Starting Battery won't hold a charge

dlochner · Oct 12, 2020

Nichole340 said:
Your right, that battery had to be on its way out and not charging it just helped it along.
From what I have read here, my situation is a fairly easy fix with the addition of a new piece of equipment.
I never would have picked up on this without this post.
I still plan to post a photo of my current battery compartment as it is from the factory. As soon as I get back to the boat later this week.

I’m really surprised that more people don’t have these smaller portable Solar Panels. I see quite a few large panels and wind power attached but not the small ones just for topping off purposes. Maybe I’m wrong about there value, might be more trouble than they’re worth. For that reason there aren’t many you can ask about them.
More reading I guess.

Nigel Calder estimates the total daily output of a solar panel is about 3 times the nominal rating of the panel, i.e., a 120 watt solar panel will on average produce about 360 watt hours of power a day. That amounts to about 30 amp hours a day. From Monday morning until Friday afternoon the panel would produce about 150 amp hours. Not all of that energy goes back into the battery, some of it is lost to charging inefficiencies.

Fully charged healthy Group 24 batteries have a capacity fo about 75 amp hours, place 2 in parallel and the bank's capacity is 150 amp hours. Of those 150 ah only about 75 are useable because it is best to not discharge the batteries more than 50 percent.

To size the solar panel it is helpful to have a good estimate of the power consumption of the boat and the ways to charge it. That's the first step. Another way of looking at this is how much power is consumed over the weekend, how much is put back into the battery from motoring while using the boat, and how much power must be put back into the batteries during the week.

Assuming the boat is only used on weekends and assuming the house batteries are drawn down to 50% SOC, the solar panel would have to put back 75 ah by Friday afternoon. Before factoring in the charging inefficiencies (the Peukert equations), the solar panel would need to produce at least 15 ah per day. Using Calder's estimates, a 60 watt solar panel would be the minimum assuming no charging inefficiencies. Practically a panel closer to 100 watts would be a better choice.

Of course if your power consumption. on the weekends is less, then a 60 watt panel may meet your needs. That goes back to the point about knowing what your power consumption is, what your charging capacity is, and ultimately how depleted your batteries will be when you leave the boat on Sunday.

Scott T-Bird · Oct 12, 2020

I purchase my boat this year with some older flexible solar panels mounted on the bimini. The previous owner kept the boat on a mooring and ran the refrigerator full time, so he needed solar to keep the batteries charged. He basically had 2 small panels (22" x 21") at about 55 watts each and 2 larger panels (42" x 21") at about 110 watts each for about 330 total watts. I priced out replacements, pretty much in kind, and found that panel replacement and an MPPT controller would cost about $900 to $1,800 depending on brand selection. It seems like there is quite a spread depending on where you buy. The current generation seemed to be about 150 amp-hours per day, if I have that right. That seems like it should be plenty for some moderate cruising. Your charging needs may be significantly less. This is just one example for a similar-sized boat. I'm very new to the solar power idea, so I am also just getting started in that regard. I don't have a significant need for solar, since I have shore-power and primarily re-charge with an AC charger.

dlochner · Oct 13, 2020

In the December/January 2020 issue of Professional Boatbuilder, Nigel Calder takes an in-depth look at the solar panels. The cost differences between panels is due to the construction quality and cell quality. This leads to improved panel efficiency, more power per square foot and more power production in less optimal conditions (early/late in the day, overcast skies, etc.).

The industry is also filled with questionable and misleading marketing information. The higher end panels (such as Solara and Solbian) use very high quality cells to attain high efficiency. Sunpower makes some of the highest quality cells, however, they market cells of varying quality which is reflected in the price of the finished panels. Panel manufacturers seldom, if ever, specify the quality of their Sunpower cells.

This is the just the tip of the iceberg when it comes to solar panel technology, cost, and efficiency. Calder's article is quite lengthy.

Professional Boatbuilder is a magazine well worth reading. Subscriptions are available to the general public and well worth the modest subscription fee. The magazine is published by the same people who publish Wooden Boat.

sailcapt340 · Oct 13, 2020

Dave,
From reading your post and the article attached there is a wealth of information here. This subject could go on forever in regards to sailboats and individual needs and wants. And it is a buyer beware situation.
I think most, at least myself, are looking for enough power for the occasional Refrigeration, but mostly Battery Maintaining.
I for one, have lots of reading to do now.

As a side note, put me down as a plus 1, we bought our 2000 340 new in January of 2000. Had it commissioned by the yard, "the experts" and I had the "exact" same battery wiring as Nichole340 is diagraming. Everyone must have gone to the same class that year.
I found mine to be wrong after the first season when I was looking at 2 friends boats and saw their wiring.

This original post opened some eyes I think, I hope.

dlochner · Oct 13, 2020

sailcapt340 said:
Dave,
From reading your post and the article attached there is a wealth of information here. This subject could go on forever in regards to sailboats and individual needs and wants. And it is a buyer beware situation.
I think most, at least myself, are looking for enough power for the occasional Refrigeration, but mostly Battery Maintaining.
I for one, have lots of reading to do now.

As a side note, put me down as a plus 1, we bought our 2000 340 new in January of 2000. Had it commissioned by the yard, "the experts" and I had the "exact" same battery wiring as Nichole340 is diagraming. Everyone must have gone to the same class that year.
I found mine to be wrong after the first season when I was looking at 2 friends boats and saw their wiring.

This original post opened some eyes I think, I hope.

Glad you found it helpful.

As the saying goes, "knowledge is power" the more we know and understand the systems on our boats the better able we are to avoid problems and enjoy the boats more. Or, long for a simple day sailor with no electronics or diesels to maintain.

Richard19068 · Oct 13, 2020

Nichole340 said:
I’m really surprised that more people don’t have these smaller portable Solar Panels. I see quite a few large panels and wind power attached but not the small ones just for topping off purposes. Maybe I’m wrong about there value, might be more trouble than they’re worth. For that reason there aren’t many you can ask about them.
More reading I guess.

It depends on what you consider small. If you are really just "topping off" and trying to get the batteries up to 100% from say 80% over a few days then you might not even need as many watts as dlochner might suggest in his good take off from Nigel Calder's comments. I have been very happy with my 50W Sunpower flexible panel. I have a smaller bank than yours and don't have refrigeration but for topping off it provides all I need.
https://us.sunpower.com/sites/default/files/sp-e-flex-50w-specsheet-525321_0.pdf
These are available for around $100.

It is light, semi flexible, relatively small, easy to stow when not deployed and easy to hook up.
It is also fairly easy to expand with the addition of another panel if you find you need more.

You will need a charge controller. If you do get a smaller panel I would suggest getting a controller that will handle enough amps so that if you do want more solar power later you won't have to replace that. But given the assumption of a relatively low amp solar system that should not be too hard.

Stu Jackson · Oct 18, 2020

Nichole340 said:
I think there are to many connections in the Link 20 monitor wiring, so I plan to cut them and make 1 connection in each. The monitor works as it should but it seems like to many cuts in the wiring to me.

Those appear to be connections to the required in-line fuses. Doesn't appear to need ANY remedial work.

Ward H · Oct 18, 2020

Mount the ACR wherever convenient.
I think it’s already been said but if not, you should mount a positive bus bar near your house bank.
All charging sources, the house bank positive and one side of the ACR should attached to this bus bar. Wire the house side of your battery switch to this bus bar as well. The other side of the ACR to you other battery bank.

Scott T-Bird · Oct 18, 2020

Before you make any modifications to the battery monitor wiring, you should study the manual to see what is involved. I have a Xantrex LinkPro and I can see some similarities. What you seem to be showing is some kind of shunt (I don't recognize it) and the bundle of small diameter wires from the batt monitor. The shunt is like a negative buss bar, but it has the specific purpose of recording the negative current that goes back to your battery bank for monitoring.

The shunt has the large diameter battery cables connected to it. The negative side of battery loads will be on one side of the shunt, and the ground cable to the system ground should be on the other side of the shunt.

From the monitor, you will have 3 positive leads to the batteries, all with a fuse. One lead is the power supply (doesn't really matter which battery it goes to, all it does is supply power to the monitor). The other 2 positive leads go to each of both battery banks. These are recording voltage, I believe. You will also have a negative lead from the monitor to a negative buss (or directly to the shunt, I suppose). This returns the current from the power supply as you undoubtedly realize that you have to have a positive and negative circuit for powering the monitor. Then there are a twisted pair of leads that have to be fastened correctly to each side of the shunt. This probably has something to do with measuring the current in amps. There may be a few other leads for alarm contacts (which are optional).

Long story short, your monitor and the wiring for it isn't related to other issues that you may be facing, and there doesn't seem to be any need to modify anything related to your monitor. I would study the diagram of negative cables to the shunt, though. It has to be done correctly for the monitor to function properly. But how your shunt is organized doesn't have anything to do with your battery charging woes. Somebody correct me if I have something wrong or am missing something!

Scott T-Bird · Oct 18, 2020

Study wiring diagrams that show the various charging sources. 3 of the most common are: Alternator, AC-powered charger, and solar. (You could add an on-board generator in that group as well if you have one). Diagrams typically show all charging sources to a positive buss bar. The ACR takes care of directing the charge to the battery banks. Beware of the need for transfer switch if using a generator while on shore power (something that I'm not familiar with). Best practice is to eliminate the standard manufacturer practice of back-feeding the alternator charge thru the starter to the selector switch, eventually to the batteries. Disconnect that lead and provide a positive cable directly from the alternator to a positive buss bar. Do the same for the negative side (cable to a negative buss bar - not the engine negative mount).

sailcapt340 · Oct 22, 2020

I see the confusion you may be having in the wiring of the ACR, it can be confusing. From your picture, you should be able to mount the ACR under the Battery Selector Switch. Check behind it though to make sure there is nothing mounted under it in the starboard locker, before you start drilling any holes. That's where my engine exhaust piping and macerator line runs. The screws to mount it shouldn't be that long anyway, but check first.
I've added a photo and put in some lines showing what lines you need to add. Your existing Positive Cables to each Bank won't change and neither will the Negative Cables. They still feed the power to the boat as before.

You will need a new Positive Cable for each Bank. Where you mount the ACR will determine their length. A new Negative Ground Wire (should come with the unit), but check on that also. And you can run that to where your Negative Cables are now.
You probably have the same size Alternator I have on my 340, if it's original to the boat in 2000. I believe mine is 80 Amps and it gives a little less than that to the batteries.
Where you buy the ACR will have the proper wiring and fusing requirements, just give them your information.
Keep the "new" Wires to the ACR short but enough play to move and work with.

If I'm wrong with any of this information someone please correct me.

I hope I've made it a little clearer as to placement and wiring for you. The picture is what we both have for our wiring now, except for the engine. And you can add the number of batteries you have to the diagram, wired correctly, easy enough. You would have 1 more House Battery, but still need only 1 New Positive wire from the First Battery in the that Bank, to the ACR.

Maine Sail · Nov 5, 2020

Nichole340 said:
I have the wiring plan understood now and understand the concept of the relay and how they work. Now that I have it in my head that the wiring to the ACR from the battery banks “only” senses the voltage, not carries the voltage. That took a while.
I thank everyone and the suggested reading lists you have given. Value beyond belief!

Unfortunately, like many threads that deal with ACR's, there can be a lot of misinformation. The part bolded in red is a misunderstanding. The A & B terminal wires carry both current and voltage and also act as the voltage sense wires.

This article, proofed by Blue Sea Systems engineers and often link to by BSS tech support, can help:

https://marinehowto.com/automatic-charging-relays/

.

Maine Sail · Nov 5, 2020

Scott T-Bird said:
I purchase my boat this year with some older flexible solar panels mounted on the bimini. The previous owner kept the boat on a mooring and ran the refrigerator full time, so he needed solar to keep the batteries charged. He basically had 2 small panels (22" x 21") at about 55 watts each and 2 larger panels (42" x 21") at about 110 watts each for about 330 total watts. I priced out replacements, pretty much in kind, and found that panel replacement and an MPPT controller would cost about $900 to $1,800 depending on brand selection. It seems like there is quite a spread depending on where you buy. The current generation seemed to be about 150 amp-hours per day, if I have that right. That seems like it should be plenty for some moderate cruising. Your charging needs may be significantly less. This is just one example for a similar-sized boat. I'm very new to the solar power idea, so I am also just getting started in that regard. I don't have a significant need for solar, since I have shore-power and primarily re-charge with an AC charger.

We typically purchase panels from quality land based solar dealers such as AltE where the panels are required to meet Government land based standards. The "cheap" solar panels you see at non-solar specialists do not meet these stringent requirements. Their AltE branded panels are very high quality, they don't waive warranty for marine use and they are one of the best values I know if in a reasonably priced rigid panel.

Go Solara and Solbian if you want semi-flexible with top grade Sunpower cells. The Solar rigid panels are also amazing but very expensive. Sunpower is a great company, their rigid panels are a gold standard, but we've seen a few of their semi-flexible panels already fail.

dlochner · Mar 26, 2021

Fuses should be matched to the wire size. A 75-90 amp fuse is way too high for a 12 ga wire. The wire will melt before the fuse blows if you are lucky. If you are not lucky the boat will catch fire.

The cable between the batteries and the ACR should be based on the charging current of the charging sources, battery charger, alternator or solar. For a charging source lower than 60 amps, a 6 ga cable should be used and that should be fused at 75-90 amps.

The only place you need a small gauge wire, the #12 or smaller, is for the ground connection.

Perhaps the confusion comes from the somewhat counter intuitive wire gauge sizing standards. The larger the number, the small the wire and the less current it can carry. Thus, 6 ga wire is bigger and fatter than 12 ga wire and can carry more current safely.

Might I suggest before going much further with wiring on your boat you purchase a copy of Charlie Wing's Illustrated Electrical Handbook or the 12 Volt Electrical Bible for Boats (Amazon Links).

Starting Battery won't hold a charge

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