200 amp DC breaker suitable for V8 engine starter motor with windings, not magnets?

Thread Starter

sdowney717

Joined Jul 18, 2012
705
2013 Cooper Bussmann Transportation Full Line Catalog (solar-electric.com)

If the engine starter initial draw is 500 amps, then as it spins is around 200 amp. It seems this breaker would work ok as it does not take that long to crank before the engine fires up? Typically, my boat engines start up in less than 5 seconds. The chart seems to be saying breaker at 200% rating of 400 amps drawn would still give 15 to 30 seconds of run time before tripping.

I would prefer a 300 amp breaker, but not finding a name brand.

Any ideas about if this could work, or a 300 amp decent breaker?
I have been thinking to breaker protect the starting battery on my boat.

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LowQCab

Joined Nov 6, 2012
1,078
This is a bad idea.
As the Charge-State of the battery gets lower, the Current can go substantially higher,
so, just having a low-Battery could cause the Breaker to trip.

There are Fuses readily available for Low-Voltage-DC,
but I wouldn't recommend putting one on the Starter.

"Starting-Batteries" are specifically designed to withstand the heavy abuse of Starting an Engine.

What problem prompted You to pursue adding a Breaker between your Battery and Starter ??
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A 300 amp circuit-breaker will do nothing for protection really, just nuisance trip during cranking.
You don't put a circuit breaker in the starter motor feed because of the very high current there.
Fuses or circuit breakers are used for the vehicle power feed- not including the starter motor.
You might be confused with a master battery disconnect?
https://www.waytekwire.com/products/1408/Battery-Disconnects/
https://www.littelfuse.com/products/switches/manual-battery-disconnect-switches.aspx
 

Thread Starter

sdowney717

Joined Jul 18, 2012
705
Ok. This is for a 38 foot boat with cabin. I agree there are issues protecting starter wires. I decided to try a 300 amp ANL blues holder and fuse. Wires are 2/0. Another idea could be use a remote start relay like a Ford. When key is turned to crank, run solenoid wire to relay. This way all starter wires are dead until key is turned to crank
And if there was a grounding wire short it would go away when letting key go. To prevent backfeed issues to other engines, you could put a 10 amp diode inline with solenoid wires for both solenoid crank wires, so cranking one engine won't put power to the start solenoid of other engine.
 

Thread Starter

sdowney717

Joined Jul 18, 2012
705
See I recently ran a 30 foot round trip 2 gauge wire to share start battery to boat generator. And was thinking what if my starter wires short out. But boat is 1970 and in 50 years nothing bad happened. I did set the house bank thru position 2 on rotary selector switch to send power to start wire bus, for emergency starting if start bat dies or fuse blew. I have not installed fuse yet. Boat has 2 bat banks. Start only and two 6v gc15 bats for house. That bank is fused at a buss for the inverter at 500 amps semiconductor fuse, lectrasan at 100 amps, house at 150 amps using mega fuses.
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Thread Starter

sdowney717

Joined Jul 18, 2012
705
From reading, wire wound starters for v8 engine initial instant amp draw of 500 amps. Then falls to from 200 to 250 Amps. Starting my engines is quick maybe 2 or 3 seconds. Anl fuse won't blow fast, blue sea has a time amp chart at 500% of its rating will blow in 1 second. 1500 Amps. Otherwise it can tolerate double its rating for maybe a minute and starting is momentary current. Unless there is a problem...
 

shortbus

Joined Sep 30, 2009
8,795
From reading, wire wound starters for v8 engine initial instant amp draw of 500 amps. Then falls to from 200 to 250 Amps.
Kind of. That amp draw and it's change is only due to the friction of the engine. Still don't understand why you think all of this is necessary. Have you ever heard of a car or truck fire caused by a started failure? I never have, and have worked on cars for ~60+ years.
 

Thread Starter

sdowney717

Joined Jul 18, 2012
705
Kind of. That amp draw and it's change is only due to the friction of the engine. Still don't understand why you think all of this is necessary. Have you ever heard of a car or truck fire caused by a started failure? I never have, and have worked on cars for ~60+ years.
I know. ABYC wants the starter either fuse protected or put in conduit, no starter wires left unprotected. Fuses are not required by them for starting wires.
I did think up another solution, use a start relay right next to the battery to keep the starter wires deenergized until you turn the key to start.
Here is a basic schematic, but I am not planning on doing this. I need continual 12volt power sent to my generator 10 feet away, so wont work for me as I share the engine start battery with the generator.

This uses 2 diodes so that turning any key wont crank both engines, just the one you want to crank.
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LowQCab

Joined Nov 6, 2012
1,078
Here's what I use on my Truck, which has the Batteries mounted in the Bed.
It's properly called "Flexible-Metallic-Conduit" and is available in Aluminum or Galvanized-Steel.

It is obviously electrically conductive,
so great care must be taken to insure that the ends can not possibly
come into contact with the bare electrical connectors on each end of the Wire.

It does an excellent job of protecting the Wire insulation
from abrasion or other physical damage.

It's available in any size You may need.
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Flexible Metallic Conduit .png
 

LowQCab

Joined Nov 6, 2012
1,078
No,
The Conduit and Wire need to be able to dry-out.
Anything that is supposedly "sealed" will retain Salt-Water, guaranteed.
Besides that, those types of Conduits and Fittings are designed to attach to a Junction-Box,
in order to be considered "Water-Tight", but there are no Junction-Boxes in this case.

Possibly continuous immersion in Salt-Water wouldn't do any damage to the Wire-Insulation,
but I wouldn't want to find-out the hard way.

The all Plastic types of Flexible-Conduits would be better from a Corrosion standpoint though.
I suppose You could drill small drainage holes in them to let the Water out.

The all Plastic types can not withstand very much Heat before melting,
The Aluminum version will actually help to protect the Wire Insulation from Heat-Damage,
while at the same time assisting in dispersion of any Heat build-up in the Wire.
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Thread Starter

sdowney717

Joined Jul 18, 2012
705
Honestly, metal conduit on a boat with potential exposure to salty bilge water is not a great idea, but it would work for a number of years. Wire is 2/0 wire, pretty decent sized. I do have some 1 or 1 1/8 inch black flexible ribbed plastic conduit which can not be cut with a knife, it is tough stuff. I have that on some of the smaller wires coming off the battery switch up to their fuses. (Alternator 6 gauge wire, 80 amp blue sea fuse) I might look into that, but it adds a lot stiffness to the wire.

Heat is not as big an issue as damaged wire insulation I think. Never seen these wires get hot from cranking the engines. Engine room might get into low 100's in the summer.
 

Thread Starter

sdowney717

Joined Jul 18, 2012
705
Your probably a belt and suspenders guy?
https://www.pysystems.ca/resources/ask-pys/fusing-a-starter-battery/

Look at the wire diagram in this PDF. Where it states, "fuse not needed for starting service" http://assets.bluesea.com/files/resources/instructions/6693.pdf

There are numerous other things on line IF you look saying the same thing.
Fusing starters on boats, it can be done, even though not required. Several big name people in boating say it should be done.

I quote Nigel Calder here:

"The net result is that nowadays, electrical shorts are probably the number-one cause of fires on boats. There is simply no excuse for not protecting all high-current circuits, including the cranking circuit."
(From the Nigel Calder Cruising Handbook)

Battery Bank Fusing Photo Gallery by Compass Marine How To at pbase.com
"I hear it stated over and over and over that the ABYC standards make an exception for starting motor circuits, and this is 100% true. The reason it is true is to accommodate HUGE engines that can not easily or simply be protected with over current protection. The vast majority of marine engines in the world today can easily be protected with over current protection. If you own a massive yacht, with massive engines, please put your starting motor conductors in a protected conduit if they can not be fused."

See the conduit recommendation again
 
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Thread Starter

sdowney717

Joined Jul 18, 2012
705
Here is another issue I have with ABYC, putting a fuse on the negative terminal post. They say no, never allowed.
A battery has 2 posts, one positive, one negative. Positive wires are the only ones to be fused, no exceptions allowed.

Here is the exception that should be allowed, fusing all of the current from a battery. A primary battery fuse of hundreds of amps rating on the negative wire that collects all the current flow for every single circuit. If the current can not flow back to the battery post any other way except by way of the main return wire from a gang junction negative buss, logically a fuse in the main and only return wire to the battery should be allowed.
Logically it makes no sense to categorically say no to doing that.

Their rationale for not fusing the negative has to do with small wire circuits. Example is, If you don't fuse a positive 10 gauge wire to a device, but fuse just its small negative return wire, and the 10 gauge positive wire touches an engine block, it will have no circuit protection. Certainly agree with that, but in that situation there are multiple return paths back to the negative battery post.
Their whole argument DIES if your fusing the main large negative wire which is the ONLY return path back to the battery.

But you see, they set the standards for the entire industry, which surveyors, workers, insurance companies, governments, boat owners are enjoined to follow. BUT this should be an allowed exception for, fusing on a negative post.

Does anyone understand what I am saying?
 

LowQCab

Joined Nov 6, 2012
1,078
Here's what I understand .......
Your Boat will not have an Electrical-Fire because of "statistics".
It might have an Electrical-Fire from incompetent maintenance,
or even a complete lack of maintenance,
but not simply because "Your-Number's-Up".

An Incompetent Mechanic can screw-up ANYTHING, including ~600-Amp Fuses,
and it's extremely difficult, or sometimes even impossible, to design anything that
might be considered to be completely "Idiot-Proof".

I've seen "repairs" that would make your hair stand on end,
and make You literally run-away in fear for your Life.

This is specifically why the US-Armed-Forces came up with IQ-testing,
and why they won't accept anyone with an IQ of less than 83.

This is why no one will ever work on my Truck or Cars unless I am watching them the whole time.
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LowQCab

Joined Nov 6, 2012
1,078
Nobody's angry,
it's just that You don't seem to be interested in benefiting from multiple, very experienced sources,
who are all basically telling You the same thing.

You seem to have had your mind made-up before you posted a question here.

Oh-well .........
You are certainly free to do as You please,
but it can sometimes be frustrating to attempt to help someone,
who then completely ignores that help.
Like I said, Oh-well .........
I certainly won't be wasting any more time in this Thread.
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