Starting Battery won't hold a charge

[Scott T-Bird]

This one:

SI-ACR Automatic Charging Relay - 12/24V DC 120A - Blue Sea Systems

Automatically combines batteries during charging, isolates batteries when discharging and when starting engines.

www.bluesea.com

Location depends on your boat and where it seems to make sense. Keep the cable runs short.

If you really want to separate the starter on the load side of the switch from the house panel, then you can use a Blue Sea DCP switch. It is 2 poles, 2 posts. But I caution that you read about the disadvantage of that switch for isolation purposes. You can use the DCP switch in conjunction with 2 on-off switches (hidden & rarely used, if ever) for isolation if the need ever arises. Most people think it is too complicated and don't understand it, but you can read about it and decide for yourself.

I'm always confused when people use the 1+2+Both switch and call their auxiliary battery a "start" battery. When the house and the starter are connected to the same output post, the smaller battery (bank) isn't a "start" battery. All 3 batteries, scratch that, both house and start loads are connected on the output side.

 

[Nichole340]

Scott,
Photos are coming that should clear up my very bad drawing. But the wiring I drew is accurate to the batteries. I messed up this spring with that one yellow ground wire. Thank you though for your interest and concern.

 

[Scott T-Bird]

All 3 batteries are essentially connected on the output side.

Scratch that, it is horribly wrong … I meant to say that your house and starter loads are connected on the output side (not the battery inputs). I don't really understand why you would switch to 2 just for starting and then switch to Both or 1 while underway. What does that accomplish? If you just leave it on 1 all the time, you are not going to ruin your batteries and you will be charging the only bank that you need to use. The battery on position #2 has no need to be used except for emergency. I think that starting on 2 and then switching to another position while underway is just killing the battery that is connected to the #2 post.

 

[Davidasailor26]

The ACR will prevent the start battery from being overcharged, when the start battery reaching a full charge, the ACR disconnects the battery from the charging source while allowing the house batteries to continue charging.

I suspect you know this, but for any future thread readers - ACR’s just keep the batteries combined whenever they were charging (above 13V or so). Both batteries will continue to charge as long as the charging source is available.

 

[Benny17441]

The one you have is toast, fully charged with little or no capacity. You are asking about adding a new battery to a couple of two year old batteries. In my experience batteries can go bad at any time and makes no sense to replace a whole bank of newer batteries for just one bad one. If they were all older, perhaps. Yes if combined the old batteries would likely suck some juice out of the new one but if those two are in good shape the parasitic discharge should not be noticeable. Just install the new battery for starting purposes and keep the other good ones for house service. The trick may come to recharge them as the older batteries will signal they are full earlier than the new one and may fool the alternator or battery charger into overworking. That should only be a problem if the difference in capacity is too large between the batteries but normally it should not be a problem. two things to preserve battery life, keep the distilled water level and recharge to full after every use. Batteries will self discharge so to periodically (once a week or two) recharge them when the boat is not in use or plugged to shorepower and the inboard charger. Over a short period of time the new battery will adjust to the other two at their capacity if combined. There are better ways to set up the batteries but none cheaper and more adequate.

 

[Nichole340]

Benny,
Your right, my original post was, at least I thought, about adding a new battery to relatively new batteries and the effect this may have on both.
To my benefit, others found I had made a big mistake in wiring the banks to the switch. They are all far more knowledgeable than I, but after this I hope I’m catching up.
It was that I had to be in a hurry the day I installed the batteries this past spring and it led to ruining a perfectly good battery. Lesson learned and a lot of reading to do.
I hope others will read this post and learn from my mistake and save themselves some time and money in the process.
These things aren’t cheap, but fortunately we all have a very knowledgeable and caring group willing to help and try to offset the costs for us.
I’ll keep everyone informed as to what I do and upgrades I make.

 

[dlochner]

@Nichole340 Don't beat yourself up on this. It was an easy mistake to make. Everyone on this forum, if they are honest, have made other simple mistakes. (If I ever post math calculations on this forum, double check my math, it is 50/50 that it will be right!)

Until you understand the nuances of electricity on boats, the mistake you made is an easy one to make. You now have a reading list and a winter of reading and planning. Enjoy.

 

[Davidasailor26]

@Nichole340 Don't beat yourself up on this. It was an easy mistake to make. Everyone on this forum, if they are honest, have made other simple mistakes. (If I ever post math calculations on this forum, double check my math, it is 50/50 that it will be right!)

Until you understand the nuances of electricity on boats, the mistake you made is an easy one to make. You now have a reading list and a winter of reading and planning. Enjoy.

A good learning experience indeed. For what it’s worth, even manufacturers don’t always get that right. Our Beneteau came from the factory with the house bank paralleled like your original diagram, with the red and black both going to the same battery. I haven’t fixed the wiring yet (the batteries aren’t right next to each other), so every 2 seasons I rotate the batteries. After 7 seasons both batteries are in fine shape, but they do live a pretty sheltered life of mostly day sailing and then going back on shore power.

 

[Ward H]

As Dave said earlier,

The batteries are to new to replace the whole system to keep everything the same age and size. And I really want the 3 battery setup I have. Just feel more confident with that amount.
How would you handle adding a third new battery?

Others have posted very good ideas for improving your battery and charging system but as @Stu Jackson said earlier, keep it simple.

Batteries within a bank should be the same type, size and age. Your starter battery is a second bank so the age difference will not be important. It should be the same type but does not even need to be the same size. You'll only have the bat switch set to both when you are charging both so one bank will not drain the other.

Here is what I would do:
Buy a new deep cycle battery to use in the bank #1 position. Unlike cars, our boats do not need starter batteries. Deep cycle batteries have more lead in them and are more suited to a boats charge / discharge cycles.

Then think about changing how you manage your batteries. Try this:
Fully charge the new single battery in bank #1. Then think of it as a reserve/emergency start battery. Only use it when bank #2, the house bank, fails.
Use bank #2 for starting AND house use. Our small diesels take very little amperage to start. The house batteries will start your engine just fine as well as powering your other electrical requirements.
When you motor all of the alternators charge output will go to bank #2.
Bank #1 will just sit there, holding its charge, until you need it.

This will save you from having to remember to switch from one battery bank to another after starting and back to both to charge when motoring.
And it eliminates the possibility of leaving the switch in the "both" position accidentally when you leave your boat and possibly draining both banks.

 

[Benny17441]

Pure deep cycle batteries are not suitable for use in boats because they are adverse to motion; they are mainly used as back up power banks in hospitals and Computer facilities. The Marine Deep cycle batteries that we use offer good performance and can handle motion very well. The difference among the batteries is the thickness of the lead plates; the deep cycle have thicker plates better suited to a gradual discharge of power while Starter batteries have thin plates better suited to a fast discharge of power. The hybrid deep cycle/starter is just a battery with an in between thickness of plates which may be useful in a small power boat with limited needs for house power. I find in a sailboat we mostly need Deep Discharge batteries.

 

[Stu Jackson]

OEM 1-2-B Switch Wiring History Alternator/Batteries & "The Basic" 1-2-B Switch BEST Wiring Diagrams

This comes from Electrical Systems 101 Electrical Systems 101

It includes links for many of Maine Sail's posts. Should give you lots of winter reading.

 

[Nichole340]

You have created a monster in me, because I have started reading. I couldn't wait for winter to do any reading.
So let me add another question that was eluded to earlier in this post.
(I understand that, If I decide to add a third battery to the house bank (for whatever reason) I would simply extend my ground to that battery and add another positive wire from the third to the second.)
But.....
Where would I connect a Solar Panel to this whole setup? Even if I get a suitable size small portable Solar Panel for the time being where do I connect its Positive and Negative Leads?
And would that be wise thing to do, given I'm on a mooring all the time?
Thanks again. I've included a new diagram.

 

[dlochner]

Oh Nichole, what a can of worms (wires) you have opened.

The negative buss bar clarifies many of the earlier comments and confusion.

If you want more capacity, it might be worth thinking about a different arrangement and use larger 12v batteries, Group 27 or 31s or make the big leap and go with 6v golf cart batteries. The GC batteries are designed to be deep cycle and the cost per amp hour is lower over time.

One goal of wiring batteries is to keep the number of connections on each terminal as low as possible, ideally no more than 4 power consuming (don't count temp sensors or voltage sensors) per terminal. This can be a challenge when there are multiple charging sources.

One simple solution is to have a positive bus bar to which the house battery/bank connects along with all charging sources, alternator, solar, and charger. From the buss bar one cable goes to the Switch and one cable goes to the start battery via an ACR. This arrangement will direct the charging current to both the house and start batteries and when the start battery is fully charged all the charging current will go to the house battery.

If the 1-2 Both switch is replaced with a Blue Sea DCP switch as @Scott T-Bird suggests, then the house and start batteries are isolated from each other and life gets really simple. The switch has 3 positions, Off, On, Emergency. In the On position both the start and house batteries are connected to their respective loads, the starter and the DC panel. In the Emergency position both batteries are connected to the house and starter. This last feature is used when one of the banks fail. With this switch there is no more worrying about which position the battery switch should be on. Simply turn the switch to on and everything works. Connecting all the charging sources to the positive buss bar ensures the house and start batteries are being charged as needed when a charging source is present.

Somewhere on Musings With Maine Sail or on MarineHowTo.com there are diagrams. I just can't remember where they are. Perhaps someone has a link for them.

 

[Stu Jackson]

If the 1-2 Both switch is replaced with a Blue Sea DCP switch as @Scott T-Bird suggests, then the house and start batteries are isolated from each other and life gets really simple. The switch has 3 positions, Off, On, Emergency. In the On position both the start and house batteries are connected to their respective loads, the starter and the DC panel. In the Emergency position both batteries are connected to the house and starter. This last feature is used when one of the banks fail. With this switch there is no more worrying about which position the battery switch should be on. Simply turn the switch to on and everything works. Connecting all the charging sources to the positive buss bar ensures the house and start batteries are being charged as needed when a charging source is present.

Before you even think about this, please read this:

AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
Darn AGM Batteries

There are serious shortcomings of that switch for sailboats. They suck. Emergency parallels a bad bank and a good one! That is simply wrong.

Somewhere on Musings With Maine Sail or on MarineHowTo.com there are diagrams. I just can't remember where they are. Perhaps someone has a link for them.

Yes, of course:

OEM 1-2-B Switch Wiring History Alternator/Batteries & "The Basic" 1-2-B Switch BEST Wiring Diagrams

1-2-B Considerations (New 2020 - Rodd finally got around to diagramming what I had done in the above link in 2009 )
1/2/BOTH Switch Considerations

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: Basic Battery Wiring Diagrams

This is another very good basic primer for boat system wiring: The 1-2-B Switch by Maine Sail (brings together a lot of what this subject is all about)
1/BOTH/2/OFF Switches Thoughts & Musings

This is a newer primer for boat system wiring design with a thorough digram: Building a Good Foundation (October 2016)
Building a DC Electrical Foundation

The Short Version of the 1-2-B Switch Stuff: Electrical Systems 101 This is a link to the Electrical Systems 101 Topic, reply #2

What are ACRs, Combiners & Echo Chargers? (by Maine Sail) [scroll to the top]
Battery Switch Question ? and Battery isolator / voltage regulator / batteries

Making Sense of Automatic Charging Relays (2019)
Making Sense of Automatic Charging Relays - Marine How To


These links are from:

Electrical Systems 101 Electrical Systems 101

 

[dlochner]

Before you even think about this, please read this:

AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
Darn AGM Batteries

There are serious shortcomings of that switch for sailboats. They suck. Emergency parallels a bad bank and a good one! That is simply wrong.

Absolutely. To be properly installed there must be a way to isolate the house bank and the starting bank from the DCP switch. The kluge way is with a wrench and removing the battery cable from the battery, the more elegant solution is with a single pole switch on the positive battery cable before the DCP switch.

I did not bring that up to avoid dumping too much information at once. Learn the big concepts first and then work out the details.

On my boat I do have a DCP switch and single pole switches on both the start/reserve and house banks.

 

[Ed Caldwell]

I just can't keep quiet after @Stu Jackson 's comment on the Blue Seas DCP and will offer the OP a contrarian opinion. I installed the DCP on a Hunter 340 15 years ago, not long after it came out. One. simple. switch. Here's the write up

Hunter 340 Owner Modifications and Upgrades

Hunter 340 Owner Modifications and Upgrades

hunter.sailboatowners.com

I have turned it "off" a couple of times when on the hard, and once, when the start battery died, I turned it to "combine" to start the engine. Otherwise in those 15 years I haven't touched the battery switch and the house and start bank do just fine, with battery replacements on about 6-8 year intervals since.

I agree with @dlochner 's comment on isolating the start battery, if I ever feel the need to do that, I will disconnect the positive cable as it is simple for me to do, and a lot easier than installing another battery switch. To Stu's comment "it sucks", I disagree. It simplified how I manage my boat on my waters the way I use it. (I keep the boat in a slip connected to 110v power year around, on an inland lake and mostly day sail, with occasional 1-2 night anchor out events)

Someday I may trace the alternator output wire as I believe it goes to the start battery pole on the switch and move it to the house battery terminal. Otherwise I am very pleased with this setup.

@Nichole340 may I humbly suggest you consider how you want to use your boat in making your decisions, using the resources Stu posted.

 

[Stu Jackson]

@Nichole340 may I humbly suggest you consider how you want to use your boat in making your decisions, using the resources Stu posted.

I agree. I believe if you read the linked article, which is by Maine Sail (even !!!) he describes why, which is as I earlier mentioned about mixing good & dead banks as your ONLY CHOICE (without rewiring in an emergency) and there is no crossover ability.
I link stuff so I don't have to rewrite the issues that are being discussed
The points are:
1 --- It's more than just the switch, it is the way the entire electrical system can work, with advantages & disadvantages detailed. Please read it all.
2 --- Everybody's different, but the bottom line is how YOU run YOUR boat.

As a management issue, it doesn't work for me because of the batteries as sources choice is lost. Others like the start separation and are willing to live with what I beleive is not so good if one bank dies.

Your boat, your choice.

 

[FastOlson]

Regarding the point about being able to easily isolate either bank, we do have a high-amperage breaker adjacent to the positive terminal for each bank. This was part of the general electrical upgrade done along with the new engine install in 2018.
I hope I never need to isolate a bank that quickly, but it's good to have the option.

 

[sailcapt340]

I'm assuming you are talking about topping the batteries off, like a trickle charger would do for a stored car in a garage, unused for the winter.
So what size Portable Solar Panel would be suitable to top off 3-4 Batteries? Do they have diodes built into them to prevent drawing power from the batteries at night or do you need to add a separate diode to prevent this from happening?
Are there small solar panels that are small, lightweight and powerful enough?

 

[Ward H]

2 --- Everybody's different, but the bottom line is how YOU run YOUR boat.

Absolutely.
Every poster needs to keep that in mind. We all have two things in common, keep the boat afloat and we would rather be sailing. After that it’s your boat your choice.
We all have opinions but you have to decipher what is best for you and your boat.

I have the DCP switch because it fits my use. I know it’s limitations and have manual (box wrench) disconnects if needed. A big plus for my manual disconnect is my batteries are easily accessible. I feel that is important. If they were not I would have On Off switches for disconnects.