YART: Yet Another Rewire Thread (Sea Ranger 19)

[robotbill]

As per Arima Owners tradition, I'd like to post my rewire plan for review.

A few thoughts and questions:

I've gone back and forth between the SafetyHub 150 and 100 because even if I do end up adding a second plug, for say downriggers, the 100 has enough fuses. I ultimately decided to put the 150 in the drawing because of the built in ground bus.

The Mini Add-a-battery manual suggests an optional switch between the battery negative and the M-ACR. What switch do people use for that?

For things that are switched at the helm, but located at the stern (i.e. anchor light) do people generally run duplex from the helm and ground them up there, or run a single wire and ground them at the stern?
(Edit: I see now that there's special bilge pump wire on Greg's Marine Wiring)

I've seen discussions arguing both ways for fusing the starter. I think I'm leaning in the fuse direction (as you can see in the drawings). Does 200 amps for a Yamaha F115 seem appropriate?

It's not clear to me how to identify where to hook up the optional starting isolation on the M-ACR. Does anyone have suggestions?

I haven't quite decided what switches to use on the switch panel. I have Contura switches in the drawings, but I'm also considering using the original panel and just swapping out the switches with newer Blue Seas toggle switches.

I'm thinking about doing this in phases. i.e. redo stern and hook the existing helm wire to the SafetyHub. Then later coming back to run new wires and redo the helm. Is this a bad idea for any reason?

Thanks,
Joe

[fishmeister]

My helm wiring kinda/generally follows what you have done.  It looks like you're using the same fuse block that I have.

[davidsea]

  The ACR is a voltage-sensing solid-state relay.  With the motor running, it senses the higher voltage from the alternator and combines both start and house batteries so both are charging.   With the motor off, input voltage drops and the ACR separates the batteries so that loads on either battery won't affect the other one.  The ACR gets its operating power from the battery leads run to it.
  The ground lead shown in the diagram completes the circuit and allows it to function.  If the ground isn't connected, the ACR won't operate.  There is a very small amount of drain (a few milliamps) from the ACR circuit even when it's not operating, so the 'off' switch eliminates that drain.  The 1A fuse inline is a 'safety'.  If something shorts out internally and connects to battery power, the fuse blows and prevents the wire from burning up.
   I have the fuse in my system, a 1A ATC fuse in a waterproof fuse holder.  I don't have the switch.  In season, with the boat being used often, the drain isn't enough to affect anything, and if I knew I wasn't going to use the boat for a month or so, I'd just pull the fuse.  Over the winter, the batteries are disconnected and out of the boat anyway, and one less switch to fail is always a good thing.
  The ACR start wire - which would normally connect to the (+) start terminal on the key switch - separates the battery outputs when the starter is turning, isolating the house electronics from the voltage drop on the start battery.   I haven't bothered with it, since my motor starts VERY quickly, and I haven't seen any issues with my electronics, but if you see any glitches at the helm while starting - that's what it's for.
   As for doing it in stages....it's possible, but once you start messing with it, probably better to get it over with.  Fewer mistakes, less re-do on what you've already done, and easiest to document everything for later additions and troubleshooting.   m2c
   

[robotbill]

Any thoughts on the MRBF fuse sizing?

Also, I'm realizing now that I have a few of the part numbers in the diagram wrong. The Safety Hub should be 7748 and the MRBF fuse blocks should be 2151.

[robotbill]

Thanks for the feedback.

I attempted to measure about how long the 4AWG to the cabin would need to be and rounding up everywhere I got around 20ft. However, I think I saw DevMah mention a much longer length for a 17 Sea Chaser. Will I have instant regrets if I order 25ft rolls of the 4AWG wire going to the helm?

[davidsea]

  Make the exact run you intend to use with some cheap twine.  Don't pull it tight.  This does 2 things: If you can't get the twine through where you want it, you can't get 4GA there either,  and measuring the twine gives you an exact length.     Remember that if you're running 4GA for power you also need 4GA for ground.  Using 2 different colors will save you some unpleasant surprises later.   I'm assuming that you'll use a fuseblock to distribute power forward.  A BlueSeas PowerPost Plus will work well to distribute the ground wires, and is cheaper than fusepanels that include ground distribution..
   https://www.bluesea.com/products/category/28/104/PowerPost_Connectors/PowerPost_Plus

[robotbill]

Thanks, yeah, I was definitely planning on two distinct colors! It's so easy to get confused otherwise.

[agoodhi]

I'm thinking about doing this in phases. i.e. redo stern and hook the existing helm wire to the SafetyHub. Then later coming back to run new wires and redo the helm. Is this a bad idea for any reason?

This is exactly what I did so I could use the boat and .  I was able to complete the stern and use my downriggers.  A few months later, ran the helm wiring from safety hub to blue seas panel (still using factory switches for now).  My last stage is to pull the tank and redo the bilge wiring w/ water witch, and add a 2nd bilge (probably should have done that first!).

[robotbill]

agoodhi, that was definitely my thinking. I want to go out on my boat, but also I'm a lot more motivated to do projects when it's not dark, cold, raining. So, trying to get the best of both worlds.

[davidsea]

  I just looked at your original schematic, and there's one thing that won't work.  Under most conditions, the ACR isn't dealing with too much current - just combining the two batteries while running to charge both.  If you have a low start battery, the switch and ACR will combine the two batteries in order to get the motor started - one of its best features. This means that nearly the full starting current will go THROUGH the ACR to get the motor running, and the two 8GA wires you show from the switch to the ACR won't handle that current.  Those 2 wires need to be the same gauge as your motor's battery cables.  If you mount the switch and ACR close together, they can be very short, going directly from the switch battery terminals to the ACR, eliminating the battery runs and associated fuses altogether.  The switch battery terminals are also a good location to hook up (+) cables for an onboard charger, eliminating separate wires to each battery.  The (-)  wires can be combined and run to any convenient ground.

[DevMah]

I just looked at your original schematic, and there's one thing that won't work.  Under most conditions, the ACR isn't dealing with too much current - just combining the two batteries while running to charge both.  If you have a low start battery, the switch and ACR will combine the two batteries in order to get the motor started - one of its best features. This means that nearly the full starting current will go THROUGH the ACR to get the motor running, and the two 8GA wires you show from the switch to the ACR won't handle that current.  Those 2 wires need to be the same gauge as your motor's battery cables.  If you mount the switch and ACR close together, they can be very short, going directly from the switch battery terminals to the ACR, eliminating the battery runs and associated fuses altogether.  The switch battery terminals are also a good location to hook up (+) cables for an onboard charger, eliminating separate wires to each battery.  The (-)  wires can be combined and run to any convenient ground.

Incorrect, ACR wires are sized according to the chart supplied. Usually sized to the alternator max output amperage.
The ACR only combines for charging not starting. In fact it will automatically disengage as it senses the voltage drop while the motor is being cranked. Voltage drops to 12.35 for 10 seconds or 12.75 for 30 seconds the contacts open.



http://assets.bluesea.com/files/resources/instructions/980014350.pdf


Dev

[DevMah]

As per Arima Owners tradition, I'd like to post my rewire plan for review.

A few thoughts and questions:

I've gone back and forth between the SafetyHub 150 and 100 because even if I do end up adding a second plug, for say downriggers, the 100 has enough fuses. I ultimately decided to put the 150 in the drawing because of the built in ground bus.

The Mini Add-a-battery manual suggests an optional switch between the battery negative and the M-ACR. What switch do people use for that?

For things that are switched at the helm, but located at the stern (i.e. anchor light) do people generally run duplex from the helm and ground them up there, or run a single wire and ground them at the stern?
(Edit: I see now that there's special bilge pump wire on Greg's Marine Wiring)

I've seen discussions arguing both ways for fusing the starter. I think I'm leaning in the fuse direction (as you can see in the drawings). Does 200 amps for a Yamaha F115 seem appropriate?

It's not clear to me how to identify where to hook up the optional starting isolation on the M-ACR. Does anyone have suggestions?

I haven't quite decided what switches to use on the switch panel. I have Contura switches in the drawings, but I'm also considering using the original panel and just swapping out the switches with newer Blue Seas toggle switches.

I'm thinking about doing this in phases. i.e. redo stern and hook the existing helm wire to the SafetyHub. Then later coming back to run new wires and redo the helm. Is this a bad idea for any reason?

Thanks,
Joe

Motor negative must goto the battery or higher amperage buss connection. (600 A)
The buss on the Safety hub is not designed to handle that capacity.

FYI
250A fuse
Dev   

[robotbill]

Thanks!

The ACR only combines for charging not starting. In fact it will automatically disengage as it senses the voltage drop while the motor is being cranked.

Cool, this aligns with my reading of the directions.

Motor negative must goto the battery or higher amperage buss connection. (600 A)
The buss on the Safety hub is not designed to handle that capacity.

Oof, I thought I was being so clever by ordering the Safety Hub 150 instead of the 100. Oh well. I updated the drawing to include a 650A Marinco bus bar #777-BBS3-650.

250A fuse

Ok, updated. I really had no idea how to estimate this other than looking at older forum posts.

[DevMah]

Thanks!

The ACR only combines for charging not starting. In fact it will automatically disengage as it senses the voltage drop while the motor is being cranked.

Cool, this aligns with my reading of the directions.

Motor negative must goto the battery or higher amperage buss connection. (600 A)
The buss on the Safety hub is not designed to handle that capacity.

Oof, I thought I was being so clever by ordering the Safety Hub 150 instead of the 100. Oh well. I updated the drawing to include a 650A Marinco bus bar #777-BBS3-650.

250A fuse

Ok, updated. I really had no idea how to estimate this other than looking at older forum posts.

Thanks!

The ACR only combines for charging not starting. In fact it will automatically disengage as it senses the voltage drop while the motor is being cranked.

Cool, this aligns with my reading of the directions.

Motor negative must goto the battery or higher amperage buss connection. (600 A)
The buss on the Safety hub is not designed to handle that capacity.

Oof, I thought I was being so clever by ordering the Safety Hub 150 instead of the 100. Oh well. I updated the drawing to include a 650A Marinco bus bar #777-BBS3-650.

250A fuse

Ok, updated. I really had no idea how to estimate this other than looking at older forum posts.

Looks good
Dev

[robotbill]

Thank you!

[robotbill]

DevMah,

One thing I wanted to double check. The Dual MRBF Terminal Fuse Block is rated for 300 Amps, but the two fuses I'll have on it add up to more than 300A (75 + 250).

In the FAQ Blue Seas has:

Q: Can each terminal of the 2151 carry a 300 amp fuse?

A: No. The total of the of the entire fuse holder is not to exceed 300 amps.

It seems that my drawing is in violation of this. I saw in http://www.arimaowners.com/index.php?topic=23103.msg272124#msg272124 that as of July 2022 you had been running a 200A on a 150HP Yamaha successfully. If I stick with 200A to my Yamaha 115 will I be at risk of nuisance blows?

[positize]

You don't want to take any chance of a nuisance trip while your starter motor is engaged.  A starter motor is a high inductance device that draws a large amount of current.  If your protector trips, this is the worst case scenario for a huge flyback voltage that has very high probability to blow up your alternator AND your electronics: a very expensive lesson.  Flyback is described by the equation V = -L * di/dt.  In the case of a starter motor trip, the L is a large number, the di (derivative of current) is a large number, and the dt (derivative of time) is a very small number.  This ends up making the voltage and stored energy a VERY big number if that protector trips.  The result is the voltage spike is so large that no Alternator Protection Device will save your bacon: there is just too much energy.   

I'm a degreed marine electrical engineer: this is NOT theoretical, it will do damage.  This is also one of many reasons that ABYC does not require a protector on your starter.  By the time you select a protector (fuse/breaker) that is large enough to definitively avoid nuisance trips (set it higher than the Marine Cranking Amps spec of your engine), that protector has minimal chance of providing protection in the event of a short since the starter wire gauge on most motors ends up becoming your circuit protector (the wire melts, the fuse does nothing). This has been heavily analyzed by a slew of competent engineers over many years by both ABYC and SAE: skip the circuit protector on your start wire because if it does trip while starting, you are not going to like the result. 

[davidsea]

 
      I agree with positize, and have no circuit protection on my starter circuit - the motor's OEM factory (+)cable goes directly to the switch, and from there directly to the start battery (+)terminal.  Also, there is nothing else in the boat run off the start circuit and battery.  My theory is that if all else fails, the only important thing is to start the motor and get home.
   My only danger for flyback damage is if the start battery goes down and I have to use the switch to combine batteries.  My house battery has a 120A circuit breaker next to it, which I feel is necessary to protect the nearly 10 foot run across the stern to the switch.  The part above/behind the fuel tank is run in conduit, but that's still too much 'invisible' risk for me.   m2c