LiFePO4 batteries

[Yannis]

If you’re contemplating a battery installation with LiFePO4 technology, you must find 50 minutes and watch this.
If you are fluent in Australian english, that is !!

LifePO4 (lithium) Batteries.Separating Myths and Facts @4xoverland

[Ironworker]

Thanks for posting, I'll take a look and see if it mirrors my experience with these batteries. Stand by.

[Ironworker]

I watched about 60% of the video before I had to move on. The video is too long for me and its pretty basic info. I won't critique the video but will share some of my experiences with LiFePo4 batteries.

My boat was built around not having a generator but using Li batteries instead. Originally, I used two traditional AGM group 31 batteries for starting the engines and 1080 amp hour house bank with four 270 amp hour Battleborn batteries. I have since moved the Battleborn batteries to an offgrid camper that I built and installed three Epoch 460 amphour batteries for a total of 1380 amphours of capacity in the B31. My system is a 12 VDC starting and house bank.

The boat has a fridge/freezer, Air Conditioner and the typical complement of electronics including electric reels and a 3 KW transducer. We have over-nighted a couple of times cooking meals with an induction cook plate. The lowest we pulled the batteries down with the 1080 amp hour bank was 40%. At the dock we use shore power for charging and on the water, I have two 250 amp alternators with Wakespeed 500 external voltage regulators. There is no solar on this boat. One of the issues that I ran into with the Battleborn batteries was that I never knew exactly how much capacity I had in the house bank except when fully charged at the dock. That restarted the meter and I knew how much capacity I used but not how much was put back into the bank by the alternators. The traditional method is measuring voltage but that doesn't work well with large Li battery banks.

The Epoch batteries have a couple of advantages. First they are substantially cheaper, second there is a battery meter built into each battery, third they communicate with the Wakespeed 500's, forth they have a warning circuit built in to warn with the BMS is going to shut down a battery (which makes them compliant with AYBS recommendations), and lastly they have a smaller footprint vs capacity than the GC3 Battleborn batteries.

I have no complaints with the Battleborn batteries. They work perfectly in my offgrid camper with solar and shore power hook ups but were not best suited for the boat. I did have one battery that was defective which I shipped back to Battleborn and they replaced the battery under warranty. Using Victron solar chargers and a Victron charger/invertor in the camper, I know exactly how much capacity that I have at anytime in the camper.

Knowing what I know now, I would have built the boat around a 24 VDC system, I thought about it during the build but I had already bought the engines and electronic controls in 12 VDC so I stuck with that.

I am extremely happy with using the LiFePO4 batteries in the boat. They work great on the hook and the only noise we hear is the waves splashing against the hull at night.

[Yannis]

I retained the following:


-The system that monitors the battery performance has to be built-in, not added externally (as you also mention).

-The battery performance is seriously hampered by high temperatures, hence INAPPROPRIATE for installation in the engine bay!

-A volt meter that would otherwise give an indication of the remaining charge in an acid/lead battery, is NOT useful as a monitoring component, as voltage in lithium batteries remains unaltered up until the last drops of charge in them.


All this may appear basic to someone who has already done their homework with Li batteries, but for me it was very enlightening.
Also, in my 11 years on this site and many decades as a boat owner, I have NEVER heard of or seen another boat (liveaboard with all the amenities) which is not equipped with either a genset or the possibility to connect to external power, thus mainly dependent on solar power, like mine.
Except for A/C and hotplates that is, for which I have a liquid gas tank that provides for hot water and a two burner stove. And all this with 4x100 Amphour lead batteries that can only be depleted to down to only 50% (or they get obsolete) one of which is dedicated to starting a motor and thus not participating in the solar network.
This is why I am interested in the Li technology (so as to improve on the limited capacity of my lead batteries) but it seems that if I ever make the transition I will have to place them away from the engine bay. Which is structurally very difficult (new cabling etc) but also practically (real estate shortage).

[Carl]

-The battery performance is seriously hampered by high temperatures, hence INAPPROPRIATE for installation in the engine bay!

-A volt meter that would otherwise give an indication of the remaining charge in an acid/lead battery, is NOT useful as a monitoring component, as voltage in lithium batteries remains unaltered up until the last drops of charge in them.

The temps I knew about. I think Tesla created and edge with by running coolant to the batteries, in any case if engine compartment is the only place I see areas getting partitioned and insulated...maybe introduce seawater or cooling system. Whats the term necessity is the mother of invention.

Not being able to monitor battery state of charge at any time is something I never heard of or considered. I just assumed there was a way to add a "thing" and know. Good info

[Ironworker]

Lets discuss temps. First most quality LiFePO4 batteries have built in heating coils. The below freezing temps mostly affect the charging cycle rather than output. However if you mostly operating in below freezing temps then Li Batteries may not be for you.

On the opposite side in high temps the Batteries BMS typically have a set temp where the BMS shuts down the battery. In my research this temp varied between 140F to 150F with most settling around the 145 F mark. This can be controlled by fans that cool the batteries.

So when I was looking at my installation, I spent a lot of time thinking about the high temps as I originally had planned on putting my batteries in the engine boxes. Cummins says that if the boxes are 30F higher than ambient temp is the max the engines should be operating. So if the outside temp is 100F then 130F is the max the engine box temps should be. I installed engine fans that will exhaust the heat from the boxes just in case. I relocated my batteries to just in front of the engine bulkhead (port side) in order to shorten the length of the battery cables. The length of the cables is a much more important than the location of the batteries, IMO.

BTW, if you have solar panels on your boat then ditching the genset and going with a Li battery bank is a no brainer. Do it.

[Yannis]

Carl,

To run coolant around the batteries...how much more complicated can one be? LOL!

Rick,

I wish I could relocate my batteries in front of the bulkhead, but this is impossible. There is simply no room for this.

Im very happy with my lead acid batteries. I can draw around 150 amps per day, which for most of the summer is easily replenished by the sun the next day. Minor issues usually start in September where the sun angle changes and it also drops faster behind the mountain, but all this is manageable either by limiting some consumption or starting the motors for 10 minutes that day.

Cost is another issue. If Lithium costs 3X the cost of lead acid, then they will have to last at least more than 15 years as I usually change batteries every 5 years. Im not too sure they can perform that long.
The only advantage I see for Li over lead acid is that you can pack considerably more amps for the volume and therefore have a more relaxed consumption pattern. You could potentially run an AC too (which I miss) but for anything else the good old leads are fine really. So long as fridge and freezer perform as needed then everything else is secondary. Oh yes, pumps too, but this is very little compared to how much more energy need the ice cubes to be produced...

[Ironworker]

Yannis,

I have a friend who has a 72" Cat sail boat. If you search on YouTube using "Atlantic 72" or "Penmanship" then you will see a boat that has no genset and no shore power hook up!!!

It only has solar panels for power with about 1400 amphours of Li batteries for storage. No wind generators nor other sources. My friend owns this boat and he parked it at my dock for a couple of months right after he picked up the boat. When he pulled up to the dock, I asked him where the shore power hook up was and he said, "I don't have one". (This is a $10 million boat!) He said he had shore power on his last boat and never used it therefore he wasn't going to spend the $75 for a shore power hook up. BTW, this boat is now in Indonesia on an around the world trip. He and his family of 8 have been living on it for 2 years. It has a full kitchen and two air conditioners. Its quite a remarkable boat, all carbon fiber.

If I ever take on another boat restoration, I'll be using carbon fiber.

[Yannis]

Rick,

What’s truly remarkable is to have boats like this, fully solar that is, appear like needles in a haystack.
Instead of striving for all this free energy as a viable alternative to fossil fuels, boat builders and individuals consider solar as a nuisance...or just as back up, whereby, as it proves out, solar can become the unique source of power. Provided of course that you operate in climates like mine here, or elsewhere, where the sun is abundant during most of the day. You cannot be completely solar if you live in Maine or Canada for example. But in Florida?

However, what is not immediately obvious here, is that a catamaran has significantly more real estate available for solar panels. This exercise is more difficult on power boats where solar surfaces are scarce and not always appropriate.

Im on my second set of panels and I can attest to the significant improvement of technology comparing now and what I had purchased 13 years ago. Today, my two panels not only are more powerful nominally from the previous ones (for the same surface), they are even placed in a less advantageous position on my boat and still produce more electricity than before!
As for the cost? Peanuts indeed!

[Ironworker]

Yannis,

I have given great thought to how to get solar on my B31. I have been looking at a shade structure pivoting off the tower. Solar panels would provide shade and produce power. My problem is it would block my view of the cockpit which would be a big problem while fighting fish.

I have also considered some flexible panels on the area where I glassed in the windshield and on the bow. which is likely going to be the best solution. With a little care they would look mostly like windshields.

Now I'm looking at vertical bifacial panels. Still no viable solution but the quest continues. Currently, I have all the power that I need with the alternators or shore power, primarily that I don't spend much time at anchor except at night.

[Yannis]

Rick,

Go back to my post "Solar panel on B28".

There you will see the whole construction and how it eventually looked. The idea was to leave a few centimeters between the bimini and the panels for aeration; they perform better when they keep cool. also, they were almost invisible!
It worked fine for 13 years until a bad weather on a return trip literally demolished this whole construction which was very sturdy, or so I thought, with 4 stainless stays all around, braced and cross tied, still it's gone.

So, I thought to myself, I'll change completely.
I placed 2x150w flexible (not rigid like before) on the sloping area below the fb, above the front windows. I took a risk in that they are not ideally placed, not horizontal and on top like before, but they work.
In that same post you may see my fridge/freezer which was being built at the time. Only with a top loading fridge combo and the outrageous insulation thickness like this can you hope for cold food and ice made daily.

if you need more info just ask. I've done it twice so far!

[Yannis]

One other element, the shade while you captain on the fb.

A royal myth!!

Neverer than never was any bimini protecting me from the sun. For a bimini to shade on you, it has to be high noon. Who on their right mind would travel at high noon in July August in Greece. Oh, I know who! Those myriads of sailboats that need ages to reach their destination.
Haha, I’m sat w my friends over either ouzo wine or icy beer nimbling on various human feed.This is the precise reason why the fridge absorbs the power that the AC would otherwise be attributed. The amps are given and you can count them. Experience from all these years led me to understand how much longer the 12 or so volt minimum needs to happen and measures to be taken. I have nothing to measure anything, apart from a set of lights on a box that either say ok or otherwise adjust. Function over form haha.