Solar Charging Battery Bank(s)

F

Foggy

New member
The Existing Set Up:
* Battery banks - 2 (Starting bank and House bank)
* Battery switches - 3 (Starting bank, Parallel and House bank)
* Solar (165W) properly wired to charge House bank only
* Goal - provide some solar charge to both banks while in storage
(or anchored, without running engines, no shore power)

Question: To avoid adding additional solar dedicated to charge Starting
bank, can this bank be charged with existing solar by
* Turn Starting bank switch OFF, Parallel switch ON, House bank ON or
* Turn all 3 battery switches ON ?

Thanks for any input.

Aye.
 
The answer to your question needs more info:

Are the three switches simple on/off switches.
Where is the solar panel connected now- to the terminals of the house battery maybe.
Where is the parallel switch connected? To the terminals or after the on/off switches.

You need to create a path from the solar panel's output to both batteries. Closing all three switches will do it but depending on how it is wired just closing the parallel switch might do it also.

And I hope you have a solar charge controller between the panels and the battery. Otherwise you will ultimately fry the batteries.

David
 
DavidM":318wli0a said:
The answer to your question needs more info:

Are the three switches simple on/off switches. YES
Where is the solar panel connected now- to the terminals of the house battery maybe. PANELS TO CONTROLLERS, + TO BATTERY BANK, - TO SHUNT AND BATTERY MONITOR THEN TO BATTERY BANK
Where is the parallel switch connected? To the terminals or after the on/off switches. NO IDEA. WHEN 'ON' IT CONNECTS HOUSE TO START BANK

You need to create a path from the solar panel's output to both batteries. Closing all three switches will do it but depending on how it is wired just closing the parallel switch might do it also. THE PATH IS THRU THE PARALLEL SWITCH BY TURNING IT 'ON' WHICH IS ITS PURPOSE TO CONNECT BOTH BANKS

And I hope you have a solar charge controller (ELEMENTARY DEAR WATSON, SEE ABOVE) between the panels and the battery. Otherwise you will ultimately fry the batteries.

David
Click to expand...

NOT YELLING. Just for clarity.

Aye.
 
Red Top has 2 10W "charging type" solar panels sitting in the motor well, both connected to the house batteries directly through 10A fuses. I thought the second one was connected to the engine battery, but is not, so I only use one and close all 3 switches to feed both batteries. When it gets cool enough to work in the boat I will switch it to "engine". The only load on the batteries when Red Top is in its slip is the sump pump that runs a lot when it rains heavily here in NC.
 
Are the batteries all of the same type and capacity; What type and capacity? What composes each "Bank"?

With 165 watts, there is some chance of overcharging the batteries, when just left in storage for a period of time.
 
Five batteries, all same Gr 31 AGM: 2 paralleled starting, 3 paralleled house.

Heafty.

Aye.

PS: Owners Manual states parallel battery switch should be 'ON', starting bank
switch 'OFF', house bank switch 'ON' if trolling with starboard engine only.
NB: port engine alternator charges engine bank only. Starboard engine alternator
charges house bank only.
 
Hey Foggy,

It might be simpler to wire your solar panels to a solar controller and then to the battery banks. There are solar controller designed for multiple banks. Check Defenders Marine or whoever you prefer.

Defenders has a: Solar Controllers-PWM. their item number is 202322, model number: GP-PWM-30, 30 amp controller. It'll handle two banks.

Good luck, take care and be safe. Spuncopper
 
spuncopper":12nesgnj said:
Hey Foggy,

It might be simpler to wire your solar panels to a solar controller and then to the battery banks. There are solar controller designed for multiple banks. Check Defenders Marine or whoever you prefer.

Defenders has a: Solar Controllers-PWM. their item number is 202322, model number: GP-PWM-30, 30 amp controller. It'll handle two banks.

Good luck, take care and be safe. Spuncopper
Click to expand...

The wiring exists now and is a done deal. It works well.
Two panels; one 55W, one 110W. Each has its own Genasun MPPT controller
(GV-5, GV-10). Positive from each controller goes to + house bank. Negative
from each controller goes to shunt to Watt Wizard monitor and to - house bank.
This is not my question.

I want to use this currant to get to the start bank via the battery parallel switch
rather than purchase another solar panel dedicated to the start bank.

But thanks anyway.

Aye.
 
Even though you have a fairly hefty set of batteries, if you are cranking the full 12 amps at 14 volts into the batteries-- with the two controllers you have, I believe there is probably some voltage/amperage limits when the battery is "full"--after reading the brochure. You may want to verify this, by watching the voltage when your Watt Wizzard shows that the batteries are at 100% State of Charge. Unfortunately the Watt Wizzard, does not measure the State of Charge. I would charge the batteries with the shore power charger, until they are in float stage--battery voltage 13.2 to 13. 6, with the solar panels off. Then turn on the solar panels--if the voltage goes up, then you may need to put a voltage limiting diode on the output of the solar panels, to be used only when the boat is in storage.

To charge the engine battery from the solar system, you need only to parallel the two battery banks, This gives you one bank of 5 group 31 AGM batteries. The capacity is somewhere in the 550 to 600 amp hours. Most likely the 12 amps will not be an issue. But to be safe it would be nice to limit the voltage to 13.5 +/- when the boat is in storage and you just want to float the batteries.



In reality the AGM have extremely low self discharge, and can go months without charging. However, we don't know what loads are on the house (or engine) batteries. For example, many MDF have some parasitic drain, stereo's do. There are bilge pumps, which may be sampling every few minutes, by turning on, or using a sensor.

There also may be intentional loads--the refrigerator is left on so your beer is cold when you arrive at the boat, the anchor light if the boat is on a mooring etc.
Your Watt Wizzard should tell you the number of amp hours or watts used over a period of time.
 
thataway":2bymwtgv said:
Even though you have a fairly hefty set of batteries, if you are cranking the full 12 amps at 14 volts into the batteries-- with the two controllers you have, I believe there is probably some voltage/amperage limits when the battery is "full"--after reading the brochure. You may want to verify this, by watching the voltage when your Watt Wizzard shows that the batteries are at 100% State of Charge. Unfortunately the Watt Wizzard, does not measure the State of Charge. I would charge the batteries with the shore power charger, until they are in float stage--battery voltage 13.2 to 13. 6, with the solar panels off. Then turn on the solar panels--if the voltage goes up, then you may need to put a voltage limiting diode on the output of the solar panels, to be used only when the boat is in storage.
I CAN READ STATE OF CHARGE OF EITHER BANK FROM AN ANALOG METER.
EACH SOLAR PANEL HAS A LIMITING DIODE. THEY ARE ALWAYS 'ON' ALTHOUGH
DO NOT DELIVER CHARGE IF BATTERY CHARGER IS 'ON' OR BANK IS EQUALIZED.
THIS DOES NOT APPEAR TO BE A PROBLEM.

To charge the engine battery from the solar system, you need only to parallel the two battery banks, This gives you one bank of 5 group 31 AGM batteries. The capacity is somewhere in the 550 to 600 amp hours. Most likely the 12 amps will not be an issue. But to be safe it would be nice to limit the voltage to 13.5 +/- when the boat is in storage and you just want to float the batteries.
THANKS. THIS WAS WHAT I SUSPECTED AND WAS AFTER CONFIRMATION.
CURIOUSLY, THE SOLAR PANEL REP DID NOT VOLUNTEER THIS AS A
POSSIBILITY - JUST SUGGESTED I PURCHASE ANOTHER SOLAR PANEL
(PLUS ACCESSORIES)...':thdown'
SNIP
Click to expand...

MY RESPONSE QUIETLY IN CAPS ABOVE.

Aye.
 
Hello Foggy,
I have the tendency use the K.I.S.S. principal with linear thinking.
I understand you want to use the panels and system already installed.

You could turn all three switches on to connect the system and it would probably slowly charge the batteries. However, you have bypassed the reasons you have three switches. They system will always try to charge the weakest battery bank.

Without having to install another solar panel, I would suggest you purchase a solar controller that will charge two battery banks. Run the first leg to the back of the disconnect switch of bank one and connect it to the battery lug.

Run the second leg to the back of the disconnect switch of bank two and connect it to the battery lug.

Since you have a parallel switch you already have a common ground so run the needed ground wires.

The solar charger will read both banks and charge whichever one needs charging or split the charge and charge both, slowly.

This way you can leave all your switches off and still charge.

Take care and be safe. Spuncopper
[/u]
 
Thanks, Spuncopper for your KISS suggestion.

My KISS solution is to not fuss with the existing controllers and wiring but use the
battery parallel switch to turn my 2 banks into 1 bank.

IF I decide to add another solar panel, it may be portable and smaller using the
Fox-062 mini plug-in charge controller (100a max, battery type selectable) via
my helm cigar lighter to charge my start bank. This might meet both our KISS
preferences.

Also, I can use it for my roadster and rent it to others who wish to get charged up.

Aye.
 
I CAN READ STATE OF CHARGE OF EITHER BANK FROM AN ANALOG METER.
Click to expand...

Yes, and I have a slide rule which does certain calculations well. There is a reason that many boaters use a Coulomb counter type of SOC meter, such as the Victron 702, Xantrex Linklite/LinkPro, Clipper BM1, Blue Seas M2, Balmar SM 44 Smart Guage, etc

As Blue Seas puts it: " The Voltmeter Method—Monitoring voltage allows measurement of the potential charge of your battery. The difference from a fully charged battery to a fully discharged one is only 1.0V in a 12V system, so the meter must have good resolution and accuracy. This method is generally sufficient to monitor batteries which experience intermittent use, such as starter or thruster batteries. However, a battery must not have been charged or discharged for over 12 hours for this measurement to be trustworthy.This makes this method unsuitable for monitoring house batteries, which are in a charge or discharge pattern much of the time"
 
thataway":1yzqwood said:
I CAN READ STATE OF CHARGE OF EITHER BANK FROM AN ANALOG METER.
Click to expand...

Yes, and I have a slide rule which does certain calculations well. There is a reason that many boaters use a Coulomb counter type of SOC meter, such as the Victron 702, Xantrex Linklite/LinkPro, Clipper BM1, Blue Seas M2, Balmar SM 44 Smart Guage, etc

As Blue Seas puts it: " The Voltmeter Method—Monitoring voltage allows measurement of the potential charge of your battery. The difference from a fully charged battery to a fully discharged one is only 1.0V in a 12V system, so the meter must have good resolution and accuracy. This method is generally sufficient to monitor batteries which experience intermittent use, such as starter or thruster batteries. However, a battery must not have been charged or discharged for over 12 hours for this measurement to be trustworthy.This makes this method unsuitable for monitoring house batteries, which are in a charge or discharge pattern much of the time"
Click to expand...

Well, Bob, you're probably correct technically given there can always be
improvements made. But you must realize your way, along with many boaters,
is not the only way to satisfaction in operating an otherwise seaworthy vessel
with an acceptable energy management system. Granted a 1.0V delta is a lot
in a 12V battery. Since my analog voltmeter reads voltage in 0.2V increments,
I have a good idea of their state of charge without the needs of a battery 'geek'.
As previously stated this is not a problem.

Blue Seas, and others, sell marine electronic equipment which I have owned and
respect knowing they would like us to purchase many of their products which we
may not need for the benefit of being 'better' than what we now use.

In addition to admiring the KISS principle, I usually go with 'if it's not broke,
don't fix it'.

Aye.
Grandpa used to say "We stand on the shoulders of giants" and quote Aristotle,
"The mark of an educated mind is the ability to entertain a thought without
accepting it."
 
Well, Foggy, we do agree on that many will do fine with just a volt meter. But even in the 80's I had gone over to a digital volt meter, and managed a 1200 amp hour battery banks for about 100,000 ocean miles over 8 years, with just the digital volt meter. On the other hand, you are measuring the amps in and out with the Watt Wizard, so you do have modern technology, and are not a Luddite.


I find advancing technology one of the interesting challenges of boating. Currently, I am trying a liFePO4 battery of usable 110 amp hours, weight 29#, (and a fraction of the size of an 8D or two group 31's), for the Freezers/refrigerators, and with the Li battery technology the old "volt meter" is no longer valid. Victron Energy recommends a Peukert's exponent of 1.05 rather than the accepted 1.25 for lead acid batteries. I suspect that lead acid batteries (including AGM) will be a thing of the past in a few years.
 
that away":2nc6qlvp said:
SNIP To charge the engine battery from the solar system, you need only to parallel the two battery banks, This gives you one bank of 5 group 31 AGM batteries. SNIP
Click to expand...

Seems simple, direct, a complete great answer to the post. Is it?

With 3 battery switches (start, parallel, house) does the above hold true regardless
of the ON/OFF status of the start and house bank switches? Then there are
ignition switches to consider...

Aye.
Grandpa used to say, "The more you know, the more you learn there is to know."
Grandma used to say, "Most of us don't know what we don't know."
 
Solar (165W) properly wired to charge House bank only
Click to expand...

To charge the generator, since they are all the same size and type, one only needs to connect the two battery banks together--that means parallel.. All other switches are extraneous to this goal.
 
Back
Top