LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

[CatNewBee]

Originally Posted by john61ct

Yes, what I keep emphasizing, good lead is 1/3rd the price and locally sold quality LFP lots more expensive and less well supported.

Completely changes the risk profile when ROI only starts after ten years.

Sail over to buy it in Europe is realistic for some I suppose?

At lest sailing the Med in the summer time is a lot of fun, you can pick up your batteries and make a nice cruise from the saved money... ;-)

[Delfin]

Originally Posted by newhaul

who do you consider a major retailer
West marine carries them .
Wal-Mart has them .
Heck your local auto parts dealer likely has them .

I didn't know WalMart carried them... interesting.

[Delfin]

Originally Posted by senormechanico

How about at least 5 years use (can't remember the exact purchase date) with discharges as much as 83% a few times? Most daily discharges are taken to 40% (60% remaining).

The 200 aH LiFePo4 bank performs like new.


Has anyone considered that mat jam might just be a troll?

Well yes, that would appear to be a distinct possibility. Generally when someone who knows nothing about a subject contradicts everyone's experience and works overtime to resist learning, one is dealing with a troll.

[Delfin]

Originally Posted by transmitterdan

In an industry obsessed with fire risk one wonders how the name Fire Fly made it out of the marketing department. Not to mention the obvious double entendre of not putting them on airplanes especially due to risk of fire. Sheesh....

The original name was Flaming Armageddon, but the marketing department rejected that.

[newhaul]

Originally Posted by Delfin

I didn't know WalMart carried them... interesting.

Yep they have them site to store . Not cheap though.
https://www.walmart.com/ip/K2-Energy...ttery/47313386

Also 12 volt starting batteries for water toys
https://www.walmart.com/ip/LiFePO4-1...xoCAxUQAvD_BwE

[john61ct]

That's their "marketplace" for third-party sellers. Just like eBay and Amazon and Ali provide.

Not actually sold and backed by the company.

If we learn of a trusted vendor selling good quality product, fine, no problem.

But hardly "sold at Walmart".

[newhaul]

Originally Posted by john61ct

That's their "marketplace" for third-party sellers. Just like eBay and Amazon and Ali provide.

Not actually sold and backed by the company.

If we learn of a trusted vendor selling good quality product, fine, no problem.

But hardly "sold at Walmart".

sold by Wal-Mart therefore backed by Wal-Mart.

[tanglewood]

Originally Posted by mat jam

...but my summary IS that LifePO4 requires a lot of physical management in that if you want a long life cycle you should be careful how you use it which requires you doing a lot of managing in terms of the loads you put on it, how low you allow it to be discharged, etc.

I really don't think this is significantly different from AGMs. It's just that we are all really familiar with AGM protocols, and not LFP protocols.


It's really not that hard. Charge to a specified voltage. Once achieved, turn charger off, or reduce voltage so it carries any loads but doesn't continue to charge the batteries. When they drop to a certain voltage, start charging again. If you over charge them, you can bake them. If you let them go flat, you can bake them.


And there are a bunch of gotchas with AGMs. Leave them at a partial state of charge for too long and you bake them. Gotta get them back to a really full, full charge every few to several days or they will be baked.


Same story, different day.

[css145hs]

Originally Posted by caveman22

Anyone have experience with the Victron Lithium-Ion HE Batteries ? They are Lithium Nickel Manganese Cobalt Oxide (NMC) technology, energy density at 180kw/kg is outstanding, 24V, air cooled but with only IP22 rating.

Yes expensive but if weight matters (and it does to me) possibly worth it. Wondering if they are robust enough for a sailing cat. Certainly marketed as "Marine".

Possible advantages in assembling a full Victron system from Batteries, BMS, to Inverter aside from the hit to the wallet ?

Like to hear your thoughts and any comparable NMC batteries out there.

They're being installed in my new cat (actually already installed, but the boat is a month from completion so no actual experience with them). I'm not worried about them being suitable for a marine environment. However, I would call out a few key differences. As you've noticed, they are half the weight of typical LiFePo4 batteries for the same nominal watt-hour capacity, but you can't discharge them below 20% (the HE battery pack will cut you off), so they sorta have just 60% more power per kg. Pricing wise, they are 19% more than the LiFePo4 victron batteries (in the US) per usable watt-hour (excluding the 20%) but 40% lighter per watt-hour.

Another major difference, is that they have a lead acid discharge voltage curve, its effectively linear from 100% -> 20%, not the flat voltage curve we're used to with LiFePo4 batteries. This does not mean that they have the voltage sag of lead acid when you apply load, just that their resting voltage drops with SoC. I personally like this, as its much easier to tell SoC from the voltage (in my experience, shunt monitors aren't as accurate as I'd hope). It also means you can easily program voltage-based cut-offs for inverters, chargers, alarms, generator auto-start, etc. That said, it will have an observable effect on voltage sensitive electronics.

For me, the inverters will hide the voltage sag for AC equipment. Most electronics don't care. However, the watermaker and the winches/windlass will behave differently ~3V lower. I don't care about the watermaker, I turn it on and come back later. For the winches/windlass, yea maybe I'm giving up a little umph, but whatever. If the solar is doing its thing, the voltage should be on the high end anyway.

[tanglewood]

Originally Posted by mat jam

There should be objective reasonable verifiable facts presented. I have yet to hear any argument against the main points presented in the video - one being - that if you take your batteries below 50% SoC you can expect hundreds NOT thousands of cycles.

There are countless research studies demonstrating full charge to full discharge for 2000+ cycles. So I think the real questions is the credibility of the "if you take your batteries below 50% SoC you can expect hundreds NOT thousands of cycles" assertion.

[mat jam]

Originally Posted by Delfin

Well yes, that would appear to be a distinct possibility. Generally when someone who knows nothing about a subject contradicts everyone's experience and works overtime to resist learning, one is dealing with a troll.

It is always easier to ridicule someone than give the right answers.

If the data is so clear, why did you need to resort to subterfuge and obfuscation. What is becoming clear is that there are a number of posters with skin in the game trying to game the system. Dare I bring up the anchor comments and the push to promote certain anchors.

The numerous attempts to suggest the video is of no relevance speaks volumes. The video addresses the basic science and chemistry of LifePO4. Meaning any significant changes would require a new designation. Example, Firefly are referred to as Carbon Foam.

I am just someone who looking for answers not marketing hype.

[mat jam]

Originally Posted by tanglewood

There are countless research studies demonstrating full charge to full discharge for 2000+ cycles. So I think the real questions is the credibility of the "if you take your batteries below 50% SoC you can expect hundreds NOT thousands of cycles" assertion.

Then kindly post some from credible data from research labs - not from manufacturers. If you really believe manufacturers data then why do we have so much litigation over this? How are the Tesla, apple, 737, etc. max customers feeling about their purchases?

[mat jam]

Originally Posted by senormechanico

How about at least 5 years use (can't remember the exact purchase date) with discharges as much as 83% a few times? Most daily discharges are taken to 40% (60% remaining).

The 200 aH LiFePo4 bank performs like new.


Has anyone considered that mat jam might just be a troll?

I see no reason why some users can not achieve these results and most likely some will get past ten years. However, the selling point suggest it is a fait accompli for most users. Marketing? If 90+ users can achieve this great. But if only 50% achieve this, then what. With any battery, with care, it is possible to get past five years and some have gone past ten.

[mat jam]

Originally Posted by tanglewood

I really don't think this is significantly different from AGMs. It's just that we are all really familiar with AGM protocols, and not LFP protocols.


It's really not that hard. Charge to a specified voltage. Once achieved, turn charger off, or reduce voltage so it carries any loads but doesn't continue to charge the batteries. When they drop to a certain voltage, start charging again. If you over charge them, you can bake them. If you let them go flat, you can bake them.


And there are a bunch of gotchas with AGMs. Leave them at a partial state of charge for too long and you bake them. Gotta get them back to a really full, full charge every few to several days or they will be baked.


Same story, different day.

One of the reasons users are choosing LifePO4 is in the belief they can take them down to 20% with no degradation. And they are adding high current gear that they normally would not have considered using which is putting additional stress on the batteries. This all points to unnecessary stress on the batteries. Every battery irregardless of brand is not indestructible. Some are more durable than others but in the end they are just batteries and limited by their properties and these properties are a known science but some posters are trying to say otherwise.

[mat jam]

All I ask is for some hard data or science. I am not interested in getting into a tug of war. Just looking for answers. Post some hard data or sciences and we can lay this topic to rest otherwise we will ASSUME the video stands as is.