Is a 345A switch enough for my engine?

[coopec43]

Originally Posted by goboatingnow

Don’t use knife switches this isn’t the 1790s

Can you elaborate please?

Also what do they mean by "Cranking current"? (see below)

Top Post Knife-Blade Style Battery Isolator Switch 250A
CAT.NO: SF2243

Avoid battery drain on an idle vehicle or boat.
• 12 - 24 Volt
• 250A Continuous Current
• 750 Cranking Current


https://www.ebay.com.au/itm/17539465...Cclp%3A2047675

[coopec43]

This would be hard to beat for value surely?

https://www.jaycar.com.au/profession...witch/p/SF2247

[LifesBetterWhenYoureBeating]

We can't seem to find the cranking rating for the Guest 2111, but with it in place my engine still starts in less than 2s, and nothing in the switch gets hot.

Even though I believe it has been in use (for this purpose) for many years (given its location), others have pointed out it may be undersized and I've also came across an analysis of battery switches (https://www.practical-sailor.com/sys...switches?amp=1) and the Guest they tested was not among the best ones, so I'd rather err on the safe side and spend a few bucks on a Blue sea HD switch

[wingssail]

Originally Posted by coopec43

I'm most certainly don't consider myself an expert but what would be wrong with a switch like this?

Or this? @ $30.39

Those switches look fine to me, I thought I was hearing that people should install a relay system.

[col50]

I have measured the starting current on my Perkins 4-108.
It fluctuates, but with the engine at about 70 deg F, it is generally about 300A after it starts cranking.

[Shaneesprit]

Originally Posted by gsalgado

My boat came with the engine starter wired to the battery via a Guest 2300A switch (rated to 600A momentary), but there's also a Guest 2111 switch (345A momentary) right next to the engine.

I'm now using the 2300A for my house bank, and plan to use the 2111 for the starter, but my engine's (Perkins 4.108) starter motor max current is 900A (according to the manual), so I'm wondering if it'd be safe to do so?

Thanks in advance

I wouldn’t be worried about this, I have fitted loads of Battery isolators on Big engines with 1000s of CA (Cranking Amps) normally the Isolator would be 500A rated. I say fitted 🤔 not often I got my hands dirty in the last few years - Mostly inspecting these days.
As it’s an isolator it’s not really designed to be switched under load. if it’s old / secondhand then cleanliness of the contacts is the only issue,

[skipperpete]

Caterpillar has been using the same battery switch across almost the entire range of equipment including 777 haul trucks and 992 loaders, almost unchanged from the earliest days of the company.......[ATTACH]265185 they seem to last a helluva long time even out in the elements. Cat alleges 1,000 amps at 12 volts and I tend to believe em.

[jmc]

Originally Posted by phorvati

Wire the starter directly to dedicated starting battery with a slow blow fuse, like 500A ANL via 1/0 welding cable. Don't forget the black return wire. Don't run it via engine block. Then tricke charge that battery via another source.
I've been using an office UPS backup AGM battery like this to start my lehman 90hp. Its been since 2018 and works really well.
One trick, my 1/0 welding cable round trip is 5 feet and all the crimps are new.
Previous owner had a starting battery, giant mastervolt 4D 160AH, 25 feet away so 50 foot round trip. I repurposed that cable for better things.

I would avoid using welding cable in place of battery cable because the insulation has no solvent resistance. I have seen the insulation literally fall off on diesel powered boats.

[Shaneesprit]

Originally Posted by skipperpete

Caterpillar has been using the same battery switch across almost the entire range of equipment including 777 haul trucks and 992 loaders, almost unchanged from the earliest days of the company.......[ATTACH]265185 they seem to last a helluva long time even out in the elements. Cat alleges 1,000 amps at 12 volts and I tend to believe em.

Yeah I will 2nd that. and those 777 pull way over a 1000A
Although CAT are also using other switches on certain setups, that old one is the dog’s dangling bits.
As your not going to be using it continuously, it doesn’t matter that much as a rating, same as battery cable.
Overall circuit resistance is the true way to size and test a starter circuit.
Or keeping it basic big cables with batteries close to the starter. and nice clean contacts.

[AKA-None]

Originally Posted by jmc

I would avoid using welding cable in place of battery cable because the insulation has no solvent resistance. I have seen the insulation literally fall off on diesel powered boats.

Hmmm not sure what kind of welding cable you have looked at as I’ve dragged lots of cable through lots of ships bilges and never noticed any issues

[Uncle Bob]

Originally Posted by coopec43

I'm not sure why you stated that? Maybe you should look at what is sold on eBay (you might be surprised)!

I buy just about all my requirements on eBay. Purchases have included:

Hitachi brands
Rule bilge pumps
Victron electronics
Renogy Solar Panels
Stainless Steel fasteners
Electrical shunts, circuit breakers, switches, meters, Electrical cable
Epoxy Resin
3000/6000 Inverter
Muir Winch.
AGM Batteries
Through hull fittings

https://www.ebay.com.au/sch/i.html?_...nogy&_osacat=0

It seems not long ago that someone here was railing against flea bay vendors, goods not as described, batteries that were faulty, rubbish products etc, cant remember who it could have been.
For what it is worth my experience lately has been that I am able to purchase products that are advertised on flea bay cheaper locally, no delivery, pick it up on the day, with a genuine warranty. Apparently your experience has been different.

[coopec43]

Originally Posted by Uncle Bob

It seems not long ago that someone here was railing against flea bay vendors, goods not as described, batteries that were faulty, rubbish products etc, cant remember who it could have been.
For what it is worth my experience lately has been that I am able to purchase products that are advertised on flea bay cheaper locally, no delivery, pick it up on the day, with a genuine warranty. Apparently your experience has been different.

I've only been caught out twice - a useless Chinese 18V battery and a Chinese "MPPT" Solar Controller (It does still work). But these days Asian sellers on eBay have all but disappeared.

"no delivery, pick it up on the day" Great!

With petrol prices the way they are have you worked out what it cost to pick them up? (Let's forget the time it takes to pick them up!) I have my goods delivered to my front door.

Manufacturer's warranties on online sales are the same as offline sale warranties? What are you getting at? (The ACCC makes sure of that)

Australians spent a record $62b online – and it’s set to double

https://www.afr.com/companies/retail...0220404-p5aaoi

[coopec43]

Originally Posted by Uncle Bob

It seems not long ago that someone here was railing against flea bay vendors, goods not as described, batteries that were faulty, rubbish products etc, cant remember who it could have been.
For what it is worth my experience lately has been that I am able to purchase products that are advertised on flea bay cheaper locally, no delivery, pick it up on the day, with a genuine warranty. Apparently your experience has been different.

Duplicated post (Cruiser Forum Database error)

[goboatingnow]

Originally Posted by Uncle Bob

It seems not long ago that someone here was railing against flea bay vendors, goods not as described, batteries that were faulty, rubbish products etc, cant remember who it could have been.
For what it is worth my experience lately has been that I am able to purchase products that are advertised on flea bay cheaper locally, no delivery, pick it up on the day, with a genuine warranty. Apparently your experience has been different.

I buy 95% of all boat stuff online. Mostly at discount pricing , I buy across all channels including AliExpress.

Just put another 20 orders for Dec delivery into Ali

[coopec43]

Originally Posted by goboatingnow

I buy 95% of all boat stuff online. Mostly at discount pricing , I buy across all channels including AliExpress.

Just put another 20 orders for Dec delivery into Ali

I put an order in today for 50 meters of Stainless steel 7/19 Balustrade wire rope for safety line. The cost delivered to my front door is $127.

Hillarys Marina is currently out-of-stock.(Cost approx $160)
Whitworths (round trip 50+ km) Catalog price $8.99/meter? Surely not? (Must be a pricing error?)

I also use Ali Express (particularly when I don't need the item urgently)

I buy all my SS fasteners (bolts/nuts/screws) online from Bolt and Nut (Aust)