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Old 06-21-2012, 03:09 PM
muffildy muffildy is offline
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Default pack a123 m1a

So i went and got myself 32 of the A123 ANR26650 M1A cells, but now i have a problem of how to connect them into a pack. From what i have read, if i were to get them tabbed, the tabbed cells would be current limited to 50 amps depending on the tab used.
http://www.batteryspace.com/A123-Sys...-2500-mAh.aspx
the above link is the website with the stated 50 amp max use for a tabbed cell; they have a link to a 90 amp copper solder bar, but upon emailing to get more info they stated they discontinued it because it was having problems.

That is not the full power of the cell, so the question is how to connect them and get the full 100 or so amps they are capable of?
I saw that one person who used screws to hold the cells together with pressure, and saw that the cells could explode if you didnt allow the pressure relief valve to operate, so that leaves that out.
I was wondering if maybe i put them into a PVC pipe with a compression spring inbetween each cell might work? that way the pressure relief valve wouldnt be 'plugged'. question then is what spring would be suitable of carrying 100+ amps that is also small enough. or maybe you guys have better ideas?
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Old 06-21-2012, 03:24 PM
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frodus frodus is offline
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Default Re: pack a123 m1a

What format of pack are you building, 32 in series? 16 in series, 2 in parallel?

What is this going into?

Springs will give lots of resistance and be severely limited in current delivery.
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Old 06-21-2012, 03:32 PM
muffildy muffildy is offline
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Default Re: pack a123 m1a

32 in series, this is a pack just for testing purposes and will not be used in the final vehicle.
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Old 06-21-2012, 03:50 PM
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Default Re: pack a123 m1a

Then just solder some copper bits between them. Don't keep the iron on it too long, and make sure the iron is SUPER hot. Melt some solder on, touch it to the tabs, let it flow, then remove.
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Old 06-21-2012, 04:12 PM
muffildy muffildy is offline
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Default Re: pack a123 m1a

that wont damage the battery? i thought soldering was very bad for those cells. Or do you mean melt solder onto the copper tab and then squish it onto the battery?
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Old 06-21-2012, 04:28 PM
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Default Re: pack a123 m1a

I mean, solder copper tabs to the actual cell itself.

Too much Heat hurts the cycle life of the battery, but do you care for a test pack?

Just keep the iron hot so it flows the solder quickly, solder it, remove heat, and use a fan to cool it off.

If you use a "medium" heat iron, it'll take too long to flow the solder, and it very well could damage it.

Guys on endless-sphere (electric bicycle forum) do it all the time. You should go over there and get some ideas.
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Old 06-21-2012, 04:44 PM
muffildy muffildy is offline
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Default Re: pack a123 m1a

i was hoping to avoid damaging the cells, after the experiments were over with i was going to tab them and use them as replacement cells in power tools battery packs.
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