12v system rewire including Balmar SG200, ACR, Solar, 1/2/B Switch and On/Off Switch

dlochner · Dec 11, 2021

Mike,

Basically you have a system that is similar to the system on Second Star. A few quick thoughts that shouldn't be budget busters.

The sense wire for the SG 200 shunt should go to the House bank, not the start/reserve bank. The start battery will be quickly charged and so you don't really need to know what's happening there. The house bank is the one that matters.

Get the Blue Tooth dongle for the SG 200 especially if you plan to add an external regulator (the 618).

Instead of the 1-2-B switch use a Blue Sea Dual Circuit Plus switch. This switch will allow combining both banks in the emergency position and other wise keeps them separate.

Add a simple On/Off switch between the house bank and the Positive bus bar. This will allow you to isolate the house bank if something fails. Take a look at the BEP Pro Series switches They are surface mounted switches that are faster and easier to install.

No need for the distribution bar after the start/reserve bank. There is nothing that should be connected to the start reserve battery except the cable to the on/off switch and then to the CP+ switch.

Don't forget the circuit protection within 7 inches of the batteries.

MikeHoncho · Dec 11, 2021

Get the ACR that is manually triggered and delete the 1/2 Both. Run your alt to the battery side of the on/off fused.

Pagan Baby · Dec 11, 2021

Mike, what I have on my boat and which has worked well for me is that I have an on/off switch between the house bank and the main + distribution bus, I then have a 1/2/both/ off switch running from the house and reserve bank to the starter. Lastly, I have an on/off switch between the main distribution bus and the panel with switched loads. Unswitched loads come through a fuse box off of the main + distribution bus.
The on/off between the house bank and main bus allows me to shut off power to everything. Normally this is left on to feed the unswitched loads like bilge pumps and the like. But, I can cut power to everything should I need to do some electrical work or an emergency. The reserve starting battery is connected through an ACR to the main distribution bus but is only used as a reserve starting battery and not connected to any other loads.

Stu Jackson · Dec 11, 2021

The Blue Seas Dual Circuit Switch is not for everyone. Here's why:

AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
Darn AGM Batteries

MikeHoncho · Dec 11, 2021

Pagan Baby said:
Mike, what I have on my boat and which has worked well for me is that I have an on/off switch between the house bank and the main + distribution bus, I then have a 1/2/both/ off switch running from the house and reserve bank to the starter. Lastly, I have an on/off switch between the main distribution bus and the panel with switched loads. Unswitched loads come through a fuse box off of the main + distribution bus.
The on/off between the house bank and main bus allows me to shut off power to everything. Normally this is left on to feed the unswitched loads like bilge pumps and the like. But, I can cut power to everything should I need to do some electrical work or an emergency. The reserve starting battery is connected through an ACR to the main distribution bus but is only used as a reserve starting battery and not connected to any other loads.

A triggered ACR replaces the 1/2/Both switch and also eliminated the potential of frying you alt by accidentally stitching the switch while the engine is running ( although you can buy versions now that resolve that), it also eliminates extra runs of large gauge wire the the need to room to mount the switch. I agree that having switches to isolate elements of the system. I have a simple switch to isolate my whole system( except the alt) to the house battery, a single switch to isolate the start battery and a single to isolate the panel. You will have all the wire ran for the ACR, a small gauge wire to a momentary switch can eliminate a large 1/2Both.

Scott T-Bird · Dec 12, 2021

Perhaps I am missing something, but it looks to me like you can't start your engine from the house bank if you have a problem with the start bank and switch it off. It seems to me that the purpose of your on/off switch is to bypass the 1/2/B switch in your normal operating procedure (you eliminated the cable from the common output post on the 1/2/B switch that would run to the starter). The purpose of having a 1/2/B switch is to always have a common output to the panel loads and the starter from 2 independent banks. If you are intending to separate house and starting loads under normal operation, then you are better served by the DCP switch, except then you would need another on/off switch to isolate the house bank if necessary. I prefer the DCP switch with 2 on/off switches because both on/off switches are essentially hidden for normal use (always on). Only when necessary would I need to switch one or the other off, depending on which bank fails. It seems that your procedure would be to have 1/2/B switched to "1" and on/off switched "ON" for normal operation? I've switched to the Blue Sea mini switches for more efficient space.

Edited: I think what I am missing is that you would put the 1/2/B in the "B" position to feed the starter through the "2" source post ... is that correct?

What it comes down to is that it seems like you are adding 1 on/off switch that you turn on for normal operation to essentially do the same thing as a DCP switch by turning on just one switch in that case. A DCP switch requires 2 on/off switches to provide isolation from both banks when necessary. I can understand utilizing the 1/2/B switch for economy since you already have it. Why buy 3 new switches when you can buy just one and pretty much have the same thing.

Scott T-Bird · Dec 12, 2021

BTW, I installed the SG200 monitor and a new mc-618 regulator this fall and love the system. I have the blue tooth connection but have not installed it just yet. I have also been modifying all the cabling and switching. The project will be continuing thru the winter.

MikeHoncho · Dec 12, 2021

I made the error and bought the smaller external regulator ( which is all that I needed for the regulation) that you can’t program with the blurry connection like you can with the 618. It would be worth the extra money to do so.

dlochner · Dec 12, 2021

MikeK2B said:
The only things that come off that as you note are 2/0 to starter switch, 2/0 to ACR, and fused aux lead to the battery monitor.

The ACR does not need a 2/0 cable, way over kill. The ACR needs a cable that is large enough to carry the largest charging current, usually the charger or the alternator. The ACR is only rated for about 100 amps (can't remember off the top of my head).

The reason to go with a DC+ switch is to "brother-in-law proof" the switch, make sure no-one leaves the switch in the both position and drains both batteries, as well as convenience, one switch to one position and everything is turned on or off and it is "B-i-L Proof." Using a DC+ does require on/off switches for both battery banks.

heritage · Dec 12, 2021

I also have an on/off switch between my start battery and the starter, but I have disconnected the alternator output wire from the starter and led it directly to the start battery which is fused at the battery post. This way, if the on/off switch is switched off while the engine is running, the alternator diodes will not be affected.

dlochner · Dec 12, 2021

heritage said:
I also have an on/off switch between my start battery and the starter, but I have disconnected the alternator output wire from the starter and led it directly to the start battery which is fused at the battery post. This way, if the on/off switch is switched off while the engine is running, the alternator diodes will not be affected.

It is better to lead the alternator output to the house battery. The start battery will be fully recharged quickly and the alternator will reduce its output, leaving the house battery high and dry.

Lead the alternator output to the house battery, charge the start battery with an ACR or similar device.

DArcy · Dec 12, 2021

I drew a similar setup but I wired the ACR to the battery side of the starter switch so it will charge while on solar or shore power and the switches are off. I am wiring the alternator to the Always On Bus so it's on the house side of the ACR. The suggestions I saw were to have the charging on the larger bank side of the ACR. I also have the fridge on the Always On Bus so I can shut off the main switch and keep the beer cold. The AO Bus 2 is just to simplify distribution of the Always On circuits the way my boat is laid out
I don't have a battery monitor but it is on the list.

Event Horizon Battery Wiring Diagram.jpg

Plumbean · Dec 12, 2021

dlochner said:
The ACR does not need a 2/0 cable, way over kill.

This is true although if the ACR is placed right near the fuses for the battery bank you can skip separate fuses for the ACR and just lean on the main fuse for your battery off-take. My winter is going to be spent doing a very similar project, and I have the ACR situated about 18 inches from the off-take for both banks (and each bank has a 300 amp MBRF fuse on it). So I just ran 2/0 cable for the ACR and called it good.

Plumbean · Dec 12, 2021

Stu Jackson said:
The Blue Seas Dual Circuit Switch is not for everyone. Here's why:

AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
Darn AGM Batteries

If you read to the end of the post Maine Sail does offer up a solution to the Dual Circuit Plus, which is to have separate on-off switches for each bank that allows you to isolate them. I've had a Dual Circuit Plus panel in my boat for a long time and I like it, so part of my wiring project this winter is installing the on-off switches to isolate the banks.

Plumbean · Dec 12, 2021

MikeK2B said:
My winter/spring project this year started with simply rewiring the mast and adding a foredeck light (adding breaker or switch for this). It evolved to include adding a wind instrument and replacing the speed and depth instruments/transducers as well. This led me back to my mess of a battery cabinet where I couldn't bring myself to leave the rats nest as is. I'll need to add a second DC panel to accommodate many of the random taps the POs had off battery terminals over the years and want to plan for solar, a battery combiner, and a battery monitor. I want to keep my 1/2/B battery selector and add an off/on start/reserve battery bank switch as well. This is obviously a very Maine Sail-influenced design (I hope his health continues to improve!) and I appreciate any comments and insight you guys have on the attached wiring diagram. I know that the alternator should be wired to the house bank and will eventually do that with some engine upgrades next season (I'm in for more than I bargained for this year).

Thanks in advance!
Mike

Is that a charger/inverter or just an inverter? Wondering if the thermal breaker the right choice for that. I have a Class T fuse for my inverter (which I believe is the usual recommendation) and I know from talking to him that Maine Sail was not a huge fan of a thermal breaker for my alternator even though Balmar seems to think it is okay. In my re-wire I am keeping the Class T fuse for the inverter but going with ANL fuses for my charger and my alternator.

dlochner · Dec 13, 2021

Plumbean said:
This is true although if the ACR is placed right near the fuses for the battery bank you can skip separate fuses for the ACR and just lean on the main fuse for your battery off-take. My winter is going to be spent doing a very similar project, and I have the ACR situated about 18 inches from the off-take for both banks (and each bank has a 300 amp MBRF fuse on it). So I just ran 2/0 cable for the ACR and called it good.

There is a limit to how many connections can come off a battery post. A better solution than using one fuse for 2 loads is to use a dual post MRBF, each lead gets its own appropriately sized fuse and cable. Or use a positive bus bar and feed all the charging and loads to the bus bar, each appropriately fused.

Using 2/0 cable and a 300 amp fuse will allow too much current to flow through the ACR with potentially bad consequences. The fuse must protect the cable and in the case of an ACR the ACR is functionally part of the cable so it must be fused as if it were a cable much smaller than a 2/0.

Plumbean · Dec 13, 2021

dlochner said:
There is a limit to how many connections can come off a battery post. A better solution than using one fuse for 2 loads is to use a dual post MRBF, each lead gets its own appropriately sized fuse and cable. Or use a positive bus bar and feed all the charging and loads to the bus bar, each appropriately fused.

Using 2/0 cable and a 300 amp fuse will allow too much current to flow through the ACR with potentially bad consequences. The fuse must protect the cable and in the case of an ACR the ACR is functionally part of the cable so it must be fused as if it were a cable much smaller than a 2/0.

I have a positive bus bar just off the maine battery fuse that handles this. If you use the dual post MBRF fuse block note that you are limited to 300 amps total between the two posts in terms of fuse capacity. The SI-ACR is rated for 210 amps intermittent (5 minutes) capacity. So using the battery bank fuse does seem to mean that I am not fully protecting the ACR itself, although I know that Maine Sail endorses this approach.

From Maine Sail's post on ACR's:

"TECH TIP: If you make the “A” & “B” terminal wires for the ACR the same gauge as the house and start bank wiring eg: 2/0 and 2/0 the ACR can share the house and start bank fuses, if so equipped. Start banks are not required to have over-current protection but it never hurts."

See: Making Sense of Automatic Charging Relays - Marine How To

Scott T-Bird · Dec 13, 2021

dlochner said:
A better solution than using one fuse for 2 loads is to use a dual post MRBF, each lead gets its own appropriately sized fuse and cable. Or use a positive bus bar and feed all the charging and loads to the bus bar, each appropriately fused.

I've had a question about this point and thought about another thread, but it does sort of relate ... I used the dual post MRBF for both the house bank and the start bank to connect the positive leads and the ACR leads. Positive leads are 1/0 with 225 Amp fuse and ACR leads are 2 AWG with 150 Amp fuse. Therefore, the ACR leads are connected directly to the batteries. I have DCP selector and On/Off switches to isolate both battery banks. The positive buss that connects positive leads from alternator, shore charger and solar charging is between the On/Off (house bank) and the DCP switches. Therefore, if either On/Off switch is opened, the ACR leads are isolated with the respective battery.

Is this a problem to be corrected? I've noticed that Mainesail's diagram shows the ACR leads connected to the buss with alternator/charger/ solar on the house side and directly to the post on the DCP side of the On/Off switch for the start Batt. If I make either one of the On/Off switches open, than the ACR leads would seem to be isolated, no?

I'm also curious if it is correct that the dual post MRBF is limited to just 300 Amps total. That would seem to defeat it's purpose, wouldn't it? It doesn't sound right to me.

BTW, at the house bank end, I have a 1/0 cable linking the 2 positive posts of the batteries connected directly to one side of the post and the dual MRBF on the other side, connected with a thru bolt. The linking cable is therefore not fuse protected ... is that an issue?

12v system rewire including Balmar SG200, ACR, Solar, 1/2/B Switch and On/Off Switch

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