Building a lithium bank

[SVSeaHawk]

So I have an AGM house bank with about 1200ah. I want to replace it with 1200ah of lithium and I need some help understanding the terminology of the battery specs…

I want to get these cheapos from amazon. Read good things from battery gurus and think they’ll to the trick…
Redodo 12V 100Ah Mini LiFePO4


https://www.amazon.com/gp/product/B0BVVWYVHZ

My plan is to buy 12 batteries and connect them in parallel but I am not sure this will work. The specs say …
“max 20.48KWH. Suggested expanding to a max of 4P4S as a 51.2v 400 ah system with a max load power of 20.48kw.”


https://www.redodopower.com/products...1-28kw-likenew

Given that I do not need huge loads, 100 amps seems plenty. Meaning of course I’d rather have more amp hours than load capacity.

My question(s) is this…

Can I create a 1200ah house bank with these batteries?

If so how?

Ideally I’d connect them all in parallel and be done with it. I’m guessing it’s not that easy.

If there is a max 400a load limit on these batteries, as it seems to be saying, does that mean the system can’t be put into one massive 1200ah battery (12P0S)?

If doing that would be a problem, is there another configuration that would allow me to build a 1200ah house bank with these batteries?


Maybe three separate banks of 4P0S going to one bus.


Also, I’ve head about there needing to be particular care taken when sizing the connections between lithium batteries when creating a bank. My understanding is this has to do with the BMS. Given that these batteries each have their own BMS, does this consideration still apply?


Given the 4P0S going to one bus idea above, I would potentiallyneed to vary the length of the connections.


Anyway, this is the first volley of what will surely be many questions to come. Thank you in advance for your thoughts and advice. It’s much appreciated…

[Pete7]

Well that's a huge lead acid battery bank you have at the moment but also you don't need to replace it with a 1200Ah LifePO4 (LFP) bank, you can use a smaller LFP bank and still have the same useable amount of power. This assumes you don't go lower than 50% with your lead acid very often.

Next I wouldn't buy 12 x 100Ah batteries, but 3 x 300Ah, or even 2 x 300Ah if you think that will suffice. Depends what you want to do with it. Therefore either record good stats from the existing lead acid bank on how much you use each day or work out an energy audit with a spreadsheet. You could buy two now and add a third later if you need to add capacity.

Also take into consideration how many connections you will need with 12 batteries. 3 will be much simpler, all going to bus bars.

Finally, those LFP batteries don't have any means of external communication like BMS or CANbus etc. Therefore, personally I wouldn't buy them because you can't alter the settings or see what is going on at cell voltage level. There is a reason they are cheap and a lack of features plus there is no such thing a class A batteries, is a red flag.

This is going to be an expensive installation, please don't cheap out on the batteries. If you wanted one to run a trolling motor and willing to accept it low quality fine, but for a large house bank, please find something else.

Have a good look at Will Prowse on You Tube and his battery tear downs were he shows what is in side for starter.

Pete

[Pete7]

This is what the Fakespot app has to say about one of the Amazon adverts I ran the app on

Pete

[SVSeaHawk]

Yes, I may not put in the full 1200ah but really I'm more concerned with understanding the limits of the battery I'm looking at. When people like Will Prowse talk about building large banks, they increase voltage. I dont want to do that. I want a large 12v bank.


I am somewhat limited with space so 100ah batteries are the best option despite the added complexity. As for external communications, I don't have that now with the AGM and doubt I'll miss it.


I don't know what you mean by "there is no such thing as a class a battery" they claim to be Grade A.

"And they are manufactured by Grade A LiFePO4 Cells with higher energy density, highest-level safety based on UL testing certificates. And we do 100% testing of all Redodo batteries before shipping to you, get it without any worries."


As for Will Prowse, he seems to be a fan back when the same battery cost ~$400 (and were s0ld under a different name), they are $224 now...

https://www.youtube.com/watch?v=74iBMHE3StM

I do like your suggestion that I use larger batteries and fewer but space is a huge problem on my boat. Right now I am looking for ways to stuff larger units into the space.


Thanks for the feed back. Please continue to dissuade me, it's helpful...

[CarlF]

Different brands of lithium batteries have different specs.

And length of warranty is very important when buying drop-in batteries. The better brands have 7-10 year full replacement warranties. It’s easy to sell for less on Amazon if you don’t have to worry about warranty costs.

So I would strongly suggest using a more established brand like Battleborn who has engineers who can help you with the design rather than asking people on the internet who don’t know anything about the brand you are buying.

I have a 1200ah bank of four 300ah batteries from Kikovault. The maximum number of batteries they allow in parallel is 4. More than that invalidates the warranty. Other brands allow more in parallel - although I don’t know if any allow 12.

And even though Will is a good guy he doesn’t know marine standards for lithium installation. If you ever have an insurance claim your insurance company will inspect the batteries and may deny the claim if your installation doesn’t meet ABYC specs.

[CarlF]

Different brands of lithium batteries have different specs.

And length of warranty is very important when buying drop-in batteries. The better brands have 7-10 year full replacement warranties. It’s easy to sell for less on Amazon if you have a crappy warranty.

So I would strongly suggest using a more established brand like Battleborn who has engineers who can help you with the design rather than asking people on the internet who don’t know anything about the brand you are buying.

I have a 1200ah bank of four 300ah batteries from Kikovault. The maximum number of batteries they allow in parallel is 4. More than that invalidates the warranty. Some other brands allow more in parallel but I’m not sure any allow 12. The advertised maximum bank size is usually based on using the maximum parallel AND maximum serial in the same bank.

The more batteries you have in parallel the more likely it becomes that your bank becomes unbalanced causing a few batteries to do most of the work and wear out sooner. The best parallel installations use “equal length cables” to avoid imbalance.

And even though Will is a good guy he doesn’t know marine standards for lithium installation. If you ever have an insurance claim your insurance company will inspect the batteries and may deny the claim if your installation doesn’t meet ABYC specs. Some also require a licensed marine electrician to do lithium installations and will ask for his name and phone on your insurance renewal form.

[Wandering]

Large banks of parallel 12v cheap batteries will cause problems over time. Cheap lifepo4 batteries with no ability to interrogate cells voltages are not a good idea. If something is going wrong, you don't know what it is. Having a BMS that allows you to see and adjust settings is important. Cheap batteries with passive balancers do a poor job of balancing cells. If you have a rogue cell, they may not be able to keep up with cell balancing. This will often lead to the battery doing a high cell voltage trip.
Passive balancers in battery cases can cause hot spots on cells, leading to premature failure.
There are so many reasons not to buy cheap drop in lithium batteries. Don't do it, especially if you plan to put multiple in parallel.
You would be far better off with 2 or 3 better quality lithium batteries in parallel to meet your capacity needs. Those batteries should have active cell balancing and a good user adjustable Bluetooth BMS.
If you were happy with 1200Ah of AGM previously, assuming you didn't take them below 50%, so had 600Ah of usable capacity, you would likely be more than happy with 1000Ah of lithium. This would allow you to cycle them in the 20-80% range for great battery life and have similar available capacity.

[Pete7]

Originally Posted by SVSeaHawk

Thanks for the feed back. Please continue to dissuade me, it's helpful...

So if one of these Redodo batteries fails in a few months, what is the company address you are going to use to send it back? I can't see the address.

Little bit different with Battleborn or Dakota Lithium.

Pete

[CrispyCringle]

Why do so many Asian manufacturers that intend to market to the US have such ridiculous names- Redodo?! Absurd! I couldn't buy it for the name alone. Amazon is littered with company names like this. How much man-on-the-street market research does it take to figure out almost anything is a better name than what a lot of these companies come up with?

And now we return to your discussion about marine batteries....

[dannc]

I would suggest that the OP go read https://marinehowto.com/drop-in-life...ated-consumer/ regarding drop in batteries and other articles on Rob's website.

Later,
Dan

[sailingharry]

Originally Posted by CarlF

If you ever have an insurance claim your insurance company will inspect the batteries and may deny the claim if your installation doesn’t meet ABYC specs.

You hear this a lot on here. It may indeed be true. But I look at it the question slightly differently.
Is this a safe installation? Will it burn my boat down? Will it leave me stranded at sea?
I consider insurance coverage on any incident that a battery could hypothetically create as being secondary to my living through the incident.
If a battery has a non-trivial risk of leading to an insurance claim, it has about the same risk of leading to my death, and it won't be on my boat. However, I believe the mantra that we hear over and over again that LFP is at least as safe as AGM. Even cheap no name LFP.
I believe that LFP in general is every bit as safe as AGM. And I believe that cheap LFP have a significant risk of blowing up my alternator or initiating a load dump at an inopportune time (which would be a direct result of my being inatentative or careless), but I don't believe that they carry a significant risk of initiating an insurance claim.
What kinds of failures do you see in a cheap LFP that could result in an insurance claim? I don't see any.

[sailingharry]

Originally Posted by CrispyCringle

I couldn't buy it for the name alone. Amazon is littered with company names like this. How much man-on-the-street market research does it take to figure out almost anything is a better name than what a lot of these companies come up with?

And now we return to your discussion about marine batteries....

Along those lines, what idiot came up with the leading slip reservation app? Dockwa? Seriously?
Even putting aside the name, I hate it with a passion. It adds cost to the process, complexity to the process, and adds no value.
But the name? I can't even say it without barfing!

[Kd9truck]

As a retired captain on the FDNY I will caution the purchase of lithium batteries from questionable sources. NYC is suffering a now 5 year spike in fire related fatalities directly because of the indiscriminate use of “cheap” lithium batteries.

The fault in charging tech is the cause, be careful.

[landsend]

Originally Posted by sailingharry

Along those lines, what idiot came up with the leading slip reservation app? Dockwa? Seriously?
Even putting aside the name, I hate it with a passion. It adds cost to the process, complexity to the process, and adds no value.
But the name? I can't even say it without barfing!

Got you beat! How about.....WAWA...seriously!

[GreenWave]

Originally Posted by Kd9truck

As a retired captain on the FDNY I will caution the purchase of lithium batteries from questionable sources. NYC is suffering a now 5 year spike in fire related fatalities directly because of the indiscriminate use of “cheap” lithium batteries.

The fault in charging tech is the cause, be careful.

Respectfully, this is apples and oranges. 99.9% of lithium battery fires have nothing to do with LiPO4... even cheap ones.