necessary, this would be clamped with bolts or self tapping screws through the tabs


I also thought hose clamps could be used with sections of copper/alu pipe to provide uniform clamping pressure on the tabs...


Or this with thick blocks of copper and the hose clamp, I would have to get these professionally cut but they would probably handle higher currents (I need 200 A continuous)


Any suggestions welcome.

[999zip999]

A 24s6p or 144- A123 20ah cells ? 120ah.

[megacycle]

Can you bend it on the vertical if you have room, should be well within the pack confines anyhow.
Along the end tab. Edit opposite plane to your first photo.

[jonescg]

At these levels of complexity, a tapped brass block and copper terminations like I showed a couple of pages earlier is probably the easiest way to go. It would be difficult for 1p, but for 2,3 or 4p, I think my clamping method would probably suffice. It's an extension on what Cell_Man did on my 4s,3p A123 packs.

[flexy]

A 24s6p or 144- A123 20ah cells ? 120ah.

I might take it down to 5p (100Ah) this would give enough room for built in charger.

At these levels of complexity, a tapped brass block and copper terminations like I showed a couple of pages earlier is probably the easiest way to go. It would be difficult for 1p, but for 2,3 or 4p, I think my clamping method would probably suffice. It's an extension on what Cell_Man did on my 4s,3p A123 packs.

Are you referring to the PCB with slots? that did look a bit expensive for me but it would be a tidy solution.

Can you bend it on the vertical if you have room, should be well within the pack confines anyhow.
Along the end tab. Edit opposite plane to your first photo.

I was originally going to go with two plates with bolts through to clamp;

this does give good contact and more copper is conducting, but I am a bit concerned about the stress on the top of the cells being squashed sideways, has this caused anyone else problems?