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Discussion Starter #1
I have always understood that so called "maintenance free" batteries were not truly maintenance free. Indeed, on my last boat I had to add water to my maintenance free batteries once in a while.

On our current boat we aren't getting anywhere near the rated capacity so I thought it was time to pull them and check the electrolyte levels. That is a bit of a job because all of the cabling has to be removed to get at them. The engine battery has the same housing as the house batteries so I thought I would pull that one first. The problem is, I can't figure out how to get the top off to access the cells. I have tried gently prying at different points but it seems awfully tight. I am wondering if these batteries are even meant to be opened or are they TRUELY maintenance free. I've never encountered a battery that can't be opened, but it feels like the plastic will break if I use any more force on these.

I thought I would put this out there before I proceed with applying more brute force. Should I be able to open these? If so, are there any tricks?

The little dot in the window is green, but I am only getting about 120ah out of a 550ah house bank before I reach the 50% level...


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Flooded maintenance free are not designed to be opened. Not usually a great choice for a house bank either, for this reason. If you want maintenance free, go with AGM or Gel, but the charging systems need to be changed for those chemistries. If you want to be able to check water and electrolyte, just get real flooded.

Be sure your charging system is set up properly, preferably with a three stage charger, no matter what you have.

They sound like toast, if you're getting so little Ah, so time to think about what you would like going forward.
 

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Discussion Starter #3
Yeah they were installed in 2016, so not that old, but no idea how much they were abused by the PO. The boat has only alternator and shore power charging so they were probably cycled too deep. I was just hoping to get a few more years out of them before I do a system upgrade.

We still got through a long weekend off grid last weekend, so we still have useable capacity.

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Discussion Starter #4
I just installed a Victron BMV712 and have been watching it for a few weeks. The first thing I noticed was that the monitor was showing a slow but steady discharge while on shore power with the charger on.

I have a Cristec cps2 charger. I opened it up to see what settings I have and found that "Boost" mode was turned on. From what I understand this mode should not be used if the batteries are on the charger for long period. This boat has spent most of it's life at the dock with shore power, so I guess that qualifies as "long periods"!

I think this Boost mode might explain the discharging the monitor is indicating, and it may also explain the poor battery performance after 4 years of boost mode!

I will leave that feature off unless there is a compelling reason to use it!

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The only sealed lead acid chemistries that perform well in House bank conditions, in other words quality true deep cycling

are GEL and the AGM varieties, aka VRLA.

They generally do not last as long as FLA all things being equal, and cost much more, especially "$ per Ah per year".

And no, do not try to force open any SLA.

There are many checklisted protocols to follow in maintaining **any** bank you paid lots of money for

and topping up water on FLA is a very minor aspect.

But there is a use case for every type, justification for every choice, no one way is right for all, just try to choose according to your preferences, based on knowledge.
 

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5 years is about the life expectancy of the battery type you have.

I have Close to the same charging set up you may have. Same Victron, 100 Amp Balmar with AR5 external alternator plus a Mastervolt 3 stage 40 amp shore power charger.

My batteries are also difficult to get at. Would be hard to fill with water so no flooded for me. I have 6-6 volt Lifeline AGM. 720 ah. Can be stacked. Can be equalized so no sulfatung issues. Can handle them easily.
Each set lasted 10 years, so worth the expensive price. Shop on line as prices can be all over the place,
 

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A Jeanneau 39 would not likely have come with sealed flooded batts. Jeanneau seemed to like using Gels for their house bank for a while. I wonder if they were crushed, because the charging system is not designed for flooded.
 

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Discussion Starter #8
A Jeanneau 39 would not likely have come with sealed flooded batts. Jeanneau seemed to like using Gels for their house bank for a while. I wonder if they were crushed, because the charging system is not designed for flooded.
That is an interesting thought. I will have to investigate that!

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Another thought, along those lines. Theoretically, the charger should have some dip switch settings for different battery chemistries. The Cristec chargers don't have the best reputations. I still use mine for the accessory batteries (winches, thruster, windlass), but long since changed out the house bank for a good three stage charger.

Gels (if that was originally designed) require lower charge voltage settings, which are sometimes crudely engineered in, with long cable runs that cause voltage drop. Not ideal, but better than charging on the wrong profile. This can be tested with a multimeter at the batteries.

The conspiracy theory is that you may be using lower Gel voltage to try to charge a flooded battery, which would never properly charge it and cause pre-mature sulfation.
 

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My current set of batteries are "maintenance free" lead-acid cells. I had never heard of sealed deep cycle batteries before, so didn't even occur to me to ask about this feature when ordering them at our local battery shop. Anyway, I ended up with these sealed batteries where I can't see the electrolyte.

I bought them in 2015, and they've served me well in all that time. They continue to perform just fine, and I expect to get a few more years out of them. But I really dislike not being able to access the cells. My next set will definitely have removable caps.
 

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Sailnetters... weigh in

I have 2 AGM house 8Ds at about 500 AH and a Optima Start at 55AH. All charging is to the 8Ds

Optima is charged by an echo charge. Batteries are the same age.. 8yrs.

So would they age the same? Or are the 8Ds working harder and will expire sooner?

If the house is pooped and its voltage is say 12.8... will it continue to charge the Optima?

Will solar give a false reading of 8D's state of charge when there is sunlight?

Would that then charge the Opitma?
 

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We also echo charge our odyssey off the house bank of 720 ah (. 6-6volt Lifelines) . I don’t think they age concurrently.

Our start odyssey has lasted 13 years so far. Reads 12.8.
 

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Yes all the aging factors are different between two banks, so. . .

DoD% is a huge one, cranking duties are trivial.

Might seem nitpicky, but

the echo charge drops down half a volt or so from source, I think 14.4V is its top limit

While 14.4V is at the very bottom of what you want to see at the Odyssey posts.

Technically Odyssey would also like to see much higher currents than the 15A max the echo allows. . .
 

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Discussion Starter #14
Another thought, along those lines. Theoretically, the charger should have some dip switch settings for different battery chemistries. The Cristec chargers don't have the best reputations. I still use mine for the accessory batteries (winches, thruster, windlass), but long since changed out the house bank for a good three stage charger.

Gels (if that was originally designed) require lower charge voltage settings, which are sometimes crudely engineered in, with long cable runs that cause voltage drop. Not ideal, but better than charging on the wrong profile. This can be tested with a multimeter at the batteries.

The conspiracy theory is that you may be using lower Gel voltage to try to charge a flooded battery, which would never properly charge it and cause pre-mature sulfation.
I spoke to the broker who sold the boat originally and he said the standard equipment was FLA, and AGM were optional, but most didn't check that box.

Since I started this thread I have discovered that the bank was wired incorrectly, with multiple negative connections that would result in unbalanced charging. I have since corrected the wiring, and have my battery monitor reading accurately. I am currently on the boat, off grid, and have had to run the engine to charge the batteries after only 2 days with just the fridge, pressurized water, and led lights for loads. Not very impressive for a 550ah bank! We are getting about 160ah before voltage alarms start. We also see big voltage drops when the fridge kicks in.

I definitely think these batteries are toast. It is too bad, because I was hoping to get a couple more years out of them so I could plan and save for a full system upgrade. I might have to get more FLA batteries to hold me over.


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Maintenance Free, Sealed Lead Acid Batteries = Maintenance PROOF batteries.
 

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Discussion Starter #16
Another thing I noticed is when I ran my engine to charge the batteries the most I saw going back in to the batteries was 40amps, and even that started dropping off after a while. I am not sure what that is telling me but assume the batteries won't accept more charge.

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Sorry to hear the revelation. Seemed most likely, I'm afraid.

The brokers answer is plausible, but are they a Jeanneau factory broker or general broker. The latter often get the facts wrong.

How big is your alternator? First, it will supply the amps needed for whatever is running, then remaining capacity for charging. However, it sure seems likely that the actual capacity of your batteries is a fraction of their original rating, so charge acceptance is further up the curve than you would think by counting amp hours.

If I read your chart correctly, your at 11.77 volts, while drawing 6.8 amps? That's destroyed, perhaps dangerous, territory.

The good outcome is all the wiring errors you found and fixed. Time for new batts, I'm afraid. Think what a joy it will be to have proper power aboard. Don't replace with cheap sealed batts.
 

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Those batteries really have no place being used in a house battery/cycling application. Those are most likely starting batteries, (they are "sticker brand" batteries so impossible to tell) but maintenance free flooded batteries are not well suited to deep-cycle use, especially when taken below 12.2V.... That voltage dive is an indicator of batteries way beyond their useful life. Oh, and set the low voltage alarm for 12.1V -12.2V and you'll increase your cycling capabilities.....

What is a Deep-Cycle Battery?



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While it may not be possible for your equipment... I have found that my "cheap" 8D AGMs have done well... with little to no "deep cycling"... that is to say... I have a constant trickle charge from 110 watts of solar, and I have engine drive refer which means when I cool the refer I am pushing amps into the battery (and making hot water... and using my inverter to recharge batteries or vacuum). My batts were new in 2012 and are only now showing signs of having lost capacity... but still serviceable. Engine drive refer has worked out well for me... I don't know any other cruisers or SailNet members who also have engine drive refer. They might tell a different story.

I am well aware that most sailors use 12v refer which is a constant and larger drain on the batts.... and deal with that by large solar arrays with a windgen or maybe use a separate genset to charge their batts.

My decisions were informed by my planned 3-4 yrs of cruising and living aboard and being anchored out every day. With no shore power from a dock... I had to figure out how to meet my electrical needs. I decided on all chain and a windlass... wired it to the house bank... and decided to use an engine drive as I expected to be anchoring and moving frequently... when I would have the motor on with a high output alternator replenishing used amps. This works almost as good on the mooring, but motor use is mostly leaving and entering the harbor, motor sailing and anchoring... and using the engine on the mooring to cool the box. It takes no more than a half hr and I get my hot water at the same time... which I do consider a necessity. I have had the same two 55 watt panels since 1988 before departing... which kept batteries topped up while I was away during the week.

Circumstances inform decisions!
 

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While it may not be possible for your equipment... I have found that my "cheap" 8D AGMs have done well... with little to no "deep cycling"... that is to say... I have a constant trickle charge from 110 watts of solar, and I have engine drive refer which means when I cool the refer I am pushing amps into the battery (and making hot water... and using my inverter to recharge batteries or vacuum). My batts were new in 2012 and are only now showing signs of having lost capacity... but still serviceable. Engine drive refer has worked out well for me... I don't know any other cruisers or SailNet members who also have engine drive refer. They might tell a different story.

I am well aware that most sailors use 12v refer which is a constant and larger drain on the batts.... and deal with that by large solar arrays with a windgen or maybe use a separate genset to charge their batts.

My decisions were informed by my planned 3-4 yrs of cruising and living aboard and being anchored out every day. With no shore power from a dock... I had to figure out how to meet my electrical needs. I decided on all chain and a windlass... wired it to the house bank... and decided to use an engine drive as I expected to be anchoring and moving frequently... when I would have the motor on with a high output alternator replenishing used amps. This works almost as good on the mooring, but motor use is mostly leaving and entering the harbor, motor sailing and anchoring... and using the engine on the mooring to cool the box. It takes no more than a half hr and I get my hot water at the same time... which I do consider a necessity. I have had the same two 55 watt panels since 1988 before departing... which kept batteries topped up while I was away during the week.

Circumstances inform decisions!
yes in your situation where you really don’t draw the batteries down much you don’t see the real deep cycle advantages. They key for you is the trickle charge not the engine running.

No matter how long you run the engine once the battery capacity reaches 80-85% you hit a “wall” of battery acceptance where it makes no difference how strong the alternator is, it can’t jam in the last 15-20 of capacity the battery has. In fact it reaches a point of diminishing returns running the engine. You can run the engine for 8 hours but because of the battery’s acceptance limiting the amount actually hitting the battery it has little or no effect. Your solar however helps recover the additional ah.

it actually is counterproductive running the engine needlessly taking away from its life, wasting carbon , once your engine refrigeration has been activated for the day.

Your intended usage originally is what drove you to get this type of refrigeration system. As you stated most don’t have this type, instead opting for a 12 volt system either run off the battery or 110 run off of an inverter.

without drifting to the advantages / disadvantages of this, quite frequently a 12 volt system will run 25 ah ( efficient insulation) to 70 ah just to take care of the reefers electrical needs.

Unkess I have this wrong engine alternators reach this diminishing returns once 80% of the battery banks capacity is reached. If I have learned correctly the capacity can be continuously lowered over time if on AGM you don’t bring it back to 100% on a frequent basis. For many of us who may have slips with a shore power charging source, and don’t cruise for weeks at a time, this keeps the potential capacity at the original levels. A sufficient alternative like your solar panel can also do this. It can get that last 15-20% back into the battery bank.

Sulfating is the silent killer in this situation. Most AGM don’t have an antisulfating option. Our Lifelines actually recommend it. Wet cells require it or you will suffocate the battery eventually.

It seems prudent care will get you 5 years of usage until you see battery capacity diminish. Good batteries and good care can get you 10 years as we get on our batteries.

You get what you pay for. Rolls, Trojans, Lifelines are more expensive, but you hear time and time again from their users of their long usage. It’s similar if you don’t have to go through the aggravation of replacing every 4-5 years, plus no apparent maintainence. That’s been my philosophy.
you can buy a cheap water heater for your house or a quality one. The difference is will it take 5 years or 10 for the bottom to drop out. There’s a reason premium batteries have 5 year warranties ( even if they are prorated).

I understand not wanting to spend tons on batteries, but you have to look at your own usage and what is most cost effective for you. This part of your boat can cost lots in hidden costs. mismatched alternators with systems shortening the lives of expensive alternators. , shrinking the battery capacity over time by not bringing it back to its 100% because of lack of ability to get the last 20% into then, running off engine hours and fuel to try and get the last 20% of capacity. Even if you don’t need solar like a true cruiser does. Those on moorings should have done to achieve the continuation of their batteries potential ah.
 
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