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Curious on your thoughts for an application and the pros and cons of using a relay or a MOSFET or IGBT.

The application involves switching a 96V lead acid battery pack on and off for periods of 5 minutes upto 1 hour, there is no PWM involved so just hard switching. The load is just resistive and the current will be in the region of 20A.

For this sort of application I like the idea of a MOSFET as lower drive current and voltage, but would be interested in the pros and cons as far as reliability etc.

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  • \$\begingroup\$ Would a solid state relay do the job? \$\endgroup\$
    – hedgepig
    Commented Jun 15, 2016 at 19:18
  • \$\begingroup\$ A MOSFET SSR would be a nice choice, but I don't believe you will find it for the same money as electromechanical relay, so you'd better go with a relay. IGBTs are for HV, they have a voltage drop. \$\endgroup\$
    – Marko Buršič
    Commented Jun 15, 2016 at 19:43
  • \$\begingroup\$ Keep in mind, that a good candidate for SSR is N-MOSFET with charge pump, meaning that you will have the the intrinsic diode conducting backward, or you have a comination of ideal diode + switch. This is how it looks like, but not for such voltage range:ebay.com/itm/… \$\endgroup\$
    – Marko Buršič
    Commented Jun 15, 2016 at 19:53

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20 A is probably too low to justify the forward voltage drop of an IGBT versus spending the same money on MOSFETs.

Relay is the cheapest option but reliability will suffer since they can stick and wear over time if you switch them often.

MOSFETs are the better option if you can afford it over relay.

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  • \$\begingroup\$ Afford it over a relay? Given the requirements, I wouldn't say a relay would be cheaper than a mosfet. And that is almost never the case. \$\endgroup\$
    – dim
    Commented Jun 16, 2016 at 20:22
  • \$\begingroup\$ @dim Every cheap charger I have taken apart and even my 400 A jumpstarter has relays in it. If lifetime isn't a concern, it's a cheap and good option. \$\endgroup\$
    – winny
    Commented Jun 17, 2016 at 6:40

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