AGM Batteries

[Jay N]

djmarchand:

Your battery experience is illuminating. It was interesting that you provided total amps in and out in addition to years of service. Do you believe that total amps is more important in gauging service life? Since my battery monitor provides total amps, I've included the measurement. But as a gauge of service life, it's probably only relevant if I repeated the installation of an identical bank.


Attached is my analysis when I went shopping for the Third Battery Bank. The analysis didn't include the weakness that caused the early failure of the AGM bank, that of operating in a PSOC environment.


View attachment B1BankAnalysis 2013.pdf


Unseen in the background: The fact that I have a generator which must operate a minimum number of hours per year in order to keep the unit working well, an inability to heat water for house service outside of the generator and main engine, and an easy location for solar panel installation.


As with all things, there is a compromise and balance of systems based on existing components and service life.


If I were to start from scratch today, and no change in how the boat is cruised: No generator, hydronic furnace for water/space heat, and solar panels. Having these systems would dictate future battery options.

 

[Bacchus]

Jay:

Your battery experience is illuminating. It was interesting that you provided total amps in and out in addition to years of service. Do you believe that total amps is more important in gauging service life?

I will be very interested in what you have to say about the Fireflys in another three years or 200,000 amps, whichever comes first. They sure are expensive though!!

David

I noticed the same amp report and thought it was interesting...
Seems like a very reasonable way to measure batty service with cycle life a function of SOC. This is the first report I've seen others post where they consider more than just yrs of service which is a poor measure IMO.
Amps combines cycles & SOC and seems to be like it would be a reasonable measure especially if compared to bank capacity

 

[Moonfish]

We have 3.5 years on four Firefly Oasis carbon fiber AGMs and are quite pleased. I have inadvertently drained them down below 12 volts on numerous occasions (as low as 11.4 a couple of times) and they have bounced back with no issues. While cruising, we can be on the hook for a week or more between getting a slip. So we can rely on them quite heavily. I'd say the best characteristics in order are:

1. Ability to discharge 80% plus of capacity without damage
2. Charge rate is essentially much faster (with no sulfation)
3. Ability to perform in a partial state of charge
4. No maintenance

Regarding point number 2, here's a quick explanation Bruce Schwab made as a comment in our installation/use video:

To address some of the questions here regarding faster charging of Firefly batteries, I thought to chime in here. Note that a key factor in achieving fast recharging is how far you NEED to recharge the battery, in order to safely maintain the battery life in repeated cycling. It is common practice when recharging Pb batteries with a generator or engine, to stop charging at around 80-85% SOC, because the CAR drops off so much that fuel is being wasted (and due to the desire to not listen to the gen/engine any longer).

While many Pb batteries can be used like this for a few cycles, over as few as 30 cycles (or less) they all suffer permanent loss of capacity due to sulfation damage. Except for the Firefly MCF (Microcellular Carbon Foam), which have shown in testing to suffer no permanent loss of capacity at all from extended PSOC cycling.

What this means is that it isn't simply a high CAR that makes for shorter charging times...it is the fact that you can stop charging at a lower SOC without worrying that you are ruining the batteries. So YES, you could easily spend 1/2 the time charging Firefly that you would need to do with other Pb batteries which require the long tapering absorption charging to keep them from suffering permanent sulfation damage.

All that said, here is another recharging test that showed even when recharging to a high SOC, the Firefly performed very well vs. another high end AGM: https://www.coastalclimatecontrol.com/index.php/blog/186-firefly-batteries-new-testing-reveals.html

 

[twistedtree]

I would assess cycle life based on specs. Lots of people think the specs are BS, but they are probably as close to an apples to apples comparison you will get.

The challenge with all our responses is that no two useable patterns are the same, and likely not anywhere close. Lots of boats spend lots of time at the dock or hauled out with no battery cycling, where others cycle on a more regular basis. So nearly impossible to compare in any meaningful way.

 

[Jay N]

Thanks Darren for the CoastalClimateControl link, and comments on the Firefly batteries. They are a good fit for our needs.



TwistedTree says: "The challenge with all our responses is that no two usable patterns are the same, and likely not anywhere close. Lots of boats spend lots of time at the dock or hauled out with no battery cycling, where others cycle on a more regular basis. So nearly impossible to compare in any meaningful way."


This is so true. At the end of the day, we need to make the best decisions for our specific needs. This is a part of boating that can be seriously over analyzed. Figure out what you probably need, write the check, install the batteries, go cruising.

 

[MurrayM]

I have read elsewhere, but haven't been able to confirm, that Firefly carbon foam batteries are now or will soon be made in India.

This true? Cost coming down?

 

[sunchaser]

Regarding point number 2, here's a quick explanation Bruce Schwab made as a comment in our installation/use video:

It is common practice when recharging Pb batteries with a generator or engine, to stop charging at around 80-85% SOC, because the CAR drops off so much that fuel is being wasted (and due to the desire to not listen to the gen/engine any longer).

This has never been common practice with our FLAs. Routinely and easily charged to 98 - 100% by SOC meter and voltage at +13.5 during absorb cycle, whether cruising or at dock. Possibly a sales statement. No doubt the Firefly brand is well accepted, best they stick to what they can demonstrate with their fine product.

 

[MurrayM]

I have read elsewhere, but haven't been able to confirm, that Firefly carbon foam batteries are now or will soon be made in India.

Started a new thread about it: http://www.trawlerforum.com/forums/s4/firefly-batteries-india-41977.html#post721702

 

[twistedtree]

I’m on a long and protracted project to use LFP batteries. The decision to go in that direction was mostly about their charging behavior (full charge rate right up until they are full). So it’s based on their behavior. More expected cycles is a bonus, but’s I’m paying for them, so not free by any means.

 

[Insequent]

My house bank is 6 x Odyssey PC 1800FT for 1284Ah at 12V. They have been in 5.5 years so far. I have 2 x 200A alternators and have seen 360A charge rate from them.

About 18 months ago I changed my solar setup, increasing it slightly in size (now 2040W) and reducing the amount of shading. This enables me to get the house bank into float (assume fully charged) nearly every day even at anchor. Since that change the Victron battery monitor is telling me:
- 795 Ah deepest discharge
- 400 Ah average discharge
- 71217 Ah cumulative discharge
- charge cycles 60
- synchronisations 124
- 879.9 kWh discharged energy
- 1005.4 kWh charged energy

I think it all means that I will get quite a few more years out of them!

But I am sceptical of some of the Victron parameters/reporting. I installed a battery monitor on my windlass/thruster bank (3 x Odyssey PC 2100) and it is reporting 0 as average discharge (deepest discharge 55Ah, cumulative discharge 701Ah). And no charge cycles but 9 synchronisations.

 

[Donsan]

Would appreciate it if some of you would post pics of how you mounted AGMs on their sides. Can AGMs be stacked on their sides? Don't ABYC standards recommend battery boxes for AGMs?

 

[sunchaser]

My house bank is 6 x Odyssey PC 1800FT for 1284Ah at 12V. They have been in 5.5 years so far. I have 2 x 200A alternators and have seen 360A charge rate from them.

About 18 months ago I changed my solar setup, increasing it slightly in size (now 2040W) and reducing the amount of shading. This enables me to get the house bank into float (assume fully charged) nearly every day even at anchor. Since that change the Victron battery monitor is telling me:
- 795 Ah deepest discharge
- 400 Ah average discharge
- 71217 Ah cumulative discharge
- charge cycles 60
- synchronisations 124
- 879.9 kWh discharged energy
- 1005.4 kWh charged energy

I think it all means that I will get quite a few more years out of them!

But I am sceptical of some of the Victron parameters/reporting. I installed a battery monitor on my windlass/thruster bank (3 x Odyssey PC 2100) and it is reporting 0 as average discharge (deepest discharge 55Ah, cumulative discharge 701Ah). And no charge cycles but 9 synchronisations.

Brian

It seems serious, high battery bank draw down and off the grid cruisers like yourself, Café and others use AGMs. Anecdotal or not, your experiences and knowledge indicate AGMs and not FLAs are the smart way to go when offshore for awhile. But not all AGMs are created equal so using the right ones seems logical.

This said, one of the wonders of mankind seems a well setup diesel genset. Yesterday I walked through an art fair and saw three of them running. All over the world I've seen them running whether lighting up waste dumps for night time truck dumping at large mine sites or powering airplanes on the ramp in Kyrghyzstan.

Large quality AGM battery banks, associated electrical gear and acres of panels are not cheap to operate or install. It would seem there is a trade off point where a 8 to 10 KW genset is sensible from the economic standpoint and able to easily power ACs, chargers and watermakers. A smaller battery bank and a genset may be an intersecting alternative.The footprint, costs nor weight of a genset is not anymore than say a 800 aH of replaceable AGM batteries.

You gave this a lot of thought. Your comments would be appreciated.

 

[DavidM]

There are several types of boaters and they use different battery, genset, and recharging systems:

1. The casual, maybe one night overnight on the hook guy. All he needs is maybe a 200 AH bank, nothing more because he will be back at the dock the next afternoon and will recharge on shore power.

2. The 2-3 overnight guy who also has a smallish genset. He runs the genset morning and night to make coffee, heat water and recharge his smallish battery bank.

3. The guy who goes out overnight in the summer and runs his genset 24/7. All he needs is a small battery bank,

4. The guy who stays out 2-3 nights and has no genset. He recharges his batteries by running his propulsion engine at anchor. Not real good for the propulsion engine, but Ok for occasional use. He needs a high output alternator with an external regulator and a decent size battery bank. A few hundred watts of solar will take care of the final top off charging.

5. The dedicated long term cruiser who doesn't have or want a generator. He sets up his boat with a big solar panel system and a battery bank that will carry him through several cloudy days. He also has a high output propulsion engine alternator for when he travels to the next anchorage.

6. Combinations of all of the above.

I have a different take on the advice given in this thread so far: AGMs don't last any longer than FLAs and are double the cost. They do have other advantages though.

David

 

[Ken E.]

DM, That's really a good 'analysis by application'. For a boat's house power needs, one size certainly does not fit all. Maybe the next new and greatest thing in marine batteries will be the lithium batteries that Twisted refers to above, but that's probably quite a way out in the future for house power in boats.

 

[HopCar]

Would appreciate it if some of you would post pics of how you mounted AGMs on their sides. Can AGMs be stacked on their sides? Don't ABYC standards recommend battery boxes for AGMs?

Sorry I can’t find any photos but here is a bad drawing of how I did it. Not shown in the drawing is the strap that holds the battery to the shelf. The shelf is supported by the hull on one end and a ledger board glued and screwed to the hull stringer on the other end. This worked fine for many years and didn’t seem to affect the batteries.

 

[cafesport]

Sunchaser we have two inverter chargers which are capable of 100 amps charging output. One we have been using for shore power only, the other is for when we are at anchor and using a genny. Underway we have a pair of 175 amp alternators with balmar duo-charge external regulators. The charger settings are completely different for each inverter, but can easily be changed if one were to fail. We also have a separate 100 amp charger we use for a variety of circumstances. Underway we sometimes use it maintain the batteries since we can power it and our ac units when it’s hot or muggy underway. Other times we use it to stay in absorb overnight to fully charge the batts. In the mornings we’ll also run it in bulk mode for a half hour or so to bring the bank up to take the load off the alternators if we are getting under way. The alternators put out more heat and use more hp than our little genny does when cranking in bulk phase so running this way also shaves a few degrees off the er temps. As far as charging rate goes we can do 20C on the hook or on the dock and .35C underway. Since we rarely discharge more than 20% our acceptance rate tapers off pretty quickly so even though we have greater charging capacity the batteries won’t take it.

Insequent looking over your bmv history output I think you might want to revisit some of the bmv parameter settings. According to the manual cycles are only counted if you discharge to 65% then recharge back to 90% so doubtful you will ever see a cycle count on the thruster batts. Also you might be better served by disabling the auto sync function since you are running a big solar array. Very easy to do a manual reset once you are sure you have the batts topped off. Depending on your settings float voltage may trick the meter into thinking the batts are fully charged. If your alternator is cranking out big amps it’s because the batteries aren’t fully charged. Low current say .5% or less at absorption voltage means your getting close but you probably need to hold that voltage for several hours especially if there are any parasitic loads during this charging phase.

 

[Insequent]

Brian

It seems serious, high battery bank draw down and off the grid cruisers like yourself, Café and others use AGMs. Anecdotal or not, your experiences and knowledge indicate AGMs and not FLAs are the smart way to go when offshore for awhile. But not all AGMs are created equal so using the right ones seems logical.

This said, one of the wonders of mankind seems a well setup diesel genset. Yesterday I walked through an art fair and saw three of them running. All over the world I've seen them running whether lighting up waste dumps for night time truck dumping at large mine sites or powering airplanes on the ramp in Kyrghyzstan.

Large quality AGM battery banks, associated electrical gear and acres of panels are not cheap to operate or install. It would seem there is a trade off point where a 8 to 10 KW genset is sensible from the economic standpoint and able to easily power ACs, chargers and watermakers. A smaller battery bank and a genset may be an intersecting alternative.The footprint, costs nor weight of a genset is not anymore than say a 800 aH of replaceable AGM batteries.

You gave this a lot of thought. Your comments would be appreciated.

I take the view that unless you have air conditioning or electric hob/oven then a generator is unnecessary. Large alts and solar can easily meet my needs for extended cruising and anchoring out. It seems overly complicated to start a generator for a cup of coffee or slice of toast!

I like AGM as you avoid the messiness that can come with wet cells, and not having to check water & topup is one less maintenance item.

 

[Insequent]

Insequent looking over your bmv history output I think you might want to revisit some of the bmv parameter settings. According to the manual cycles are only counted if you discharge to 65% then recharge back to 90% so doubtful you will ever see a cycle count on the thruster batts. Also you might be better served by disabling the auto sync function since you are running a big solar array. Very easy to do a manual reset once you are sure you have the batts topped off. Depending on your settings float voltage may trick the meter into thinking the batts are fully charged. If your alternator is cranking out big amps it’s because the batteries aren’t fully charged. Low current say .5% or less at absorption voltage means your getting close but you probably need to hold that voltage for several hours especially if there are any parasitic loads during this charging phase.

Thanks for this. We only set up the basic parameters when installing the BMV. I will look into it further. But is there any problem with frequent synchronisation? And I'm not using the charge cycle statistic in any way. Is there a reason to do that?

Edit. I guess the auto sync issue is that the batts are not necessarily at full charge. So I should dig into these settings further.

 

[cafesport]

Insequent, Our inverters allow us to make coffee and toast w/o starting a genset, unless the batts are weak or the load gets high enough to to trigger the auto start. Then the inverter runs in load assist mode or as a charger or both depending on the parameters triggered.

No harm at all with soc reset as long as the batteries are really getting to full charge. Looking at your amps in amps out I think especially since you didn’t go into depth setting the parameters your bmv is not giving you a true picture. Garbage in garbage out. Key settings are true as opposed to original manufacturers spec battery capacity, for charged voltage use the absorption value and the tail current current from your battery’s manufacturer. If you decide to go to a manual sync you disable the auto sync by setting an unattainable charging parameter set. You will also want to get the proper peukert exponent for your batts. CEF is the toughest to guesstimate since in bulk mode your are charging at constant current which is 100%, but absorption a bit less and in float likely way less if at all. Out of the box the default is .95. I had a different monitor a few years ago that actually did a pretty good job of calculating this number so I’ve been using that as my setting. I think that If you do a history reset you could use the amps out over amps in ratio after you set it to 100% for a month or so. One of the keys for me identifying a bad battery was watching these numbers get out of wack.

 

[AusCan]

Yes , there is plenty of variation in how boaters use their battery banks.
My house bank of 4 x 220Ah AGM’s sustains me nicely while on the hook with a single 250 watt solar panel and a 120A alternator and a 120A alternator.

I just don’t use as much electricity as what others do. Our toast is made over the alcohol stove. Coffee is made by boiling water and a plunger type press. Lights are all LED. Toilet is manual. Large water tanks so no water maker required. Low humidity climate so A/C not required.
The electricity requirement is just for the fridge, a few LED lights, a fan on a warm night, a water pump, VHF, Music, and the odd phone or laptop charger. The only thing I use my inverter for is to charge 18V power tools.
I anchor a lot but rarely in the same spot for more than 2 nights so a small battery bank and limited charging capabilities works well for me.

Btw- my cheap Chinese no-name AGM’s are 4 years old and still show no signs of decreased capacity. Their original cost was similar to name brand FLA batteries.

 

[Insequent]

Insequent, Our inverters allow us to make coffee and toast w/o starting a genset, unless the batts are weak or the load gets high enough to to trigger the auto start. Then the inverter runs in load assist mode or as a charger or both depending on the parameters triggered.

No harm at all with soc reset as long as the batteries are really getting to full charge. Looking at your amps in amps out I think especially since you didn’t go into depth setting the parameters your bmv is not giving you a true picture. Garbage in garbage out. Key settings are true as opposed to original manufacturers spec battery capacity, for charged voltage use the absorption value and the tail current current from your battery’s manufacturer. If you decide to go to a manual sync you disable the auto sync by setting an unattainable charging parameter set. You will also want to get the proper peukert exponent for your batts. CEF is the toughest to guesstimate since in bulk mode your are charging at constant current which is 100%, but absorption a bit less and in float likely way less if at all. Out of the box the default is .95. I had a different monitor a few years ago that actually did a pretty good job of calculating this number so I’ve been using that as my setting. I think that If you do a history reset you could use the amps out over amps in ratio after you set it to 100% for a month or so. One of the keys for me identifying a bad battery was watching these numbers get out of wack.

Thanks for this. I'm across the country for a funeral, and in the midst of replacing a hot water heater on the boat but will definitely dig into the BMV settings rather than just continue with default values.

 

[SeaMoose]

Question for the experts - How do AGM batteries handle freezing? The small ones I have purchased for running the winch on my car hauler must be brought in the house for the Michigan winter or they completely die.

For those of us in the Northern climates lugging large batteries home for the winter is not all that appealing.

 

[johnma]

We have two Lifeline 8D AGM's that are 12 years old and need to be replaced in the spring. We have one group 27 AGM for the genset that need to be replaced about every 5-6 years. The 8D's stay on the boat all winter with no issues. I hook up the cables once during the winter and charge for a few hours. the group 27 comes home for the winter.

 

[RCook]

Question for the experts - How do AGM batteries handle freezing? The small ones I have purchased for running the winch on my car hauler must be brought in the house for the Michigan winter or they completely die.

For those of us in the Northern climates lugging large batteries home for the winter is not all that appealing.

The AGM's in my truck stay outside all winter, w temps to 10 below F. Those in my 26-foot trailer boat as well. If they are well charged, no problem.

 

[Delfin]

Would appreciate it if some of you would post pics of how you mounted AGMs on their sides. Can AGMs be stacked on their sides? Don't ABYC standards recommend battery boxes for AGMs?

The manufacturers will have that info. For my Northstars, as I recall, you could mount them on end, upside down, etc. But they didn't want you mounting them on their sides.

 

[Shay]

FullRiver 8L16 have worked well

7.5 years ago I installed 6 FullRiver 8L16 AGM batteries. They are used as both the house power and inverter bank.

These batteries are still going strong. This past summer after fully charging I removed the jumpers from the 6V pairs and let them rest for 24 hrs. I then compared the voltage ant rest and they were very close to each other. I then used a standard automotive battery load tester to load test each 6 volt battery, measuring the minimum voltage and current of each battery. The batterys were very close to each other in every measure.

I decided to reconnect the bank and run them another few years.

My bank is 1245 amp hours and the most current I can charge at is about 200 amps, so I've not really charged them hard.

My battery bank is charged to full almost every day. I have 660 watts of solar the see to that.

Most house banks fail from under charging and sulfating.

I absorb charge to 14.75 V at 77 deg. This is what FullRiver calls for.

Shay Glass

 

[Irish Rambler]

There are many theories on which battery type is best on personal experience, the overriding crucial factor is how they are recharged as that affects their life.
I've used various marque's of batteries in my business and finally settled for Caterpillar.
For battery charging I've also tried various 'wonder battery charging cures',
they all definitely worked, indefinitely at the cost of more batteries.
I tried the Adverc system after many years nightmare problems with tail lift trucks and I gave them the benefit of the doubt, others have come on the market since but none match the proven performance of Adverc.
Just a bit of history on battery charging, a television outside broadcast electrical engineer in Sweden whose initials were TMC marketed his invention for a while, (his patent was bought out by an English company, the system improved, and renamed Adverc),
TMC had terrible trouble charging batteries in cold climates and came up with the idea that battery charging systems should be battery sensed as opposed to machine sensed.
Your car has a battery in a nice snug warm place under the bonnet with short cable runs and once the engine has started will recharge that loss in about 20 minutes, after that it goes into a trickle mode, if you turn on the lights, it ups the output to cope, same if you turn on the aircon. That's machine sensing.
What we need on a boat is for the battery to say to the alternator HEY I NEED MORE CHARGE irrespective of what other appliances are turned on/off. That's called battery sensed charging.
That the principle in brief, if you want more info Google Adverc.co.uk all their parts are manufactured in Britain and guaranteed.
My interests are solely as a user of their system, I have no other interests or financial involvement whatsoever.

 

[Nepidae]

You asked for experiences with AGM batteries. As had been said, in a nutshell, what I got/get may not be what you get.

Regardless, AGM BATTERIES are only part of the equation. In and of themselves.

As may have been mentioned, AGM batteries have a different CHARGING characteristic than wet cell (FLA). Do you have a charger that handles different charging characteristics?

Along with that do you have a charger that provides a 3phase charging pattern, Bulk, Absorb & Float?

What do you have that will charge the house bank AGM? Are you still going to have FLA batteries for the engine?

My experiences; In '16 I had a house bank installed of 6 L16 6V AGM batteries. Each battery has about 400Ah and they were wired in series & parallel. When this was being done I had 2 4D FLA engine batteries. My charging profile setup in my Xantrex SW3012 charger/inverter was set to AGM, which I knew was not the best for the FLA batteries. Do you have an inverter?

The pervious OEM alternators on the Ford Lehman engines was 60A ea (we have twin engines) which were not the best for charging the banks I had installed, soooo, in went 2 new Balmar 120A/ea alternators. Also installed were 2 Balmar regulators, then 2 Duo-chargers and a centerfielder. The centerfielder decides where to send the charge, house or engine bank.

So, for underway we charge with 1 capability and at the dock, charge with another.

The Xantrex has a control panel so we can see at a glance that status of our house bank. I'm adding a Balmar control panel to keep an eye on the engine batteries that have been changed to 2 4D AGM batteries.

We are on the Loop and last winter we were on the hard on 1 of the Finger Lakes. There on the hard I had no power into the boat and everything shut down in the boat. The AGM stayed around 6V all winter. The FLA had to be charged 4 times. That is why I went to AGM this past spring for engine batteries.

The boat is now in Canada on the hard and I will be going for a visit mid-January to check the batteries. I'm anticipating, based on my experience with the L16's in the Finger Lakes region, that everything will be fine.

We are conservative in our power usage. We can pull into an anchorage, on a wall or mooring early afternoon. Go that day, the next whole day and the next and if we are going to stay longer I will break out our portable generator sometime in the morning and run it for several hours to charge the batteries back up. If we aren't staying the engine batteries have just been sitting waiting so we'll start our engines and move along. A normal day run for us will charge the house bank completely. Currently we have a 2500W charger, but I'm upgrading to a 3500W for '19.

I'm also installing solar panels for '19 as well, hoping to keep up with our usage. IF all goes well, I may install a fuel cell in '20.

We like to anchor and will be doing more as we transition Georgian Bay & the North Channel this coming season. I'm told 1 of the nicest area for anchoring.

BTW, when I was having all of the electrical work done I also installed an ELCI and a Galvanic Isolator. The ELCI helps with different dock power supplies.

Hopefully this shows that AGM batteries are not just AGM batteries. There are a lot of extraneous items necessary to charge and maintain properly the expenditure for AGM batteries.

So far, but mid-January will tell, they are meeting my expectations.

Any questions, email me.

Best regards,
Charles
Charles Williamson
m/v Nepidae
Albin 43 Sundeck
Nepidae.trawler@gmail.com
MTOA 3927
AGLCA 12114

Please keep in mind that emails show no emotion, often omit words, and may be perceived as the opposite of what is intended. A simple phone call is the fastest way to straighten out any misunderstanding or questions.

 

[DDW]

Beyond all of the charging and life issues, AGMs have two advantages pretty much undisputed: The have a much lower self discharge rate than flooded, and they do not spew acid or gas. For me, this alone is enough to recommend them. But your charging system must cope with them or you'll be buying more.

 

[greatpapabear]

Hi, Our (6) Lifeline AGM GPL 8-DL batteries gave excellent serviec for 10 years before needing replacement. With that experience we stayed with the same make and model.

We also have 2x Lifeline GPL-31T for the 12v DC rail.