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

[evm1024]

Originally Posted by john61ct

Interesting.

What brand / model cells?

No wonder they're careful about C-rates!

SheesH!

A Winston LFP100AHA is rated for 3 C cont discharge.

A 3.3 AH 26650 cell is rated for 3 C cont discharge.

Battleborn uses a 30P4S config of 3.3 AH 26650 cells (or equiv) and the actual cells are rated for 3 C cont discharge (3.3 x 30 x 3 ~= 300 amps)

When you compare the actual cells they come out the same in terms of discharge currents.

For those who did watch the video and also had a look at other drop-ins like Valence it would be obvious that the internal wiring is a major factor in setting the recommended cont discharge current. Simply engineering tradeoffs for a drop in.

If you were to build a house bank using the Winston cells and using the same total wiring cross section as in a Battle born you would find that the Winston would have the same recommended cont discharge current as the battle born.

I do want to add that a 1C cont discharge current is not shabby. And that battleborn lists 2 C as a 30 sec limit and larger for pulse discharges.

Battleborn batteries have been engineered to a reasonable, conservative standard. A standard that matches the intended design quite well I might add.

To compare the raw specs of a prismatic cell to a complete system such as the Battleborn is specious at best.

[john61ct]

"Rated" current has no relationship to a limit actually enforced by a sealed up, non-adjustable BMS.

Yes I agree no comparison.

If they are A123 26650s that would be nice.

K2, VariCore / Liitokala meh

Full River, pass for sure

[evm1024]

Originally Posted by Dockhead

I have 10 horsepower bow thruster, so I'm following this with interest.

I've been thinking about starting a new thread on this type of application.

I do not have a bow thruster but do have a windless and a remote battery to drive it.

Currently I've got a sealed lead acid battery with a 10 amp charger up in the bow. I'll likely replace it with a LiFePO4 setup before we start full time cruising.

If I were to start a new thread it would be to document our setup.

[evm1024]

Originally Posted by john61ct

"Rated" current has no relationship to a limit actually enforced by a sealed up, non-adjustable BMS.

Yes I agree no comparison.

If they are A123 26650s that would be nice.

What are you talking about John?

Pulse currents are greater than 200 amps from the Battleborn battery. There is no BMS limiting output current it appears. So why enter FUD into the conversation (Fear, Uncertainty, Doubt).

And why name drop A123?

You have an opinion and are welcome to have one. But please supply some Facts.

Show us the Facts that place A123 above others.

I think that we all have to up our game if we are going to stay credible.

[john61ct]

Originally Posted by evm1024

There is no BMS limiting output current it appears

So the only OCP is that supplied by the user?

[evm1024]

Originally Posted by evm1024

There is no BMS limiting output current it appears

Originally Posted by john61ct

So the only OCP is that supplied by the user?

Yes John.

Originally Posted by Battleborn Spec

100 Amp Continuous Current
200 Amp Surge Current (30 Seconds)
1/2 second surge for higher loads

[sparrowhawk1]

Damn you guys are patient. I thought this thread was started specifically for people that are actually using them.

[newhaul]

Originally Posted by sparrowhawk1

Damn you guys are patient. I thought this thread was started specifically for people that are actually using them.

That is what i assumed several years ago when i started following and posting here .
Considering the title it still should be .

[Checkswrecks]

Originally Posted by john61ct

Nor does anyone afaik use them for house banks. Obviously I was referring to the plastic-shelled prismatics, usually 20Ah and up.

Aluminum cased, I dunno.

There are definitely people using cylindrical for house banks. Start asking at the trade shows and you'd be surprised how many. I was. fwiw, NASA and other aerospace designs call for something like 1.5 mm between cylindricals to minimize heat transfer after some EVA backpack test cascading failures.

Somebody mentioned tight-packing prismatic cells and questioned whether they had internal space for movement. They do, as can be seen here.


Under pressure the big flat side will still swell slightly and this gives two problems. People in the thread have area discussed thermal transfer, but the other problem is a bit more insidious. When tightly packed, we found that even with the usual slightly arched buss bars, the strain put on the cell terminals was significant enough to break the hermetic seal. Forcing the prismatic apart in their middles would basically lever the amount of movement at the buss bars located toward the ends of the cells. Because the cells breathing as well as out, they could then "inhale" moisture laden air, creating acid and killing the cell.

Having even a mm or two of space between cells is a good thing.

[john61ct]

Originally Posted by Checkswrecks

There are definitely people using cylindrical for house banks

That term in this context meaning auxiliary loads on a boat, and House as opposed to Starter.

I am aware of DIY Powerwall efforts in S&B homes, but there non-LFP chemistries are the norm, and even recycling used cells from laptops, and other horrifically dangerous practices IMO.

[Checkswrecks]

Originally Posted by john61ct

That term in this context meaning auxiliary loads on a boat, and House as opposed to Starter.

I am aware of DIY Powerwall efforts in S&B homes, but there non-LFP chemistries are the norm, and even recycling used cells from laptops, and other horrifically dangerous practices IMO.

Don't be so quick to dismiss cylindrical because there are manufacturers building square boxes containing cylindrical cells to be used as drop-in replacements and you'd never know. I also personally know somebody in the battery industry who built his own house and starter batteries of cylindrical cells. fwiw, Mainesail even refers to cylindrical. https://marinehowto.com/lifepo4-batteries-on-boats/

[john61ct]

I'm not saying anything negative about LFP round cells, specifically I'd jump on anything a reputable pack builder makes from new recent grade-A A123's.

But I'd likely never be motivated enough to get a spotwelder to build my own, life's too short.

And the price per kWh for A123 is usually sky-high.

And the other LFP cylindrical vendors nowhere near as good.

And no way I'm touching the 3.7V propulsion LI chemistries (e.g. LCO, LMO, NMC & NCA) for House bank use inside a living space, especially a small mobile one, any more than I would EV packs.

So, do you see how all that isn't me just being "quick to dismiss cylindrical"?

I also am not impressed with any drop-ins so far, at all, and

I would not recommend buying products where the actual manufacturer of the LFP cells is not known to be excellent.

[evm1024]

Originally Posted by john61ct

I'm not saying anything negative about LFP round cells, specifically I'd jump on anything a reputable pack builder makes from new recent grade-A A123's.

But I'd likely never be motivated enough to get a spotwelder to build my own, life's too short.

And the price per kWh for A123 is usually sky-high.

And the other LFP cylindrical vendors nowhere near as good.

And no way I'm touching the 3.7V propulsion LI chemistries (e.g. LCO, LMO, NMC & NCA) for House bank use inside a living space, especially a small mobile one, any more than I would EV packs.

So, do you see how all that isn't me just being "quick to dismiss cylindrical"?

I also am not impressed with any drop-ins so far, at all, and

I would not recommend buying products where the actual manufacturer of the LFP cells is not known to be excellent.

Actually, you appear to be quite dismissive of cylindrical LiFePO4 cells. Of course you are entitled to your opinion, no question about that. I'm just wondering how you formed your opinion and what facts you base it on.

Take the comments RE spot welders and A123 cells. Cells with screw terminals are pretty much dismissed because of what? Can you point to a head to head test of (oh say) A123 vs Headway? For example.

Let's consider drop-ins. I am quite impressed with Battle born drop-ins. The specs are good. They match the capacity of each parallel cell group to the others and have some serious testing behind their product.

Hospitals use drop-in batteries for their portable medical carts. It appears that their opinion of drop-ins is such that they are willing to use them in life and death situations. As a side note I'm trying to find out how to get my hands on a few that have been placed out of service. That would go with my windless battery replacement project. I just have to find the right person here at work to point me in the right direction.

Then let's take your recommendation to not buying products where the actual manufacturer of the LFP cells is not known to be excellent. I wonder how you came to that opinion.

Take Victron LiFePO4 for example. Could you recommend these batteries (even though they are expensive)? Victron does not make the LiFePO4 cells they only repackage others cells and add in some electronics (much like Battleborn).

I am only aware of who makes the cells for Victrons 60 AH LiFePO4 battery. And I would like to know which cells they use for their larger batteries.

[nebster]

Moreover, Victron doesn’t even “make“ their larger batteries. They rebadge another company’s product line.

Ascribing value to brand is reasonable, but it’s hard to do that if the assessor doesn’t really have a clue where the market is today — how much stuff is being sold, how it’s being deployed, who is happy.

Actually living in the environment, with a lot of other consumers of this technology, and seeing what they are buying and using is very instructive. Most of them are not on a forum debating technical details, nor should they be. It’s no surprise to me that it’s hard for some internet forum people to really grasp what is going on in the real world.

[john61ct]

I'll say it again, A123 cylindricals are fantastic for what they are, but not for this use case unless

a known-good vendor was selling them reasonably priced

and I knew an excellent pack builder nearby, given the recent shipping nightmares.

I cannot imagine those factors coming together to compete with the value proposition of prismatics from the likes of CALB and Thundersky.

Also with Headways, def not as long-lived as A123, but also a moot point since I've never seen the price per kWh get reasonable, even in pallet loads sold secondhand.

In general, the secondhand market at least stateside is either grossly overpriced or **very** much a roll of the dice.

Those ex-bus packs out of Montreal are 95% dead as a doornail so not even worth the shipping. If you drove a 2-ton direct to the yard and made a deal at 5¢ per Ah after winnowing the half-good ones yourself, maybe. But worth your time? not IMO.

Yes Victron's I would trust, but seeing as their cell-level data and BMS controls are nicely accessible, even via open-source controls, I don't consider them "drop-ins", more a fully packaged system or maybe could call it a hybrid I suppose.

And I'm not claiming BB is not a great choice for some use cases, just not mine, not for me.

If I learned A123 was their OEM maybe, but they're probably K2 or Liitokala, or even Full River, meh.