Hi, Sokapu, Texaspyro and every body.
"52F is very, very big, probably massively too big for a CD welder for this application. I can blow holes in the end of cells with just under 2F at 20V, which equates to about 400 Joules of energy. Even at the lowest practical voltage for a welder of this type, around 10V, a 52F capacitor would deliver 2600 Joules; charged to 20V a 52F capacitor would deliver a massive 10,400 Joules, around 26 times more than the maximum you need." p 32 of the forum Jeremy Harris said.
and he continued:
"The big risk with using the big capacitor/lower voltage approach will be heating. The weld current pulse length is determined by the total circuit resistance and the capacitance, rather than the voltage
. If we assume that the total circuit resistance is around 30mohms (capacitor ESR plus wiring and weld resistance loss), then the weld current time constant will be 1.56 seconds, which is massively too long. The weld needs to take only around 50mS to 200mS, which would be achieved with a capacitor of between 1.6F and 6.7F.
1) Where do these "400 joules" come from as good energy to the job? Experimental or scientific argues?
2) what is the formula to obtain the result above ( 1.56 s for heating steel and+- 400J pass through ( diffuse? ).
3) If Jeremy is right,( it's only an hypothese
) he is not wrong, and so (I repeat again my question) Why i can not weld with high capacitance, low esr, low voltage, ? please explain me, i don't understand...thanks
4)for caps follow this link : http://www2.mouser.com/Passive-Componen ... dfZ1z0ixu8untill 0.28 m ohm esr!!!