It probably isn't practical for racing since many changes may be needed to
get an edge in competition, but that operation looks like a robot could do
a lot of that work, and then battery packs could be made profitable enough
to pay for the robotics after selling 1000 packs or so.  But you would have
to have a market for 1000 packs.  It would take a bit of doing to ensure
good QA, but some old printer parts and custom jigs would give a table 2-D
mobility and precision.  Some 3-D printed arms could position the cell
tangs and ensure the welder is in position before it made the spot.  If I
was unemployed, this would be a fun kickstarter.

But since I'm a beginner, the large format cells are probably what's best
for me.  Those AMD packs sure are tasty though!

sean


On Tue, Sep 3, 2013 at 3:42 PM, Bill Dube <[email protected]> wrote:

> Making large packs from small cells is the expensive way to build a
> battery pack. However, you get a _lot_ of performance from smaller
> cylindrical cells. That is why people do it.
>
> It is best if the cells are at approximately the same SOC when you weld
> them together, but they don't have to be.
>
> A new cell welder costs ~ $15,000 or more. If you know the parts you are
> looking for, you can get something on Ebay for $3500, maybe less if you are
> patient and hunt around. (The $175 Harbor Freight spot welder will not do.
> You need an entirely different welder.) You need a double pulse inverter
> welder capable of 4000 amps. You need a "fine spot" dual welding head.
>
> You can see the welder in action at:
> http://www.youtube.com/watch?**v=tQkf7jN2D1g<http://www.youtube.com/watch?v=tQkf7jN2D1g>
>
> Bill D.
>
>
> At 11:50 AM 9/3/2013, you wrote:
>
>> If I am going to go with a spot welded pack what battery has a proven
>> track record?  Are they affordable? People used to talk about 1 dollar
>> batteries.  Do these exist?  When buying a thousand batteries what kind of
>> a deal can you get?  Once you make a module these batteries are literately
>> joined at the hip.  Now one charger in effect is needed per module.  I love
>> the concept.  Bill Dube does this.  Can mere mortals do it?  Will a 175
>> dollar Harbor Freight spot welder hold up after thousands of spot welds.
>>  Lawrence Rhodes...
>>
>
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-- 
Sean Korb [email protected] http://www.spkorb.org
'65,'68 Mustangs,'68 Cougar,'78 R100/7,'60 Metro,'59 A35,'71 Pantera #1382
"The more you drive, the less intelligent you get" --Miller
"Computers are useless.  They can only give you answers." -P. Picasso
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