100 Ah 12 volt Lithium prices

[O C Diver]

They are happy to sit around at 50-70% charge for months. In fact Li battery life is extended if they are stored at 50-70% rather than 100%. I try to let my eBike battery drop to 70% before I put it away for the winter as the manufacturer recommends.

David

My Epropulsion electric outboard has a circuit in the battery that will slowly drain the battery down to 50% for storage purposes. If you charge the battery, after 2 weeks without use, it will start it's very slow discharging process until it reaches 50%.

Ted

 

[Helmsman]

I posted this source in another lithium thread. Jim Healey writes about electrical issues on boats, and has written a well thought out 2 part discussion on the state of lithium batteries in boats. Several of the topics brought up on this set of posts are discussed in his articles.
Here is part 1. You can access the link to part 2 when you read part 1.

https://gilwellbear.wordpress.com/c...-topics/lithium-chemistry-batteries-on-boats/

The issue of alternator failure is a ig issue that can be mitigated with a lead acid start battery and a DC to DC charger connected to the lithium bank. I am not sure diodes would take care of the issue.

For a new build, the design could take into consideration alternator capacity, managing a “dark ship” moment incurred with lithium batteries and the corresponding damage that can do, the cabling necessary for a higher charge acceptance rate, temperature control of the batteries through placement or cooling/heating, etc. etc. What builders may not want to get into is battery quality.

Lithium batteries rated higher than a hundred amp hours are not generally recommended in boats. The reason, according to some of the literature I have studied is that these batteries were not originally intended to handle the stresses and vibrations on a boat. They were built for a static environment. The casing these batteries live in are insufficient. Yet many folks install them. Will those batteries last as long as their charging capacity will?

A lot of good and relevant information in the attached article. I enjoyed reading through them and hope you do also.

 

[Helmsman]

And, if I understand the video, this was one of the "benefits" of a hybrid battery bank. The difference in the charging curve of the battery types means that if the charge is turned off with the LA at only 90%, the LiFePO4 batteries can "give up" some of their charge to insure that the LA gets to 100% (12.6V), even if it drops the LiFePO4 back to 70%. LA gets what it needs and LiFePO4 doesn't care that it sits at 70%. Sounds too good.

It will work, but there is a gotcha. When connecting the batteries the first time, or re-connecting them, it is important to get them both to the same charge level to avoid a surge.

 

[DDW]

Lithium batteries rated higher than a hundred amp hours are not generally recommended in boats. The reason, according to some of the literature I have studied is that these batteries were not originally intended to handle the stresses and vibrations on a boat. They were built for a static environment. The casing these batteries live in are insufficient. Yet many folks install them. Will those batteries last as long as their charging capacity will?

This cannot possibly be accurate. LFP batteries are built up of several different kinds of cells, and the cells don't know how they are going to be configured and used. What makes cylindrical cells (as an example) suddenly change vibration resistance when a few more of them are used to get to 150AH from 50AH? The casing may or may not survive a boating environment, but given that many of them are sold mainly into the RV market - which suffers much more shock and vibration - I'd say your chances are good.

That may be an argument for not bottom fishing the LFP market so that you get a properly designed and tested product, but the same can be said about any product.

 

[Helmsman]

This cannot possibly be accurate. LFP batteries are built up of several different kinds of cells, and the cells don't know how they are going to be configured and used. What makes cylindrical cells (as an example) suddenly change vibration resistance when a few more of them are used to get to 150AH from 50AH? The casing may or may not survive a boating environment, but given that many of them are sold mainly into the RV market - which suffers much more shock and vibration - I'd say your chances are good.

That may be an argument for not bottom fishing the LFP market so that you get a properly designed and tested product, but the same can be said about any product.

I think the issue comes from the market the lithium’s were originally intended for. It wasn’t the RV or Boat market. It was for stable environments, with less vibration and temperature extremes. Certainly that could be changing. The fact that failures are not rampant doesn’t establish anything in regards to quality. The question is whether the failure level is acceptable for the use case. There is little data out there that I have seen comparing battery quality of various battery producers.

There is certainly anecdotal evidence posted after folks experience those failures. I did see a study a couple of months ago about BMS failure rates due to poor soldering practices. Comparisons were made of a well made BMS and a poorly made one. Wish I could provide it to the forum, but didn’t keep a link. I believe it was the same article that questioned the stability of the battery structure itself for high vibration uses. And yes, I am sure as you suggest, that high quality batteries would mitigate the concern. The author however, suggested to limit the size to 100 amp sizes due to the concern.

It is still a bit of the Wild West out there, and without a settled upon group of standards, I am not ready for the plunge on my build. I don’t see anything coming out from ABYC that would help settle what standards would work for it. If I were a builder, I wouldn’t want to make the leap without that.

Certainly not anything to be afraid of, but certainly something that should be studied hard prior to making the leap. I think the system assessment necessary, including chargers, cabling, fusing, alternators, external regulators, whether or not to hedge your bet with a LA battery, and a quality BMS is critical. I would also think an ongoing maintenance process, measuring the balance, and some type of assessment of the BMS would be important.

Finally, a good understanding of how to manage the batteries when away from the boat, would also be important.

 

[Helmsman]

Here is a good article that breaks down some of the issues.

https://marinehowto.com/lifepo4-batteries-on-boats/

snip: “ Where drop-in LFP batteries often fail the purchaser is in marine specific engineering. To understand why, we simply need to look at the reason these batteries were originally created. Drop-in form factor LFP batteries were originally designed for telephone pole mounting where light weight and “drop-in” replacements for lead acid were critically necessary for the solar powered street lighting industry. The demand for this type of battery, especially in third world countries, is absolutely staggering.

I know many boat owners tend to assume we are a large market, but we are not, and no, many of these drop-in manufacturers are not specifically building marine batteries for us, though they certainly are marketing to us. The application of a “marine” sticker, and perhaps even a well marketed brand name on the plastic box, does not always denote a product that is well engineered or specifically engineered for use on a cruising boat.

Unfortunately, for our industry, many of the “A” graded LFP cells used in the plethora of Chinese drop-ins, are sold into the street lighting industry. For boaters this can mean the low-grade “orphaned” or “rejected” cells wind up in batteries that may look the same but are sold on Ali-xxxx, eBay or through other less reputable sources.

Sadly Ai-xxxxx has literally become a dumping ground for reject LFP cells and batteries from the Chinese factories. They get away with this because they know the vast majority of buyers have no way properly to test them. Frustrating? You bet it is.”

 

[SteveK]

I have lurked on these lithium threads.
Currently I have 6-6volt FLA for 660 Ah at a cost of $210 each or $1260 Can$. This thread speaks of 100Ah 12 volt for $365 US$

How many 100Ah Lit batteries do I need to get the same functionality. I need to get this in perspective.
Suppose you say I need 3 because Lit bats can be used down to 20% SOC.

I can use 30% of 660Ah= 198Ah of a fully charged FLA and I can use about 60% 300Ah= 180Ah of the Lit bats before a full recharge is needed.

At about $450 Can$ x 3 = $1350
At about $210 x 6 x = $1260
No real cost difference.

I understand the lithium can last twice as long. I know I will own the boat 5 years, but not necessarily 10.

What have I missed?

 

[sunchaser]

Finally, a good understanding of how to manage the batteries when away from the boat, would also be important.

This is an issue raised by many far away owners, especially for those of us that leave our vessel for months at a time.

 

[Bmarler]

i just spotted some 12v 100 ah on ebay for $284 if you buy at least 4. you can put together a 1000 ah bank for less than 3 grand. i looked for reviews of the battery on other websites and found only good ones. amazing.

 

[socalrider]

I have lurked on these lithium threads.
Currently I have 6-6volt FLA for 660 Ah at a cost of $210 each or $1260 Can$. This thread speaks of 100Ah 12 volt for $365 US$

How many 100Ah Lit batteries do I need to get the same functionality. I need to get this in perspective.
Suppose you say I need 3 because Lit bats can be used down to 20% SOC.

I can use 30% of 660Ah= 198Ah of a fully charged FLA and I can use about 60% 300Ah= 180Ah of the Lit bats before a full recharge is needed.

At about $450 Can$ x 3 = $1350
At about $210 x 6 x = $1260
No real cost difference.

I understand the lithium can last twice as long. I know I will own the boat 5 years, but not necessarily 10.

What have I missed?

Big advantages:
- You can use 100% of LFP rated capacity for the most part.
- Accept much higher charge rates
- Can be left at partial state of charge for long periods of time without issue
- No watering required
- Much smaller and lighter

Obviously some of these are less relevant than others depending on application. I have a similar FLA pack to yours that I bought 2 years ago. My next one will probably be LFP even though most of the above advantages aren't too important to me. I think with another few years of costs coming down & better marine engineering will make a it a no-brainer by then.

 

[Max1]

I was looking around the internet about what happens when a BMS system on a lithium battery shuts down (overheat, etc.) while the alternator is running. Not good. I suppose if it were a bank of lithium and only one BMS shut down it might not matter, but a few sites said to avoid the issue by putting a small lead acid battery in the lithium bank. That led me to this video on mixing lithium with lead, although for a different purpose. The basic idea is to program an external alternator regulator (which I have) with an existing lead battery bank (which I have) that comes close to serving the house purposes (which mine does), but also benefit from the properties of lithium.

The basic idea is to get the lithium and lead batteries at the same level of charge (so that the lithium doesn't go crazy trying to charge the lead), and then set the external regulator to a "hybrid" setting to charge the batteries. Say a 200Ah lithium battery is added to a 520Ah lead bank. Once charged, the lithium would be at 13.2V and discharge about 80% at which point it would be at 12.6V. Then the lead batteries would kick in, keeping the lithium from fully discharging. The effect would be that one could get the full usable potential from the added lithium (180Ah). The lithium would cycle a lot (which it can handle), the lead would cycle less (which it likes).

There is a follow-up video talking about a potential product to increase the charging efficiency of a hybrid system, but I'm not sure that the tweaking is worth it. Lots to think about from the first video.

I have been running Lead+Lithium on my travel trailer this past summer after having watched Clark's video of combining the two. I have had no problems, and the fact that the BMS shutting down the max charge and min charge makes destroying your alternator a very real threat if you only have LiFe's on your boat and the BMS cuts off your battery from your alternator when they reach maximum charge.

For my boat, next spring I will be running two 100A FLA and one 200A LiFe in parallel from my Solar system.

 

[sunchaser]

A very smart marine electronics expert is Jeff Côte from Pacific Yacht Systems. He has a fascinating blog called Dock Talk. I recently was watching him and Nigel Calder talk about lithium batteries, BMS, ABYC and related subjects.

Nigel spent some time talking about the certification by UL, expanding why it is best to buy lithium batteries that have a UL 1973 sticker. Jeff's blog is a gem for serious cruisers.