Starting from scratch

[Jeff Fro]

This is a slight modification of a schematic I saw on a google search. It seems like a viable direction, but I just can't seem to believe that it is not a bit overkill. I'll be starting off with a 2 battery house bank and one starting battery in the system. Currently I have a 55A alternator, plans are to upgrade it to 105A. Plans are to have a 12 position fuse block up front with a common Neg buss and a 6 fuse block with a common Neg buss back by the engine. The engine, trim tabs, lower trim, and the nav lights will all be powered from the starting battery. I'm thinking there are a few too many fuses with this setup. See anything wrong/right with this setup?

Comments? Questions? All are good.

 

[alldodge]

Might want Nav lights on the house side. Reason is if you stay out over night then the anchor light will need to stay on

 

[Jeff Fro]

Aren't the nav lights and the anchor lights three different lights?
This is the way I'm understanding the nav/anchor lights, correct me if I'm wrong.
Red and green on the front and a white one on the back for nav lights. Only time the nav lights are on are when the boat is underway?

One white light on the highest point on the boat for the anchor light? For when the boat is anchored.

 

[alldodge]

Correct, the three lights are ON when under way at night. The stern light becomes the anchor light when boat is at anchor. All three lights are controlled by on switch ON-OFF-ON (ON Nav lights-OFF-ON anchor light only)

 

[Jeff Fro]

I'll be mounting an anchor light on top of the console/t-top. The rear light is actually flush with the back of the transom and won't be able to be seen by someone coming from the front when anchored.

 

[samntrllr]

Question, should your neg. feed to the secondary negative buss be a separate wire? Not using the 3 house battery terminals? I also have a secondary neg buss. on a direct connection to the main ground.

 

[alldodge]

I'll be mounting an anchor light on top of the console/t-top. The rear light is actually flush with the back of the transom and won't be able to be seen by someone coming from the front when anchored.

Then the white light on top needs to be ON when ever boat is running at night

 

[Jeff Fro]

The stern light is the same as the "power boat under power" upper pic. So it looks like I will have to have all 4 lights on.

 

[Jeff Fro]

Question, should your neg. feed to the secondary negative buss be a separate wire? Not using the 3 house battery terminals? I also have a secondary neg buss. on a direct connection to the main ground.

From what I am understanding is the loads that are hooked to a specific battery will use the charge from that battery. House loads will pull from the house battery and the start loads will pull from the start battery. However, if the batteries don't have a common neg the alternator won't charge one of the batteries.

 

[dingbat]

The whole schematic kind of confusing.

Why the floating bus bar up front? Grounds should be connected to buss bar on the front load center to prevent ground loops.

Don't feed switches from different load centers. Possible feedback loops through the two battery switches.

Nothing should be connected to the cable running between the two battery banks except the ACR.

Power for the 12V (House) should originate from one battery bank. The 12 V (Start) should originate from the other battery bank.

Don't see a load center for "start" which to connect your trim tabs, etc.

Don't understand the ALT and charger connections between power and ground. Alternator goes directing to starting battery as does the battery charger.

 

[Jeff Fro]

The whole schematic kind of confusing.

Why the floating bus bar up front? Grounds should be connected to buss bar on the front load center to prevent ground loops.

Don't feed switches from different load centers. Possible feedback loops through the two battery switches.

Nothing should be connected to the cable running between the two battery banks except the ACR.

Power for the 12V (House) should originate from one battery bank. The 12 V (Start) should originate from the other battery bank.

Don't see a load center for "start" which to connect your trim tabs, etc.

Don't understand the ALT and charger connections between power and ground. Alternator goes directing to starting battery as does the battery charger.

The front bus bar is part of the fuse block for the front circuits.
Where ever I pull power from, the neg will return to it.
The two squares are battery selector switches for emergency starting from the house bank if needed, will not be connected otherwise.
Haven't drawn the load center for start as of yet.
Most of the circuitry has shown the charging circuit going towards the house side of the battery system with the idea that the ACR will charge the starting battery as needed.

 

[dingbat]

The two squares are battery selector switches for emergency starting from the house bank if needed, will not be connected otherwise.

I have the Off -On- Both switch on my system.
It has four (4) terminals on the back - House in/out and Start in/out
OFF - All power off
On - Power to Start (piggy backed Start load circuit) - House Load Center
Both - Combines House and Start batteries to motor

Most of the circuitry has shown the charging circuit going towards the house side of the battery system with the idea that the ACR will charge the starting battery as needed.

That's opposite of the way it was designed.

Designed to maintain Starting battery. Once start is fully charged, ACR opens and dumps the Alt charge to House battery.
Guess you could charge house and dump excess to start, but defeats the idea of isolating the starting to assure your going home.

 

[Jeff Fro]

I have the Off -On- Both switch on my system.
It has four (4) terminals on the back - House in/out and Start in/out
OFF - All power off
On - Power to Start (piggy backed Start load circuit) - House Load Center
Both - Combines House and Start batteries to motor

That's opposite of the way it was designed.

Designed to maintain Starting battery. Once start is fully charged, ACR opens and dumps the Alt charge to House battery.
Guess you could charge house and dump excess to start, but defeats the idea of isolating the starting to assure your going home.

Trying to learn here. If the alternator is hooked up to the starting side of the ACR to maintain the start battery as a priority, and the ACR opens, that would mean that the start battery is the only battery getting a charge, per pic.

Interesting article...ACR's

Versus this pic of a circuit with an alternator connected to the house bank. As long as the ACR is closed, both banks get charged. When it's open, the house bank gets charged. Which will be depleted more than the starting battery. Isn't the job of an ACR is to provide automatic charging to the bank/banks that need it? If the ACR senses that the start battery need to charge, won't the ACR close and provide charge to it? If most all systems are using the house battery, how much of a drain does the running of an engine cause on a battery?

 

[dingbat]

The primary function of an ACR is the keep the “Primary” battery fully charged then route any excess charging capacity to the "Secondary" batteries.

The ACR is controlled (open/closed) by voltage/time thresholds. On my setup, the connection between the "Primary" to "Secondary" battery closes when the voltage of the "Primary" battery exceeds 13.0 V for 2 min. or 13.6 V for 30 sec.

The ACR maintains the connection until/unless the voltage of the "Primary" battery drops below 12.75 V for 30 sec. or 12.35 V for 10 seconds. At which time the connection is opened (primary disconnected from secondary) until the voltage of the "Primary" meets threshold conditions again.

Typically, all critical demands such as starter motor, power for primary navigation lights and electronics, bilge pumps, trim tabs, etc. are powered by the “primary” battery. Non-essential and backup systems go to "Secondary" battery.

Certainly no reason why you can't assign the "house" load as "Primary", but then you risk compromising your "Starting" functions.

So the question becomes..........at the end of the day, do you want a fully charged Starting battery and the possibly of a compromise "house" bank (alternator does not meet demand) or.........a fully charged "house" battery with the possibility of being stranded with an under charged starting battery.

http://assets.bluesea.com/files/resources/instructions/990310020.pdf

 

[Jeff Fro]

Typically, all critical demands such as starter motor, power for primary navigation lights and electronics, bilge pumps, trim tabs, etc. are powered by the “primary” battery. Non-essential and backup systems go to "Secondary" battery.

Certainly no reason why you can't assign the "house" load as "Primary", but then you risk compromising your "Starting" functions.

So the question becomes..........at the end of the day, do you want a fully charged Starting battery and the possibly of a compromise "house" bank (alternator does not meet demand) or.........a fully charged "house" battery with the possibility of being stranded with an under charged starting battery.

http://assets.bluesea.com/files/resources/instructions/990310020.pdf

First off, I wouldn't want any of my electronics running off of the start battery. To me, the start battery is there for primary underway functions. Like you said, starter motor, power for primary navigation lights, lower trim, and trim tabs. Not much else.

It doesn't really matter which side of the ACR the charge is connected to, the ACR will maintain both battery banks through it's normal operation. However, if it isn't charging the start battery, there is always the combine switch on the battery selector switch to be able to start the engine thus not leaving one stranded.

To help prevent cycling of the relay....A simple solution for boats with a large House battery bank and a relatively small Start battery bank, including many sailboats, is to connect the charging source to the House battery bank (see wiring diagram). This solution works because the Start battery bank is typically smaller and less discharged than the larger House battery bank. When the battery banks are combined for charging, there isn’t a significant drain to lower the system voltage to the disconnect level.

Bluesea

ACR

ACR Myth & Lore:​

1- “An ACR charges the start battery first then isolates it and charges the house” = FALSE
The ACR does not in any way do this, it is either in parallel or it is not in parallel. Very simple.
2- “An ACR gives priority charging to the start battery” = FALSE
Please understand that even if you feed charging to the start battery first, which is not advised on a cruising boat with disparately sized banks, 30 seconds of charging is not charging, even for a minimally depleted start battery. A battery at 99% SOC is in the worst range of charge efficiency. Despite being minimally depleted it still takes a good bit of time to reach an actual 100% SOC again. Each Ah we deliver to the battery, at a high SOC, is not being stored at 100% or even 50% due to the horrible Coulombic efficiencies at high SOC. The logic delays in the ACR are not there to create “priority charging” for a start battery or house battery they are there to eliminate relay-chatter and to help minimize relay-cycling or on/off/on/off/on/off behavior.


We may just agree to disagree.

 

[alldodge]

That was a good read, thanks.
The difference is what is called "cruising boat". There identification of a cruising boat is one which has several house bats and one start bat. In this case they state its best to wire ALT to the house and not the start

That said, there is no way I would let my ALT be connected to the house bat and take a possibility that ACR would open. My motor runs off the start bat, the ECM needs a good smooth power with no spikes. The ECM cost to much to even think about taking a chance. Then again I have one start and house bat which are close to same side, just different types. The write up did specify this is normal for this setup

 

[Jeff Fro]

That was a good read, thanks.
The difference is what is called "cruising boat". There identification of a cruising boat is one which has several house bats and one start bat. In this case they state its best to wire ALT to the house and not the start

That said, there is no way I would let my ALT be connected to the house bat and take a possibility that ACR would open. My motor runs off the start bat, the ECM needs a good smooth power with no spikes. The ECM cost to much to even think about taking a chance. Then again I have one start and house bat which are close to same side, just different types. The write up did specify this is normal for this setup

With an ECM tossed into the mix, I wouldn't run the alternator to the house bank either. However, I don't have an ECM so either way would work. Learn something new every day. Thanks Alldodge

 

[dingbat]

First off, I wouldn't want any of my electronics running off of the start battery. To me, the start battery is there for primary underway functions. Like you said, starter motor, power for primary navigation lights, lower trim, and trim tabs. Not much else.

I'm a offshore guy.....a functioning Chart plotter and DSC VHF are not optional 50 miles off the coast

Do as you like... I don't have to live with the consequences...

 

[Jeff Fro]

I won't be 50 miles off the coast, but I will be out on the rivers. VHF w/DSC is on my list to get next.