Sailboat Power

[Naptown]

No Sir that is not what I am saying.

If I understood you correctly it sounds like you plan to take batteries off line, or disconnect and rotating batteries in and out of circuit. If that is what you intend to do you are playing with fire. In other words let's say for example you are going to use two 12 volt batteries. One off-line, and the other on-line. When you connect two batteries together in parallel that are at different state of charge, you will have massive amounts of equalizing current flowing between the two batteries. The battery with a higher state of charge will try to equalize and pull up the lower state of charge battery. With the size of batteries you are using that can be up in the thousands of amps, and if there is no over current protection devices (like fuses) on each battery there is no way to break the connection and the wiring will act as a fuse by bursting into flames and melting the copper wire. It is bad enough if that happens on dry land, but really bad on boat and planes.

So please don't get offended, I just care about folks safety.


On a different subject what are you going with 12 volts? Why not 24 or 48?

Marine battery switches are mad in two flavors. Most are make before break so one can switch banks with the engine running and not fry the alternator.
In this case house loads should be isolated with a battery isolator and starting bateries always connected to the alternator.
switches between battery banks (very normal on a boat to allow combining batteries) in this case should be break then make

[ChrisOlson]

Plan on buying a new set of batteries every year.

At night you have to have running/anchor lights, and in a cloudy week with no solar, you will murder the batteries.
Please consider even a small honda eu1000 to power a backup battery charger. Yes, there are gasoline storage issues, but they can be dealt with. At some point dead batteries will not boot up the solar charger, and then you are goner.

Doesn't this boat have dual battery banks? We have solar on our sailboat with a MidNite KID controller. But we also have two battery banks, selectable with a switch (can be seen to the right of the controller in this photo):



Also Mike, most cruisers run the propulsion engine once a day for hot water onboard on passages. Sailing yachts typically have 90 - 200A alternators on the propulsion engine (depending on the size of the boat) for the express purpose of charging batteries.

NEVER use a portable generator on a yacht. Your Mastervolt equipment has neutral switching, depending on whether you are on shore power or at sea. Plugging the shore power cord into a portable generator does not take the place of the neutral ground bonding that you get on shore power when connected. If you want to cause lots of galvanic corrosion on your boat and eat all your zincs off running a portable generator onboard is a good way to do it. But I only ask one thing - stay the hell away from my boat when you come into an anchorage and drop hook, then run your portable generator. I don't care if you want your rudder post to get ate off. But I'd like to keep mine intact, thanks.

[Naptown]

switching will become a real issue trying to switch controllers between batteries.
Mostly because you will have very high voltage from the panels if in series and you need to connect in order. battery first then panels so if you disconect a battery bank you will need to disconnect and reconnect the panels to the controller which is at higher voltage and requires a whole different flavor of switch.

[Mike90250]

Whoa. The big problem is, you are on a boat. Even worse, a sailboat, with masts, stays, lines, shrouds and all that. The shadows from even a small stay, will shut down a PV panel. 200w panel. 15 watts coming out. ARGHHH!!

You cannot build a infinite bank of paralleled batteries, especially AGM. Their internal resistance is low enough that the differences in the parallel cables, will imbalance the bank. Regular flooded batteries have a bit higher internal resistance, and using buss bars to parallel batteries becomes feasible, unless you are on a boat, then everything has to be tin or nickle plated. Stranded wire in the cables, buss bars, breaker terminals. Everything. The moist salt air will turn plain copper to swiss cheese in just a couple years.

A boat full of expensive batteries, needs to have a backup charging source, not wind, but some kind of reliable ICE generator, or aux alternator on the drive motor.

If you plan to have Air conditioning and electric heat, it's NOT going to happen with solar on a boat, unless you tow a raft with a huge solar array (that is not in your mast shadow). Just food refrigeration will be a problem (all those pesky shadows).

And there are ways to deal with gasoline issues, you can't just write off a whole line of portable power like that.

This is going to need a major rethink, of what your critical uses are, and how to get power to them. Conserve, conserve, conserve.

[Sunking]

Sunking - "Cannot interconnect batteries that way" ... Do you mean having certain banks and/or all batteries connected to a main panel to supply power and have each bank also connected to all MPPT controllers through a secondary panel?

No Sir that is not what I am saying.

If I understood you correctly it sounds like you plan to take batteries off line, or disconnect and rotating batteries in and out of circuit. If that is what you intend to do you are playing with fire. In other words let's say for example you are going to use two 12 volt batteries. One off-line, and the other on-line. When you connect two batteries together in parallel that are at different state of charge, you will have massive amounts of equalizing current flowing between the two batteries. The battery with a higher state of charge will try to equalize and pull up the lower state of charge battery. With the size of batteries you are using that can be up in the thousands of amps, and if there is no over current protection devices (like fuses) on each battery there is no way to break the connection and the wiring will act as a fuse by bursting into flames and melting the copper wire. It is bad enough if that happens on dry land, but really bad on boat and planes.

So please don't get offended, I just care about folks safety.


On a different subject what are you going with 12 volts? Why not 24 or 48?

[D_e_n_n_i_s]

OK guys, you've been very informative and patient with me so try not to get frustrated with me as I try to wrap my head around all of this. We were all newbs at one time ... some of us still are

Sunking - "Cannot interconnect batteries that way" ... Do you mean having certain banks and/or all batteries connected to a main panel to supply power and have each bank also connected to all MPPT controllers through a secondary panel? Most small panels can't handle heavy enough wiring so I'm guessing that is what you mean. An issue with the amperage sending smoke signals?

For the record, I have my current bank of two 8D batteries hooked into the "House" side of my main panel with heavy battery sized cables - I believe it's 1/0, but certainly heavy gauge. Same thing for the pair of Group 27 batteries hooked to the "Engine" side of the D/C Panel. Of course, even though I significantly increased the wire size going from each panel switch to the board, that's the weakest part as it goes through volt/amp gauges (I just beefed these up, though not enough I suspect for 6-8 batteries) and then distributes to power bars and fuses.

I don't think you were referring to taking banks of individual batteries (hooked in parallel to each other) and hooking these banks together in parallel as this would maintain voltage while significantly increasing amperage. I am going to need to calculate what gauge wire to use in the event I ever wanted to connect all banks at the same time to the board ... That does seem scary ... Fortunately, I have a professional doing the battery installation for me (Why are you applauding that) ?? Hey, what are you sayin' ??


Rich - OK, MPPT controller senses 12-volt load kinda like what happens with wind generators ... The load dictates things so the batteries are always safe since they will only receive a charge that they can handle ... too simplistic ?? altogether wrong ??

Good - Rotating the battery banks ... We're on the same page there

Charge Controller hooked to each bank ... OK, I get that now with your edit for me, but let me ask you this. If you have a fully charged battery bank and two other battery banks that are at 50% charge, I was thinking that a flexible switching system (with sufficient gauge wire) could be used to dynamically take the charge controller's Panel bank originally connected to the fully charged bank of batteries and divert it to add extra charging power to the pair of discharged battery banks. This is where things get dangerous, but potentially more effective if done right.

For the record, I'll be sleeping in the forward berth, not in the aft berth over the batteries ... except maybe in the winter. Kidding ... kidding ...

[Naptown]

Gotcha - 60 amp MPPT controller should be fine in real world use ...

Aha - There's another great idea and exactly the kind of insight I was hoping for, but let me make sure I understand it correctly:

1. Connect 2 solar panels in series (thereby increasing voltage) TO MPPT Controller, allowing for smaller gauge wire Correct
2. Connect MPPT controller to battery with heavier gauge wire

I'm guessing that the MPPT controller will sense the 12-volt battery load and charge it at 12-volts at higher amperage? again correct

3. Repeat creating banks of PANELS this way.

When you note "Rotate your banks as you use them" are you talking about the BATTERY Banks? yes So I would have 3-4 SOLAR PANEL banks that would all be connected to the D/C Panel (through their respective MPPT controllers) ... All charging any BATTERY BANK switched to "feed" the D/C Panel. charging each individual bank use as charged

I'll have to think on this a bit. I may set it up kind of like I set up my A/C battery charger where I used a separate 4-port panel so that I could flip my two 8D batteries to connect for charging, then I could cut those off and turn on the charging to my two Group 27 batteries because you always want to charge the same battery type with an A/C battery charger. Perhaps I could modify this for the additional SOLAR Panels (Not just a single A/C battery charger) and for the additional BATTERY Banks (Not just 2 banks). Interesting ...

That's just simple brilliance to hook the solar panels in series ... not brilliant just a better way of doing things
Then, I suppose the MPPT controllers would all be hooked up in parallel ... no you will have a Cc connected to each bank so all charge when available No, just all hooked directly into a D/C charging panel? Um, let's talk about that part. I want to maintain 12-volts and let the amperage increase to the batteries from the MPPT controllers. Would each MPPT controller sense the others and change the charging curve ... whatever that means in reality ?? Reduces something, increases something else ... perhaps could damage the batteries ??

I should re-word "feed" the main battery panel with "connect to" the batteries through another channel such as a secondary, small panel. Batteries could feed the main panel and be charged whether or not they are actively feeding the main panel this way. I'm I losing it ??

comments in red

[Sunking]

Dennis you cannot interconnect batteries in the manner you described. If you do you will set your boat on fire period. Each string voltage must be equal, exactly equal. If they are off say by more than 1/4 volt, and you connect then your wiring will catch on fire, and you will not be able to disconnect because what ever point you connect them (like a switch or disconnect) with will become welded together. The equalizing currents will be uncontrollable and far exceed the wire capacity.

[D_e_n_n_i_s]

Gotcha - 60 amp MPPT controller should be fine in real world use ...

Aha - There's another great idea and exactly the kind of insight I was hoping for, but let me make sure I understand it correctly:

1. Connect 2 solar panels in series (thereby increasing voltage) TO MPPT Controller, allowing for smaller gauge wire
2. Connect MPPT controller to battery with heavier gauge wire

I'm guessing that the MPPT controller will sense the 12-volt battery load and charge it at 12-volts at higher amperage?

3. Repeat creating banks of PANELS this way.

When you note "Rotate your banks as you use them" are you talking about the BATTERY Banks? So I would have 3-4 SOLAR PANEL banks that would all be connected to the D/C Panel (through their respective MPPT controllers) ... All charging any BATTERY BANK switched to "feed" the D/C Panel.

I'll have to think on this a bit. I may set it up kind of like I set up my A/C battery charger where I used a separate 4-port panel so that I could flip my two 8D batteries to connect for charging, then I could cut those off and turn on the charging to my two Group 27 batteries because you always want to charge the same battery type with an A/C battery charger. Perhaps I could modify this for the additional SOLAR Panels (Not just a single A/C battery charger) and for the additional BATTERY Banks (Not just 2 banks). Interesting ...

That's just simple brilliance to hook the solar panels in series ...

Then, I suppose the MPPT controllers would all be hooked up in parallel ... No, just all hooked directly into a D/C charging panel? Um, let's talk about that part. I want to maintain 12-volts and let the amperage increase to the batteries from the MPPT controllers. Would each MPPT controller sense the others and change the charging curve ... whatever that means in reality ?? Reduces something, increases something else ... perhaps could damage the batteries ??

I should re-word "feed" the main battery panel with "connect to" the batteries through another channel such as a secondary, small panel. Batteries could feed the main panel and be charged whether or not they are actively feeding the main panel this way. I'm I losing it ??

[Naptown]

Naptown - Great idea ... I don't think I recall seeing a 60A version at the time I was looking, but I'll certainly look again - Thanks !! This technology will keep you on your toes !!

Here is what I was figuring:

How do I size my charge controller:
Take the total wattage of your array (number of panels x watts per panel) and divide it by the voltage of your battery bank to get amps, then round up. The amp rating of your charge controller must exceed this number and it is usually recommended that it be 125% of this value.
320 Watts / 12v = 26.6666 x 1.25 (125%) = 33.3333 = 34 amp controller
35 amp controller per panel

I suppose 60 would be close, but I wonder if they make a 70-amp controller (I'll look around)? It seems that sharing 2 panels on 1 charge controller would be a good thing in terms of wiring, cost, etc. and still seems like it would be able to calculate a good point for charging even averaging from 2 panels, but I'm really just guessing there ...

It will be a rare instance that you will get full wattage from a panel or panels.
I figured 600/12= 50A still at 125% of wattage under ideal conditions.
Put banks in parallel pairs with switching to the main panel for each 2 pairs using a battery switch.
Rotate your banks as you use them. each will be charged individually.
The beauty of this is you can use much smaller wires from the panels in series to the controller as it will allow an input voltage of 150V I'm thinking #10 or 12.
Then the only big wires you need are from CC to battery and battery to loads
So for design purposes add voltage of two panels to get Vmp Imp will be the same for two panels in series (voltage adds amps remain the same)

[D_e_n_n_i_s]

For Sunking:

MasterVolt AGM Batteries - $849.99 for 12-volt 270AH Group=Super 8D
Kyocera 300 Watt Solar Panel (320-Watt Max) - $439.08
Morningstar TS-MPPT-45 --> TriStar 45 Amp 12/24/48 Volt MPPT Charge Controller - $400.00

1 Battery = $849.99
1 Panel = $439.08
1 45-Amp Controller per Panel = $400.00
Total cost = $1689.07 (without tax) x .06 (6% state tax) = $1790.42
$1790.42 x 5 batteries = $8952.1
$1790.42 x 7 batteries = $12,532.94
$1790.42 x 12 batteries = $ 21,485.04

I'll just stop there and cry for awhile ... Cutting down controllers to 1 for every 2 panels saves $400 + a pop ...
Fishing and foraging to eat because I'll be broke ... cost of being free of Corporate America sooner than later
Having electricity in every port, including deserted islands ... priceless

[D_e_n_n_i_s]

Naptown - Great idea ... I don't think I recall seeing a 60A version at the time I was looking, but I'll certainly look again - Thanks !! This technology will keep you on your toes !!

Here is what I was figuring:

How do I size my charge controller:
Take the total wattage of your array (number of panels x watts per panel) and divide it by the voltage of your battery bank to get amps, then round up. The amp rating of your charge controller must exceed this number and it is usually recommended that it be 125% of this value.
320 Watts / 12v = 26.6666 x 1.25 (125%) = 33.3333 = 34 amp controller
35 amp controller per panel

I suppose 60 would be close, but I wonder if they make a 70-amp controller (I'll look around)? It seems that sharing 2 panels on 1 charge controller would be a good thing in terms of wiring, cost, etc. and still seems like it would be able to calculate a good point for charging even averaging from 2 panels, but I'm really just guessing there ...

[Naptown]

Think about using the 60A version of the CC
It will allow you to put 2 panels on one controller however you won't get individual MPPT on each.

[D_e_n_n_i_s]

What voltage are you looking at for batteries?

My biggest concern is using expensive batteries in parallel as it is asking for trouble. If you know what you are doing you can put 2-strings in parallel for redundancy and maintenance. But big trouble if you disconnect one string for a day and reconnect.

Wow, I should have specified that my system is 12-volt. I envision having batteries in individual banks with each bank of batteries connected with parallel connections so that the voltage remains at 12-volts for the entire system no matter which battery bank is brought online (Interconnected banks in parallel so no voltage increase as well). All D/C devices on the boat are 12-volts so I keep everything at 12-volts for simplicity and safety.

Also, these are AGM batteries in case that makes a difference. I've had a pair of West Marine SeaVolt 8D AGM batteries hooked in parallel for years along with a pair of Seavolt Group 27 batteries as well with no problems. Why do you say it's asking for trouble? I would think changing up voltage on a system would be much more likely to cause a mistake at some point. Yep, that's gonna be a lot of pressure with serious amperage, but I do plan to mitigate that a bit with having 3 or 4 banks and only bringing online what I need to power a given set of appliances at any given time.
Edit - The 8D's were connected in parallel and were never connected to the Group 27 batteries, which were also connected in parallel - Just to clarify ...

The pair of 12-volt 8D batteries were never disconnected, but I will have a switch for bringing on various banks of batteries. Keeping them all in parallel should simply add more amperage when I bring them online and not cook a device that is expecting 12-volts. Just my thoughts ...

[Sunking]

What voltage are you looking at for batteries?

My biggest concern is using expensive batteries in parallel as it is asking for trouble. If you know what you are doing you can put 2-strings in parallel for redundancy and maintenance. But big trouble if you disconnect one string for a day and reconnect.