tips on a quality 24v solid state relay

[HouseHasWheels]

Hi, new to the forum here. I'm looking for some tips:
I need recommendations on a decent solid state relay for a dump-load, that will be switched by my raspberry pi (this part I have down, just need help on the relay).
Here are the specs for what the relay needs to run.

• 25amp (600watt) resistive load water heater element (would prefer a higher rated one than the actual load)
• 24 volt DC.

I'm seeing lots of junk with terrible reviews, so I'm asking here in hopes someone has some sources for quality one.

 

[John Frum]

I've not tested it but, how about this https://www.thornwave.com/collectio...v-80a-dc-unidirectional-solid-state-relay-ssr ?

 

[kouts5]

As you have stated, most of them are junk, BECAUSE they are mislabeled. From what I've seen on youtube the FOTEKs which are all over aliexpress and ebay, although they are rated for example, at 40A, if you check the datasheet of the mosfet they are using, it is rated for 16A. You could either open it up and replace the mosfet with another one that is rated for 30 or 50A (a bit messy modification), or maybe run 2-3 of them at 10 amps each. I haven't found a decent SSR either.

I'd also like to see you raspberry pi idea, as Im looking to do something similar with my arduino.

Edit: I just read that you want to power one water heater element, so multiple SSRs is not an option. You could use a few 100w power resistors instead.

 

[RCinFLA]

I've not tested it but, how about this https://www.thornwave.com/collectio...v-80a-dc-unidirectional-solid-state-relay-ssr ?

For 24v system you have to make sure the SSR breakdown voltage is greater than 35vdc. This SSR is only for 12v system. Manual states 20v max voltage. MOSFET's used have 25v Vds breakdown spec. (three PSMN0R9-25YLD mosfets in parallel). It will handle 80 amps but only for a 12v system.

 

[John Frum]

For 24v system you have to make sure the SSR breakdown voltage is greater than 35vdc. This SSR is only for 12v system. Manual states 20v max voltage. MOSFET's used have 25v Vds breakdown spec. (three PSMN0R9-25YLD mosfets in parallel). It will handle 80 amps but only for a 12v system.

The doco says its good for up to 45 volts.

https://cdn.shopify.com/s/files/1/0156/8492/7536/files/tl-ssr2480dcu_um.pdf?v=1626307988

 

[RCinFLA]

The doco says its good for up to 45 volts.

https://cdn.shopify.com/s/files/1/0156/8492/7536/files/tl-ssr2480dcu_um.pdf?v=1626307988

Looks like their web page on first link has the wrong user manual button link to 12v module.

Model TL-SSR12100DCU, specs 0.25 milliohm input to output, has the three parallel PSMN0R9-25YLD 25v 0.8 milliohm mosfets

Model TL-SSR2480DCU, specs 0.45 milliohm input to output, can't read mosfet part number in manual picture.

Based on model specs it uses 50v 1.4 milliohm mosfets. Likely three parallel PSMN1R5-50YLH mosfet's so it should be fine for 24v system and 80 amps. At 80 amps it will have about 3 watts of dissipation heating.

 

[efficientPV]

Why, if you are able to use a raspberry pi, don't you just buy some real FET and verify they actually work as they should. Many FET are fake and don't meet half their spec. Loading them with just two amps will verify the on resistance. And with a micro you could be doing some real diversion instead of simple on/off.