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

[newhaul]

Originally Posted by john61ct

I never said they didn't. "They" refers to **Samsung** 18650s, which dozens of instances none are LFP.

I also stated I have no interest in the cylindricals in general, which out of dozens of form factors also happens to include the tiny 18650s.

If we "really need" to be snide about it,

maybe you need to try improving your reading skills.

Now personally, I'd really prefer it if we could refrain from the personal sniping Rob, don't you think that would be a nice resolution for this New Year?

nothing sinde about pointing out when a person states something that is not correct.

It helps everyone to learn

[john61ct]

Originally Posted by newhaul

https://voltaplex.com/lithium-ion-ba...8&s_chemabv=22

Can't get there from here ATM.

Maybe link to Samsung, or a datasheet?

Lots of misinformation at reseller sites

[john61ct]

Well since you removed the sniping from yours, I've done the same, appreciate it man. . .

Originally Posted by newhaul

nothing sinde about pointing out when a person states something that is not correct.

[evm1024]

Originally Posted by john61ct

You're the one brought up Samsung 18650s, are you trying to say they come in LFP?

Assumptions tisk tisk. Let me quote myself:

Originally Posted by evm1024

I only have 8 in the 18650 form factor. Samsung if I recall correctly.

But I'll grant you that it is hard to know everything about 18650 offerings.

Originally Posted by Samsung

The Samsung 11Q is a popular LiFePO4 lithium-ion cell. It is intended for use in 18650 battery packs. It can power a wide range of devices including a health monitor, watch recorder, or ignition system.

Originally Posted by john61ct

Have yet to hear anyone I'd trust give good long-term feedback on Headways, much less any no-name stuff. And have you priced how much 100Ah (smallest I'd make) would cost?

I could get by with a 50 AH bank provided the peak current rating was compatible with the peak current rating of my windless.

I don't know why you would limit yourself to making a (min) 100 ah bank. You could buy a battle born.

In cylindricals so far A123 (now part of Lithium Werks slong with Valence & Super B) is the only maker I'd bother with, and then only if I needed something pocket sized.

For prismatics, only Winston/Thundersky, CALB, GBS and Sinopoly.

It is nice that you endorse those companies. They do have name brand presence - but besides that what do you base your recommendations on? Having and expressing an opinion is everyone's "right". But having an opinion that has value is a different story.

For example:

I just went out to the garage to see what 18650 cells I have. My memory is not very good. It turns out that the cells are A123. If you asked me about those cells I would tell you that I picked them based on A123's reputation and that I did not have enough experience with them to form a useful opinion.

Just my way of seeing the world - others can do it their way.

[john61ct]

11Q / 11P

Wow, I'd forgotten about those, used to be in DeWalt packs over five years ago, surprised still on the market, but I suppose might be NOS.

Price is right, but under 2Ah, I don't think so, not for me anyway.

______
Yes anything from A123 over 20Ah maybe even 15Ah

known good trusted seller ideally North American warranty handling

Grade A new, recent mfg date

at a decent price per Ah compared to the others I listed

would be a very solid choice.

[newhaul]

Originally Posted by john61ct

Can't get there from here ATM.

Maybe link to Samsung, or a datasheet?

Lots of misinformation at reseller sites

https://voltaplex.com/samsung-11q-18...y-ifr18650-11q

And screenshot of relevant data on the page

[john61ct]

Originally Posted by evm1024

I could get by with a 50 AH bank provided the peak current rating was compatible with the peak current rating of my windless

Well the whacko propulsion guys will crank a huge diesel off 10Ah,

just because you can, doesn't make it something I would recommend.

But 20-30C should be pretty conservative, if you're not looking for much longevity.

Especially in the cold!

Personally, 2-3C is my limit, and that for only a few seconds at a time.

What size bank would that translate to for your windlass?

[evm1024]

Originally Posted by john61ct

11Q / 11P

Wow, I'd forgotten about those, used to be in DeWalt packs over five years ago, surprised still on the market, but I suppose might be NOS.

I see that your memory is much like mine.

I have 18650 to play with and to test out battery monitors on. Cost me $15 or $20 for the cells. Easy to get experience this way.

[john61ct]

Originally Posted by newhaul

https://voltaplex.com/samsung-11q-18...y-ifr18650-11q



And screenshot of relevant data on the page

So 1.1Ah. . .

[newhaul]

Originally Posted by john61ct

So 1.1Ah. . .

yes 1.1ah but they are Samsung Lfp 18650 cells .

[john61ct]

And what's your point in repeating that? Looking for a written apology for my mistake?

I'm sorry.

My point is, completely irrelevant to the actual main points under discussion.

Would **you** buy 364 of them at $2/Ah ?

So to build a 12V 100Ah pack, $800+ plus shipping and that's for just cells not counting all the other costs involved in building that sort of pack?

Plus time, research then buildout, holders, plates / strips, foam, tape, enclosure, wiring connectors?

Sorry the whole idea strikes me as just ridiculous.

And no, a drop-in would not be "better", no idea of longevity / build quality / chemical purity, who even makes the internals? Inaccessible cells, sealed BMS, depend on the company's survival for support, not for me.

Completely different product category anyway, not a component for a bank where flexibility and potential high rates are involved.

[john61ct]

Originally Posted by evm1024

I see that your memory is much like mine.

Probably much much worse, since I was a kid too, would lose my head if it weren't screwed on.

[newhaul]

Originally Posted by john61ct

And what's your point in repeating that? Looking for a written apology for my mistake?

I'm sorry.

My point is, completely irrelevant to the actual main points under discussion.

Would **you** buy 364 of them at $2/Ah ?

So to build a 12V 100Ah pack, $800+ plus shipping and that's for just cells not counting all the other costs involved in building that sort of pack?

Plus time, research then buildout, holders, plates / strips, foam, tape, enclosure, wiring connectors?

Sorry the whole idea strikes me as just ridiculous.

And no, a drop-in would not be "better", no idea of longevity / build quality / chemical purity, who even makes the internals? Inaccessible cells, sealed BMS, depend on the company's survival for support, not for me.

Completely different product category anyway, not a component for a bank where flexibility and potential high rates are involved.

Dont want anything i was just pointing out that they were Samsung and lfp 18650 cells thats all .

[john61ct]

As I acknowledged 8 posts ago, several times now

[evm1024]

Originally Posted by john61ct

Well the whacko propulsion guys will crank a huge diesel off 10Ah,

just because you can, doesn't make it something I would recommend.

But 20-30C should be pretty conservative, if you're not looking for much longevity.

Especially in the cold!

Personally, 2-3C is my limit, and that for only a few seconds at a time.

What size bank would that translate to for your windlass?

My understanding is that in a respectful conversation between equals people exchange information. I've asked a number of questions and not gotten answers.

But in the spirit of a respectful conversation between equals I'll answer your question.

I'm using an Ideal BHW windless that typically pulls 90 to 120 amps while pulling up my chain and anchor. It is rarely run for more than 60 seconds which works out to about 2 AH.

One reason I am considering 50 AH of 10 AH 38120 Cylindrical cells is due to their 3C continuous discharge spec with 10C for 30 seconds. That works out to 150 amp (3C) for the 60 second anchor pull with plenty of headroom for peak loads lasting a few seconds. Total discharge is around 4% of capacity.

As I said in the spirit of a respectful conversation between equals I hope that you will answer my question. I'm trying to figure out if the information and recommendations that you post are based on book (I guess internet now days) learning or if there is hands on experience or training behind the recommendations. Don't get me wrong, book learning is very valuable after all don't we say RTFM?

The question is: how many LiFePO4 packs do you have hands on experience with, what size pack and who made the cells?

Please do ignore this question if you find it disrespectful, threatening or otherwise out of line. I ask with a true desire to understand the basis of your recommendations so that should I act on your recommendations I do so with full confidence in the validity of your recommendations.