Revised Diagram . . . Cables and Fuses Correct?

[davisr]

After conversations with tech support at Blue Sea Systems and a visit to the local Trojan Battery dealer I've once again updated this diagram.

ACR

1. I've changed the fuse size on the 4 AWG cables for the ACR to 100 amp.

2. I've added an LED indicator light. There is no negative for this light. The negative is instead supplied by the neg/ground wire beside it.

3. The neg/ground is fused (as it was in the last two versions of the diagram). The reason Blue Sea recommends a fuse on this wire is that it offer protection in the event of a catastrophic failure (which has not happened, but theoretically could).

4. I've added a note about the Starting Isolation. This is usually unnecessary for outboards on sailboats, according to Blue Sea. Thus, I will only add this if it proves necessary.

Iota 45

Iota Engineering recommends that a 50 amp fuse be placed within 18 inches of the battery. I described my setup with the terminal fuse on the bus bar at a distance of 4.5 ft from the battery and was told that this was okay.

Batteries

1. I've changed the 1/0 AWG, which joins the two House Bank batteries in series, to 1 AWG. This makes the starting circuit all one gauge (except for the 4 AWG outboard leads).

2. Two Trojan T-105s or T-125s (which are identical in dimensions) fit well inside the Noco Dual 6V Battery Box. More importantly, the Terminal Fuse Block (that I plan to use on the House Bank) leaves enough room for the lid on the Noco Box to shut. The Trojan terminals I tested were LPT (Low Profile Terminals).

3. The Trojan LPT terminals are 5/16 inch, whereas the Blue Sea Systems Terminal Fuse Blocks are 3/8 inch. Nevertheless, there was enough space at the base of the LPT terminals for the ring to make full contact.

Lingering Questions

1. I am still in doubt about the fusing of the House and Reserve with 175 amp terminal fuses. Not sure if these are two big or two small.

2. Still unsure about the placement of an ANL fuse in the 10 ft run from the motor to the battery switch. The issue is that I have a mixture of 4 AWG and 1 AWG.

Would really appreciate some help from the forum with these final questions.

Roscoe

[Jbaffoh]

Originally Posted by davisr

Lingering Questions

1. I am still in doubt about the fusing of the House and Reserve with 175 amp terminal fuses. Not sure if these are two big or two small.

2. Still unsure about the placement of an ANL fuse in the 10 ft run from the motor to the battery switch. The issue is that I have a mixture of 4 AWG and 1 AWG.

Would really appreciate some help from the forum with these final questions.

Roscoe

Is the 10-foot run to the motor one-way or round-trip?

I would select a fuse for the reserve battery terminal that accounts for the 4 AWG, rather than adding another fuse after the battery switch. Something around 150 amps should protect that entire 1 AWG - 4 AWG run (assuming the 4 AWG is 10-feet round trip) or 135 amps (if the 10 feet is one way), while avoiding any nuisance blows.

The best way to check for starter current needs, is to use a good clamp meter that captures the inrush of current when starting an ice cold motor.

Even if the fuse blows, you have the pull starter as a backup, right?

Nice battery box--I have one for my T-145's.

[davisr]

Thanks for the reply, here are the measurements:

The 4 AWG Positive and negative leads from the Yamaha are 8 ft. (thus 16 ft. total)

The 1 AWG Positive run from the Dual Power Post to Bat Switch is 2 ft.

The total distance of the circuit (including the 1 AWG runs to and from the bus bars) is 32 ft.

Roscoe

[DeepFrz]

I suggest you throw away those wing nuts on the battery and replace with regular nuts.

[davisr]

Thanks DeepFrz. I'm thinking I'll use regular hex-nuts or maybe self-locking nuts. Haven't actually purchased the batteries yet. Waiting until close to the end of the rewiring project so they'll be as new as possible. That pic with the wing-nuts is actually from the Trojan website.

Regards,
Roscoe

[davisr]

Several more conversations with tech people and some more research have led me to revise the diagram one more time. Hopefully, this is the last.

1. 285-Series Thermal Breaker: I've downsized this from 80 amp to 70 amp due to a recalcuation of my house loads. At first I had calcuated for 50 total amps. I realized, however, that I was including bilge pumps in this (which are not a part of the house loads/branch circuits). With a 40 amp load for the Trojan T-125s with 960 CCAs I arrived at a 70 amp breaker as optimal. Used the Blue Sea Systems DC Circuit Wizard for this.

2. Terminal Fuses on House and Reserve Banks: I've upsized these from 175 amp to 250 amp, because I realized, upon further thought, that these cables would not be bundled.

3. ANL Fuse: I added this to the starting cable. I spoke with Yamaha Customer Support. They said that if I wised to protect this 10 ft run then I should size the fuse to the smaller cable (thus the 4 AWG, not the 1 AWG). I spoke with Blue Sea Systems tech support. They said that yes, despite the fact that ABYC does not require fusing of the starting cable it's never a bad idea to fuse it, as long as you can figure out how to size the fuse properly for your cable and engine. I selected a 150 amp ANL Fuse for the 4 AWG cable based on the ampacity/fuse table on the Blue Sea website. In terms of this sized fuse being sufficient for the 245 to 323 amps necessary for cranking the Yamaha 9.9 High Thrust, I'm working off of the information provided by Maine Sail on ANL fuses in this posting:
ANL fuse size at battery - SailNet Community

Unless anyone sees anything amiss with these changes I've made to this version of the diagram, I believe I'll go with it.

Thanks,
Roscoe

[Jbaffoh]

Originally Posted by davisr

Several more conversations with tech people and some more research have led me to revise the diagram one more time. Hopefully, this is the last.

1. 285-Series Thermal Breaker: I've downsized this from 80 amp to 70 amp due to a recalcuation of my house loads. At first I had calcuated for 50 total amps. I realized, however, that I was including bilge pumps in this (which are not a part of the house loads/branch circuits). With a 40 amp load for the Trojan T-125s with 960 CCAs I arrived at a 70 amp breaker as optimal. Used the Blue Sea Systems DC Circuit Wizard for this.

2. Terminal Fuses on House and Reserve Banks: I've upsized these from 175 amp to 250 amp, because I realized, upon further thought, that these cables would not be bundled.

3. ANL Fuse: I added this to the starting cable. I spoke with Yamaha Customer Support. They said that if I wised to protect this 10 ft run then I should size the fuse to the smaller cable (thus the 4 AWG, not the 1 AWG). I spoke with Blue Sea Systems tech support. They said that yes, despite the fact that ABYC does not require fusing of the starting cable it's never a bad idea to fuse it, as long as you can figure out how to size the fuse properly for your cable and engine. I selected a 150 amp ANL Fuse for the 4 AWG cable based on the ampacity/fuse table on the Blue Sea website. In terms of this sized fuse being sufficient for the 245 to 323 amps necessary for cranking the Yamaha 9.9 High Thrust, I'm working off of the information provided by Maine Sail on ANL fuses in this posting:
ANL fuse size at battery - SailNet Community

Unless anyone sees anything amiss with these changes I've made to this version of the diagram, I believe I'll go with it.

Thanks,
Roscoe

My only issue is the redundancy of fuses on the starter battery. Why not put the 150 on the battery terminal, and forget about the 250? Spend that $$ on beer!

[Maine Sail]

Originally Posted by davisr

In terms of this sized fuse being sufficient for the 245 to 323 amps necessary for cranking the Yamaha 9.9 High Thrust,

Roscoe,

A 10HP outboard if you're lucky will draw 50-75A average and about 110-150 in-rush as measured with a Fluke meter that captures to 100mS. I just recently tested this on a Honda 10 HP four stroke OB on a Pearson 26. Over six starts the highest in-rush measured was 132A and the lowest was 102A. Average was bouncing between 45 & 65A with the stop button pushed in while cranking. Even if the in-rush is higher than that, for less than 100mS, it really does not matter to the fuse. I would be SHOCKED if you nuisance blew a 150ANL. We have a YC Junior race program chase boat with a 90HP OB that uses a 150ANL and has been now for the last two years. These boats are often started and stopped 20-30+ times per day.

[davisr]

Originally Posted by Maine Sail

Roscoe,

A 10HP outboard if you're lucky will draw 50-75A average and about 110-150 in-rush as measured with a Fluke meter that captures to 100mS. I just recently tested this on a Honda 10 HP four stroke OB on a Pearson 26. Over six starts the highest in-rush measured was 132A and the lowest was 102A. Average was bouncing between 45 & 65A with the stop button pushed in while cranking. Even if the in-rush is higher than that, for less than 100mS, it really does not matter to the fuse. I would be SHOCKED if you nuisance blew a 150ANL. We have a YC Junior race program chase boat with a 90HP OB that uses a 150ANL and has been now for the last two years. These boats are often started and stopped 20-30+ times per day.

Thanks Maine. That's really useful information. I guess I've been wrongly associating the listed CCA (Cold Cranking Amps) and MCA (Marine Cranking Amps) in the Yamaha 9.9 Owner's Manual with in-rush, which obviously is something different.

Appreciate the advice Jbaffoh about saving $$ for beer. That's always something that gets my attention. In terms of fusing the House Bank and Reserve Bank with with terminal fuses, I've been working under the assumption that these were necessary to protect the 1 AWG cables that terminate at the battery switch, since they are separate from the positive starting cable itself (which is 8 ft of 4 AWG and 2 ft of 1 AWG). I've sized the ANL for 4 AWG, so I think I'm on the right track in fusing the banks themselves.

Roscoe

[Jbaffoh]

Originally Posted by davisr

Thanks Maine. That's really useful information. I guess I've been wrongly associating the listed CCA (Cold Cranking Amps) and MCA (Marine Cranking Amps) in the Yamaha 9.9 Owner's Manual with in-rush, which obviously is something different.

Appreciate the advice Jbaffoh about saving $$ for beer. That's always something that gets my attention. In terms of fusing the House Bank and Reserve Bank with with terminal fuses, I've been working under the assumption that these were necessary to protect the 1 AWG cables that terminate at the battery switch, since they are separate from the positive starting cable itself (which is 8 ft of 4 AWG and 2 ft of 1 AWG). I've sized the ANL for 4 AWG, so I think I'm on the right track in fusing the banks themselves.

Roscoe

If the 150 is moved to the battery terminal, it protects the entire run of 1AWG and 4AWG. You'll be sizing for the 4, and offering even greater protection for the 1.