Critique my wiring diagram?

[Jerry Woodward]

Just finished reading Nigel Calder's book and of course reading 100's of threads on CF and Mainsail's blogs. It is apparent that my battery system and charging wiring on my boat is not optimal. While everything works, I think I can improve it. The current setup consists of two stock alternators, one on each engine, two starting batteries and a house bank of 4 golf cart batteries, 400AH. Both alternators go through a Powerline PLI-2-70-2 battery isolator to charge both house and start batteries. The alternators don't charge very well and I believe there is significant voltage drop caused by the Isolator as Calder discusses, although I haven't measured it yet. There are also two 1,2,B switches at the starting "bank" to isolate one or the other starting batteries. I also have 145W solar, Wind gen, and Freedom 20 charger/inverter.

The attached wiring diagram is my attempt at simplifying and modernizing. I don't have to buy anything except an echo charger and some fuses. The major changes I am considering are:
1. Remove one of the starting batteries. This will save a lot of weight and I simply can't see why I need two. I can also remove the two switches. If the start battery goes bad, I can jump from the house bank. I also have a Honda generator as a backup.
2. Remove the Battery Isolator and wire both alternators to the house bank. Make sure voltage drop is kept to a minimum.
3. Add an Echo charger to keep the starting battery charged.
4. Add a Victron Battery monitor and shunt (already purchased). Yes, I know all the limitations of these monitors and will follow all the suggestions of Mainsail and others.
5. See how the two stock alternators perform with this new setup and if necessary, upgrade one or both alts at a later point.

Any and all advice welcome!
Thanks

[waeshael]

You would have charge regulation issues unless you have disconnects for each of he devices. The regulators will adjust their output according to the highest incoming voltage, so that the wind or solar will pump the voltage up and stop the alternator charging because it thinks the battery is fully charged. So you will have to choose which device will be charging. You could split the battery banks to allow two different charging devices.
You won't notice the problem unless you measure the actual charge current from each device when all are connected to the battery bank at the same time.
If you go motoring around you will find the alternator will put out very little if the solar/wind system is charging.

Now solar and wind systems want to see a load, so you can't open the circuit after the charge controller, you need a breaker/switch in the incoming solar or wind line itself.

GCM E.E.
More info if you need it.

[Jerry Woodward]

Originally Posted by waeshael

You would have charge regulation issues unless you have disconnects for each of he devices. The regulators will adjust their output according to the highest incoming voltage, so that the wind or solar will pump the voltage up and stop the alternator charging because it thinks the battery is fully charged. So you will have to choose which device will be charging. You could split the battery banks to allow two different charging devices.
You won't notice the problem unless you measure the actual charge current from each device when all are connected to the battery bank at the same time.
If you go motoring around you will find the alternator will put out very little if the solar/wind system is charging.

Now solar and wind systems want to see a load, so you can't open the circuit after the charge controller, you need a breaker/switch in the incoming solar or wind line itself.

GCM E.E.
More info if you need it.

Hmmmm, that's different from what I've read. Nigel Calder and lots of apparently knowledgeable folks in here seem to say that multiple charging sources are generally not a problem. My understanding is that if the battery bank is in bulk mode accepting a lot of current, then the charging voltage from solar will not be high enough to cut off the other chargers. So say the solar controller is putting out 14.4 volts and capable of supplying 10A of current, but the battery can accept 50A because it is sufficiently discharged, then the voltage at the bank will not be 14.4 volts, it will be a lot less and the bank will happily accept current from both the alternator and solar, and they will both happily supply it up to their respective capacities. Only when the bank gets close to fully charged will the charge acceptance rate, i.e. current, go down and the voltage will rise. My understanding is at this point, the charge devices will begin dropping out as their set point voltage is reached until finally there is only one controller with the highest set point putting in a small amount of current. As soon as you turn on a load, all the devices can start contributing again because the voltage will drop below their set point.

Again, this is my understanding from reading and I could be wrong. But it's an extremely important point and I want to make sure I understand it correctly.

[waeshael]

Yes I knew Nigel Calder's book. He is not an electrical engineer. He is a mechanical engineer, sailor and author. For electrical information you should get The Marine Electrical and Electronics Bible by John Payne who is an Electrical Engineer.

Glad to have a chance to chat about these things.
I once designed a 100 KiloWatt Inverter for a medical company and ran it from a 480 V car battery bank. The hardest part was getting the batteries charged and serviced! I have helped many yachties during my years cruising fix their electrical problems. I am sure that there may have been technological improvements in charge controllers over the years, but the liquid filled batteries are just the same, and the charging is done through a chemical reaction which can't be hurried.

The solar system and wind generator are current sources not voltage sources. The voltage on any part of the system is determined solely by the load - the battery. If the voltage measure higher at the solar panel when under load it is because you are losing voltage in the internal drop of the controller or in the wires from the solar panel. If the connections, wire sizes and controller is efficient then the solar voltage and the battery voltage will be almost the same.
This is true also of the alternator. Each device monitors the battery voltage at the terminals of the battery (this is important) and adjusts the current to either flow into the battery or not according to the limits you set for charging for each device. A battery that is 50% discharged will be 12.0 V, and current will flow into it. As the current flows in the terminal voltage increases due to the internal resistance of the battery. You cannot force feed the battery with high amps because of this internal resistance which causes the terminal measurement to be much higher than the real internal voltage of the battery. If you stop charging you would see the voltage drop down to its real internal voltage. This is one reason that manufacturers recommend relatively slow charging rates. And why current drops quickly as you charge. The limit is due to the chemical changes that have to be made inside the battery to store the energy. Some batteries like Lithium can be fast charged, but lead-acid can't. My experience is with lead-acid batteries.
If the amount of current into the battery produces a high terminal voltage, such as 14V, then the regulators will reduce the feed current, assuming the battery is getting close to a float charge level. So with several devices trying to charge at the sane time the terminal voltage will appear to be high,( though not its internal voltage,) and the controllers will reduce their current. Remember all that the charging devices do is send electrons to one side of he battery to be stored in the liquid/plates. Whatever voltage appears on the system bus is that of the battery terminals, assuming you have good wiring with no resistance. The open circuit output of most solar panels for a 12V system is 22V, but this is a number that only gives you an idea of how much current the panel can drive into a battery of 14 v, say, As panel temperature increases, the OC voltage drops, and the current falls also. There must be a differential in no-load voltage to begin with for the device to send electrons to the battery, but once the load is on, then all devices in the system must equal the load voltage which is the battery.

You can easily try an experiment on your boat by combining the outputs of your devices and seeing what happens to the charging currents for each device. As you add devices and the battery voltage starts to climb, then each device will cut back, assuming you have programmed its charge controller to switch from bulk, to float at say 13.8V which is normal for lead acid batteries.

Regardless, there is benefit to being able to switch charging devices in and out of circuit for troubleshooting, and for educating others about how batteries respond to various charging systems.
Thank you for your very good questions.

Cheers

[dave777]

Hi Waeshael,

Thanks for that in depth explanation.

Does the same hold true when you have an MPPT charger on the solar cells? My understanding is that the MPPT charger is a DC to DC converter and essentially reduces the charging voltage to the lowest amount which will still charge the battery.

In any case, what do you recommend when motor sailing with a solar charger. Should we turn solar off when motoring and hopefully remember to turn it back on when the motor is off?

[smac999]

Alternators should be wired direct to house bank. Not after switch. With own fuses.

Inverter charger needs own switch. It can not share the house switch. And should have own fuse.

So likly the bus should go before the house switch. Put hiuse switch between bus and house panel. Use the bus as unswiched bus. Then you can out the wind and solar onto it as well.

I would start both motors off the start battery. Ideally with each motor having own switch. Or even better, get a 2nd start battery and echo charger.

All chargers to battery is just fine.

[Albro359]

Regulators of any sort generally control voltage. The battery will take as much current as it can up to its max acceptance rate....that's what determines the charging current...and that falls off as the voltage increases.
You say you have "stock" alternators, I take that to mean that they have standard automotive regulators in them which are only designed to charge start batteries.
To charge deep cycle batteries properly and to maximise their life,you need a proper 3 stage regulator...for the alternators and the solar panels, and the shore power. You can use an Echo charge from the house bank to charge the start battery...agree you only need one...we have one start battery that serves our 100Hp Yanmar propulsion engine and our 7.5kVA genset...however each engine has a "stock" alternator on it for only charging the start battery.
The Yanmar has a 180A alternator with a Next Step 3 - stage reg for charging the house bank.
Each of our charging sources - 100A and 30A AC chargers, engine alt and solar MPPT are set to the same absorption and float voltages, all have temperature and direct battery voltage monitors ...and everything is permanently connected (except for fuses and breakers) to the battery bank.
We are a 24V system and we have 3 parallel banks of 4 x 6V 220Ah AGM batteries..AND we have battery balancers on each bank to ensure the voltage on each 6V battery is a pure 1/4 of the total bank voltage at all times.
Trust this may assist you in your plans
Cheers
Alan

[ramblinrod]

Originally Posted by Jerry Woodward

Hmmmm, that's different from what I've read. Nigel Calder and lots of apparently knowledgeable folks in here seem to say that multiple charging sources are generally not a problem. My understanding is that if the battery bank is in bulk mode accepting a lot of current, then the charging voltage from solar will not be high enough to cut off the other chargers. So say the solar controller is putting out 14.4 volts and capable of supplying 10A of current, but the battery can accept 50A because it is sufficiently discharged, then the voltage at the bank will not be 14.4 volts, it will be a lot less and the bank will happily accept current from both the alternator and solar, and they will both happily supply it up to their respective capacities. Only when the bank gets close to fully charged will the charge acceptance rate, i.e. current, go down and the voltage will rise. My understanding is at this point, the charge devices will begin dropping out as their set point voltage is reached until finally there is only one controller with the highest set point putting in a small amount of current. As soon as you turn on a load, all the devices can start contributing again because the voltage will drop below their set point.

Again, this is my understanding from reading and I could be wrong. But it's an extremely important point and I want to make sure I understand it correctly.

Your understanding is correct. When the batteries are discharged, they will consume all of the current the connected charging systems can deliver (assuming acceptance is greater than total charge current. As the battery charges, and can accept less current, the charging system with charge voltage less than battery voltage will simply stop contributing, because there was s no difference in potential.

[MJH]

I would also like to create a wiring diagram for my boat. What is the name of the software you used to produce yours?

~ ~ _/) ~ ~ MJH

[ZULU40]

I think the charger and sources should be connected to the battery,

My charger has 3 separate battery sources it can feed, it does them all simultaneously at rates suitable to the detected battery type

Alternator goes to engine start battery only.

Discharges go off the hot busses to the switch panel with its own blade fuse, there are 20 circuits off two common sub busses with blown fuse detectors. Some relent to common supply like cabin lights (LED) all through the one switch. Although there is emergency lighting (red) is also off the hot busses

Bilge pumps (3) come off the hot busses via individual wiring through their own blade fuses and switches.

The main hot busses can be sourced via the rotator to either battery, although obviously house is the most desirable

[Jerry Woodward]

Originally Posted by MJH

I would also like to create a wiring diagram for my boat. What is the name of the software you used to produce yours?

~ ~ _/) ~ ~ MJH

Believe it or not, it is plain old Excel. It has the basic drawing tools that are pretty much the same in the other Office products, Word and Power Point. I like it because I have a master Excel sheet with all my boat info on separate pages, Maintenance records, to do lists, etc. I'm also very used to using it so there was no learning curve for me. There are certainly much better drawing programs for this sort of things, but this is all I need. I have Adobe Acrobat plug in so I can easily convert it to a PDF file.

[Jerry Woodward]

Thanks smac for your helpful suggestions. If you don't mind, I have a couple of questions in red below:

Originally Posted by smac999

Alternators should be wired direct to house bank. Not after switch. With own fuses.

My logic is that the switch close to the house bank will be solely an emergency cut-off or an isolation switch when I am off the boat. When on the boat it will always be on, and located in a place where it won't be accidentally turned off when the engines are running. My thinking is that if I smell smoke, I would shut down the engines if running and then turn off the switch completely cutting off current to everything, including the alternator cables. Solar will not be switched so I can keep the batteries charged when I'm off the boat. Solar and wind have their own switches at their controllers. Is this the wrong way of thinking about this?

If the alternator cables are the same size as the other battery cables, 2/0, won't the single 300a fuse at the battery suffice for the alternators?

Inverter charger needs own switch. It can not share the house switch. And should have own fuse.

The inverter is controlled by a Link 2000 control panel at the nav station which allows me to turn charging on and off as well as other functions like equalization. So do I need another switch? Yes, I will definitely add a fuse here.

So likly the bus should go before the house switch. Put hiuse switch between bus and house panel. Use the bus as unswiched bus. Then you can out the wind and solar onto it as well.

I would start both motors off the start battery. Ideally with each motor having own switch. Or even better, get a 2nd start battery and echo charger.

Yes, I have both starters starting off the start battery. I currently have two start batteries and propose to eliminate one to save weight. Yes, I have an echo charger charging the start battery.

All chargers to battery is just fine.
Thanks, glad I have that concept right.

[Zil]

yes. alternator fuse at the positive battery end.

[hlev00]

You should should swap where either the negative or positive enters the bank to the bottom pair. As you have it the two pair at the top will charge / discharge differently than the bottom pair. Some may say the difference is so small that there is no reason to do this. I think it is best practice though.

What size cable are you planning to use for the series connections?

[smac999]

Originally Posted by Jerry Woodward

Thanks smac for your helpful suggestions. If you don't mind, I have a couple of questions in red below:

Originally Posted by smac999 View Post
Alternators should be wired direct to house bank. Not after switch. With own fuses.

My logic is that the switch close to the house bank will be solely an emergency cut-off or an isolation switch when I am off the boat. When on the boat it will always be on, and located in a place where it won't be accidentally turned off when the engines are running. My thinking is that if I smell smoke, I would shut down the engines if running and then turn off the switch completely cutting off current to everything, including the alternator cables. Solar will not be switched so I can keep the batteries charged when I'm off the boat. Solar and wind have their own switches at their controllers. Is this the wrong way of thinking about this?

If the alternator cables are the same size as the other battery cables, 2/0, won't the single 300a fuse at the battery suffice for the alternators?

Inverter charger needs own switch. It can not share the house switch. And should have own fuse.

The inverter is controlled by a Link 2000 control panel at the nav station which allows me to turn charging on and off as well as other functions like equalization. So do I need another switch? Yes, I will definitely add a fuse here.

So likly the bus should go before the house switch. Put hiuse switch between bus and house panel. Use the bus as unswiched bus. Then you can out the wind and solar onto it as well.

I would start both motors off the start battery. Ideally with each motor having own switch. Or even better, get a 2nd start battery and echo charger.

Yes, I have both starters starting off the start battery. I currently have two start batteries and propose to eliminate one to save weight. Yes, I have an echo charger charging the start battery.

All chargers to battery is just fine.
Thanks, glad I have that concept right.

if the house switch guaranteed never gets turned off with engines running. by you, or anyone else on the boat. then it's not so bad. but just because you may know how things work, doesn't mean everyone on the boat does too.

fusing does 2 things, makes a boat safer, and makes a boat more reliable. the single fuse makes the boat safe if all cables are 2/0. but is horrible for reliability. if the alt or alt wire shorts out. it will take out the main 300a fuse. and you just lost VHF radio, nav lights, cockpit lights everything. a main fuse should never blow. each thing should have it's own that goes first.

inverter chargers should have their switch because A: often at docks when boats are unatended house switches get turned off. if this happens your charger no longer charges the batteries, making the dock plug in useless.

also if plugged in and charging , and the house switch is turned off. (say to work on the DC panel) the charger will keep feeding the panel direct. so your house swtich is off, but everytying is still powered. direct from the charger, which is really bad on the charger, and also confusing when all your lights are still on when the house switch is off.

for some reason I thought one engine was off the house but I see both off engine batt now. you should also have a parallel switch between engine and house battery. handy to have if engine battery is low and won't start.