Poke holes in my wiring plan

[DeepFrz]

Charging from alternator - I could put a relay on the ACR to only connect it when the engine is running.

That is exactly what the ACR does. You do not need to add another relay.

[sailingunity]

Originally Posted by DeepFrz

That is exactly what the ACR does. You do not need to add another relay.

But it will also connect when the solar is charging.

[Captain Graham]

Originally Posted by sailingunity

But it will also connect when the solar is charging.

Here is a diagram that will give you more control over which battery bank gets charged from what.

Like you said all you have to do is put a switch or relay next to the ACR.

The Motor can charge the Starting Battery only or both battery banks.
The Solar charger can charge the house batteries only or both battery banks.

[sunluvr]

Originally Posted by Captain Graham

Here is a diagram that will give you more control over which battery bank gets charged from what.

Like you said all you have to do is put a switch or relay next to the ACR.

The Motor can charge the Starting Battery only or both battery banks.
The Solar charger can charge the house batteries only or both battery banks.

I keep looking at your diagram, scratching my head at the 2 house batteries, each having 2 +ive terminals..

[Uncle Bob]

Originally Posted by sailingunity

But it will also connect when the solar is charging.

Hi, you can add a relay to the negative side of the acr activated by the engine ignition, acr then only activates when the ignition is switched on and off again when the ignition is switched off. Works well to isolate banks from each other when no alternator power available.

[mitiempo]

Originally Posted by sunluvr

I keep looking at your diagram, scratching my head at the 2 house batteries, each having 2 +ive terminals..

I agree. A battery bank should have only one positive and one negative terminal used for output and charging - whether it is composed of one battery or 10 batteries.

[mitiempo]

Originally Posted by Captain Graham

Here is a diagram that will give you more control over which battery bank gets charged from what.

I hope you wouldn't wire a system like you are drawing it. The powerposts do not make sense. You have added too many unnecessary connections.

Negatives from house bank should go to a bus. From the bus one cable goes to the engine and another to the DC panel. The bilge pump and vhf can also be connected to this bus, solar as well.

Positive from house bank - the only one - to a bus. This accepts positive charging cables from solar and shore charger as well as bilge pump and vhf connections - all fused appropriately at the bus. From this bus one positive to the main switch. From the switch one cable to the DC panel.

Battery banks should be fused at or very near their positive posts.

As posted the relay is not necessary as the ACR has one built in able to be externally switched, assuming Blue Seas product used.

[mitiempo]

Originally Posted by sailingunity

I was actually wrong in my previous example. When the alternator kicks in and puts 10% into the bank, even though in reality 3 AH are going into the start bank, the shunt is measuring the 10AH in and giving that all to the house bank. So that would add 10% to the 67%, coming to 77%. It actually winds up being accurate again.

If I put the starter and the start battery after the shunt, those loads won't show up on the AH counter at all, however any charging that goes is all getting seen by the shunt even though in reality it is still getting split. I think that since the starter loads weren't recognized that the charge would wind up being overstated.

Still, starter loads are quite small, and as I understand it an SoC based on amp hours alone is not the most accurate, so I'm sure I'll just have to live with a small amount of inaccuracy.

You are seriously over-thinking this. The shunt accurately measures all current going into and coming from the house bank - as long as the shunt is the first item after the negative post of the bank - without errors.

[Stu Jackson]

Originally Posted by sailingunity

Yes I get that all current will be measured regardless of which battery it comes out of, from an AH counting point of view it will be accurate. But if the AH counter is using total battery capacity as a way of viewing SoC percentage, it seems like it could get thrown off by loads put on the start battery.>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


This is an overly simplistic example, and I'm not an electrical engineer, just speculating. In the end I think I would just need to live with using the AH counter as a rough idea, and voltage as a true measure of SoC!

You are incorrect.

Sometimes someone posts questions that simply baffle those of us who seem to understand how all this stuff works BECAUSE they question the most basic concepts that we all have absorbed over the years, whether from reading or actually using the gear and reading some more, and both.

This is one of 'em.

Look, the shunt is a flow meter. You have chosen to measure JUST the house bank. Given that, could you simply forget about the danged start bank?

Your ACR keeps the start bank charged. That's all it does.

The shunt only measures what goes into or comes out of the HOUSE bank.

It really is that simple.

Why not keep it that way?

Your "...regardless of which battery it comes out of..." makes NO sense.

BTW, many of us "got over the hump" of understanding how shunts work a long time ago, and as Maine Sail has said repeatedly, here and on other boating forums, the number of mis-wired shunts he sees is mind boggling.

The respondents to your stuff here are trying to help. You might wanna re-read what they've been saying to you all along.

*****************************
FWIW, you seem to be new here, so you don't know me from a hole in the head. But I've owned my boat for 21 years, immersed myself into boat electrical systems when I got it. Since then I have helped many, many folks both online in these types of forums as well as individually off line. Eventually, I got tired of seeing these questions come up simply because almost every single one of them is trying to reinvent the wheel. Sure, it's new to you. None of us was born an electrician. But many of us provide links to known, simple boat wiring diagrams with optional switching arrangements and still get grief from newbies about things that have been proven to and do work. I eventually decided to stop responding to these "comment on my wiring" posts.

In this case, I have commented, because I'm not commenting on your wiring plan at all. I am questioning something else about your approach to this and the input you've received and your replies. Different things.

Good luck.


Oh, and I do repeatedly contribute this link to many boating forums:


Electrical Systems 101 http://c34.org/bbs/index.php/topic,5977.0.html

[Captain Graham]

Originally Posted by sunluvr

I keep looking at your diagram, scratching my head at the 2 house batteries, each having 2 +ive terminals..

LOL you have good eyes.
I copied the image of the battery from the internet and did not notice the mistake.
The Neg side of the battery was labeled wrong.

I attached the new images with the battery labeled correctly.

I like the first wiring diagram so that I would charge both battery banks all the time.
But there is nothing wrong with adding a manual switch or relay to disconnect the two battery banks while charging, the second diagram.
It just depends what you want on your boat.

Some have noted that you do not need all of the power posts.
That is true but I like to keep things modular.
Using power posts keeps the field wiring and internal locker wiring separate making it easier to wire and troubleshooting.

Most of the time it is the wiring that is spread out around the boat (field wiring) that goes bad.
The wiring spread out around the boat (field wiring) is subject to rubbing, flexing, getting soaked in salt water and general wear and tear.

If you do it well the internal wiring inside the 2 lockers should not give you any trouble.

Also notice I am using breakers to protect the batteries.
I like resettable breakers instead of fuses because it you have a short the breaker trips you can then fix the short and simply reset the breaker.

[mitiempo]

Originally Posted by Captain Graham

Also notice I am using breakers to protect the batteries.
I like resettable breakers instead of fuses because it you have a short the breaker trips you can then fix the short and simply reset the breaker.

Breakers AIC rating are not high enough for a large battery bank. Fuses of the appropriate type are a better choice - ANL, MRBF, or Class T.