Using solid state relays (SSRs) on cars

[@2slofouru]

The current and voltage are obviously important, but another spec that needs to be mentioned is the highest PWM frequency in Hz the SSR can operate at. Even the best/highest priced SSRs can only operate at a max of 1kHz. That may not be ideal for something like a fuel pump, so far as longevity are concerned. A fuel pump would benefit from a controller that switches at a fairly high frequency, preferably also past the range of human hearing for example.

[@JulianEdgar]

Yes, if you intend pulse width modulating (PWM) it, you should also pay attention to this spec.

[@railgap]

Because of heat, a car is one of the worst possible applications for an SSR. Because of how hot "ambient" (under a car hood, in the summer) gets, the required heat sinks are enormous. I'm stunned you didn't cover this.

[@JulianEdgar]

I thought it so obvious that you don't place heatsinks in hot environments that no, I didn't cover it.

[@billwilliams6338]

Yes thanks Chrysler and Dodge use TIPM, do you know anything about CAN buss signals? The TIPM using a bunch of SSR relays but I'm not sure why cars use SSR relays, any reasons why?

[@JulianEdgar]

Correctly specified SSR relays never wear out. CAN is covered in my book Car Electrical and Electronic Systems - www.amazon.com/Electrical-Electronic-Systems-Julian-Edgar/dp/1787112810

[@ml5554]

good explaining👍

[@JulianEdgar]

Thank you 😃

[@billwilliams6338]

JULIAN EDGAR, Does SSR relays use JFETS or MOSFETS? and why are SSR relays better compared to other relays?

[@JulianEdgar]

MOSFETS I think - but I am not certain. The advantages of SSRs are covered in the video.

[@railgap]

@@JulianEdgar You're presuming to school people on SSRs and you didn't know the answer to that question? You got a lot of balls, buddy.

[@billwilliams6338]

Juilian Edgar, How does a TIPM work or what does it do, i seen relays on TIPM works often

[@JulianEdgar]

TIPM seems to be a Chrysler specific product? A box with mechanical and solid state relays, perhaps? For company specific products, best to look them up on a web search.

[@amiabledave50]

Do you need to put an inline fuse or circuit breaker on both supplies?

[@JulianEdgar]

You can do that, yes.

[@Adam-hs5pn]

How hot do these get when running a big load like a cooling fan or something? Do you need them to be in pretty well ventilated space or fine to have them buried away in an enclosure?

[@JulianEdgar]

When running a big load you would usually mount the SSR on a heatsink and then have that somewhere relatively cool (ie not near a hot exhaust manifold). I wouldn't put one in a sealed enclosure if running a big load.

[@dharmendrasuthar4342]

What is the meaning of 80dd 100dd mentioned on ssr? 🤔

[@railgap]

mfr's model no.

[@aaaaaaaaaaaaaa4151]

How are these for an extra injector driver, taking a signal from one of the cars injectors? thanks

[@JulianEdgar]

Yes you could do that, but normally there are better ways of adding the extra fuel. What is the project?

[@aaaaaaaaaaaaaa4151]

@@JulianEdgar thanks for getting back to me, I have a motor cycle, GSXR1000, with a turbo, these engines are very good, but the cranks can not stand any pre ignition, Im wary of having a glich in the fueling, so trying to keep it simple, so looking at adding extra injectors & using a FMU. I was thinking of having double relays just in case one went down. I have used a piggy back before which had a driver go down, I feel uncertain about being too complex.

[@JulianEdgar]

@@aaaaaaaaaaaaaa4151 An extra injector then requires the intake manifold to flow a fuel/air mix (not just air) leading to potential variation from cylinder to cylinder. Can't just use a rising rate fuel pressure regulator, perhaps with slightly bigger injectors?

[@aaaaaaaaaaaaaa4151]

@@JulianEdgar I have mounted a injection rail with 4 injectors, they shoot down each throttle bore. this camme from a Honda 1100 sports bike, so lots of capacity & very cheap too. Are you the man behind the Jaycar projects?

[@JulianEdgar]

@@aaaaaaaaaaaaaa4151 OK, four injectors sounds better than one. I co-designed most of the Jaycar automotive projects.

[@charleshayes1771]

So Output... Positive = Common. And Negitive = NC/NO

[@JulianEdgar]

No N/C on a solid state relay. Just think of it as a normally open switch that is polarised (ie has plus and minus terminals).

[@railgap]

Fotek relays are so cheap, they cannot be heat sunk unless you mill the base flat, since A) it's rounded and B) there is a screw sticking out of it!! Inside, you will find a switching device (often a triac instead of SCRs - very bad) which is rated anywhere from half to 1/10 the nameplate rating. Anyone who specifies cheap SSRs like Fotek is either ignorant, or has accountants for masters.