AGM or Wet Cell

[Maine Sail]

Originally Posted by a64pilot

I have 1KW Solar charging a 660 Ah bank of AGMs and cannot get to 100% SOC in south Fl in summer, so for sure the rest of the year it's not going to be possible as there are less Solar hours.

We need to remember that in hot climates the panels can't produce as much, and any MPPT boost may be minimized.

That said I have done a lot of solar bulk charge data logging, usually in 7 day periods, and I come up with about 0.224Ah per watt, per day for real world flat oriented situations (keep in mind this is no shade but panels are flat mounted here in Maine with temps from 50F to 95F).

So a 1000W array, with zero shading from the boat, could be capable, on average, of somewhere around 224Ah +/- per day.. Some days it will be quite a bit more, some days less, but it will generally average out close to this unless your skies are always clear..

Some math:

• 600Ah bank (assumption only it's likely smaller)
• *Charge Rate - Rounded to Approx 40A or .07C (AGM's can easily take .3C to .4C and this is actually good for them)
• Ah Consumption @ 50% SOC = -300Ah
• Average hours to recharge at 100% Efficiency = 7.5 Hours (not enough solar hours to produce 40A continuously for 7.5 hours)
• Average hours to recharge at 85% Efficiency = 8.6 Hours (not enough solar hours to produce 40A continuously for 8.6 hours)
• Hours to recharge if you drop to float too early = Fagedaboutit
• Average hours to recharge with shading = Impossible to predict but a lot less than no shade

*None of this includes for daily sun-up hour DC consumption. Your on-board consumption can chop your 40A by quite a bit.. If you use say 15A on average your time to 100% from 50% at 100% efficiency just went from 7.5 hours to 12 hours, and this is with zero shading.....


Rx - Use the genset early in the day for bulk, lengthen solar absorption duration, and you should be able to get to 97-100% SOC in all but the worst conditions. If you don't run the genny daily, and actually drop to 50% daily, you are going to be experiencing some PSOC walk down....

[john61ct]

Rod does really make the **best** soup!

The large consumption active while charging is a huge factor, in this case going over 100A may well be worthwhile.

And even more of a case for Firefly or LFP.

[sailorboy1]

Funny that in 6 years of real life usage (5 in the north) that I know my 290W panel will do 90-100AH on a sunny day (sometimes even 120AH).

But I feel the AH/watt number is meaningless by itself. If I were to start the day with my batteries at 95% SOC on a sunny day then my same 290W will do 22AH if nothing is running.

[foggysail]

MainSail's analysis continues to make me regret not purchasing an 85A controller rather than the 70A that I did purchase. But all in all, so far with very limited use time, I have only seen 69 amperes with my 1180 watt (4 X 295) flat mounted panels. If I consider 13v+ while being charged at 70 amperes my input wattage drops to just over 900 watts. Could be with clouds and sun angle though, I might not ever see higher outputs regardless of the controller.

The next time I go out and my batteries enter float, I am going to measure their SOC

[foggysail]

Originally Posted by Maine Sail

Rx - Use the genset early in the day for bulk, lengthen solar absorption duration, and you should be able to get to 97-100% SOC in all but the worst conditions. If you don't run the genny daily, and actually drop to 50% daily, you are going to be experiencing some PSOC walk down....

OK with genny but greater emphasis must be placed on the charger. Most of the boats I have been on including my own (Xantrex 5012) have over rated, inadequate, sub-quality chargers.

[softdown]

FLA wet cells give you whole lot more bang for the buck. GC2's (golf cart batteries) are very effective solar batteries at low cost. Perfect to learn with.

Maintaining wet cell batteries just isn't as hard as people make it out to be. Check the water levels once/month. I think a lot of people keep too much water in their batteries....thus the batteries are constantly boiling over. Add the water, if needed, when the batteries are fully charged.

I use both. The AGMs are convenient for me but I would not buy them without a few years of experience first. I would not have bought them without a great price either.

It isn't just the convenience that is nice. They do not outgas vapors that often produce corrosion on the terminal area. If I had to keep batteries under the bed, AGM would be more attractive.

Changing the subject here: Has anybody found a reliable way to get the best price for old lead? I'm in Colorado if that becomes pertinent.

[Maine Sail]

Originally Posted by foggysail

OK with genny but greater emphasis must be placed on the charger. Most of the boats I have been on including my own (Xantrex 5012) have over rated, inadequate, sub-quality chargers.

Absolutely, it goes without saying.... A 50A charger is ok for shore charging a medium cruising bank but with a genny you really want to be able to feed that current and get as much back into the bank in short order as you can. There is no sense in lightly loading a generator so the charger is quite important, same with engine alts.

With genset charging an inverter charger of 100-120A or larger is usually a good bare minimum to aim for, on a 32+ foot cruising boat. A charge rate of .2C would be about my minimum goal for genset charging. As the boat and bank get larger you'll often have two+ chargers for genny bulk...

In June we were anchored behind a guy who's boat I had worked on last year. He got 1.5 seasons out of his last AGM bank (about 30-35 actual deep cycles) before they were beaten into submission due to chronic undercharging and PSOC use. His factory alternator was only capable of about 25-30A max when hot, his boat was on a mooring and he refused to add solar because "It looks cheesy"...

When his Hitachi alt gets hot, his voltage is about 13.7V or basically float. You can't charge 400Ah of AGM's, with a float voltage, and keep them healthy..

Long and short he ran the engine up-wind of us, for well over an hour, while we sucked on diesel fumes.. What made it that much worse was that I knew it was doing SQUAT for his bank............ This hour of run time, in-reality, needed to be multiplied by about 6-10+ hours to even get close to doing anything..

After the battery replacement, and a bit of tweaking, there were plenty of written instructions & a quote/estimate including multiple cost based scenarios, on how to proceed, if he wanted optimal life from his bank, which he said he did. He was rather voraciously complaining about the cost of AGM's so I gave him multiple different things to choose from, he still chose AGM's... I tried to talk him into less expensive FLA's, T1275's would have fit nicely and cost a lot less per Ah, and was brutally honest that his new bank would suffer the same fate.

He's still not addressed his charging system and I am pretty certain I will be getting a call any day now saying "These new AGM's suck".... You can lead a horse to water........

As I generally repeat over and over, a battery bank for a cruising boat is a "system" it needs to work together in concert and be designed as a system...

[daletournier]

Originally Posted by sailorboy1

Well then you have something wrong and people definitely should not follow your advise!!!!!!!!

Abit harsh! Personally I trust a64's understanding, one of the more informed.

[a64pilot]

Originally Posted by ranger42c

So you are currently running the genset in the mornings, 2x/week, now? And then solar the rest of the day?

And you're not reaching 100% SOC? Is that not reaching 100% SOC on all days, or just non-genset days?

What's the impediment to running the genset more days per week? Or even daily?

-Chris

OK, I have 185 amps charge on generator with two chargers, it's about all the little 3.5 KW gen can run so I can't go bigger. But it doesn't stay in bulk for long, usually only 10 or 15 minutes as the banks SOC according the the Smart Gauge is in the 80's sometimes 70's if it's been a couple of days usually.
Yes if I do the generator run early then I will get to an honest full charge by late in the day as long as I don't get excessive with power consumption.

I don't like running the thing, if I am in an anchorage, people around me don't like hearing it, and most don't believe ai need it and think, well he ought to run that thing around lunch as they don't understand batteries and charging, after all they get by by running their motor once a day, right, or pure Solar and don't realize they are shortening the life of their bank.

I do it, or more accurately plan on doing it twice a week as a compromise between not running the thing and killing my bank early.
I say plan because so far I have never sat very long in one place and honestly motor a lot, and of course motoring with the Balmar 614 with a 125 amp alt charges the bank just as well as the generator. Also I don't want to run the thing daily if I can help it because there are only so many hours in the thing and daily runs of course will shorten its life and we are now full time. I am trying to get away from Diesel as much as I can, without sacrificing the luxuries that go along with it too much.

If so crank the motor I like to run it an hour to get it completely warmed up and I put it under a load, use it to move the boat, usually move to a pump out facility etc. once a week anyway.


If the bank is down enough so that it will always accept whatever the array can make I will get 300 or so AH out of it, I'm glad to see Maine Sails numbers as I thought I had issue with it, cause I expected to see close to 80 amps at full sun, but have never seen even close to that, I don't think I have hit 50 truth be told.

I was an aircraft manufacturer, and through Lifelines aircraft battery group called Concorde I was sent to talk to Justin Goodbar I think his name was, and discussing things with him came to the twice a week generator run to get to full charge and once a month equalization to get a decent life out of my bank, he told me to expect five years.
Now understand that is five years to be "legally dead" I feel many, many people are cruising around with banks that meet that description just have slowly adapted to the declining capacity, but don't do anything about it until one of more batteries actually get a short and are stone dead.

[SV.Maverick]

Rod I just looked at your site on how to articles looks very interesting as in the next 6 mos I'm going to have to install both a battery bank of some kind and solar of some kind.

[a64pilot]

Originally Posted by daletournier

Abit harsh! Personally I trust a64's understanding, one of the more informed.

No, don't listen to me, listen instead to Maine Sail that does this for a living and has the equipment to actually conduct scientific testing, and since he makes a living at it, he sees real world examples too, not just lab tests.
I'm just a hack trying to get a good understanding about how and why, that's all.
According to my contact at a Lifeline apparently years ago a very well respected Marine electrician was teaching to charge your bank when it got to 50% and stop when it got to 85% or so as that maximizes charging efficiency and if your charge source is you boats motor, it reduces engine run time to as little as possible.
However it also will kill a Lifeline AGM in short order, and that of course does nothing good for their reputation, like Maine Sails example of his customer that will call complaining about those bad AGM batteries that he is going to kill.
If the firefly becomes more available and if it really does after a few years actually hold up to its claim, it will be a game changer for sure.
Surely there will be other copy cat batteries and hopefully competition will drive the price down, I hope.

[a64pilot]

Originally Posted by fSymo

What kind of charge controllers are y'all using?

I am using one Outback 80, panels wired in parallel going to a fused combined box and stupid big cable from there , 2 Ga.
I see the logic with multiple controllers, but I wanted the programmability etc the Outback 80 offer and it's remote control etc. and simple wiring with one controller.

Don't buy into the charge efficiency and greater charge rate etc of an AGM bank if your charging with Solar. Yes my bank can accept initially something insane like over a couple of hundred amps of charge initially, but can you imaging the size of the Soar array or produce that? Unlikely and if you have that big of an array, likely you have a monster battery bank too, so there goes the huge charge rate.
It's good to kick them hard with a generator though first thing in the morning, you can put an enormous amount of amps in an short time, but very soon the charge rate tapers off of course, then you go to Solar to finish it off.

[daletournier]

Originally Posted by a64pilot

No, don't listen to me, listen instead to Maine Sail and others.
According to my contact at a Lifeline apparently years ago a very well respected Marine electrician was teaching to charge your bank when it got to 50% and stop when it got to 85% or so as that maximizes charging efficiency and if your charge source is you boats motor, it reduces engine run time to as like as possible.
However it also will kill a Lifeline AGM in short order, and that of course does nothing good for their reputation, like Maine Sails example of his customer that will call complaining about those bad AGM batteries that he is going to kill.
If the firefly becomes more available and if it really does after a few years actually hold up to its claim, it will be a game changer for sure.
Surely there will be other copy cat batteries and hopefully competition will drive the price down, I hope.

A64, your advice is the same as mainsails, whether your repeating it or not and I'm in complete agreement.

I think the problem here is what some think is 100% just isnt.

I have 480w solar and what I consider fairly average power usage. Although my amp counter may hit full most days I know they aren't 100%. I monitor voltage each morning and acceptance rates but not obsessively. Two or three times a week I start the genny early on to give them abit of a kick but mostly I accept they dont get to 100% and live with it. How high do I get soc? Not sure really, would just be guessing, pretty hard to tell, but higher enough real world speaking.

I doubt that many fulltime liveaboards (not including lithium users) get to 100% including sailorboy, they just think they do. This is the real world not a battery testing lab.

Im fairly confident my system dosent have a problem.

I also agree with you regarding conservative charger setting, both in solar regs and mains chargers (not all).

[ranger58sb]

Originally Posted by a64pilot

OK, I have 185 amps charge on generator with two chargers, it's about all the little 3.5 KW gen can run so I can't go bigger. But it doesn't stay in bulk for long, usually only 10 or 15 minutes as the banks SOC according the the Smart Gauge is in the 80's sometimes 70's if it's been a couple of days usually.

I've noticed I can sometimes make our chargers active again by turning them off for a few minutes, and then back on. The older charger is limited to a maximum 4-hour absorption phase, so that seems to be more useful after long periods of onshore charging. I guess the newer inverter/charger figures out absorption time all by itself; at least there's not user-configurable setting... Anyway, the results are that I can seem to get more amps into the batteries that way. It might be similar to the idea of X minutes of genset/charger in the morning, followed by Y more minutes of genset/charger later in the morning.

?


Yes if I do the generator run early then I will get to an honest full charge by late in the day as long as I don't get excessive with power consumption.

I don't like running the thing, if I am in an anchorage, people around me don't like hearing it, and most don't believe ai need it and think, well he ought to run that thing around lunch as they don't understand batteries and charging, after all they get by by running their motor once a day, right, or pure Solar and don't realize they are shortening the life of their bank.

Are you in tight anchorages? Is your genset extra loud? Can you hear your genset when you're more than about 20-30 yards from your boat? IOW, are you sure somebody else might be noticing?

I do it, or more accurately plan on doing it twice a week as a compromise between not running the thing and killing my bank early.

Also I don't want to run the thing daily if I can help it because there are only so many hours in the thing and daily runs of course will shorten its life and we are now full time.

The genset won't last something like 10K+ hours? One of our owners just passed the 11K hours mark on his...

I am trying to get away from Diesel as much as I can, without sacrificing the luxuries that go along with it too much.

Fair enough. But what does it use, maybe 1/3-gal per hour?

I was an aircraft manufacturer, and through Lifelines aircraft battery group called Concorde I was sent to talk to Justin Goodbar I think his name was, and discussing things with him came to the twice a week generator run to get to full charge and once a month equalization to get a decent life out of my bank, he told me to expect five years.

Do you not think you could extend that to 7-8 years if you recharged to 100% (as near as you can get) on an almost daily basis? Woulld 7-8 years be an improvement worth shooting for?

Comments inserted...

FWIW, I'm paying special attention since we just installed a 440-Ah bank of Lifeline GPL-4CTs... and we have no solar. OTOH, we're usually at a marina, usually only anchor out for 2-3 weeks at a time (at most), and even then because we have electric cooking our genset is on for a couple hours in the morning and again in the evening almost every anchored day... so our charging regime is likely more favorable than yours...

-Chris

[john61ct]

Yes, along with the high amps, programmability for the charge algorithm is critical.

Any dino juice power source should ** never be driving a lowered voltage, just a massive waste of fuel and engine wear.

Shore charger should have just as much programmability as a good solar controller.