Kweld spot welder

Darkie02 · November 3, 2019, 6:59am

Kweld is rated up to 2000A then it should self protect
Recommended 1500A supply
Recommended min 1200A supply
Absolute min 800A supply

I would try 3s2p possibly 3s3p I found 1 3s1p 6000ma Turnagy graphite gave me 1200A

3s2p(paralleling a2nd battery) gave me 1800a (added 50%)

I never tried a 3rd as I dident want to exceed the maximum 2000a. Just saying 3 might exceed the units limit of 2000a.

The battery ideal internal resistance and voltage was talked about above

tatus1969:

It’s really just Ohm’s law. Desired current is 1500A. The resistance of the kWeld system is roughly 3.2 milliOhms (stock cables). The weld spot itself contributes another 1 milliOhm typical. This gives 4.2 milliOhms total. To push 1500A through that, you need U = R*I = 6.3V from an ideal battery. For every milliOhm of battery’s internal resistance, you need another 1.5V accordingly. Or in other words, for every volt above 6.3V that the battery has, it needs to have 1 milliOhm of internal resistance to stay in the sweet spot for the current. A 3S battery therefore needs to have 12-6.3 = 5.7 mOhms. Then calculate the power loss in the battery: P = 0.5 * R * I^2 = 6412 W. That explains why they heat up quickly, even though the pulses are short. Now consider a 6S battery. That must have an internal resistance of 24-6.3 = 17.7 mOhms. Then P = 19912W. You see that the power loss in that battery is huge. This is why I recommend 2S to 3S batteries for the welder.