Gel or Flooded?

[kenbo]

Originally Posted by a64pilot

Here is the issue, Gel is almost certainly “better” no maintenance and almost certainly lasts longer.
Due to sizing constraints, I’m pretty much stuck with a group 31 battery, and in that size you can get a good quality flooded battery for $1 an AH.
Gel costs roughly three times as much.
So for a 600AH bank it’s $600 for flooded and $1800 or more for Gel.
I say more as I’ve not really researched shipping costs etc, the flooded I can pick up myself at Sam’s club so I know it’s $1 an AH, less tax.

So is Gel worth three times or more cost? Will a group 31 Duracell (Deka) flooded battery last five years in actual use?

I want Gel, but am having a hard time convincing myself it’s worth the additional cost

Those Group 31 batteries at Sam's Club are the sealed, antimony doped lead type. You can't add water and they won't last as long as a true flooded GC 6V.

[sailorboy1]

I add water to my fla T105s every 2 months and this is based on 3 years experience with them. They could probably go longer, but i manage to find the 20 minutes of time every couple of months.

I have no use for the advantages of gel, agm. Lithium etc etc and as such have not desire or need to spend money money for them.

[Sternwake]

My experience with flooded group 27 and group 31 batteries, was that their water usage increased exponentially with accumulated cycles, starting at about deep cycle 350 to 400.

These 12v marine batteries, if one checks specific gravity, hoping to see it at baseline maximum, will often find them well below, and that an hour or two more of absorption is needed. Even when one figures out the right absorption time to achieve near max SG in their specific usage, in a couple dozen cycles that time might increase again.

More time in absorption to reach true full charge, means more regular watering. If true full charge is not attained then they sulfate and start searching for the nearest cliff to jump off screaming.

I had a group31 USbattery, that in my regimen, required a Solar absorption setpoint of 14.9v for 3 hours then a solar 'float' of 15.3v for the remainder of the afternoon, to come within 0.005 of baseline maximum specific gravity, and that would just walk down and down until the next EQ charge which was required within 14 cycles and that was getting fully charged or nearly so every cycle.

Injecting higher alternator amps into this equation, especially in the morning, changed everything and this regimen then required lesser absorption for lesser duration and the 15.3v float for the remainder of the afternoon was not required, or only required for 15 to 30 minutes. I got about 500 cycles from this battery before the bottom of the cell closest to negative pole started heating badly at absorption, and I relegated it to workshop duty and light cycling and minimal care.

The same age Northstar AGM that took over at that point, and went on to accumulate ~1300 deep cycles, and I did not even see its lid for the last 3. It is now the workshop battery and still regularly cycled.
Watching an Ammeter while holding absorption is much less work than removing caps and checking specific gravity, and performing EQ charges every 14 cycles.

I've no experience cycling GC-2s into the ground, I don't have the height requirement for them, but flooded marine batteries, 27s and 31s, make for poor deep cycle batteries in my experience and opinion. They take far too much voltage and time to reach true full charge, and then still require regular EQ charges, and their watering needs to be done more and more frequently. All my 27's, which was previous to the single 31 whose cells I dipped frequently, due to a much more convenient location to do so, I found some dry plates in some cells when I went to check levels, and they took a nosedive soon after.

I'm staying with AGM in 12v formats. I don't care that i could cycle 3 12v marine batteries to death for the price of one AGM. Not having to check specific gravity and not having to baby sit them to determine if they are getting fully charged, is well worth the price, to me. My Agm, to restore performance after a bunch of low and slow solar is a discharge well below 50% and 40 to 65 amps per 100Ah of capacity, applied from that most depleted state applied until 14.7v is reached and then held until amps taper to 0.5 or less. It became very obvious by voltage retained during discharge under X amount of load when this 'reset' was required, and it was always effective until the very end.

I expect 20F temperature rise during that high rate charging, and adjust absorption voltage down as required.

The group 31 USbattery, after 4 additional years of workshop duty, mostly light cycling with main charging source a 100watt panel facing south, was requiring watering every 2 weeks and one cell was especially bad needing it weekly. The concrete under it was crumbling within the baking soda dam I set up around it. as it was an Acid spewer as well by that point.

Pretty much done with 12v flooded batteries in anything remotely resembling deep cycle duty, but I'd make an exception for the trojan t-1275 or EastPenn Deka's gc-12 size, but again I do not have the height for them without unwanted modifications.

I'd urge you to not consider flooded group 27 or 31 batteries in deep cycle duty, unless battery maintenance and babysitting is something you eagerly look forward to.

No experience cycling trojan 27 or 31's though, just Crown and USbattery 27's and 31 and wally worlds versions before those. I never felt I came anywhere close to achieving the number of cycles I should have with any of them considering the light depth of discharge considering the extra capacity I carried and did not need. I just cycle a single AGM deeper now, and get more cycles per $ and spend much less time on maintenance and babysitting to deduce true full charge.

[a64pilot]

My battery box is under the settee, so no I really can’t raise height by much, I could maybe get another 3/4” by removing the plywood cover and using a thinner plastic one that sat on the battery or something.
Thought about cutting the bottom out of the box and may still do that, but believe one side is right against the hull, so that may or may not work, the rest of the settee has deep storage that I could put any kind of battery in, including the Trojan Solar I believe based on the L16 size, and if I move the batteries that’s what I may do, and use the battery box for canned good storage.
I’d only need three of them and price wise they are good, and if you believe Trojan they will last more than 2000 cycles.

Gel has a proven track record for longevity, and one thing that’s attractive to me is no equalizing, equalizing is a pain to accomplish monthly, takes long hours of generator running, because as you know you first must be fully charged before equalizing can begin and getting to fully charged and then running a several hours long equalizing charge means Solar can do one or the other, but not both.

Difference in bank cost if you go Firefly is $600 for flooded, over $3,000 for Firefly, so while many may think they are great, for an over 500% markup in price they had better be.

I waffle back and forth, $600 is low enough to not really worry about the bank all that much and even if you buy new ones every other year the cost isn’t too much to just eat, that’s $50 a month if you replaced every year, $25 a month every other year.

Gel, three times as much, but should last long enough to justify cost, and real attractive thing is no maintenance, and no equalization, the true zero maintenance battery.

The big Trojan Solar batteries are in between the cheap flooded and gel in cost, but ought to really do the job, it is what they are designed to do, and in truth they would take up the least space as they would take up one complete storage compt, but now I have batteries in a storage compt, and in my battery box.
But surely a battery that tall needs to be equalized or it’s electrolyte will stratify if you don’t?

I keep gettin back to this one thought though, if the Gel is so good for deep cycling Solar systems, how come it hasn’t taken over the market completely? They should be the only true install and forget battery bank for off grid installations, and should last a decade?
Modern charging systems you can get the voltage very precise, I mean very precise so that isn’t an issue.
By precise I noticed that my Sterling Pro charge Ultra leads if you will my other charge sources and I wondered why, measured its output and my other charge sources with my Fluke, the Sterling when you set a voltage say 14.3, it outputs 14.35, the other sources output 14.30.
I guess they chose to round if you will, and that extra 5 hundredths of a volt is consistent and steady. It’s not like in the old days when 14ish was all you could hope for say 14.5 plus or minus .5.

Anyway so modern chargers seem to be so precise in voltage that Gel’s ought to be easy now from a voltage perspective.

Anyway thoughts are flooded is cheap enough to be considered a consumable item, just replace as necessary,
Gel ought to the true install and forget battery, no maintenance at all, no equalizing, but three times the cost of flooded.
Big Solar batteries are twice the cost of cheap flooded, still require all the same maintenance, but really ought to last a long time, perhaps as long as Gel?

[a64pilot]

Originally Posted by s/v Jedi

If you go gel then get the right ones. If they don’t fit then go for Lifeline, Firefly, Battleborn (good to best, expensive to more expensive)

Here’s the good stuff (picture attached as well): A600

Thank you for the link, it’s informative, it also seems to agree that Deka is the US source for the Sonnenschein “technology”

[s/v Jedi]

Originally Posted by a64pilot

Thank you for the link, it’s informative, it also seems to agree that Deka is the US source for the Sonnenschein “technology”

They are, but not every gel battery has the deep cycle performance and lifespan of the series I linked

If you think of moving the bank to where 3x L16 fit, then look at the 4V L16 Firefly’s. I think three of those in series will be more cost effective than anything when usable capacity and partial charge performance is included in the equation.

[a64pilot]

Originally Posted by s/v Jedi

They are, but not every gel battery has the deep cycle performance and lifespan of the series I linked

If you think of moving the bank to where 3x L16 fit, then look at the 4V L16 Firefly’s. I think three of those in series will be more cost effective than anything when usable capacity and partial charge performance is included in the equation.

$780 ea, three needed for 450 AH @ 12V so $2340 for 450 AH, or $5.20 an AH.

[sailorboy1]

I read an article that given FLA, AGM, Gel that Gel was the only one that DIDN’T have an advantage over the other 2.

I am a fan of the T105 type. They are tough, cheap, low usage cost wise, easy to find/replace, minimal maintenance really.

But personally i cant see the OP ever going over to them from his current agm setup.

[s/v Jedi]

Originally Posted by a64pilot

$780 ea, three needed for 450 AH @ 12V so $2340 for 450 AH, or $5.20 an AH.

Yes but I think they will have a considerable longer lifespan than the group 31 Firefly’s, plus you don’t have any cells in parallel which is so much better from an engineering standpoint.
If this is three times the cost of Trojan L16’s, then I would still go for it. And I have used Trojan L16’s happily for many years. I bought 6 of those in 2004 and again in 2011. In 2018 I replaced them with 4x Lifeline L16’s because I could not get the Firefly L16’s which had just been announced (would have bought 6x the 2V ones). I notice that I have less capacity now but not that much difference with AGM not dropping voltage that much.

I will replace with LiFePO4 next time, even though it costs more.

[RickG]

Originally Posted by a64pilot

Lithium is still in my opinion a science experiment.
I’d be more likely to go that way, if I wasn’t spending most of our cruising time where even a light bulb just isn’t available.

A light bulb might be easier to find than distilled water. In the US Virgin Islands the few pharmacies that sell it are usually out of it.

We had 450ah of GC2s and were quite happy with them on the dock. Off the dock, they rarely got to full charge with 660 watts of solar. We had no generator. When we left the marina two years ago to cruise I installed 7 116ah Firefly Group 31s. They were a life changer. I was able to increase the bank size by putting batteries under our aft bunk and we can go three days without good solar. Our energy budget is about 200ah per day and we are usually 120ah to 200ah down in the morning.

You say you have easy access to the batteries? We added distilled water every month. This is a pretty easy decision with your generator, FLA is good enough. Keep 5 gallons of distilled water on the boat in good thick jugs. When their capacity diminishes to where it's a hassle, replace then.

I expect our next set of batteries will be LiFePo4s in 15 years.

Cheers, RickG

[sailorboy1]

Originally Posted by RickG

A light bulb might be easier to find than distilled water. In the US Virgin Islands the few pharmacies that sell it are usually out of it.

It is easy to make pure water for battery use. For $27 i got an ion-exchanger filter off Amazon that you just run your tap water through and it makes it pure water.

[a64pilot]

Originally Posted by sailorboy1

It is easy to make pure water for battery use. For $27 i got an ion-exchanger filter off Amazon that you just run your tap water through and it makes it pure water.

Used to do that in My Father’s Dental office as a boy for mixing the chemicals to develop the X-rays.
It’s not distilled, but de-ionized, which I guess is just as good?

[ranger58sb]

Originally Posted by a64pilot

$780 ea, three needed for 450 AH @ 12V so $2340 for 450 AH, or $5.20 an AH.

That's a calculation of initial cost/Ah, yes? Without yet having factored in various predicted cycles over lifetime, at various DoD?

I'd guess that analysis would need lots of speculation, or at least analysis of potential ranges... but it wouldn't surprise me if Battery X at high initial cost might be less expensive over a lifetime than Battery U at lower initial cost...

OTOH, I assume none of that is new thought...

-Chris

[Compass790]

The ion exchange filter sounds like a good idea, we use the water out of a dehumidifier.
Maybe if you have a/c you can collect it's drain water. Don't know how close to distilled it is but I imagine it's better than tap water if you go to places you can't get distilled.
If watering the battery is a concern maybe water miser battery caps will help. I dunno, haven't used them.
When I was a schoolboy I pumped petrol/gas after school & the garage owner had a bottle that was marked with distilled water for customers who requested that for their batteries.
Guess where he filled it from?

[NYSail]

You could have gotten the same battery from sams club under Duracell name for much cheaper.