Battery/alternator/solar wiring schematic

[swift1894]

I'm going to fit my 6 Trojan T105s this week which will involve a complete rewire, as my current 12v batteries are 4 X 180Ah with different terminals positions.?

So it's time to tidy everything up. I've got 2 x 4 pole busbars, a 160A engine alternator, a split relay (for the starter battery when the domestics are fully charged), 2 x Tracer MPPTs with 800w solar panels, a shunt to the Mastervolt battery charger and inverter.

Just wondered if there are any wiring schematics I could look at, as an inspiration as to what the final configuration should look like.?

Edited March 2, 2016 by swift1894

[bottle]

All positives go to one end of the battery bank and all negatives go to the other end.

 

As you have bus-bars use those instead of the battery terminals, then it will just need one cable from each bus-bar to the batteries.

 

The shunt assuming it for for reading of amperes(gauge), should go in the negative from the bus-bar to the battery bank

[swift1894]

All positives go to one end of the battery bank and all negatives go to the other end.

 

As you have bus-bars use those instead of the battery terminals, then it will just need one cable from each bus-bar to the batteries.

 

The shunt assuming it for for reading of amperes(gauge), should go in the negative from the bus-bar to the battery bank

Thanks. The bus bars should make things a lot simpler and tidier than the bird's nest that has developed over the years, as I added the solar setup in 2 separate stages ( started with 500w then added another 300w)

[by'eck]

Thanks. The bus bars should make things a lot simpler and tidier than the bird's nest that has developed over the years, as I added the solar setup in 2 separate stages ( started with 500w then added another 300w)

 

They certainly neaten up a battery installation, allowing easier battery replacement and simple addition of an future circuits.

 

Some suggest that there are issues with the extra connections and use existing ones at battery or isolator switch. I would find this acceptable if its limited to max two connections per terminal post, but becomes counterproductive in terms of contact resistance if many more.

[swift1894]

They certainly neaten up a battery installation, allowing easier battery replacement and simple addition of an future circuits.

 

Some suggest that there are issues with the extra connections and use existing ones at battery or isolator switch. I would find this acceptable if its limited to max two connections per terminal post, but becomes counterproductive in terms of contact resistance if many more.

Each bus bar has 4 terminals so I thought alternator, 2 MPPTs, Mastervolt charger (negative via shunt) and a shared connection from each bus bar to the pos and neg poles should do nicely.

[Paul C]

Looking at the original post, it can be neatly split into 2 aspects:

 

Where to "tap" power off the battery bank? - once you've determined this, there's a simple principle - everything uses the same points, no exceptions. No snakes wedding over the batteries, etc.

 

How to wire everything else - ideally needs a diagram.

[Tony Brooks]

Each bus bar has 4 terminals so I thought alternator, 2 MPPTs, Mastervolt charger (negative via shunt) and a shared connection from each bus bar to the pos and neg poles should do nicely.

 

Not sure from what you say exactly where you intend to put the shunt but assuming its for an ammeter I would have thought that it needed to go between the busbar and battery. Otherwise it would only measure the charger current. I also can not see where you intend to connect the feed and return for the loads (engine panel, domestic distribution box).

[swift1894]

No snakes wedding over the batteries,.

It's as if you've been in my engine room!

Not sure from what you say exactly where you intend to put the shunt but assuming its for an ammeter I would have thought that it needed to go between the busbar and battery. Otherwise it would only measure the charger current. I also can not see where you intend to connect the feed and return for the loads (engine panel, domestic distribution box).

Important point. It's to feed a Mastervolt MICC. I was going to put the shunt between the busbar and charger. So it needs to be between the busbar and the battery? That makes a difference? I can't see what the difference is but I know nothing!

Btw I don't have an engine panel (Gardner 4LW with 3 mechanical dials).

Where should the feed/return for the domestic distribution go/come from?

Edited March 3, 2016 by swift1894

[Tony Brooks]

Important point. It's to feed a Mastervolt MICC. I was going to put the shunt between the busbar and charger. So it needs to be between the busbar and the battery? That makes a difference? I can't see what the difference is but I know nothing!

 

The shunt needs every electron flowing in or out of the battery to pass through it otherwise the meter it is connected to will tell lies. Even more to the point your MICC, that in any case will rather tend to be misleading re state of charge, will have no clue about the charge going to the battery from the alternator & solar or (based on your exact words) how much is being taken out of the batteries.

[swift1894]

The shunt needs every electron flowing in or out of the battery to pass through it otherwise the meter it is connected to will tell lies. Even more to the point your MICC, that in any case will rather tend to be misleading re state of charge, will have no clue about the charge going to the battery from the alternator & solar or (based on your exact words) how much is being taken out of the batteries.

Thanks that's saved me from making a mistake.

What a great forum!

[Paul C]

Apologies if its not world's neatest diagram:

 

 

Notes:

 

1. The alternator should go to the domestic bank first. It should also be the switched side of an isolator switch

2. Because the combi is an inverter (as well as a battery charger) it must go the switched side of an isolator switch

3. Because the solar controllers are (only) chargers, they can go the battery side of an isolator switch but must be fused

4. The shunt is in the negative, and is the ONLY thing connecting to the -ve battery terminal. No exceptions

5. The voltmeter connections should go to battery terminals to get a proper reading, but MUST be fused.

6. The big battery is the domestic bank, the little one is the engine/start battery.

7. I need a new pencil

8. I need a rubber too

9. And a ruler

[Tony Brooks]

Thanks that's saved me from making a mistake.

What a great forum!

 

When you sort it please come back so those who know can explain how to set up the MICC to minimise the "stet of charge" error

[WotEver]

1. The alternator should go to the domestic bank first. It should also be the switched side of an isolator switch

2. Because the combi is an inverter (as well as a battery charger) it must go the switched side of an isolator switch

 

I disagree with #2, but the cables must be fused at both ends. It is important (imho) that you be able to charge the batteries with the isolator switched off.

 

I also disagree with #1 (you can kill an expensive alternator like that) but the BSS insists that it be this way.

 

Tony

[Paul C]

Mastervolt MICC shunt goes in the negative:

 

http://www.liveantares.com/pdf/Manuals/MasterVoltMICC.pdf

I disagree with #2, but the cables must be fused at both ends. It is important (imho) that you be able to charge the batteries with the isolator switched off.

I also disagree with #1 (you can kill an expensive alternator like that) but the BSS insists that it be this way.

Tony

 

 

#1 is imposed by BSS

 

#2 is acceptable with fuses BUT based on experience, I'd want the ability to totally isolate an inverter from the battery. I've had one catch fire and without its own isolator switch, the boat engine needed to be shut down and the isolators turned off to isolate it properly. The fuse is a mega fuse which requires tools to remove.....so no use just pulling the fuse to isolate it. I suppose one could fit its own isolator switch and fuse but then there's more connections...... I suppose I should redraw the diagram to show my preferred wiring for an inverter/charger, since the one I posted is neither here nor there in terms of isolation or location of wires. Also, I am sure that a battery charger is exempt from needing to be the switched side of an isolator switch BUT is an inverter also exempt? And if so, why?

[Paul C]

Re-done, just the positive connections on the domestic bank:

 

 

 

Yes, its unashamedley "what would I do" - I'd not have a combi, I'd have separate inverter and charger.

 

Also worth mentioning, when I leave the boat I never isolate the electrics, but I always isolate the inverter (due to the fire).

[WotEver]

I'd not have a combi, I'd have separate inverter and charger.

Me too...

 

1. If either one breaks the other one is still working.

2. If either one breaks it's cheaper to just replace that one.

3. Wiring can be made safer, keeping the inverter on the switched side of the isolator.

 

I know it may be a little more expense up front but I think it's worth it.

 

Tony

 

I am sure that a battery charger is exempt from needing to be the switched side of an isolator switch BUT is an inverter also exempt? And if so, why?

Is...? Yes, if it's part of a Combi, otherwise you couldn't have the charger connected.

Why...? Because it's part of a Combi.

 

Tony

 

Edit to tidy it up

Edited March 3, 2016 by WotEver

[swift1894]

Thanks for the drawings and comments.

Much appreciated.

[Paul C]

There's also the issue (highlighted in another thread) that the mains wiring, while similar, is not the same. The shoreline AND inverter output both need RCD and MCB protection, because in one mode its a load (when the battery charger is operating) and in another mode, its a power source (as an inverter). So that means when it "passes through" shoreline using the same wires, each needs RCD/MCB.

[WotEver]

#1 is imposed by BSS

Yeah I know. I said that

 

I don't agree with them though.

 

Tony

[Paul C]

 

Is...? Yes, if it's part of a Combi, otherwise you couldn't have the charger connected.

Why...? Because it's part of a Combi.

 

Tony

 

Edit to tidy it up

 

Having checked the BSS regs, it specifically mentions in its "list of allowable items" that an inverter or a combi can be connected to the battery side of an isolator switch.

 

Here is the list:

 

• automatic bilge pumps;

• security alarms (including marine radios);

• fire pumps;

• electronic navigation equipment with memories;

• any other equipment where the manufacturer’s instructions indicate or

specifically require direct connection to a battery, such as diesel‐fired

central heating boilers;

• battery charger outputs;

• inverters or combination inverter/chargers;

• solar panels and wind turbines.

 

For me personally it dilutes the value/purpose of the isolation switch, I'd want anything that is a "load" in itself able to be isolated. And I'd argue that one switch more clearly serves this purpose than having 2, 3 or more isolation switches. Hence, I'll stick with my original assertion in post #11 (point 2) that the inverter should be the switched side of an isolator switch of some kind.

[WotEver]

And yet the BSS insists that the Alternator must be on the switched side. So now there are at least two things that I disagree with BSS on...

 

Tony

[Paul C]

If the terminal sizes on the 2x bus bars are the same, and the wires are suitable length, 5 minutes with a spanner can ensure a BSS pass, then another 5 minutes with the same spanner can revert the boat to the better electrical configuration.

[WotEver]

If the terminal sizes on the 2x bus bars are the same, and the wires are suitable length, 5 minutes with a spanner can ensure a BSS pass, then another 5 minutes with the same spanner can revert the boat to the better electrical configuration.

My alternator cable has done the swap more than once.

 

Tony

[Paul C]

.....Worth bearing in mind, when re-doing cables.......

[cuthound]

Why not use two isolators in series, with the things permitted to be directly connected to the batteries contacted between them?

 

That way everything can be isolated in and emergency, whilst leaving bilge pumps, chargers, inverters etc connected for normal use but isolatable if necessary.