Need a fast switching relay!

[turbovanman²]

I need to relay my Alky controller, it appears the older models, aka mine, use an internal unit that burns out over time, so I am replacing it but it was suggested to have the controller switch a relay that way it takes the load off the controller. Of course I can buy a new controller that doesn't have that issue but I am not spending $150. The really needs to be able to switch extremely fast due to the controller cycling the pump to get its desired results. Pump is 12 volts, 30 amps.

Thanks.


This is the chip that burns out-

http://ca.mouser.com/ProductDetail/STMicroelectronics/VN920/?qs=sGAEpiMZZMutXGli8Ay4kDPppcqj2EY6OXW%252b70Omhg E%3D

[shackwrrr]

Is it mounted on a heatsink? Looks as if they are driving it at its Max capacity and without a heat sink that's what's killing them.

[bakes]

replace the moffset on the board.

[turbovanman²]

Is it mounted on a heatsink? Looks as if they are driving it at its Max capacity and without a heat sink that's what's killing them.

No, its small, but its not very strong per say so if you lose a ground or similar, pop.


replace the moffset on the board.

That's what it is and that's what I am changing, but I don't to want keep doing this, it lasted 3 years so not so bad but if I can get a relay, then I'll never have to worry, :nod:

[zin]

I've run the standard Bosch "ice cube" relays at a pretty high HZ... Do you know the frequency it runs at?

Also, is it really using 30amps?!!?? If so, you'll need to find a 40amp version, the 30 are common, but I never like running things at capacity...

Mike

[turbovanman²]

The chip is rated for 30 amps, its a 200 psi pump, so I can see it pulling 30 amps at full output. I agree, 40 amps would be a better choice. I'll see if I can dig up the specs on the frequency.

[Force Fed Mopar]

The Bosch style relays work good.

[bfarroo]

Your best bet would be to look for a solid state relay. Any standard relay is not going to hold up well in the long run to the frequency of switching. The solid state has no moving parts so it lasts a lot longer. The drawback is they are going to be more expensive than a regular relay especially in the amperage rating your looking for. I really can see the pump pulling 40 amps. I'd bet the pump has a 12 gauge wire on it which is rated at 20 amps. I'd do some searches online and see what you can come up with but I'd bet you'll be in the 20-50$ range.

[RoadWarrior222]

Ford fuel pump PCM drivers... forgot what years, handle amps, switch fast.

[turbovanman²]

Your best bet would be to look for a solid state relay. Any standard relay is not going to hold up well in the long run to the frequency of switching. The solid state has no moving parts so it lasts a lot longer. The drawback is they are going to be more expensive than a regular relay especially in the amperage rating your looking for. I really can see the pump pulling 40 amps. I'd bet the pump has a 12 gauge wire on it which is rated at 20 amps. I'd do some searches online and see what you can come up with but I'd bet you'll be in the 20-50$ range.

$20-$50 is fine, as long as they last.

I would guess the wiring is 12 gauge.

I guess any online store will carry one?

[RoadWarrior222]

Errr. PCM meaning pulse code modulation, not powertrain control module, think they usually call them just "fuel pump driver" modules... used in a lot of lat 90s up fords with returnless fuel systems (They are high speed, high current switching for the fuel pump control pulse)

[RoadWarrior222]

Ah there's a diagram...
http://i37.photobucket.com/albums/e54/BrandonDodson/dual_FPDM_wiring.jpg

That's how to rig them for dual pumps, but you can see the PCM input (Which is actually both meanings LOL) which I'm thinking is where you could stick your controller output, then ignore the status output, the CCRM is just like the enable from the ignition switch or ASD... wire relays in or not as you like...

[bakes]

Ah there's a diagram...
http://i37.photobucket.com/albums/e54/BrandonDodson/dual_FPDM_wiring.jpg

That's how to rig them for dual pumps, but you can see the PCM input (Which is actually both meanings LOL) which I'm thinking is where you could stick your controller output, then ignore the status output, the CCRM is just like the enable from the ignition switch or ASD... wire relays in or not as you like...

i like that diagram i think it could be used with the turbonator alky routine if a PWM was added to the code

[turbovanman²]

Ah there's a diagram...
http://i37.photobucket.com/albums/e54/BrandonDodson/dual_FPDM_wiring.jpg

That's how to rig them for dual pumps, but you can see the PCM input (Which is actually both meanings LOL) which I'm thinking is where you could stick your controller output, then ignore the status output, the CCRM is just like the enable from the ignition switch or ASD... wire relays in or not as you like...

I'll hit the wreckers on Monday or maybe the local PaP tomorrow.

[rbryant]

Most of the Neons had a solid state fan relay so that would be a cheap thing to try.

-Rich

[turbovanman²]

Most of the Neons had a solid state fan relay so that would be a cheap thing to try.

-Rich

Too bad it has a high failure rate, as does most of Dodge's fan relays, :(