Switch from AGM to Lith-ion

[carstenb]

Ok, I'm not an electrical guru so everyone please keep your answers at the level of talking to a 10 year child (maybe I'll understand).

Our 600AH AGM house bank is on its final legs and i want to go with LITH-ion. I've stay clear of these before because I was always told you needed to be an outright expert to install one.

But here in the Marquesas, I meet 4 boats that have all told med the same thing. Buy the batteries (winston), make sure they are charged correctly, hook them up in series (4x3V=12V) then in parallel and don't worry about them.
My Sterling regulator has a setting for Lith-ion. I have a 160AH alternator on the boat.
Our normal needs for charging are met by our 700W solar array.

OK - so is what I've been told correct? all four of these guys were EE's so they should know what they are talking about.

Do I need a special charger to charge the cells the first time? If I use shore power through my Sterling charger - is that good enough?

thanks carsten

[a64pilot]

Oh GOD, here it comes

[TassieBloke]

Carsten,

Dude, for love of God read the mammoth thread on LFP batteries. That way we'll be saved from the usual suspects hijacking your thread 🤯 [emoji846] and reading all the same stuff again lol

[Reefmagnet]

To save you the search, here's the link everyone usually recommends: https://marinehowto.com/lifepo4-batteries-on-boats/


And people will deride you for referring to "lith-ion" or even "lithium ion". They're "lithium iron phosphate", "LiFePo4" or just "LFP". These have different properties compared to what is commonly known as "lithium ion" batteries.


BTW, from the above link, Mainesail isn't too keen on the Sterling ProCharge Lithium algorithm.

[a64pilot]

I looked into it myself as the benefits seem amazing.
The more I learned it seemed the less I knew, and the more “stuff” that I had to have or I would kill the bank, and obsessing is taken to a lifestyle apparently. I decided that they are a “Science Experiment”
I eventually decided I wasn’t smart enough, rich enough, or as dedicated as I needed to be for an LFP bank, and gave up.
I believe when my AGM bank dies, I’m going to look real hard at Gel myself.

[witzgall]

Do not assume that because a charging source has a "Lithium" setting, that it is correct, or safe, for the batteries or cells you wish to use. Our MC-614 regulator has a lithium setting, but I think most users tweak it for the actual setup they have. I have a Sterling battery charger, and the Lithium setting has voltages that are way too high for my liking. The ability to change the voltages, etc to your needs in any charging source is very important when dealing with LFP (Or any lithium chem.)

Chris

[a64pilot]

You know even the AGM settings in my chargers are incorrect, they are close, but with it being so easy to program exact, why not?

I don’t think they should have settings, yes I know that is a marketing feature, I think they should be fully programmable, and that’s it.

My take on LFP, is you May not be an electrical guru, but you will be before it’s over, or you’ll be poor.
This from no experience, just reading. It way more complex than I’m willing to be.
So my AGM only lasts five years, or GEL ten, I can get over that.
Actually my AGM are I believe five years now, and near as I can tell have had no degradation yet, we still wake up with them at 75% to 80% every morning depending usually on how much TV we watched.

LFP would mean the end of having to run a generator though, no other advantage for me.

[Pelagic]

Ditto with what A64 feels.

I am obsessive enough with seamanship and fishing , because they give me both a feeling of security and independent sustenance.

Geeking over the holy grail of batteries, is a distraction at this stage in their marine use.

A64...... Why Gel?

[Flod]

I am in the middle of doing the switch and of course there is a lot to consider. However I think that it is probably easier than the experts sound like. I mean there used to be the same discussion with lead, gel and AGM before and now the focus have shifted. I have been abusing my lead bank for 5 years and now it died. If I would have been nice to it and doing everything correct By the book it would maybe have survived another 2-3 years. My guess it’s the same for Lifepo4. If the experts get 2500 cycles I might get 1500. I don’t really care as long as I don’t have to worry about power when out sailing and instead concentrate on.... sailing

[a64pilot]

Originally Posted by Pelagic

A64...... Why Gel?

I keep hearing that as long as they are properly charged that they have phenomenal life spans, I mean 10 years plus, and that they are more tolerant of not being fully, 100% charged every day.
Currently I ensure my AGM bank is, it’s not hard to argue that I regularly overcharge as I often hold absorption voltage for a coupe of extra hours.
With Gel it’s my understanding that you don’t have to be so anal about being fully charged nearly every day.

I believe that Gel back in the day got a bad name because they were tossed in and charged the same as a flooded battery.
My boat apparently came with Gels, had an old fashioned charger that held some constant voltage, never wavered, as did of course the stock alternator, and I assume overcharged the Gels and killed them pretty quickly, as did many other boats.
It was a Raritan 30 amp. About a foot square and probably weighed every bit of 25 lbs, had a monster transformer.
So due to a lack of proper charge voltages and no float voltage, they got a bad rep.
At least that is what it seems that I have pieced together anyway, cause it would seem that for a lead acid battery, they should be THE choice for long term Cruisers, and they aren’t, why?

Nolex for example I believe uses Gel, and with the cost of that new boat and being able to spec the battery box size and shape etc. he could have used anything, but used Gel, why?

Besides they will fit my battery box, GC2’s won’t and my Lifelines are actually about 1/8” too tall.

[jtsailjt]

Originally Posted by a64pilot

I looked into it myself as the benefits seem amazing.
The more I learned it seemed the less I knew, and the more “stuff” that I had to have or I would kill the bank, and obsessing is taken to a lifestyle apparently. I decided that they are a “Science Experiment”
I eventually decided I wasn’t smart enough, rich enough, or as dedicated as I needed to be for an LFP bank, and gave up.
I believe when my AGM bank dies, I’m going to look real hard at Gel myself.

From my non-EE perspective, I have to agree with your 'Science Experiment" characterization.....

I've had pretty good luck with AGM's but I did have a series 27 gel cell that still seemed OK when I switched over to AGM's back in '98 or thereabouts. I had no use for it so charged it up and put it in my basement where it sat for about 15 years and then I thought I'd give it a try as the only battery for my 17' Boston Whaler. In the winter I keep it plugged into a battery tender. So, it's now about 20 years old and was used for a couple of years originally as part of a house battery bank and more recently mostly as a starting battery seasonally for the past 5 years and my 135hp outboard still turns over with absolutely no hesitation. I realized the charging voltage from an outboard isn't optimum for a gel battery and a deep cycle gel cell isn't optimum for use as a starting battery, but had no other use for it so thought I might as well give it a try and it's far exceeded my expectations. So far it shows no signs of fading so I plan to keep using it for years to come.

[Oceanride007]

Carsten. Think a good source of information are those yachts that have them already. Each charging source needs evaluation, there is a shortage of schematics I noticed, and I suppose those that have them have there own habits that keep them safe. Thats why you need to talk to your neighbors.
Using Existing switch gear & Assets on your boat, makes every system unique. You are recommended to use qualified installer. You may have difficulties with Air transport and dangerous goods.
But any way come up with a plan, the early adopters on the long thread, are largely minimalist. Bells and whistle solutions are there. But so are the $$$.

[hellosailor]

Gel got a bad name years ago, because it is SO easy to quickly destroy them by overcharging. Once they out gas, there's no way to restore the electrolyte, so they are unforgiving. And since "normal" 12 systems designed for wet lead batteries will kill them...the complications were enough and batteries cheap enough to replace every 4 years anyway.

Then along came AGM and the companies that made both swore AGM beat the pants off everything. Drop-in replacement for wet lead and nicely sealed and wouldn't outgas with normal 12v charging systems. Ooopsie, they found out after maybe five or ten years that AGM won't outlast wet lead. That it has some advantages but STILL needs some special care. That the high charge acceptance can make many alternators overheat and burn out early. And even five years ago, Deka/East Penn (which makes all of them) was saying GEL not AGM was the best way to go, if the whole system was matched to it.
The wheel turns.

With lithium now...there are still a lot of contradictory "rules" but a lot of folks having success, and some of the batteries with a built-in BMS and also coming with longer warranties. Packing 2x the useable amp hours in 1/2 the space and 1/3 the weight is AWFULLY tempting. Even with all the trouble of changing charge sources and controllers.

And with the annual price rises in lead, lithium gets more competitive every year as well. As long as you don't fall for junk from fly-by-night companies making ludicrous claims.

[a64pilot]

See, all my charge sources are both programmable and temp compensated, I don’t think Charger wise I’d have to change to go LFP.
I’m going to wait for a true drop in solution, I know I keep being told that will never, can’t happen, but I don’t believe that, I think it can.

[Dockhead]

Originally Posted by a64pilot

I looked into it myself as the benefits seem amazing.
The more I learned it seemed the less I knew, and the more “stuff” that I had to have or I would kill the bank, and obsessing is taken to a lifestyle apparently. I decided that they are a “Science Experiment”
I eventually decided I wasn’t smart enough, rich enough, or as dedicated as I needed to be for an LFP bank, and gave up.
I believe when my AGM bank dies, I’m going to look real hard at Gel myself.

I came to the opposite conclusion.


The key is to throw in the trash everything you know about lead battery setups and how you operate them, and start from zero.


Once you free yourself from that and stop trying to translate lithium into lead concepts, it's not at all so complicated. I think the management parameters are actually simpler than for that Dr. Frankenstein era Victorian technology we currently use, namely lead acid, which belongs in museums, not on our boats. Managing lead batteries is really complicated -- if you look at it objectively. Give them finishing charges often, like daily if possible -- they are that sensitive. Don't leave them in a PSOC. Don't let them get too low and stay that way -- and I'm not talking about near 0, I'm talking about under 50% or 60%. Don't forget Peukert. Measuring SOC is really difficult and there isn't even a real consensus on the best way to do it. Make sure you choose batteries which can stand up to real deep cycle use. Don't forget that the charge acceptance rate falls off rapidly at only 80% or 85% SOC and then you have to charge for hours and hours to get a really complete charge, something which presents real problems to people charging with a generator, trying to somehow juggle not wearing the generator our and not killing the batteries because you don't get them full.



Screw all of that!!! This is just a ridiculous technology.



Lithium is actually much simpler. You start out with the beautiful fact that within the usable SOC range, which is something like 10% to 90%, a lithium bank is just like a fuel tank - pour it in whenever you have it; take it out whenever you need it, and just don't worry about it until it is really starting to run out. Wow! Just imagine that for a moment.


Then, you just need the right installation, which has nothing to do with how your lead batts were set up, so start from a clean sheet. Basically you just need, for safety, high voltage and low voltage cutouts, then you need some protection for the alternator so you don't blow up the diodes in case of a sudden cutoff, then you need to arrange the right charging voltage and for a way to shut off all charge sources when the batts get full, or going to a float voltage which doesn't actually float the batts but will power on board load without drawing the batts down.


Then you need some way of measuring and correcting cell balance.


That's really about all there is to it, and indeed it's simpler than lead if you're starting from scratch. There are multiple ways to achieve all of this; the Big Thread linked above covers all of them. It's not rocket science. I'm absolutely sure that A64 and Carsten would have no trouble whatsover implementing one of these installations if they would just throw out all the lead prejudices and look at it from a clean sheet.



For Carsten who is off grid for a couple more years I think it makes eminent good sense, will be much easier and more pleasant to use, much less (or zero) worrying about the batteries, and will be cheaper, as the cost per cycle of lithium cells is now considerably less than lead.



Lithium is actually easier to implement on a boat like Carsten's, with a single alternator charging both start and house banks, than on a boat like mine with dual alts and separate systems. That's because in Carsten's case, the start batt can be used as the buffer, with pretty much all of the existing infrastructure left in place, so that all you do is charge the lithium via the start batt with an appropriate B2B charger. The Big Thread has all the details, and there are several quite knowledgeable people on here who will be happy to help, I'm sure.