Protecting Super-Caps

What is the rep rate of the pulses?

Check out the terminal voltage with a scope and trigger at 70% of the battery voltage to see if it has a sudden voltage drop for few us.

In you case that does not matter, but if the battery is used to power some control circuit, that may cause problems.

The PCB has 6mF of onboard low-esr capacitance that can supply 500A for 25us. The control power, typically 24V, is separate from the high-current rails, 8 to 35 volts.

The sense resistor needs 1.25 volts, and the MOSFET, changed to an IXFH400N075T2 for 500A operation, needs a few volts, the rest is available for the D.U.T.

The battery voltage is almost too high, because beyond delivering 500A for a few half-sine cycles at 60Hz, it the power MOSFET may overheat. See Figure 19 in the datasheet, which shows the thermal mass is used up by 15ms, and heat then flows to the heatsink. I'll need a new version of the PCB, with two or three power MOSFETs.

Hey, Mikko OH2HVJ, you wanna play with one of these PCBs?

You could reduce the power dissipated by the MOSFET with a power resistor (of appropriate R and W) in series with the battery.

Flyguy wrote in news: snipped-for-privacy@googlegroups.com:

They called you a wastoid back in school too, eh?

After a short search nothing showed up, But it does reference two different papers written in 2016, so it's not real old. Mikek

As Win says, "that's a lot of heft, for only 8ms."

low ESR prismatic Lipo can probabkly do it, that's those pocket sized jump starters.