Lithium for the love of God

[john61ct]

Sorry, are you asking how long it takes between the different chemistries?

Or something else?

[john61ct]

Originally Posted by exMaggieDrum

john61ct - for you this is an economic decision. So go with your figures and don't worry about it or trying to convince everyone else that this same analysis should work for them too.

Actually, I'm just clarifying that aspect, at least for my location, different markets different numbers.

I am actually going with DIY LFP, for my main/House bank, and feel paying 3-5 times more is worth it. But not what I consider the crazy money required for the proprietary integrated solution versions, and I'm not a wealthy racer.

Where lead is a better fit, between AGM and flooded, I prefer flooded, unless a given scenario presents a compelling reason, like tight install space.

Or Firefly Oasis over LFP, for simplicity and/or cost reasons when PSOC is inevitable.

[barnakiel]

Originally Posted by john61ct

Sorry, are you asking how long it takes between the different chemistries?

Or something else?

Imagine 100Ah batteries. One is a l-a flooded. The other is a l-a AGM. Both discharge to 50%.

We charge both with best applicable charger for each. We are not limited by alt output.

Now if the plain battery needs (say) 8 hours to be at 99% full, how much time does an 'identical' AGM need to be charged, to be at 99%?

b.

[daletournier]

At the risk of getting flamed I'll add my 2cents worth. I like new stuff, therefore im attracted to lithium batteries BUT.

My problem with them is this, if you are traveling locally in places like Australia where you can get what ever you need then I would be happy with Lithium , reason being is if something goes wrong its no big deal. During my travels ive had a Balmar smart regulator become not smart and also a solar regulator start pumping in a constant 15.5v, on my last boat I had 6v trojans, that just took these problems in their stride, both these issues occured a long way from jump on the phone type help.

Also had a friend while in the Philippines couldn't continue with us due to some Lithium cells failing and not being able to get then locally, had to wait to get them freighted from the US which was causing some difficulties.

Simple lead acid batteries arent as a efficient as lithium, from what I read, BUT most will take a beating and replacements can be found all over the world, these replacements will slot straight into current charging setups and your on your way again.

My point is everything has the potential to fail on a cruising boat, the ease at which you can deal with these problems has to come into the decision making process.

[Pizzazz]

I also like new technology but only when it brings real benefits. In my analysis, nothing beats golf cart wet cell batteries on a boat:

1. Golf cart wet cells retail for less than $100 per 100AHrs and are available everywhere. Based on the data so far lithiums cost 7-10x more per AHr.

2. Deep discharge wet cells could easily be discharged to 10-20% state of charge, charge cycles will be reduced by half to around 700. So you could run wet cells "nearly" like luthiums, i.e. 15-85% for wet cells vs. 5-95% for lithium. Insignificant difference and how many of us will draw down the batteries to 5% on a regular (non-emergency basis)?

3. Charging wet cells in bulk mode is just as efficient as lithiums. Yes, lithiums can take more current but in practice we are charging current limited on boats (wet cells can take 1/3C, which means 150A for a typical bank. How many of us can charge at more than that?

4. You can draw more current from lithiums with less voltage drop but really, when do you need this? To run AC off batteries? Heat water off batteries?. Forget about it.

5. Lastly, on the cycles issue, hard driven wet cells would give you 700 cycles or at least two years of use. Say lithiums give you 7,000 cycles. An investment that pays off in 20 years? Not for me.

[john61ct]

Originally Posted by barnakiel

Imagine 100Ah batteries. One is a l-a flooded. The other is a l-a AGM. Both discharge to 50%.

We charge both with best applicable charger for each. We are not limited by alt output.

Now if the plain battery needs (say) 8 hours to be at 99% full, how much time does an 'identical' AGM need to be charged, to be at 99%?

b.

You are referring to Charge Acceptance Rate.

Impossible to generalize by chemistry, depends on the marque, or even specific model.

If you see one battery's spec A is maximum of .2C - so 20A per 100 AH.

And another B is .6C, then up to about 85% full if you have a huge current charger, B will accept three times the current.

But the last 15% will still take say 3-4 hours, since amps accepted then is very low for all lead.

Which is why best to do that stage with solar rather than burning dino juice.

Big advantage with LiFePO4, is not only can you pump on those mega amps all the way to full in say one hour, there is no need for longevity to fill them up at all, in fact better to stay a bit below full if they're not constantly under load, and keep them way down if not in active use.

[john61ct]

Originally Posted by Pizzazz

3. Charging wet cells in bulk mode is just as efficient as lithiums. Yes, lithiums can take more current but in practice we are charging current limited on boats (wet cells can take 1/3C, which means 150A for a typical bank. How many of us can charge at more than that?

4. You can draw more current from lithiums with less voltage drop but really, when do you need this? To run AC off batteries? Heat water off batteries?. Forget about it.

5. Lastly, on the cycles issue, hard driven wet cells would give you 700 cycles or at least two years of use. Say lithiums give you 7,000 cycles. An investment that pays off in 20 years? Not for me.

Good points, but some that mitigate the other way:
Some people can't do flooded at all.

It is possible to get a DIY setup going for 2-3x the price of decent lead, faster payback.

If you don't have much solar, many FLAs only accept .15 or .2C, running alts just to charge can be very expensive per hour.

Having a massive bank with huge CAR may make fitting high-amp alt(s) worthwhile, with FLA no point.

Some inverter usage does suffer from voltage drop even short of A/C.

Light weight for racing.

Up to each to decide for themselves, can't over-generalize.

[senormechanico]

For those of you who think Lead Acid is so great, even if you don't care about the extra weight and holes in your clothes, look up the Peukert Exponent.

When you read up on it and REALLY understand all the nuances and do the math,come back and try to convince anyone who has switched to LiFePo4 to go back.
Good luck with that !

[Pizzazz]

I have looked and while I acknowledge the 20-25% capacity reduction for lead acid when supplying large currents, such situations on a sailboat are rare. Hence you are getting something that you do not need.

To give you an example. A typical cruising sailboat will have 450 AHr battery bank and will use about 1/3 that amount per day. Well below the 20-Hr discharge rate. It would happily supply loads up to 20A within it's rated capacity. Even if you use the windlass, power tools, microwave, etc for a few minutes a day, the total impact on the capacity reduction due to the Peukert exponent is minimal.

Yes, lithium is better and for some people having the best is a priority. But you cannot justify it this way unless you have some special high current need.

Lightweight for racing boats makes sense. Mounting off vertical - probably. Desire to have the latest and greatest - yes! The other reasons I cannot logically explain but to each her own.

[StuM]

Originally Posted by senormechanico

For those of you who think Lead Acid is so great, even if you don't care about the extra weight and holes in your clothes, look up the Peukert Exponent.

When you read up on it and REALLY understand all the nuances and do the math,come back and try to convince anyone who has switched to LiFePo4 to go back.
Good luck with that !

That's another reason to prefer a large AGM bank to a minimal FLA bank. Peukert has a minimal effect on capacity in that situation.

[daletournier]

I love stuff like "Peukert principal"the reality is people have been cruising successfully for decades on simple lead acid batteries, are they better? nope! are they simple and do they work well? Yep! are more people out there successfully cruising on lead acid? Id say yep! Most cruisers wouldn't even know what peukerts principle is and they get by quite well.

[john61ct]

I don't think many make the change "backward" from LFP to lead, but recently someone did post about exactly that.

But for someone watching their budget and without a compelling reason I completely agree they are right to let others be the pioneers wait for the mainstream market adopt first and wait for the price differential to narrow.

Even Firefly at >$500 per 100AH is a stretch for many vs Sam's GC2 at <$100. For drop-ins we're looking at $1000 right?

Originally Posted by StuM

That's another reason to prefer a large AGM bank to a minimal FLA bank. Peukert has a minimal effect on capacity in that situation.

I don't understand, isn't the specific issue there large vs small? What about a huge FLA s
vs small AGM?

Does the chemistry itself have a major difference wrt Peukert? Or does it vary by make & model like CAR?

[exitstrategy]

Thank you guys so much for clear crisp recommendations, and also thank all of you for all of your contributions in all of the other threads and blogs.

(Back from the relatively remote Ilets de Petite Terre, and now have some data roaming off my phone.)

Going LiFePO4 not new AGMs
I am definitely sold on the benefits of LiFePO4. @Navy_Davy the Carbon Foam batteries seem like a really good solution for upgrading lead, but I actually do want to have the full benefits of Lithium and I am enjoying the learning process.

Fully integrated solutions?
@OceanPlanet Bruce Schwab, JOHNMARDALL, I have much respect for your work and recommendations, and I have also studied Emerald Sea Life's installation on a sister Lagoon 450. I am sure these solutions are excellent. While I can afford a fully integrated-marine installation, I do not want to spend money that I do not need to spend. As I have already purchased a Xantrex FW3000 and 3 Outback 80s I believe I already have good sub-components to work with. And a DIY LiFePO4 project would push me to learn more about my boat – which is actually a major sub-goal of cruising for me. I will review again the OceanPlanet website when I get true WIFI and try to figure out what I am missing of the more integrated solutions. The MasterVolt website really didn't explain to me what you are buying.

DIY Solution High-Level

Handling Overcharging:

Solar:
As 44'cruising cat pointed out, the Outback 80s I have can be set to 13.8 bulk and 13.5 float so as to effectively turn off float charging after charging the batteries. This handles over-charging from solar.

Generator:
We also have a Onan generator that I now run once every couple of months, really to just keep it use. As the 2000 watts of solar cover all of our current needs as long as we stop the inverter for the laptops around 8-9pm. The generator output is coming into a Xantrex Freedom 3000 charger / inverter that has custom battery settings, and even a two-stage no-float mode. So, like the Outback I can program the charger to keep the Lithium safe. So even if we are starting and stopping the generator manually, if we are having an evening party and we are distracted we will not take the Lithiums above the knee for high voltage.

Alternators:
Finally, the alternators. We have the stock 80 amp alternators running into I believe under-sized stock Cristec 40 port & Cristec 60 stbd battery chargers. If we have the engines on, it is usually for the relatively short period of anchoring. If however we have decided to thumb nature and insist on motoring windward for hours and hours, then it seems like I have the option to shut-off the circuit breaker for these chargers. To do this safely, I turn off the engines, shut the circuit breaker, then fire up the engines again and continue to motor into the wind? But there is probably a more elegant voltage detecting relay device that I could put in here that would handle this automatically, as well as turn it back on!

This handles over-charging right? I do not need a diversion load setup? (Although my wife would love hot showers inside of the boat instead of the hanging camp shower )

Under-charging
This seems like not a problem to me. We already live under a low-voltage alarm regime with the current AGM setup. So there would be no difference to us for an alarm to sound and to respond. However, going a bit deeper. We are full-time cruisers and have yet to leave the boat overnight, but we will at some point want to leave the boat for a week or two. I would think that I would empty the fridge & freezers, turn them off. The inverter would be off, the bad-boy off. The only loads that I could think we would want remaining would be the bilge pumps, (possibly a light and some 12 fans). In the case of the bilge pumps I would rather drain the Lithiums down to 0% than to disconnect the bilge pumps. So it seems to me that low-voltage automatic cut-off is not required. I am most likely missing something? (Also I believe I am currently throwing away 300 amp-hours a day on the lead batteries, so as a practical matter, I do not see how I get to low-voltage unless I am filling SCUBA bottles - also below.)

What about my lead-acid starting batteries?
Besides the house battery bank, I have a starter battery for port, starboard and the generator. Can't I just leave them as-is and have them charged with the custom Lithium profiles above? Even if these are sub-optimal charging profiles, these are used just for start-cranking and by definition charge themselves as soon as they are used. But maybe I am confused and these 3 lead batteries are only charged by the dino-gas engines and I do not have to worry about the differing profiles.

Creation and Installation:
Alright so I buy quality cells from Winston, Sinopoly, CALB or A123.

Space & Size – this is easy, my battery bay is 15 inches tall so I do not even have to worry about laying them on their side. I could theoretically fit 20 cells of 400 ah each for 2000 ah at 12v! Wow that is a ridiculous amount of amp hours. Currently I believe I will go for about 700-900 amp-hours of Lithium. So space, no problem.

Then it comes down to reputable dealer, stock, shipping to St. Martin and then finally price. Would love current, specific recommendations. The various threads go back years and vendor performance changes.

So, assume that I buy 8x 400 ah prismatic cells to build a 2p4s 800ah house bank. This would take up less than half my battery bay and have room left over in case our energy consumption changes in the future. I see I can buy 0.8C for $466, and 1C for $508, it is a small price difference, but I have no known use for draining my batteries even at 0.8C, so I should just go with the 0.8C – correct? These would have a nominal cost of about $3800 from Lithium Batteries - Prismatic

I ship these 8 cells to St. Martin and buy/borrow a quality bench top power supply and perform the top-balancing that is well documented in several places.

While allowing these batteries to settle as long as possible (2-6 weeks), I build a compression case to hold these batteries and protect them from vibration wear and tear.

Day of Switch-Over
Change the power charging profiles on the 3 Outbacks and the Xantrex while still connected up to the Lifeline AGMs.

1. Shutoff all equipment.
   
2. Remove all equipment from the 12v socket receptacles.
   
3. Kill the solar via the circuit breakers.
   
4. Use the manual disconnect for the house bank
   
5. Use the manual battery disconnect for the 3 lead acid starter batteries
   
6. Disconnect the AGMs. Lift those heavy f*ckers out the stbd hatch.
   
7. Install the compression case for the Lithium
   
8. Install the individual Lithium cells, now in their final 2p4s configuration (do this at least once before day of install to be sure the bank is working as planned and fits into its compression case).
   
9. Connect the Lithium house bank
   
10. Verify voltages (DVM) and wiring (pretty much all the time.)
    
11. Manually re-connect the house bank
    
12. Check the voltage at the 12v socket receptacles.
    
13. Turn on something simple and cheap like fans, assuming that the fans are working and happy, start turning on equipment in escalating value
    
14. Once everything the house normally runs is up and running, start to verify charging is working well.
    
15. Manually re-connect the solar at their circuit breakers, verify the Outback is still on the current charge profile – maybe it got reset with the power off – so check again.
    
16. Verify that the Xantrex has its correct profile. Assuming that the house bank was at 50% SoC, before the Solar takes up, turn on the generator and have the Xantrex fill the lithiums, verify that it shuts off and not over charges. This should also be a good test of the Outbacks.
    
17. And done, I have a working lithium house bank.

I also have an unexpected benefit of this setup:
By using the Outbacks and Xantrex charge profiles, I still have the ability to re-install a lead house bank if for example I had a total failure of the Lithium bank in a remote Pacific Atoll with only some lead available on the supply ship.

The current draw-backs that I know of:

1. Relying on the pack-level voltage monitoring of the Xantrex and 3 Outback controllers, so after the initial balancing I would not have cell-level voltage monitoring. But I could address this by buying some more stuff (would appreciate suggestions) for these 8 cells.
   
2. No automatic low-voltage load cutoffs. The Outbacks actually have low-voltage option so I could isolate my lower priority loads to a bar to be automatically cutoff. The Xantrex already has a low-voltage setting for the inverter and this is practically the only thing that sends my house battery low right now. So I still feel like I do not need this.

Other Questions:
What are the smaller bits that I should buy at the same time as my order?

1. Bits?
   Some braided connectors? My own desktop power supply? A few more manual emergency disconnect switches? Heavy red&black cable (expensive on islands)? Terminals.
   
2. Induction Cooking?
   We currently use propane and butane for cooking gas. I like the idea of switching over, or at least having the option of using an induction cooktop. In daily use, what is your typical amp-hour usage for cooking by induction. And I assume that the Xantrex 3 kw inverter is strong enough? (If I know what typical induction amp-hour usage is, it might change my designed size to 1200 amp-hours of Lithium.)
   
3. Filling SCUBA Bottles?
   Does anyone have experience using a Baer Junior air compressor with the electric option? What does it take to fill an 80L tank? I have seen estimates of 220v @ 14 amps for 18 minutes = 77 amp-hours to 600 amp-hours. With our 2050 solar install, I have been averaging 700 amp-hours per day here in the West Indies. We have 3 divers on board and typically dive 2-3x a week. Fills are sometimes hard to get ashore. I would like to avoid a gas-driven compressor. If it took say 200-300 amp-hours per bottle, then a group dive is 600-900 amp hours. Our typical daily use about 430 amp-hours including washing clothes, ice and water-making. So, I believe I am currently throwing away ~300 amp-hours of energy every day. With planning it seems like I could keep our bottles filled off of solar/lithium/invert with careful use of each day's power generation. If not, I have the 5k generator to supplement the solar on a big fill day. Am I thinking about this wrongly?

Thank you again for everyone being so generous with their time and hard-won experience and skills.

-Erik

[barnakiel]

Originally Posted by john61ct

You are referring to Charge Acceptance Rate.

Impossible to generalize by chemistry, depends on the marque, or even specific model.

If you see one battery's spec A is maximum of .2C - so 20A per 100 AH.

And another B is .6C, then up to about 85% full if you have a huge current charger, B will accept three times the current.

But the last 15% will still take say 3-4 hours, since amps accepted then is very low for all lead.

Which is why best to do that stage with solar rather than burning dino juice.

Big advantage with LiFePO4, is not only can you pump on those mega amps all the way to full in say one hour, there is no need for longevity to fill them up at all, in fact better to stay a bit below full if they're not constantly under load, and keep them way down if not in active use.

Thanks John !

Yep. This is what I meant. Going from flooded to agm does not offer similar benefits that going from agt to litium does. The total charge time is largely limited by the last 15%.

This is actually important even more with solar charging, at least in our 100Ah boat - the battery cycles mostly through 80-100%. So we are virtually always charging the 'remaining 15%'.

I have found there is a simple and elegant solution. It is to split into house1 and house2 where 1 is lithium and sized at what the boat normally cycles daily. Bank2 is then a reserve used only if and when the 1 gets depleted in one cycle. Bank 1 (say 35Ah) can be lithium and Bank 2 can remain plain car batteries.

I have made some calcs and this is way faster to charge (and of course) way less expensive than one big lithium bank.

I think I am buying a litium NEC ALM for our next adventure. 35Ah lithium + Bank 2 60Ah Varta flooded sealed car grade.

Thanks!
b.

[john61ct]

Originally Posted by barnakiel

I have found there is a simple and elegant solution. It is to split into house1 and house2 where 1 is lithium and sized at what the boat normally cycles daily. Bank2 is then a reserve used only if and when the 1 gets depleted in one cycle. Bank 1 (say 35Ah) can be lithium and Bank 2 can remain plain car batteries.

I have made some calcs and this is way faster to charge (and of course) way less expensive than one big lithium bank.

Very interesting, I have had the same thoughts, but not "plain car" (that means Starter batteries to me?) but good,lead deep-cycle, maybe even Firefly.

There is a very strong consensus here among those much smarter than me about batteries that it is always better to put all your House eggs in one basket, Peukert effect and all (which I believe doesn't apply to LFP, yet another advantage).

This brings me back to a related idea I have, very strong disapproval last time I raised it, but I think worth at least testing one day, I think may prove worthwhile in some contexts.

Let's imagine very robust high-amp capacity open-close switch, wiring, fuses etc and a current-limiting device between two banks, one large high-acceptance lead-based, and one even larger LFP.

Run dino-fueled huge-amp charge source for an hour into both banks (yes different voltages, not a technical challenge, just money) long enough to get the LFP back to "safe full" and the lead one up to that 85% point.

Turn off the charge source. Open the switch between the LFP and lead banks. I personally believe that current from the larger and higher-voltage LFP will flow into the lead bank, continuing to charge the latter at a reasonably low amp rate.

As long as large loads don't interfere too much in the meantime (and maybe they don't even affect the process?), within a few hours, likely less, the lead bank will be back up to 100% full as it requires for max longevity, and the LFP will be nicely depleted as it prefers.

It may be necessary to boost the voltage a bit with a DCDC converter/B2B charger, but at low amps that is not expensive, and in my case I'll have one handy anyway.

It is true that some percentage of total energy will be "wasted", consumed in the inefficiency of the charge/discharge cycle. But if the engine run was needed for other reasons anyway, no issue there except theoretically.

It is true that a large enough solar array would be better, but there are scenarios on boats where that just isn't possible.

Any and all feedback on this idea would be most welcome.