Equalization

[a64pilot]

We are sort of making the same argument, but I don't think I'm being very clear.

I've not looked at that thread and don't think I want to, some people like to get wrapped around semantics, I'm not one of those people, but do understand how if you don't say things correctly, you can change the meaning.

But what I'm saying is this really, I have three charge sources

60 amp shore power charger a Pro Charge Ultra and an on board gen to run it.
a 140 amp alternator with three stage regulator
750 W of Solar panels, with possibility of adding more if needed.

It appears my at anchor usage is 55 AH, but I like a margin so say 100, that's a nice round number anyway.
My panels should be able to supply about 200 AH on an average day in the Caribbean.

At first I didn't think my panels would fully recharge my batteries, my plan was to run the generator twice weekly to make water, wash clothes whatever I wanted to do for a few hours early in the morning to get at least thru the high current charge portion and then let the panels finish them off, that would get me to full charge twice weekly, but now it's looking like the panels may be able to do the job by themselves.

I'll know eventually, it's all theory at this point.

But to get back on topic, my belief is that partial SOC cycling an AGM battery is even worse for an AGM than a regular FLA, and when you factor in the higher price point of an AGM over an FLA, it seems that an AGM may not be a good choice for most cruisers.

[Sternwake]

With the Lifelines, Northstar and Odysseys, I feel that the higher amps that can be mustered when they are most depleted, the happier the battery will be.

When I charge my group27 Northstar(90AH) on 200 watts of Solar alone day after day from 50% SOC, on the fifth day the voltage held under load is much worse than on Day one, even if amps had tapered to 0.42 at 14.46v each day by the end of the day on Solar alone.

A 40+ amp recharge the next morning restores performance, and If I am running the engine, and the alternator makes 55+ amps, it appears to love this higher charge rate even more as it holds even higher voltages that night under discharge..

Solar is great for topping off and reducing depth of discharge, but solar only recharging and AGM batteries that are actually cycled deeply to the 50% range, is not a good combination in my opinion, and experience.

I've not tried anything close to an Equalization charge cycle on my Northstar AGM, but I have forgotten to turn down the voltage from 14.46v over night and my monitor said the battery was accepting 0.0amps at 14.46 the next morning.

Obviously some amperage was required to hold it at 14.46v, but was not within the resolution of my monitor.

I have close to 200 Deep cycles on this 90AH Northstar over 23 months, and when I take 45AH from it it still reads over 12.23v under a 1.1 amp load before sunrise.

So by no means a true capacity test, It still seems to have most all of its original capacity, and perhaps more than the rated capacity, and my discharge rate often exceeds the 20 hour rate. I find it to be an impressive battery, but It also gets high amp recharged regularly from its most depleted state, and fully charged each time it is discharged. I avoid the partial state of charge cycling of it and it appears to be very happy.

If it did not lose performance when low and slow solar only recharged I would marry it, but it needs a high charge rate every so often or it becomes petulant, and I cannot handle petulant.

[Maine Sail]

Originally Posted by Sternwake

With the Lifelines, Northstar and Odysseys, I feel that the higher amps that can be mustered when they are most depleted, the happier the battery will be.

When I charge my group27 Northstar(90AH) on 200 watts of Solar alone day after day from 50% SOC, on the fifth day the voltage held under load is much worse than on Day one, even if amps had tapered to 0.42 at 14.46v each day by the end of the day on Solar alone.

A 40+ amp recharge the next morning restores performance, and If I am running the engine, and the alternator makes 55+ amps, it appears to love this higher charge rate even more as it holds even higher voltages that night under discharge..

Solar is great for topping off and reducing depth of discharge, but solar only recharging and AGM batteries that are actually cycled deeply to the 50% range, is not a good combination in my opinion, and experience.

I've not tried anything close to an Equalization charge cycle on my Northstar AGM, but I have forgotten to turn down the voltage from 14.46v over night and my monitor said the battery was accepting 0.0amps at 14.46 the next morning.

Obviously some amperage was required to hold it at 14.46v, but was not within the resolution of my monitor.

I have close to 200 Deep cycles on this 90AH Northstar over 23 months, and when I take 45AH from it it still reads over 12.23v under a 1.1 amp load before sunrise.

So by no means a true capacity test, It still seems to have most all of its original capacity, and perhaps more than the rated capacity, and my discharge rate often exceeds the 20 hour rate. I find it to be an impressive battery, but It also gets high amp recharged regularly from its most depleted state, and fully charged each time it is discharged. I avoid the partial state of charge cycling of it and it appears to be very happy.

If it did not lose performance when low and slow solar only recharged I would marry it, but it needs a high charge rate every so often or it becomes petulant, and I cannot handle petulant.

AGM batteries do benefit from higher current charging and it is yet another piece of the puzzle that helps net the longest life. Odyssey wants to see a minimum charge rate of .4C or 40A for a 100Ah battery...

Northstar's also benefit, in a PSOC environment, from higher temp compensated absorption voltage. 14.6V to 14.7V will yield less cycling sulfation..

[sailinglegend]

Originally Posted by a64pilot

....We are sort of making the same argument, but I don't think I'm being very clear.....

My point and Maine Sail's extensive comments on the article I linked to is that the Charge efficiency is very non-linear and does adversely effect any charging source during the last 10% SOC. We are not talking semantics, but a very important research document that is specially targeted at PV charging. This is also backed up by many other sources and as far as I know this has not been discussed in such length before on this Forum.

Originally Posted by a64pilot

....But to get back on topic, my belief is that partial SOC cycling an AGM battery is even worse for an AGM than a regular FLA......

Justin at Lifeline would disagree with you.

[a64pilot]

Just there are some glaring discrepancies, while I know and understand you don't get to move energy around without losses, there is no free lunch, I do not believe I have to return 300 amps to a battery that I withdrew 100 amps from, that's 300%. The Lifeline manual states "typically between 102% and 110% have to be returned, page 19 under section 5.4 charging. I'd cut and paste, but seemingly can't?
www.lifelinebatteries.com/manual.pdf

Now, time to reach a full charge, they have a formula for that on the same page, and assuming a large enough charger, you can go from 50% SOC to 100% in as little as 4 hours.

Now I know that these numbers are probably a little skewed, probably using new or at least nearly perfect batteries in lab conditions that are un-achievable in a boat, but 102% to 110% compared to 300% is a very large spread, something's wrong, they both can't be even close to correct.

Just as the four hour quote for a battery at 50% SOC to be fully recharged in four hours is certainly not achievable in a boat, but I don't see why if I have enough Solar I can't go from 85% to 100% in a full day? Having enough excess Solar is the key here, it doesn't matter where the electrons come from, ones you get from burning old dead Dinosaurs are the same as the ones you get from a PV array.

Now I had to go back and look at emails, but Justin wan't the one I was conversing with, it was David, whatever that's worth. I honestly don't what either's position in the company is.
I was sent to him from aviation contacts from the Concorde aircraft battery, which I believe may be the same company. Anyway they sent me to David for me to get some batteries for my boat, he and I conversed several times on the phone etc., and again without dropping names he didn't like that a very well known marine electrical Engineer seemed to have people trying to work their batteries between 50% and 85% SOC, and he stressed to me that his batteries were great batteries just like the Concorde's, but partial SOC cycling would kill them sooner than anything else would.
The implication was that was their weakness and that if I wanted a good long life out of them, ensuring they were fully recharged every cycle was they way to do it. I went to him saying my plan was to fully recharge them at least once a week using a generator, I came away with the idea that I needed to find a way to fully recharge them every cycle.

[transmitterdan]

A64,

The charging efficiency depends a lot on where the battery spends most of its life in terms of state of charge. If you think a small bank is best and you therefore cycle your batteries between 20% and 80% then the charge power will be in the 102-110% that of the discharge. But if you don't like the lifetime reduction this regime will produce you might want a huge bank. So if you build a bank that only discharges to 80% and always top up to 100% then the 300% spread is realistic. So it all depends on what charge/discharge region you plan to use.

[Maine Sail]

Originally Posted by a64pilot

Just there are some glaring discrepancies, while I know and understand you don't get to move energy around without losses, there is no free lunch, I do not believe I have to return 300 amps to a battery that I withdrew 100 amps from, that's 300%. The Lifeline manual states "typically between 102% and 110% have to be returned, page 19 under section 5.4 charging. I'd cut and paste, but seemingly can't?
www.lifelinebatteries.com/manual.pdf

You won't need to overcharge by 300% but above 90% you are operating in the least efficient range.

Originally Posted by a64pilot

Now, time to reach a full charge, they have a formula for that on the same page, and assuming a large enough charger, you can go from 50% SOC to 100% in as little as 4 hours.

With my test equipment, even with brand new batteries, just barely broken in, I have yet to be able to achieve Lifeline's defined 100% SOC (0.5% Acceptance at 14.4V) in 4 hours (eg; I have not been able to cycle to 50% DOD then recharge for 4 hours and pull back out the energy I put in without going beyond 50% DOD, which means I am not getting to 100% in 4 hours). I can easily get to the high 90's which most will cruisers will consider "full enough" but not to 0.5% @ 14.4V in 4 hours which Lifeline defines as 100% SOC (some others use 0.3% at absorption voltage as 100% SOC).

I suppose there is an ideal "C" rate where I could achieve this but I have not found it yet. The new and broken in batteries I have tested are all in the 5+ hour range and slightly used batteries wind up closer to 7 hours+..

Originally Posted by a64pilot

Now I know that these numbers are probably a little skewed, probably using new or at least nearly perfect batteries in lab conditions that are un-achievable in a boat, but 102% to 110% compared to 300% is a very large spread, something's wrong, they both can't be even close to correct.

I don't know where the 300% number came from but unless your batteries are totally squashed you won't need to return 300% of what you took out. You can likely get there as the batteries age but you won't start there...

If continually cycling in the upper reaches of SOC your charge efficiencies will be a lot lower than the "overall" in the tech manual. Remember bulk is near 98% efficient, and this is used in an "overall lab efficiency" of 110%. Course you will be starting in absorption so you can't really use 102-110%....

Without the actual specifications as to what "full" was defined as for the 102-110%, or the "C" rates, it is really tough to say other than this is an "overall" efficiency number including the very, very efficient bulk stage and most likely from 0% SOC to 100% SOC, or close to it.. During testing I found that at .46C I needed more than 110% to achieve 100% SOC because the batteries hit absorption a bit earlier.

As the batteries sulfate the time to 100% SOC will increase. New batteries can't be directly compared to used batteries for obvious reasons but all manufactures use lab conditions on new or broken in batteries. Not that this is bad, but it is not what we will see in the real world, for very long..

Originally Posted by a64pilot

Just as the four hour quote for a battery at 50% SOC to be fully recharged in four hours is certainly not achievable in a boat, but I don't see why if I have enough Solar I can't go from 85% to 100% in a full day? Having enough excess Solar is the key here, it doesn't matter where the electrons come from, ones you get from burning old dead Dinosaurs are the same as the ones you get from a PV array.

If you have the current this can be done but as batteries age it may take more hours to get to full than you have sun for. Now you start PSOC cycling... The best you can do is get them as full as you can every day and achieve a good healthy absorption cycle..

Originally Posted by a64pilot

Now I had to go back and look at emails, but Justin wan't the one I was conversing with, it was David, whatever that's worth. I honestly don't what either's position in the company is.

I believe David is Justin's brother but there is also Dave V. who is their chief engineer. They are all great guys!

Originally Posted by a64pilot

I was sent to him from aviation contacts from the Concorde aircraft battery, which I believe may be the same company. Anyway they sent me to David for me to get some batteries for my boat, he and I conversed several times on the phone etc., and again without dropping names he didn't like that a very well known marine electrical Engineer seemed to have people trying to work their batteries between 50% and 85% SOC, and he stressed to me that his batteries were great batteries just like the Concorde's, but partial SOC cycling would kill them sooner than anything else would.

And here is where the confusion stems from. That is not necessarily what the "marine engineer" wants to see people do it is a reality of charging with fossil fuels.

Most sailboat boat owners do not have the space or ability to fit alternative energy that can accommodate getting to "full" each day, especially as batteries age.. If you do the batteries can last a very long time..

While fitting enough alt energy can be done, it rarely is. The point of the "marine engineer" is that using engines or generators to charge much beyond the transition from bulk to early absorption is wasteful and horribly inefficient.

On the other hand David is 100% correct in that cycling these batteries from 50% to 85% continually will destroy them in short order. Which I why I have been urging folks to install AGM batteries as a "system" so they can actually realize the investment they paid for. Getting to 100% as often as is humanly possible will result in the longest life.

Originally Posted by a64pilot

The implication was that was their weakness and that if I wanted a good long life out of them, ensuring they were fully recharged every cycle was they way to do it. I went to him saying my plan was to fully recharge them at least once a week using a generator, I came away with the idea that I needed to find a way to fully recharge them every cycle.

Yep... This however is a weakness of all lead acid batteries though some deal better with it than others. Flooded deep cycles batteries charged at 14.7V to 14.8V, and equalized, tend to last a good long time even when cycled to 50% to 85% quite regularly. Try that with some AGM batteries, that can't be equalized and you get a big hole in your pocket pretty quickly..

Some AGM's than can't be equalized can lose as much as 1% per deep cycle when used in a PSOC environment. AGM's DO vary in quality so you can "get what you pay for". In my experience Lifeline, Odyssey, Northstar and Firefly are the top premium AGM's out there. On the Chinese AGM front Full River batteries seem to do okay, but I really don't see enough of them to make a qualified statement like I can with the others where I have a lot more experience......

I think you will do fine with your Lifeline's, better than most, but as they age and you find you can't get to 0.5% to 0.75% @ 14.4V each day then you may need to consider fossil fuel to finish them off or just run them till you feel you got your money's worth.

The issue with solar is not always how much energy you have but how much time there is in a day before it turns off. The batteries determine the time to 100% once in absorption..

[a64pilot]

Maine Sail,
Got it, I may end up running the genny more than I want I guess, and may get another 60 amp charger as the bank could handle it. I can't explain how it seems I can get them charged quicker than seven hours though, maybe it because they are new. They did go through a break in phase, they did gain capacity as they accumulated a few cycles. I didn't expect that.
I assume I can continue to rely on the Smart gauge to give me an accurate SOC early in the morning, just before the charge cycle begins?

My batteries are new, and as I only have the Smart gauge and not an amp counter, I ran my average nightly anchor load all night, and pulled 12% out of the 440 AH bank.
at exactly 0800 I turned on my charger, by a little after 0900 it was in float, I cycled the CB which put it back in Absorption, and by 1000 it was back in float and indicating about 6 amps or so. (My fridge pulls just under 5) Smart Gauge read 99%, it does that it will take a really long time to get to 100%, I assume that an honest 100% SOC is nearly impossible without 24 hr charger power, but that maybe 98% SOC is acceptable to be consider fully charged?
I know the closer to full you get, the harder it is to get there, acceptance rate goes to nearly nothing, and the last few percent take longer than say the first 20% did.

But I've also noticed something that I cannot explain.
I have two banks, one 220 AH, one 440 AH, both identical batteries, identical age etc.
If I pull 50 AH out of the 220 bank it takes longer to recharge it than if I pull 50 AH out of the 440 AH bank. That is opposite of what I would have thought, why is that?

I've even considered combining them into one 660 AH bank with the combiner switch, I don't worry about killing my start bank.

[zboss]

Originally Posted by a64pilot

Assuming your charger has an equal or higher capacity than the batteries can accept, then yes it is true.

So, when we are sitting at anchor somewhere in the Bahamas using our 30 amp max output solar, expensive AGM batteries have no advantage over cheaper flooded lead acid batteries.




Sent from somewhere other than where I want to be!

[a64pilot]

I wouldn't say no advantage, I mean you don't have to add water for example, they can't spill acid and I don't why you would want to, but I guess you could mount them on their side?
I said that at least to me it seemed that AGM is not a good choice for an average cruiser, because it seems to me that you need a lot more "infrastructure" to realize the advantages, and most don't have that infrastructure, and if money is a concern, then AGM's do seem to cost more.
Silly analogy, but you won't get race car performance out of your family sedan by putting racing tires on it, there is a lot of other "stuff" that makes those tires work.

Now my battery box is rather shallow, sort of forced me into AGM's, if I could have put in Golf Cart batteries, I would have as it sure seems that they have the highest value as defined by AH per $ and expected life.
I could have moved the bank or built a deeper box, but I'm in the middle of a re-fit or whatever you want to call it, but I have plenty to keep me busy, so I spent the $ on AGM and saved the time that moving of building a box would have cost.

[transmitterdan]

Originally Posted by zboss

So, when we are sitting at anchor somewhere in the Bahamas using our 30 amp max output solar, expensive AGM batteries have no advantage over cheaper flooded lead acid batteries.

I would not say there is "no advantage". AGM batteries don't require maintenance other than periodic checks of the terminals. They don't off-gas unless seriously abused. They can be safely located in places that flooded batteries should not be. And if your solar panels can often charge the batteries to 100% then they should last longer than flooded cells.

Plus if you have high current charging source(s) other than solar then they offer a big advantage in bulk charge time.

I think the point about solar is that in the last 10% of charging a huge solar array doesn't buy you much because the battery acceptance rate will be the limiting factor whether you have AGM or flooded.

[malbert73]

As far as location goes- my house bank is under aft part of vberth. Boat came with agms. Kids sleep in vberth. I always figured I would need to keep batteries that don't have a chance of gassing (agm) given their location. Opinions? I.e. Does anyone have FLA batteries under their v berth in use?


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[a64pilot]

I have never heard of any problems with Hydrogen accumulation and a hydrogen explosion,
But they are your kids, and with my kids I wouldn't take the chance no matter how minuscule it was, now I'd sleep on them any day

[malbert73]

Kind of what I thought. Won't take any chance with kids. Just wasn't sure what the chance was I would be taking


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[a64pilot]

That's just my opinion, don't take it as an informed one, just with kids, the risk I'll accept for them is considerably lower.