[chbot] Battery spot welder
helmut.walle at gmail.com
Wed Jun 2 09:28:48 BST 2021
from memory... there is no shortage of battery spot welding tutorials on
Youtube. The quick and dirty DIY method essentially consists of an old
car battery (a new one would theoretically do as well, but as your
project is about recycling, using new equipment might be self-defeating
in this case) and a few wiring cut-offs (again, thinking up-cycling
here), something like 2.5 mm^2 single-strand insulated copper wire. The
conceptually simplest (no built-in safety - so that would be something
to add for any practical application) method connects a piece of wire to
each battery pole, and then the ends of both wires are pressed down onto
the nickel strip that is to be welded onto an end of a cell, with the
contact points about a couple mm apart. The exact current probably does
not matter too much, as long as it is high enough to get the required
amount of energy into the welding spots quickly (slow-cooking would lead
to excessive heat dissipation, which is neither good nor safe for the
cell being welded onto). Experiment to get the timing right (and as
target times ought to be something like a second or even shorter, this
may require an electronic timer and a beefy contactor for switching the
welding current), keeping in mind the amount of energy is proportional
to I * I * t, where I is the welding current, and t the duration... the
welds should hold better than the surrounding nickel strip; so if you
are trying to pull the nickel strip off it should tear. If the nickel
strip comes off easily without visible damage to the strip, the energy
was too low, and the weld did not get hot enough.
And make sure you get the appropriate nickel strip for this purpose (I
believe it's something nickel, but don't take my word for it.).
That's it in a nutshell; HTH & YMMV.
Keep us posted on path chosen and outcomes, please.
On 2/06/2021 09:02, Marshland Engineering wrote:
> I've got heaps of old batteries. Some may be worth recycling. There are many
> types and brands of spot welders on Aliexpress. There seem to be 3 options,
> battery, supercap or mains with a microwave transformer. Can anyone recommend
> one, or, a good reliable method including what probes to use.
> Thanks Wallace
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