Confusing battery replacement

[Brooksie]

I've started my 354 ci Perkins for decades on group 31's RV batteries from Walmart also constantly run a small refrigerator when cruising. I'm on a mooring so no dockside power ever.

 

[Bacchus]

Mako
My experience is also very different and I think if you do the research the facts do not support you position re AGM. They are not the answer for all situations but there are advantages in addition to the no maint.
AGM self discharge is a fraction of FLA and is one of the reasons I switched all my battys 9 yrs ago. I had no access to power for charging over 6 mos winter storage. I be sure to FULLY charge and disconnect in fall and have measured 12.5-12.6V in spring before reconnecting. All 3 8D AGMs still doing well after 9 seasons.
AGMs do not like being left at partial charge for EXTENDED periods of time but what I've read a full charge about weekly is sufficient. Not req'd every cycle.

Solar is an excellent way to fully charge when used in conjunction with a gennie. Gen provides the bulk charge efficiently but not the last slow lo amp end of the charge profile where solar excells. It takes some monitoring and management but FLAs are somewhat similar and don't like being discharged for extended periods.

AGM need full charging between draining and don't hold their charge as well (think winter storage). If you live off the hook then you likely rely on your solar and are not reaching full charge each day. AGM work better for shorter bursts of high energy, versus long slower draining. Hence, great for starting batteries!

Gels are a bit more sensitive and need proper charge-management also, but perform better on deep discharging and partial charging back. Hold up well to colder temps than AGM and keep their charge better when you're away from the boat for months.

Interesting. My experience with agms is much different than yours.
I find the self discharge of my previous agms to be much less than the fla I’m running now. Also, the resting voltage on my agms has always been a little higher, as well as operational voltage.
It always took a cycle or two to sort of wake them up for the season, but they always performed well for me.
I’m getting ready to change all my batteries, a pretty big investment, so battery talk is on my radar right now. Thanks for sharing your thoughts.
Anyone else have a bad experience with agms?

 

[ranger58sb]

Changing architecture takes away all the decision making and manual switching to choose the start or house bank. It keeps the start bank isolated from house loads so there’s always power to start the engine. Battery monitors or state of charge instruments are usually designed to monitor one main “house bank” and one or two other banks for voltage only. This way you can see exactly where the batteries are, and when you need to replenish them. The start batteries are automatically charged when the engine starts and the charge voltage rises above a certain threshold.
His current system works, but it takes thought and manual switching to keep a battery isolated for starting, or choosing what battery to cycle for house loads.

Some people like that as they get full control of the batteries, but automatic frees you from having to give it any thought.
I like agms for house batteries. In fact, I like them for both start and house duty. I hate filling batteries, and inevitably run them too low. Luckily, my wife has taken that duty from me, and she keeps them topped off. When I replace them though, agms will be my choice. That’s a big budget item on my boat. 16 gc2s cost a couple of bucks.

Ummm... well, I guess.

Our several boats over the year have all come with combined start/house banks. No "selection" decision-making to do at all.

I did increase capacity for banks on the previous two boats, as circumstances and available space allowed.

But our only decisions are about recharging at anchor: one hour morning and evening, or two? Easy. (And it coincides with making meals in our electric galley, and heating water.)

I agree ref watering batteries, and we usually switch to AGMs as well. Mid-process on this current boat.

-Chris

 

[Mako]

@Baccus, I'm reminded that anecdotal experience is not evidence, so my experience is not going to be same as anyone else's likely.

Truth is, any battery installation can be satisfying if it is installed properly and maintained correctly. Both these conditions are rather easy to satisfy. If a guy's budget is zero-dollar tight, then a starter battery from WalMart can be used for his house needs. Probably get at least one year out of it.

 

[catalinajack]

As another responder posted, there many ways to skin the cat. My boat has an eight golf car FLA house batteries which also serve to start my engines. I have two generators that have their own starting battery bank charged via a Blue Sea ACR. In the highly unlikely event that I stupidly drain my house bank below 30%, I can start my engines via the generator or by using the generator starting batteries (two Group 27s). I have two externally-regulated Balmar 100s tamed by a Balmar Centerfielder. Simple, effective, and still with redundancy in the case of stupidity.

 

[tiltrider1]

As another responder posted, there many ways to skin the cat. My boat has an eight golf car FLA house batteries which also serve to start my engines. I have two generators that have their own starting battery bank charged via a Blue Sea ACR. In the highly unlikely event that I stupidly drain my house bank below 30%, I can start my engines via the generator or by using the generator starting batteries (two Group 27s). I have two externally-regulated Balmar 100s tamed by a Balmar Centerfielder. Simple, effective, and still with redundancy in the case of stupidity.

This works. However, your generator batteries are being overcharged if they are continuously connected to the house through a standard ACR. I would prefer a Smart ACR in this application. If you test your generator batteries at the beginning of each season to see that they continue to meet specifications then I don’t see you getting caught with a flat generator battery.

 

[Bacchus]

@ Mako...
I'm not talking anecdotes I'm talking published info, data from knowledgeable sources. Here is just one from Battery University. My post was meant to say my experience (agree anecdotal) supports the Batty Univ claims not that my experience is proof. I think you will find similar claims of +/- for AGM by other knowledgeable and unbiased sources.

https://batteryuniversity.com/artic... lead acid batteries,has a low self-discharge.

"AGM has very low internal resistance, is capable to deliver high currents on demand and offers a relatively long service life, even when deep cycled. AGM is maintenance free, provides good electrical reliability and is lighter than the flooded lead acid type. While regular lead acid batteries need a topping charge every six months to prevent the buildup of*sulfation, AGM batteries are less prone to sulfation and can sit in storage for longer before a charge becomes necessary. The battery stands up well to low temperatures and has a low*self-discharge.

The leading advantages of AGM are a charge that is up to five times faster than the flooded version, and the ability to deep cycle. AGM offers a depth-of-discharge of 80 percent; the flooded, on the other hand, is specified at 50 percent DoD to attain the same cycle life. The negatives are slightly lower specific energy and higher manufacturing costs than the flooded, but cheaper than the*gel battery. Table 1 compares AGM batteries to gel batteries on key performance characteristics."

Granted this is AGM vs FLA and I agree there are some advantages of gel but they comes at a higher cost premium than AGM.

Some interesting info that supports some of your Gel claims...

https://batteryuniversity.com/article/bu-201b-gel-lead-acid-battery

"A gel battery generally lasts longer than AGM; improved heat transfer to the outside is one reason. (The gel separator moves heat whereas the absorbent glass mat of the AGM acts as insulator.) A further advantage of gel is the dome shaped performance curve that allows the battery to stay in the high performance range during most of its service life before dropping rapidly towards the end of life; AGM, in comparison, fades gradually.

Gel is known for good performance at high ambient temperatures, is less prone to sulfation than other systems, but it needs the correct charge and float voltages. In comparison, AGM is superior at low temperatures with better current delivery because of low internal resistance. The cycle count on gel is said to be larger than AGM and the secret lies in holding more acid due to its design. Because of higher internals resistance, gel batteries are not used for high current applications."

 

[NWpilot]

How about this:
- each alternator charges its own start battery. Sterling charges each start battery.
- each start battery supplies a 30 amp dc-dc charger to house.

That should allow you to use existing charger and alternator regulation, and give you high quality 60a charge to your house bank. And you can use whatever type of battery you want for the house bank.

This is a very intriguing and simple approach. I'm going to look into the equipment to facilitate it.

 

[Jeff F]

This is a very intriguing and simple approach. I'm going to look into the equipment to facilitate it.

I'm pretty sure the Victron units can be linked together so they work as one. I've got them, and they're highly configurable and have a very good reputation.

If you do it, come back and we can talk about how to configure them. They can be set to only come on when the source battery is at full charge, so no danger of draining the start battery or cooking the alternator.

This is also a lithium friendly arrangement. You could use a drop-in LiFePo battery for house if you wanted to.

 

[catalinajack]

This works. However, your generator batteries are being overcharged if they are continuously connected to the house through a standard ACR. I would prefer a Smart ACR in this application. If you test your generator batteries at the beginning of each season to see that they continue to meet specifications then I don’t see you getting caught with a flat generator battery.

Forgive my ignorance, but what is a "standard" ACR as opposed to a "smart" ACR? I'm not certain what I have. If I do have a dumb ACR, why would the generator batteries be overcharged and not my house batteries? I am not seeing it. I have Blue Sea m-Series ACRs.

I don't test my generator starting batteries any more than I test my vehicle starting battery. When they quit I will replace them. They are not critical to operating the boat. If they fail while cruising, I can jump start them using jumper cables. Or, if I had a mind to, I could add a paralelling switch to my house batteries. I see no risk here.

 

[Bacchus]

Forgive my ignorance, but what is a "standard" ACR as opposed to a "smart" ACR? I'm not certain what I have. If I do have a dumb ACR, why would the generator batteries be overcharged and not my house batteries? I am not seeing it. I have Blue Sea m-Series ACRs.

I don't test my generator starting batteries any more than I test my vehicle starting battery. When they quit I will replace them. They are not critical to operating the boat. If they fail while cruising, I can jump start them using jumper cables. Or, if I had a mind to, I could add a paralelling switch to my house batteries. I see no risk here.

No expert here but I will suggest that the cause of gen batty over charging may be the difference in batty size / capacity. House battys tend to be large banks and gen batty relatively small.
When I bought our Mainship the 3 bank shore charger was charging 3 8Ds... 2 house/start and a thruster. The gen batty was tied to the house via a diode isolator. I didn't like the imbalance or use of diode isolator. I chose to separate the gen from shore charging and let the gen alt take care of the GP24 gen batty.
A TF member reported doing the same on their MS and his replacement of the gen batty on/off switch with a 1-2-all-off sw and using the 2 position to cross connect the house batty. The sw had the same foot print & bolt pattern making the sway very easy. I have done the same on mine and while I have never needed to start my gen it provides peace of mind and a simple way to "top off" the batty charge periodically when desired.

 

[Bmarler]

This is a very intriguing and simple approach. I'm going to look into the equipment to facilitate it.

I’d think carefully about implementing this strategy. You can deplete the start batteries charging the house bank unless you put in some sort of safety to disable the dc chargers.

 

[Porgy]

Of course Rod at Marine How To has an extensive article on ACRs and dispels a number of myths about them. https://marinehowto.com/automatic-charging-relays/

 

[tiltrider1]

Of course Rod at Marine How To has an extensive article on ACRs and dispels a number of myths about them. https://marinehowto.com/automatic-charging-relays/

This article completely backs up my recommendation. The only difference is the article discusses batteries of similar chemistry. When mixed chemistries are involved, the article says ACR’s are not the answer. This is why I always recommend Smart ACR’s. It solves the mixed chemistry situation. Further, most dead batteries are caused by human error, often by accidentally bumping a switch or by unattended children. My recommendation removes the Human error. It also allows for future upgrading of battery chemistry with out needing to redesign the system. Another thing I don’t mention, my recommendation allows for some one to easily set their boat up to handle 220v in foreign ports by just adding a battery charger, assuming the boat already has an inverter.

 

[Jeff F]

I’d think carefully about implementing this strategy. You can deplete the start batteries charging the house bank unless you put in some sort of safety to disable the dc chargers.

Typically that's done by setting the charger to only turn on above a certain source voltage threshold - say 12.8v. The Victron has an algorithm to throttle back and check no-load voltage periodically.

 

[Porgy]

This article completely backs up my recommendation. The only difference is the article discusses batteries of similar chemistry. When mixed chemistries are involved, the article says ACR’s are not the answer. This is why I always recommend Smart ACR’s. It solves the mixed chemistry situation. Further, most dead batteries are caused by human error, often by accidentally bumping a switch or by unattended children. My recommendation removes the Human error. It also allows for future upgrading of battery chemistry with out needing to redesign the system. Another thing I don’t mention, my recommendation allows for some one to easily set their boat up to handle 220v in foreign ports by just adding a battery charger, assuming the boat already has an inverter.

What he alludes to and maybe to clarify is that (with the exception of LFP) it’s the charge voltage that matters, not necessarily the chemistry. But since chemistry drives the desired voltage it’s mostly the same result and he gives examples, especially pertinent to mixing with GEL. However, he does say it may be possible to mix FLA and AGM if their charge voltages are within range.

He does say overcharging the start battery is a myth with regard to ACRs.

I still don’t see or can find what a “Smart ACR” is. I’m familiar with DCC chargers and chargers that call themselves smart but, but no smart ACR or VSR or combiner that functions differently than my Blue Seas ACR.

And apologies to Sunchaser who had already previously cited the Marine How To article.

 

[sunchaser]

I still don’t see or can find what a “Smart ACR” is. I’m familiar with DCC chargers and chargers that call themselves smart but, but no smart ACR or VSR or combiner that functions differently than my Blue Seas ACR. .

Possibly "Smart" is a marketing term. Our Blue Seas ML ACR is pretty smart by design, isolating the start bank from the house bank when starting with benefits to instruments during that quick voltage spike. Or maybe the ML series' three position switch is "Smart"?

All I really know is the ML ACR works as advertised, Rod Collins vouches for them and our very capable marine electrician has installed them on dozens of vessels up to 100' and beyond.

 

[luna]

Mr. Tiltrider1

I googled "Smart ACR" and got nothing useful. Can you provide a manufacturer and/or Part Number for these Smart ACRs?

An ACR or VSR provides a different set of features that a DC-DC charger does not.

With an ACR you get the ability to pass to the depleted battery bank almost the full charging current from the charge source. This is useful as when underway as the start/run batteries get charged quickly and the depleted house bank then receives, if needed full alternator output. Yes, I know an alternator and DC-DC charger wired to/from the house bank can do that as well, but I'm in the camp of keeping your alternator directly connected to your start/run batteries as engine stopping failures are less likely.

But an ACR also works the other way. If your start/run battery fails, your house battery will likely be able to start/run the engines once the failed start/run battery is isolated.

A DC-DC charger can't do that.

In my case I have 4 Battery Banks, thruster, 2 Engine start/run and House, all 24V. The start/run banks have no loads on them other than the engines. They are paramount.
All except the house bank are cheap JCI produced 1000 MCA group 24 batteries bought from Walmart that are now 8 years old, use no water, are held at 13.5 V or higher for extended periods of time and continue to start the 1100 cu. in. Cats just fine. Resting voltage remains at 12.7V.


WRT the issue of an ACR overcharging the start/run batteries I agree with Rod Collins. It's a myth. You can determine this yourself by simply measuring the voltage of the battery in your car when it's running. If the car was made this century you will find it to be about 14.3V. If you drive your car one hour a day, thats 360 hours a year, how long does your car battery last?

 

[tiltrider1]

Here is one example.

iMarine USA


Example of an echo charger but I have seen better examples

Auxiliary Battery Charger

The Blue Seas ML-ACR had a lot of marketing hype listed, much of it suggests a lot of capability. I would need to read the manual to find out just how capable it is. I can’t recommend it and I can’t discount it at this time. I would recommend anyone updating their system to fully research the differences between these systems.

Wile not relevant to the OP’s situation, many boats are now locating auxiliary battery banks in various ends of the boat to eliminate the need for running large cable. It is not uncommon to have a thruster bank, a house bank, a start bank and a crane bank. This is another area that Smart ACR’s, Echo chargers and Dc to Dc chargers come in handy.

 

[tiltrider1]

He does say overcharging the start battery is a myth with regard to ACRs.
.

Yes he said this but he had conditions on his statement. Meaning there are conditions were it is not a myth.

 

[grahamdouglass]

A good battery selection

An 8d battery is good for hernias and heart attacks, not much more.
I replaced my 2 8ds with one group 31 for start and golf carts for the house. I think this is what the majority are suggesting.

 

[luna]

Ok, the Magnum ME-SBC Smart Battery Combiner is indeed one of many (including the Blue Seas ML-ACR) voltage followers that in effect pass through to one battery whatever charge voltage is being applied at the time, to the other battery. It has no ability to produce a specific charge profile like a DC-DC charger does. Smart in this instance appears to me to be a marketing term only.

The SBC does have settable (within a limited range) combine, low voltage and high voltage disconnects, but so does the ML-ACR except that they a not settable but are set at a suitable value and time, that has a slightly different voltage value based on a different duration. This helps reduce short duration high load disconnects (cycling) and allows generally for an earlier connect.

The SBC is capable of only 25 amps continuous, while the ML-ACR does 500 amps continuous and 1450 amps for cranking. Interestingly the people at Magnum fitted the SBC with a Solenoid terminal so that you could fit an optional high current solenoid to enable the passage of higher currents. This likely raises the price to that charged for the ML-ACR.

I doubt if the SBC could be considered a low or high voltage disconnect for Lithium batteries as required by the new, yet to be published TE-13 report from ABYC even if it's the sole charging source.

So is this SBC a more modern advancement over a ML-ACR? In my mind.....No. Is it smart? No, as it is just a voltage follower, like the ML-ACR.

 

[Bmarler]

An 8d battery is good for hernias and heart attacks, not much more.
I replaced my 2 8ds with one group 31 for start and golf carts for the house. I think this is what the majority are suggesting.

i tend to agree that 8d's are a tough sell for most applications. however, i'm having trouble deciding whether or not to replace my 16 gc2 batteries with 8-8d's.
i'm replacing my trojan t-105 fla with agm's. i'm pricing out the trojan equivalents and ran into the victron super agm 8d's. these look like really interesting options but the size is just a little different and the boxes i have would need to be changed out to accommodate them. i can get some young backs to do the labor, but am having trouble deciding...

 

[ranger58sb]

i'm pricing out the trojan equivalents and ran into the victron super agm 8d's. these look like really interesting options but the size is just a little different and the boxes i have would need to be changed out to accommodate them.

If it helps, Lifeline and Odyssey both have 8D AGMs, presumablky the standard BCI Group 8D dimensions...

-Chris

 

[Bmarler]

If it helps, Lifeline and Odyssey both have 8D AGMs, presumablky the standard BCI Group 8D dimensions...

-Chris

thanks,
but the battery boxes i have are actually for the golf cart batteries, not 8d. if i go to 8d it will be for the newer victron super agm's. they have some impressive features. they are the only reason i'm considering moving to the larger size.
i'm pretty sure i can get odyssey and lifeline in the gc2 size as well.

 

[RickyD]

Some clarifications to the puzzle.

- The boat is normally at anchor in the marina and the batteries are kept charged by a Sterling 60A charger which will handle 3 banks.
- I plan on taking extended trips when ready, then to Astoria (180 mi. R/T) and eventually up the Columbia River to Idaho (600 mi. R/T). I will travel at a leisurely pace of about 50 mi. per day.

- I have estimated my electrical usage when at anchor for overnights at about 130 AH and based the battery draw down at 50% max. so 260 AH for a 16 hour period at anchor. I'm thinking that if I design for a 300 AH expandable house bank then I wont have to combine it with a start battery.

- If I end up with some 8D no maintenance batteries I can enlist relatives to help place them and not have to crawl into the bilge afterward to add water. I can't sit upright in my bilge. Everything is done laying on my side.

- At this point in time I'm looking at going on the less expensive route since I still have many repairs to make and all new electronics.

What I'm currently looking at is sealed FLA group 31 batteries with about 1000 CCA each for starting and a sealed FLA house bank. I would like to consider AGM for house but my Sterling charger only accepts one type of battery. I'm still working on sketches on the proposed system.

I replaced 2 8Ds with six Trojan L16s. They are FLA so will match up with the 31s. The Trojans are 6v 435 amp hrs. They are taller of course. The way I’m set up my six L16s start my stb engine and are my house bank. My start bank starts the port engine and Genset which charges the house bank. My Genset #2 charges it’s own battery, the start bank, and the house bank.

 

[Jeff F]

Wile not relevant to the OP’s situation, many boats are now locating auxiliary battery banks in various ends of the boat to eliminate the need for running large cable. It is not uncommon to have a thruster bank, a house bank, a start bank and a crane bank. This is another area that Smart ACR’s, Echo chargers and Dc to Dc chargers come in handy.

Right. That's the architecture I've adopted. Giving each bank its own dedicated charger (or chargers, if they play nice) maximizes battery health and longevity and also gives complete freedom to pick the appropriate chemistry for each bank.

I kinda think Smart ACR’s, Echo chargers and Dc to Dc chargers are essentially the same thing. We have some terminology challenges, as usual.


Sent from my moto g play (2021) using Trawler Forum mobile app

 

[luna]

RickyD

What if anything do the Port & Stbd. main engines charge?

 

[ranger58sb]

thanks,
but the battery boxes i have are actually for the golf cart batteries, not 8d. if i go to 8d it will be for the newer victron super agm's. they have some impressive features. they are the only reason i'm considering moving to the larger size.
i'm pretty sure i can get odyssey and lifeline in the gc2 size as well.

Ah. Thought you meant it was the other way around.

In that case, Lifeline also has GC2-sized 6V AGMs. Plus taller versions.

-Chris

 

[NWpilot]

OK, I've made a little progress.
- I've decided to go all AGM's with group 31's (925 CCA) for starting and Renogy 8D's (200 AH) for house for a total of about $1400. You only have to manhandle them once.
- I've shown the alternator connected to the house side as they will be the most depleted in the AM after a night at anchor as suggested by Rod Collins.
- I chose to go with ML-ACR's to have each alternator charge a start and house battery and they allow me to parallel the start and house in the event of a low start battery.
- I want to place a start and house battery on each side on the boat to better distribute the weight (200 lbs per side).
- The always on is for sump pumps, lights, etc.
- I haven't shown any fuses but will install them.
- I drew in an inverter with wiring but have no faith in it working as shown because I'm pretty sure I'll get feedback from the alternators working against each other. This is my main problem to solve.

I'm at about $2700 thus far plus a lot of labor.

Anyhow I hope the sketch helps to explain my thinking.
BTW- I downloaded and read everything pertinent by Rod Collins.