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Solid State Power Relays

EFI Wiring Fundamentals

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Discussion and questions related to the course Motorsport Wiring Fundamentals

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I am not using a PDM in my setup, but was thinking of using a simpler solid-state relay block, called the Amplink. Do you think this would work well as a dedicated set of EFI relays? It offers 6 x 20A circuits, with a max current draw of 60A. You can toggle the relays and configure via a Bluetooth app. It is limited to 3 different triggers (low or high side), but I think that would work fine with: Ignition + Fuel Pump trigger (ECU) + Radiator Fan trigger (ECU). 20A is more than enough capacity for my fan and fuel pump.

Interested to hear if you think this would be a nice, compact EFI relay solution:



or you could just use $10 relays. It will take the same amount of wiring. The only reason for solid-state relays is if you are trying to control a device with pulse-width-modulation. PWM with Solid-State Relays is used for speed control on pumps & fans.

Depending on your fan motor design, and the possible spikes, this bit may be an issue "Amplink outputs are not capable of sustaining repeated fly-back voltage spikes from inductive loads".

It doesn't seem to have a price, so hard to say if it is preferable to a bank of fused relays which, like David, might be my preference - maybe with intelligent fuses that reset. One of the big advantages of PDMs is the ability to use auto-reset and intelligent load sensing, but that doesn't seem to be an option here?

If you need PWM, it would have potential, as mechanical relays are very poor in that application. It also does appear to be fairly compact, so as that seems to be a criteria, why not if the price is reasonable?

My personal opinion is that at 250US$ a piece, I would probably go with mechanical relays as well, controlled via the ECU. If you are not using a PDM for the rest of the car, why use it only for the fan and fuel pump?

Thanks all. It's available for 215 USD. I figured that a traditional relay setup would probably run around 100 USD when you include everything.

One of the attractions for me is the small size of the thing, since I have a tiny car: 3" x 2" x 1". What are the approx. dimensions of a 6-relay unit? They seem a lot bigger when you include the standoffs for all the wiring?

I technically am using a PDM for the chassis harness (in the sense that it is solid-state, but it is not a fancy CAN one). It does not have enough outputs for EFI functions, though.

Good point about the fan - I will ask about that.

Lookup the Eaton Bussmann power distribution available at Waytek in the US. That is what I have just picked up and has enough scope to wire my whole car for around the $180USD mark.


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