Charging 4 banks from 1 alternator?

[skipmac]

I said I wouldn't respond again but since you address me directly I guess I'll get back into it.

Originally Posted by ramblinrod

Just one more point...

Where the alternator IS capable of delivering the max current (at 50% SOC) the house bank and usual house loads (when motoring) may draw, I do recommend connecting the alternator directly to the start bank.

Mitiempo already addressed this. Hi charge current to a 50% SOC house bank and the cycling caused by the voltage differential between the start and house bank is another reason for connecting the alternator to the house and not start bank.

This is a more "failsafe" approach, in that in the event the ACR fails, or ACR fuse blows, the start battery still gets charged.

Failure rate of the various combiners is very low. I'm sure it happens but I haven't read of any direct reports of a modern voltage controlled combiner, properly sized and installed, that has failed.

In the case of the OP, with a 120A alternator and a 400+ Ahr house bank, it is cutting it close, so I recommend connecting the ACR directly to the house bank.

If an ACR is used for both the house bank and the thruster bank, I recommend using ML-ACRs rather than SI-ACRs due to the high potential current demands of the thruster.

Don't have a thruster but do have an electric windlass. It may not be the cheapest but certainly the KISS solution for me is to run heavy, marine grade cables from the house bank to the bow for the windlass. Avoids extra batteries in a remote location, proper installation and maintenance of those batteries, managing the charge. This is one situation where I think there are several "correct" solutions, each with corresponding advantages and disadvantages. I think the larger the boat (which of course means larger windlass and thruster, longer and larger cables, etc) then the more sense it makes to add a forward battery bank.

However, due to the cost (of both the ACRs and the heavy cables) I recommend using an ACR (ML-ACR is high loads may be present) for the house bank, and considering charging the thruster bank with a discrete AC charger mounted forward, and running the AC generator to charge it up after any significant thruster or windlass use. Especially because a non-operator initiated load (Electrosan) is also on the thruster bank, a remote battery monitor, (even just voltage) on the thruster bank would be a good idea.

[skipmac]

Originally Posted by ramblinrod

Correct.

As far as fusing, it is not there to limit current but for safety reasons, as all fuses are.

All fuses are current limiting devices. That is how they invoke safety in a circuit, by not permitting current to exceed the current carrying capacity of the wires or devices they are connected to.

I think this is a matter of semantics .

One could call a fuse a current limiting device which it does in a certain sense, however that phrase is commonly used to refer to an active device that sets a maximum current in a circuit but doesn't fail like a fuse but allows the circuit to continue functioning at the current limit established. A fuse in this context is not a current limiting device.

[boatbod]

A fuse is more correctly called an "overcurrent protection device" since that is all it can do. Not a good choice for current limiting.

[skipmac]

Originally Posted by boatbod

A fuse is more correctly called an "overcurrent protection device" since that is all it can do. Not a good choice for current limiting.

[ramblinrod]

Originally Posted by boatbod

A fuse is more correctly called an "overcurrent protection device" since that is all it can do. Not a good choice for current limiting.

Gentlemen, let's not throw the baby out with the bath water. A a fuse or breaker an overcurrentprotection device? Yes it is. Is a fuse or breaker a one-shot current limiting device? Yes it is.

The important thing to know, is when over current protection or current limiting or max limit coulomb interupter is necessary.

[ramblinrod]

Correction a breaker is a resettable current limiting device.

[skipmac]

Originally Posted by ramblinrod

Gentlemen, let's not throw the baby out with the bath water. A a fuse or breaker an overcurrentprotection device? Yes it is. Is a fuse or breaker a one-shot current limiting device? Yes it is.

In the same sense one could say blowing up the engine in a car is a one shot speed limiting device. Yes it is, but one isn't using the commonly used and accepted terminology in either case.

Casual discussions it may not matter as much, but in a discussion focusing on technical issues using the proper terminology can be important to maintain clarity and understanding. Common example, the difference between amps and amp hours.

[boatbod]

Point being, a fuse or breaker prevents excess current flow from burning something up. In the situation described here, there was a need to LIMIT current flowing through an undersized ACR solenoid but not stop it flowing entirely. Really the best answer is upsize the ACR to handle full load, or change technologies and substitute with a DC-DC battery charger (Echo Charge or similar).

[ramblinrod]

Originally Posted by skipmac

In the same sense one could say blowing up the engine in a car is a one shot speed limiting device. Yes it is, but one isn't using the commonly used and accepted terminology in either case.

Casual discussions it may not matter as much, but in a discussion focusing on technical issues using the proper terminology can be important to maintain clarity and understanding. Common example, the difference between amps and amp hours.

No, those are not the same things, fuses and breakers are commonly referred to as current limiting devices.

[skipmac]

Originally Posted by ramblinrod

No, those are not the same things, fuses and breakers are commonly referred to as current limiting devices.

That terminology was never used when by any of the professors I had when I got a degree in electrical engineering. Don't recall anyone using that terminology.

[skipmac]

Here is a current limiting device. Note that the instructions specify that it needs a circuit breaker, sold separately.

LA-33-RN | ConTech Lighting

[mitiempo]

Originally Posted by ramblinrod

Just one more point...

Where the alternator IS capable of delivering the max current (at 50% SOC) the house bank and usual house loads (when motoring) may draw, I do recommend connecting the alternator directly to the start bank.

This is a more "failsafe" approach, in that in the event the ACR fails, or ACR fuse blows, the start battery still gets charged.

In the event the ACR fails the banks can be paralleled by the third switch if wired that way or by the 1/2/both/off switch in the "both" position. That is "failsafe".

While I guess a few ACR's have failed I have never seen one. I sell both Victron and Blue Seas ACR's, lots of them.

As I posted before Blue Seas correctly suggests connecting the alternator to the larger of the battery banks to prevent the ACR from opening and closing as the current going into the large bank drops the voltage on the small bank.

[skipmac]

Originally Posted by mitiempo

In the event the ACR fails the banks can be paralleled by the third switch if wired that way or by the 1/2/both/off switch in the "both" position. That is "failsafe".

I am wired and switched for redundancy in starting but as a last ditch backup I also keep a set of heavy gauge jumper cables on the boat. Just one more very KISS backup if anyone feels the need.

Originally Posted by mitiempo

While I guess a few ACR's have failed I have never seen one. I sell both Victron and Blue Seas ACR's, lots of them.

As I posted before Blue Seas correctly suggests connecting the alternator to the larger of the battery banks to prevent the ACR from opening and closing as the current going into the large bank drops the voltage on the small bank.

Originally Posted by mitiempo

While I guess a few ACR's have failed I have never seen one. I sell both Victron and Blue Seas ACR's, lots of them.

Sounds like you have a lot more personal dealings with these than I do but my more limited experience is the same. Have never personally heard of a failure of a properly sized and installed unit.

Originally Posted by mitiempo

As I posted before Blue Seas correctly suggests connecting the alternator to the larger of the battery banks to prevent the ACR from opening and closing as the current going into the large bank drops the voltage on the small bank.

And one would think the manufacturer of a device would, in most cases, recommend the best way to use their product.

[skipmac]

Originally Posted by ramblinrod

Correction a breaker is a resettable current limiting device.

Correctly, a circuit breaker is a resettable current interrupting device.

[ramblinrod]

Originally Posted by skipmac

Here is a current limiting device. Note that the instructions specify that it needs a circuit breaker, sold separately.

LA-33-RN | ConTech Lighting

Sir, there are many types of current limiting devices, one shot (fuse) resettable (breaker) and continuous (solid state). Wikipedia, search "Current Limiting Device", "A fuse is the most basic current limiting device".

Can you please focus on the important matters than trying to force everyone to use your preferential wording.

Referring to a fuse as a current limiting device is ABSOLUTELY correct and I will continue using this proper terminology for as long as I choose.