Need a ignition switched electrical source

[The Wingnut]

Hey folks,

Here's the idea: I picked up a new aftermarket fuse bus and would like to connect it to a reliable ignition switched source. I'll be connecting accessorries such as the rad. fan, stereo and other items to it that only need to be used when the motor / ignition is on.

What's a high-load source I can tap into? I'm not too experienced with auto electrics(know basics) and don't want to hose anything. I've already made my heater blower quit working(fuses are good) by connecting the radiator fan into the harness(still haven't fixed this...not sure where to start) and don't want to do more damage.

[Nissanman]

My advice would be the following: -

Use the feed to the ignition coil.

"T" into this wire, do not break continuity to ignition circuit.

Wire it to the coil tag of one [or more] SPST auto relay.

Earth the other side of the coil.

Connect your new fuse box to the battery with the appropriate gauge wire to handle the new fuse.

On the distribution side of your new fuse, wire to one of the contacts of the above relay, using appropriate gauge wire.

Wire from the other contact of the relay to your new accessories.

This means that you are only using the ignition wire to sense key on/engine running by operating a heavy duty relay.

The relay does all the hard work switching power from the battery, via your new fuses, to the new load.

Existing wiring is not overloaded, new wiring must be adequate dimension for the new load.

Relay rating must not be exceeded, use more than one, they come cheap.

A lot cheaper that wiring looms and engine bay fires:tapemouth

If you need a drawing just let me know:classic:

[The Wingnut]

Thanks for the help. A diagram would be helpful if it's not too much trouble.

Do you have any recommendations for relay amperage and wire gauges? I assume I have a 60 amp alternator, which would dictate a 60 amp relay unless I'm mistaken.

Using more than one relay isn't really possible with this fuse bus, as it's got a common power delivery to all of the fuse positions. The is a single input for power to a strip running through all of the fuse positions.

[Nissanman]

[Nissanman]

If you can't read this properly , email me and I'll send you the original file.

[Nissanman]

Revised power feed drawing.

[DeesZ]

I thank you for this, also, Nissanman! And thanks to Wingnut for asking the question in the first place. I've been considering relays for a fan, radio/amplifier, etc., as well as the headlight & tail light conversions being sold on this site.

Your explanation makes the task seem like something I could do without frying my car (or myself). Taking the question a step farther, what recommendations are out there that would neatly 'consolidate' several relays and circuit fuses? When I do this I'd be trying to keep a neat appearance and an organized approach to adding the components. Any suggestions on location and equipment will be very welcome.

I have a '72, and am running an internally regulated alternator, which gives me a bit of free space where the old VR was once mounted. What's been done out there to accomplish this? I'm sure someone makes a unit that will accept several relays, but I must be looking in the wrong places.

Thanks!

[Nissanman]

Fuse blocks: -

http://www.narva.com.au/Fuses_16.html

Relays: -

http://www.narva.com.au/Switches_18.html

There are some relay bases which clip together to create a nice "bank" of relays.

Try your local wrecking yard and see if you can find them.

Also, use relays which have a protection diode [or resistor] connected across the coil.

This prevents the back e.m.f. of the relay, when it releases, generating a voltage spike into the wiring .

The diode makes the relay polarity conscious but the spike suppression is well worth the effort.

If you have ever chased electrical gremlins in electric door locks and alarm systems, you'll know what I mean:finger:

Any relay socket can be modified to insert this diode [resistor], which then means you don't have to use the relays with the protection built in.

Depending on design, relays and fuse blocks should be OK in the engine room.

Just avoid heat, oil and water splash.

If you have the real estate available, inside the cabin would be ideal.

My advice is DO NOT use Nissan relays.

They seem to be a design all on their own.

Stick to the more conventional types like Narva, Bosch, Hella etc. which use the 30, 85, 86, 87, 87A pinouts.

The last thing you need is some weird arse wiring requirement which applies to one relay type only:ermm:

[Nissanman]

The relay bases on the left are Bosch slide together type and have part number #3 334 485 008 stamped on them.

The base on the right is pre-wired and you can just see the diode mounted below the connectors.

[DeesZ]

I think I am getting the idea - thank you very much for the details - I am electrically challenged. I did some Internet surfing last night and found this gem by Spal. Is this the answer (of course in addition to the recommendations that you have made)? Pictures attached.

The description follows / price is about $25.00 USD.

"This fused relay block works great to safely control your aftermarket fan(s), NOS, fuel pump(s), water pump, etc. The block includes two 12v/20a relays fused to a single 10a fuse. The block has provisions for up to 5 relays through 4 fused links. The cover protects the relays/fuses, while the wires cleanly route out the back. Eliminate multiple relays with one block unit."

[sblake01]

IIRC, my good friend Blake sells those. Haven't seen him for a while but i don't go to as many Datsun gatherings as I once did. That picture might even be from his auction. He's excellent to do business with. He knows his Datsun stuff. He builds 3.1L strokers that work, and is a carb, efi, and turbo guru. I'd never hesitate to buy from him.

[DeesZ]

Stephen, this is at auction on eBay... seller name is "blax240" location Nismo Heights.... The seller name hints at your description!

Thank you for your feedback. This unit may be a solution for me.

John