what amps for breakers?

need some advice for running the fuse breakers. Making sure i have this correct. I plan to use fuse breakers for things that are important to keeping the car rallying. The non important stuff (horn, turn signals etc) will be on a regular fuse block. The breakers come in 10, 15, 20 and 30, just for your information.

Fuel pump - 20Amp
Ignition (power to ECU, etc) - ??
Cooling Fans - 30Amp
Headlights - 30amp
Rally Lights - 30amp
Auxillary Power (nav. light, cig. lighter, etc)

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First Rally: 2010 First RallyX: 2004 (a bunch)
Driver (0), Co-Driver (7)
Organizer (3), Volunteer (3)
Cars Built (2.5), Engines Blown (2) Cages Built (0) # of rotations (3.5)
Last Updated, Apr 9, 2023

15 is plenty for a fuel pump, they generally draw 1A per 10psi, and peak on startup is roughly 1.5 times running current.

A 55w bulb is around 4-5A each.

Cooling fan at 30a is ok.

The ECU, that depends on how much of the load is on the one breaker. If the ECU turns on a relay for all the load dependant things like coil, injectors, ect, then it may only use 3-5A of current.

For acessories, I would not gang things together too much. Don't put something unecessary for operation on the same breaker as something esential, like a cig lighter socket to charge your phone on the breaker for the nav light.

Oh, and Aircraft Spruce has nice aircraft breakers in many more amperages for about $6 each. I think they go: 1,2,3,5,7.5,10,15,20,25A Push to reset, easy to package.

Thanks for the amperage information. And thats much better variety and about 2 bucks cheaper. thanks!

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First Rally: 2010 First RallyX: 2004 (a bunch)
Driver (0), Co-Driver (7)
Organizer (3), Volunteer (3)
Cars Built (2.5), Engines Blown (2) Cages Built (0) # of rotations (3.5)
Last Updated, Apr 9, 2023

We've got these: http://www.summitracing.com/search/Product-Line/Bussmann-Type-III-ATC-Footprint-Circuit-Breakers/

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"Talk about drugs. Driving a car like that, going that fast, it’s like all the drugs at once." - Tommy Byrne

"Now, Pinky, if by any chance you are captured during this mission, remember you are Gunther Heindriksen from Appenzell. You moved to Grindelwald to drive the cog train to Murren. Can you repeat that?" - The Brain

Here are the Tyco's http://www.aircraftspruce.com/catalog/elpages/pbcircuitbrkr3.php

I prefer the ring terminal with screw like the Tyco has over a spade terminal.

also, ive seen relays in the panel before. what do they use for that? im guessing some sort of connector that attaches to the panel. but where do you source something like that?

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First Rally: 2010 First RallyX: 2004 (a bunch)
Driver (0), Co-Driver (7)
Organizer (3), Volunteer (3)
Cars Built (2.5), Engines Blown (2) Cages Built (0) # of rotations (3.5)
Last Updated, Apr 9, 2023

I searched all over for panel mount relay sockets, and found none. i ended up buying some relay pigtails and riveting a small L shaped alluminum bracket to each side. I used the ones that hold 2 standard Bosch relays.

I have never found a panel mount relay either (that puts the wire side against the panel) other than the PCB mounts (which might be a clean way to make a custom DIY relay panel that would save a lot of wiring clutter if you wanted to design a PC.

I like the Micro ISO relays for most moderate current stuff on a typical car. They are small and package nicely. The bases interlock together and I have them with loose terminals so they can be crimped to your wiring (I don't like pigtails that most relays have, and adding one more splice).

There are also some fuse box options I have used that allow you to mix and match "modules" containing different relay/fuse configurations which lets you do a custom setup that ends up being very much like an OEM fuse box. I will try and put some pictures up later if anyone wants, just finished a car with one of these and it worked well and wasn't too expensive either.

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John Reed
John Reed Racing
www.johnreedracing.com
johnreedracing@gmail.com

the junkyard is full of GM's with these nice little sealed relays, and 4 prong relay brackets atatched to GM products

okay need to bring this back up again

So currently i have the following on their own switch (and fuse if i numbers down). Need to figure out how to best sort it all out.

Fuel pump 1 @ 15A
Fuel Pump 2 @ 15A
Ignition
cooling Fan @ 30A
Headlights
Rally Lights
Co-Driver Light

for the ignition, megasquirt recommends breaking it down into the following.

3 for ECU
5 for fuel injector bank 1
5 for fuel injector bank 2
20 for Coil / Ignitor
10 for pulse width idle valve
10 for Wideband 02

and i guess i should probably have a fuse for the starter?

The headlights are two sealed beams. Not sure on the wattage, but probably 55w each? Should i combine this with the running lights (tails and side lights?)

Recommend Amps for the turn signals?

Ill have to see what the rally lights draw. There are four big guys.

Co driver light seemed smart to have on its own.

Aside from that i still would have things like dash lights (which i could combine with the running lights and have separate from the headlights). Wipers. Blower motor, washer tank, whatever the gauges need for power etc.

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First Rally: 2010 First RallyX: 2004 (a bunch)
Driver (0), Co-Driver (7)
Organizer (3), Volunteer (3)
Cars Built (2.5), Engines Blown (2) Cages Built (0) # of rotations (3.5)
Last Updated, Apr 9, 2023

Uuuuh, guys, the Tyco aircraft type breakers are not designed to withstand much mechanical shock. The data sheet rates them at 10g shock. That is fine for small aircraft, but a hard mounted panel in a rally car will see waaay more than that in a good hit on a hole or rock. I can see these popping out at the most inopportune time in a rally; they are somewhat notorious to do so in small aircraft in a hard landing or even in a badly turbulent sky (Had that happen to me).

The breakers that Wilson listed are auto rated for mechanical shock. (50 to 100g). Use those or one that meet SAE J553.

Also, these are all thermal or thermal-magnetic breakers; they depend somewhat on heat to trip. That means they have resistance to generate the heat, and that resistance will create voltage drops that you are probably not aware of. These may not be a big issue, but it will take a long time to trip for overloads < 4 times the rating. Wire gages may need to be increased.

Also, to feed the injectors, I'd rather have a direct feed with a disconnect. Any inductance in the breaker's coils could have an impact on rise times. Think about that.

Fuses have a lot going for them: Shock rated, selectable blow timing, very low voltage drop, no false trips (they go bad, period). I think putting breakers in critical circuits in a rally car is asking for erratic issues and using the aircraft type is a bad idea.

Mark B.



Edited 1 time(s). Last edit at 01/20/2013 09:08PM by starion887.

Fuse for the starter? No, yer asking for trouble, IMO. It is only temporarily activated and is critical.

Halogen 100W Rally lights will take 7-9 amps each. Fuse and switch the driving and spots and fogs separately.

The TYCO's seem to be working fine for me, and I have driven hard on some very rough road.

On the Merkur, everything in the engine bay is handled by a seperate fuse box, utilizing blade fuses, and relays for the high current stuff.

I used the same TYCO's in Derik Nelsons M3, and he drives that car hard, still no issues with breakers tripping.