right relay

[chpr1972]

Went to Napa today to get a 20 amp relay as backup for my HP EFI. Their relays do not have an amp rating. I took the tyco number off the original relay and called tyco and they gave me a gobbley goo run around as what the relay is actually rated. According to her it is rated at 16v and 30 to 90 amps. I had the same problem with Tanks inc. when I called them and he said read the flow chart amp and choose from there. I finally got the info out of him to use a 25/30 amp relay.The pump spikes at 22 amps and runs at 15 amps.] I realize that different fuel psi might use different amp rates but they should list a max amp rating for their product as that is to protect their product as well as the vehicle.
It use to be relays ratings was shown on the product. Products had max or recommended ratings.



Is my old brain wired wrong? Will any old relay work?

Can the manufactures not put recommendations on their products in plain sight? They give you such info as it is a 12v system and requires 14.3+ volts to work properly. They give you a whole bunch of DO NOT ....... or the ? will main or kill you!

Can they not understand that most of their customers are not shops but little guys who do not understand all the super tech BS?

[andrewb70]

Relays are definitely rated:

https://www.waytekwire.com/products/1401/Relays/

Andrew

[gray86hach]

I use the Spal relay kits never had issues with them on fuel pumps. Dads car has over 25k on it with not a problem using a tanks 255

Tim

[H2Ogbodies]

Equally important to amp rating is the number of switching cycles @ full load. For example, TYCO commercial grade 12v relays are rated @ 250,000 cycles. This is directly related to the type of contact material that is used-molybednum and nickel have very good wear characteristics....but that may be getting a little gobbly-gooey.

[nokones]

Check with Holley and see if you can buy the appropriate relay from them.

[chpr1972]

NOKONES

Try calling Holly to ask a question. If I knew how I would send you to my post on calling Holly. Lets just say if you are lucky they will call you back the same day and maybe the next day. It is so bad that 2 well known tech centers from other vendors can not get a hold of Holly tech right away. I did get the right info from one of them but it took a lot of research on his part.
My beef is they tell you what the operating voltage is and what is the high and low is but NOT what rated amp circuit breaker to use. Say if you use a 40 amp rated relay and that much amperage will destroy the electronics and then they will not warranty their product. Relays are a switch, yes but they are also a protector of the system unless my head is screwed on wrong again.
Most companies sell a relay kit for their product, but what if you want to run a 4 gang block to keep moister out and look better. I have 2 relays for my dual fans, another for the fuel pump, 2 more for the low and high beam headlite, One for the convertible top, one for the stereo amp, one for the horns,one for the HP EFI,2 for the AC. Now some use 20a some 30a and some 40a. That does not count the fuses and circuit breakers protecting those circuits.

[parsonsj]

yes but they are also a protector of the system unless my head is screwed on wrong again.

I think your head is screwed on wrong. Relays are not a substitute for a fuse or a circuit breaker. You shouldn't use a relay rating to protect downstream circuits.

[nokones]

Here is a link to the Holley website for relay you need from Holley.

https://www.holley.com/search/?q=Relay

It would be best to buy it from Holley rather than using a cheap part from an unknown source.

[H2Ogbodies]

Holy crap-$35+ bucks for a Single relay? I'm all for supporting Holley BUT-that thing better say "Made in USA" and be rated higher than 40A! The 40A TYCO relays are made in Portugal as are Hella (also Spain, some US also) but damn....even at my cost for that kind of money I can order a parallel diode equipped screw-down relay rated @ over 100A for less than $35!

Anyway, Hella makes splashproof relay enclosures....as does Bussman, heck you can source OEM style mini relay/fuse stations with a little junkyard searching too. Most people really don't put as much effort into a proper electrical system as they do everything else but hopefully as more people focus on it, the aftermarket will open up with more purposeful electrical products.

[parsonsj]

heck you can source OEM style mini relay/fuse stations with a little junkyard searching too.

I'm with you here. I try to use those relays when ever possible. Waytek has some nice panels to make custom setups:

https://www.waytekwire.com/item/4599...63-HWB60-Base/

[chpr1972]

John Parsons II Much Fabrication.
Yes I am not using a relay in place of a fuse. But doesn't a relay have a amp rating for uses that help protect the circuit? If not why are relays rated at different amps like 20/30/40 amps? There are 2 fuses at the HP EFI, one is for the fuel pump igniter and one I guess is for the unit it's self?, The HP EFI is wired directly to the battery as per instructions with NO fuses. So what you are telling me is I can use a 40 amp relay in place of a 20 amp with no problems to the system.

[parsonsj]

Yes I am not using a relay in place of a fuse. But doesn't a relay have a amp rating for uses that help protect the circuit? If not why are relays rated at different amps like 20/30/40 amps? There are 2 fuses at the HP EFI, one is for the fuel pump igniter and one I guess is for the unit it's self?, The HP EFI is wired directly to the battery as per instructions with NO fuses. So what you are telling me is I can use a 40 amp relay in place of a 20 amp with no problems to the system.

Lots of questions here, so let's unpack them.

Circuits should be protected with fuses or circuit breakers. Full stop.

Relay ratings are for sizing circuits and are about cost. Running a 40A relay in a 20A circuit hurts nothing (assuming the rest of the circuit is wired and fused correctly). You are just paying for a higher-rated relay that you don't need that costs more than a similar rated 20A relay. It's like running a 10g wire when a 14g wire will do.

I can't answer why you don't have a fuse between your Holley device and the battery. I think that's a bad idea -- I *never ever ever* run something from the battery without a fuse. Maybe the unidentified fuse is for the connection to the battery... I'd double-check to be sure.

Hope that helps.

[nokones]

If you are using an authentic Holley power cable, the fuse is approx 6 inches from the ECM connector. It is the black doo hickey on the red lead. The 40 amp fuse has a black plastic weather type cover. It is the only thing on red power lead.

[chpr1972]

Yes that is the second fuse I mentioned. It is a cover and a mount bracket. Holly instructions says that both their power cables and grounds should go directly to the battery. That is why I wired it that way. Yes I actually read the instructions.
thanks for the info!

[dhutton]

I think you misunderstood. They were meaning do not connect the fused line to something other than the battery (the alternator or fuse block for example). The fuse should be used or you risk damage to your unit. It does not have any negative effect on your unit performance.

Don

[chpr1972]

DHUTTON
The instructions says:Wires should run directly to the battery. 10 gauge wire is used. The harness comes with a 40 amp fuse pre installed. Do not sub smaller gauge wire. So I wired it like the instructions says.
I went to auto mechanics school in 1966 and worked in the field till 1986. A lot of the modern stuff like FI I am a dummy on but basic mechanics I am well versed on. ONE auto dealer I worked for, I got ALL the electrical problems to solve.

[dhutton]

So did you use the 40 amp fuse or not? I hope you did. It is needed to protect your controller.

Don

[CarlC]

jp, I think your link is funky. Perhaps this? https://www.waytekwire.com/products/...ays&NO-Amp=40A

40A should be sufficient for the normally open rating. A 2x relay rating vs. the circuit is a good rule of thumb for long life. However, the challenge with the larger amperage relays is that the plug is not the "standard."

I've fried 70A relays when used with Mark VIII fans where the on amperage is 40A but the turn-on surge is closer to 65A (if memory serves.)

[parsonsj]

I've fried 70A relays when used with Mark VIII fans where the on amperage is 40A but the turn-on surge is closer to 65A (if memory serves.)

Carl, good point! In-rush current can be twice as high as steady-state current. One of the nice things about some of the more advanced control modules (like the InfinityBox PowerCells) is that they support "soft start" that prevents current spikes when the device is turned on.