Starter Switch for Perkins 4.107

[Kokonut]

Hi there,


I'm looking at a Starter Switch that is rated for 50A. I'm sure you will immediately gauge my ignorance on these matters by my question, but is this OK to wire onto my boat. I read somewhere that I needed a battery with a CCA rating at least 500+.


Is there any relationship between the high CCA and a switch that will only carry through 50A?


Many thanks, as always.

[stormalong]

Originally Posted by Kokonut

Hi there,


I'm looking at a Starter Switch that is rated for 50A. I'm sure you will immediately gauge my ignorance on these matters by my question, but is this OK to wire onto my boat. I read somewhere that I needed a battery with a CCA rating at least 500+.


Is there any relationship between the high CCA and a switch that will only carry through 50A?


Many thanks, as always.

Where did you come up with the 50 amp load? The starter switch only needs to carry the current for the starter solenoid. Far less than 50 amps. The starter solenoid is a high current relay that carries the starter motor current. I do not know how much current the solenoid draws but I expect that it is less than ten amps. Any ignition key switch will be designed to carry the solenoid current.

[Emmalina]

Do you mean an ignition switch with a key or a button ? I doubt you need 50A rating as this will operate you start relay or solenoid. As for CCA depends where you are a normal 100Ah is normally enough for a 4107 If you are in a cold area the batteries sold locally are rated normally for the local climate CCA should not be a problem.

[Kokonut]

The 50A is the maximum load of the momentary ON switch.
The ignition key is wired to the Starter switch.


Thank you for the answers, if I understand correctly, the power going through the Switch will never exceed 50A (unless it's a fault), because it's only passing through enough juice for the solenoid.

[Andante II]

Yes you will just be switching the solenoid so don’t need 50a. Check a wiring diagram or follow existing wiring so you understand how it works. Then if you are replacing ignition switch remember you can now put it wherever you want, plus you don’t need an actual ignition switch. I just have a normal switch to power the stop solenoid and gauges and then a press to make start switch. Should be cheap and easy and you can use waterproof switches.
Lastly make sure it’s fused properly. Mine was originally wired straight from the starter with nothing protecting the smaller cables.
Cheers

[jimbunyard]

Most modern engine wiring harnesses use a system where the ignition or starter switch actuates a relay, which actuates the solenoid, which actuates the starter.

If you're making your own harness, or otherwise wiring your starter, a high amperage starter switch can take the place of the solenoid-activating relay, and many people do this.

Your 50 amp switch should be fine, but the circuit should be protected with a fuse or breaker, and the wire size should be dictated by the round trip run(length) of the wire and the amperage of the starter solenoid.

[Wotname]

Originally Posted by Kokonut

Hi there,


I'm looking at a Starter Switch that is rated for 50A. I'm sure you will immediately gauge my ignorance on these matters by my question, but is this OK to wire onto my boat. I read somewhere that I needed a battery with a CCA rating at least 500+.


Is there any relationship between the high CCA and a switch that will only carry through 50A?


Many thanks, as always.

By the way, did you replace the solenoid that you asked about in a previous thread?

The starter switch is the thing that carries the current to activate that solenoid and is likely to be less than 10 amps.

[Scaramanga F25]

Automotive store.

[KadeyKrogen38]

The starter switch for a standard Perkins 4-108 has a heat application for the glow plug in the air intake. It draws way more Amps than the Starter Solenoid. The would check this amp draw, but would think 50 amps adequate

[BruceS]

When I had mine I set it up with a solenoid that could be manually activated by pressing the bottom of the plunger in it as well as the heater switch both in the engine bay. Made it easier for those odd cold morning starts. Just had to remember to give a few revs & turn on the key before I got in position!

[GoneIsland]

Sorry, but I’ve never heard of a Perkins 4108 or any Perkins for that matter having glow plugs. I’ve got two boats with Perkins in them and don’t have glow plugs 🤷🏼

[BruceS]

Yes well I called it a heater switch.
It is a plug in the inlet manifold that has both power and fuel connected to it. When it gets to the 'glowing' stage it opens the fuel inlet and it dribbles fuel onto the red hot end of the plug. It quite often bursts into flames & at that stage you hit the starter & away it goes. Immediately stop the heater & it stops the extra fuel as well.
Most of these motors sold in Australia never had the heater connected to the key switch as we never (or seldom) see freezing conditions. Mine came with the heater so I hooked it up. I used a small tin above the engine to gravity feed the fuel into it.

[GoneIsland]

Sorry Bruce, that was intended for kadeykrogen38. Not from Australia so I’ve never heard or saw anything like what you describe on any Perkins I’ve worked on or owned in the last 15 years of working on boats in the states. Learn something new everyday!

[stormalong]

It is called a cold start aid. My 4.108 had one but it was not wired. It works exactly as BruceS described. I wired it up and never ended up using it.

[Kokonut]

Great memory @Wotname, ... I didn't replace the solenoid as I thought I'd replace the wire first. On removal, I noticed it was frayed and looking somewhat ordinary with exposed wires in a couple of spots along the wire covering. I'm very grateful to the individuals who suggested that.

That alone solved the smoking mystery, and saved me a bit of coin (on a new solenoid).

Just on the discussion of the 'Cold Start Aid', I do have one of those.

@Andante II, I agree, I will follow the current wiring design because I bought a new Ignition switch, that clicks once to power on, then turn once more and hold (I was told about 20secs) to warm the engine, which then springs back on release to the on position

I then push the momentary switch on to get old girl turning. No more smoking from the solenoid area.

I should post some pics of the work in progress, as I'm sure I've invested a lot of blood, sweat and tears (and coinage) over this newfound interest.

Thanks again everyone!