Alternator Ground - Best location?

[SeattleBuddy]

reetings all,

I've appreciated all the information and wisdom on this board over the years.

Recently I've used it to help figure out the best way to upgrade systems prior to adding solar and Lithium Batteries.
I am ready to start the installation of a 150A Balmar Alternator, Regulator and Pulley Kit along with a Victron Orion DC to DC charger for the starter battery.

I will upgrade wiring, add fuses, and eliminate the old Battery combiner and the Digital Echo Charge.
I plan to wire directly to the House batteries from the alternator.

Where should I run this ground to?
The ground from the Alternator is undersized so I will upgrade this as well. It currently runs to a ground point, along with some other connection on the engine block about 16" away. Then a larger wire runs to a Ground block near the battery switches and then it connects to the ground switch where it also connects to the house bank ground here.

It seems like there are a few options:
1 - Stay on the engine block terminal
2 - Go to the House bank ground terminal on the Shunt about 5' away?
3 - Go to the ground black about 15' away?

What do you suggest for best performance and safety?

I spent hours today chasing and following wires to understand the system and I think this is the last question to answer before digging into the installation. Any other advice on the project is welcomed!

[Frankly]

I think sharing a single large engine ground (battery negative to block, starter, alternator, instruments, ect) is a electrically reasonable and cost / resource effective solution. Using a single shared conductor is done all over electrical/ electronic systems (circuit board traces and wire). There are cases where this is a bad idea but not typically.

Size it according to starter requirements. Modern alternator controllers typically don't even start ramping up the current until long after stsrting.


Frankly

[Fishspearit]

Originally Posted by SeattleBuddy

Then a larger wire runs to a Ground block near the battery switches and then it connects to the ground switch where it also connects to the house bank ground here.

What do you mean by 'ground switch'? You should only be switching the positive side. You just want one ground terminal on your engine (put the alternator neg. here) and that should go straight to the negative side of your house bank.

Make sure your ground wire can handle the 150 amps that the alternator can put out.

[CharlieJ]

OP:
I disagree with @Frankly Post #2: The starter is a load and it is the only circuit on board that is not required to be fused. The alternator, on the other hand is a source and its output is required to be fused at the battery. Therefore, Option 2 is the best option.

Ensure that the alternator B- is properly sized and is landed on the low side (system side) of the shunt. Only the B- from your house battery bank will be landed on the high side (battery side) of the shunt.

[SeattleBuddy]

Charlie, Thank you.

The plan is for the Alternator to be fused at the battery with a 200A Fuse.
You suggest taking the ground going directly to the Battery which is not much further than the block. I just wanted to make sure this was typical and safe, vs going to the Ground Block, which in my case is much further away.
Thanks!

[SeattleBuddy]

Fishspearit:

Yes, there is a factory-installed ground switch.

For some reason the grounds are connected to a switch, the same design as the house and engine switches, just black vs red. I don't understand why it's there either. Maybe for some safety reason. I will upgrade to a 1 or 2 wire for both + and - to the battery.

[Searles]

Are you talking d c negatives or earthing I e grounding neither should be switched .⛵️⚓️

[SeattleBuddy]

Searles, the question here is regarding just DC negatives.

[LittleWing77]

Originally Posted by Fishspearit

Make sure your ground wire can handle the 150 amps that the alternator can put out.

Originally Posted by SeattleBuddy

The plan is for the Alternator to be fused at the battery with a 200A Fuse.

What does Balmar recommend for circuit protection? Use Balmar's specs or if anything goes wrong, the warranty will be void and/or the manufacturer absent liability.

Does anyone else think that a 200A fuse sounds like too much?

Also, as Charlie says, the size of your wiring needs to be factored in. Wire size will be dictated by the distance from the power source - according to ABYC standard.

Fair winds,
LittleWing77

[Wotname]

Originally Posted by LittleWing77

What does Balmar recommend for circuit protection? Use Balmar's specs or if anything goes wrong, the warranty will be void and/or the manufacturer absent liability.

Does anyone else think that a 200A fuse sounds like too much?

Also, as Charlie says, the size of your wiring needs to be factored in. Wire size will be dictated by the distance from the power source - according to ABYC standard.

Fair winds,
LittleWing77

The circuit protection is for the wire with the battery being the source. The alternator being in essence a regulated voltage output limited current source should not need any circuit protection if the wire is correctly sized.

200A fuse (located near the battery) is not uncommon.

[LittleWing77]

Originally Posted by Wotname

The circuit protection is for the wire with the battery being the source. The alternator being in essence a regulated voltage output limited current source should not need any circuit protection if the wire is correctly sized.

200A fuse (located near the battery) is not uncommon.

Thanks Wottie.

I was installing some batteries for a large genset last week that had 160-amp circuit protection, so I was just thinking about correct options.

When we were taught alternators, they emphasized (like FishSpeirit) that the conductors be capable of carrying an alternator's output and what you said - that an alternator is essentially self-regulating - it will only ever put out what it's rated for, i.e. a 150-amp alternator will only ever put out a maximim of 150-amps.

Maybe I need to go read the Balmar manufacturer's specs myself!

As always,
Wottie-is-King
Madame President, Wotname Fan Club
(aka LittleWing77)

[LittleWing77]

Okay Wottie,

I took my own advice. Here's what Balmar stipulates for their alternator installations:

GROUNDING
Alternator models designated as Isolated Ground (IG) feature an independent ground terminal that’s isolated from the alternator case. Isolated Ground alternators are used in applications where the engine is not desired to be a part of the grounding system. This is commonplace in steel or aluminum hull boats, or with engines that depend on sophisticated electronic ignition systems. In other applications, isolated grounding simply ensures that the alternator is sufficiently connected to system ground. The alternator’s ground cable should be the same size as the alternator’s positive output cable.

FUSING
The American Boat and Yacht Council (ABYC), in its standards for safer boating, recommends that cable runs to your battery banks be fused to protect the boat and owner against damage and injury. Circuit protection, as described by ABYC standards, can be accomplished by installing either a resettable circuit breaker or a fuse. The fuse or breaker you choose will depend on both the amperage rating of the alternator and the size of cable used. The following considerations can be used to determine fusing:

1. The largest available circuit protection device smaller than the amperage capacity of the cable being protected.
2. Larger than the maximum continuous current that will flow in the circuit. We find that a circuit protection device sized at approximately 140% of your alternator’s rated amperage is typically suitable for the circuit being protected. For more info about circuit fusing, see http://circuitwizzard.bluesea.com

So according to Balmar 200-amp fusing is just about right (it's a little less than 140%).

I've also attached the Balmar alternator's Owner's Manual so our OP can verify.

Good luck, Seattle!
LittleWing77