Maximum recommended cell size.

[UFO]

Originally Posted by GILow

I would love to see more of your battery build.

FWIW, 280AH cells seem to be the sweet spot in Australia at the moment. Can’t speak for other countries.

Yeah the 280's are cheap to buy, ship and import into Australia



I have moved off the boat onto land very recently - Giving the kids some real school time, rather than our flaky homeschooling



Next time I am down there I will try and remember to grab some photos - Not an easy angle to photo though to get a good idea of the ply enclosure - They are underneath one of the beds with lots of other stuff.

[s/v Jedi]

I just ordered a 2-pack of Li-Time 24V 200Ah batteries. I’ll get to test and compare Winston vs cheap drop-in batteries. With Winston you get more capacity than their rating but I think these Li-Time batteries have 205Ah cells so that will make 410Ah too.

There’s a 5% off coupon for Presidents Day.

[UFO]

Originally Posted by s/v Jedi

I just ordered a 2-pack of Li-Time 24V 200Ah batteries. I’ll get to test and compare Winston vs cheap drop-in batteries. With Winston you get more capacity than their rating but I think these Li-Time batteries have 205Ah cells so that will make 410Ah too.

There’s a 5% off coupon for Presidents Day.

Got 1120Ah Eve (12V) for less than that! You just have to be willing to negotiate directly with the factory and do all the importation yourself.


The risk being though, if you get a dud or duds its your headache to sort out.

[s/v Jedi]

Originally Posted by UFO

Got 1120Ah Eve (12V) for less than that! You just have to be willing to negotiate directly with the factory and do all the importation yourself.

The risk being though, if you get a dud or duds its your headache to sort out.

These are not cells, but 24V drop-in batteries with a 200A BMS each.

I paid $3,200.- for the Winston cells but then had to pay for international shipping, duty, tariffs and all the materials to build the battery from those cells.

[UFO]

Originally Posted by s/v Jedi

These are not cells, but 24V drop-in batteries with a 200A BMS each.

I paid $3,200.- for the Winston cells but then had to pay for international shipping, duty, tariffs and all the materials to build the battery from those cells.

Yeah I got they were drop-ins, just seemed a really expensive way to go.



You are right though that there is an ancillary cost of setting up the cells.



Just out of interest What happens if you exceed 200A with the BMS? - Does it cut off supply or does it fry?


Managed 285A out of my batteries once and even more on one time, as we had the air fryer and both induction rings going and then my wife turned on the toaster - Breaker switch went instantly at that point.

[Loredo]

I just finished the build of my battery pack made out of EVE LF280K (twin screw terminals). The most IMPORTANT part is getting the hands on REAL(!!!!) grade A cells. Nkon in Europe (NL) delivered!
I've learend a lesson doing it. It's a lot of work and further expenses for various stuff (after the cells) takes also a lot of boat bucks.

[rabbi]

Re EVE cell quality and QR codes:
There is a lot of junk out there. I don't think it's hard to identify genuine cells once you have them in front of you, but nearly impossible when ordering.

EVE tests each cell leaving the factory. Good ones (A grade ) receive a QR code laser engraved into the case at exactly the point shown below.
If the QR code is on the other side of the overpressure hole or any other place: Fake. Possibly B grade with a new fake QR and a new black top cover to hide this.
If it's a sticker and not engrave into the original case: Fake


If a cell does not pass the test for A grade, the QR code is overwritten at the EVE factory with a "B". Nobody knows the reason why a B grade cell is B grade, it could be anything but I would not believe a supplier stating it was just for cosmetical reasons.
A big "B" doesn't necessarily mean it's a B grade EVE cell. Could be anything, I have seen cells with "B" fake stickers.

True genuine A-grade cells come straight from a sterile factory and they look like that. Not even the smallest spot of dust or dirt, no stain, no scratch, no fingerprints. Just like a brand new sealed IPhone doesn't have finger prints or "tested" stickers.

You can decipher the QR code with a few apps, they give you some information about the cell (serial number, production date, plant line).
Genuine suppliers will send you the EVE test report upon request, which is a Excel sheet with about 1000 cell results, where you can look up the serial number. Gives you capacity, shipping voltage, weight down to the gram, and what not ...

Any shop promising "matched" cells, or "tested" cells, and even put test result stickers on them: fake
True A grade don't need any further test, they are already "matched". Only B grade cells need matching.

So where to buy? I am aware of three sources I would trust.

EVE
AFAIK it's hard to get a direct deal with EVE but not impossible. They recently started taking orders from German customers, which are fulfilled by a recently opened German warehouse.

https://NKON.NL/
I recently received genuine A-grade EVE LF280K cells (QR codes OK, cells produced about 10 weeks ago, with test report and all that) from NKON
NKON also sells untested B grade cells at much lower prices, and are reported to be very fair when it comes to replacing the odd cell that doesn't match the others. From a "bang for the buck" perspective these are good deals IMO

https://nge-tech.en.alibaba.com/
About a month ago a buddy received the same genuine A-Grade cells from NGE via Alibaba. If you purchase from NGE make sure you also order their busbars to connect the batteries without stressing the poles (very few busbars on the market for the new cells with twin terminals).


I would have preferred Winston but their quote was 3x the NKON quote. While surely good cells it's unlikely they will last 3x longer.
And if they did I won't be around anymore.

[rabbi]

Originally Posted by GILow

I have found what appears to be a legitimate vendor of Eve cells here in Australia. He claims to be selling new cells, but what are called storage grade. He says they are cells that have failed quality control in China for electric vehicles. All new, all QR coded and all wth warranty.

In his favour is that he is somebody who actually answers the phone when you call him. Something that is increasingly rare these days. He also has a physical address that checks out.

On balance, I think I trust what he is selling.

Storage grade means the cells have failed the EVE quality control for automotive - but the supplier thinks it is OK for "ESS - Energy Storage Systems" like house, RV, boat.

Some cells may fail the test requirements due to minimal deviations, others may be junk. Nobody knows but EVE.
So OK for "energy storage systems" can mean anything. Just not good enough for automotive.

[s/v Jedi]

Originally Posted by UFO

Yeah I got they were drop-ins, just seemed a really expensive way to go.

You are right though that there is an ancillary cost of setting up the cells.

Just out of interest What happens if you exceed 200A with the BMS? - Does it cut off supply or does it fry?

Managed 285A out of my batteries once and even more on one time, as we had the air fryer and both induction rings going and then my wife turned on the toaster - Breaker switch went instantly at that point.

The extra costs are significant. I paid $700 for transport, $224 tax, $385 tariffs and $600 for extra materials for building the battery, total $1,909.- extra plus the $3,200 for the cells is $5,109.- for the 10.24kWh battery using Winston cells.

And that’s cheap because others buy a BMS that’s already $1,000.-

Note that there’s two batteries in parallel so 400A capacity. The BMS will disconnect the battery when amperage goes over this value. There’s a 5 year warranty.

[Loredo]

GILow,

I think you did not yet get a clear answer to your original question. What AH
cells to use? I *think* the answer is this : cells like EVE have a thin aluminum case, contrary to Calb / Winston which come in a stout plastic case. That thin aluminum case is then wrapped with an even thinner plastic sheet.

So, with EVE style cells you need to make sure they can't move and / or get punctured or otherwise damaged. At the same time the EVE terminals are a bit on the fragile side. Since the (EVE) cells expand and contract a bit during charge / discharge, you want to compress the cells in order to not put stress on the terminals due to them moving. Anyhow, with a correct build I don't see why the 280AH size cell shouldn't be used for our applications.

I'd venture to say that you build your batteries choosing the cells based upon the physicle size that fits your needs best. At least that's what I did, no Winston cell size would've fitted in my boat giving me decent AH's.

Everything rabbi sez above : AMEN!

[noelex 77]

Getting back to the original question: the concern with large cells is that there is more potential for internal damage caused by shock loading and vibration acting on the large surface area.

Yachts can suffer from high shock loads when, for example, pounding in large seaway.

I have no idea how valid this concern is, or if it is an issue then at what cell size does this becomes a practical problem. It would be nice to hear some opinions.

[s/v Jedi]

Originally Posted by noelex 77

Getting back to the original question: the concern with large cells is that there is more potential for internal damage caused by shock loading and vibration acting on the large surface area.

Yachts can suffer from high shock loads when, for example, pounding in large seaway.

I have no idea how valid this concern is, or if it is an issue then at what cell size does this becomes a practical problem. It would be nice to hear some opinions.

There is not more potential for damage with large cells. There have been stories in the far past which probably were old wives tales from people killing their cells but unable to accept they did.

The biggest LFP thread on CF centers around an installation with 1,000Ah Winston cells. I wonder if they still work, I thought I remember some trouble but I don’t think anything about them being too large.

[GILow]

Well, the thread drift has drifted back to the original question, but, frankly, it’s mostly been pretty relevant drift my my point of view, so no complaints from me.

It does seem the question of cell size is not a the problem my friend thought it might be, but even in our discussion he was clear that he wasn’t sure, he just flagged it as a possible concern.

On a side note, the whole shock loading thing from pounding boats did make me laugh. One of the side benefits of sailing heavy old conservative (and slow) boats like mine is that pounding or shock loads just don’t seem to happen. We were stuck in a moderate gale a few weeks back, after being blown out of the bay we were anchored in a number of times, sailing back and forth waiting for the winds to abate. At some time around 3 am a freak wave hit us with a mighty bang and some light spray made it into the cockpit. We were both almost indignant that something like this could happen. It was the first time in over 5000 miles of sailing. I’m not sure how the new boat will compare, but I suspect it will be a similarly gentle ride.

[CaptainRivet]

Originally Posted by s/v Jedi

There is not more potential for damage with large cells. There have been stories in the far past which probably were old wives tales from people killing their cells but unable to accept they did.

The biggest LFP thread on CF centers around an installation with 1,000Ah Winston cells. I wonder if they still work, I thought I remember some trouble but I don’t think anything about them being too large.

CatNewBee has 4x1000AH, effective 1200AH cells and they run fine.
He had bit of trouble after a year as the bank run out of balance as is heavily using them and only charged them to 3,55V. Charging to 3,65V and Additional active balancer on his REC BMS cured that.
Looking at Jedi price for Winston in total you can buy directly Victron drop ins, they have Winston cells internally.

[s/v Jedi]

Originally Posted by CaptainRivet

CatNewBee has 4x1000AH, effective 1200AH cells and they run fine.
He had bit of trouble after a year as the bank run out of balance as is heavily using them and only charged them to 3,55V. Charging to 3,65V and Additional active balancer on his REC BMS cured that.
Looking at Jedi price for Winston in total you can buy directly Victron drop ins, they have Winston cells internally.

I still did not need to balance my 8x Winston 400Ah and I’m 2 years in.

While ai do like the Cerbo GX, I don’t like the high level of Victron integration of their batteries, BMS and Cerbo GX.