12V 280Ah LiFePo4 battery Build and Test

[MatMat]

I would of love to see a rendering of your design, I'm not quite following it

pls. see the picture above - hope that explains the idea better. The side panel will be customized to hold the BMS, fuses, battery computer etc.

The (6) studs going trough the small the holes of the modules holding the case together are not yet visible on this sketch...

 

[Ampster]

What would be the main advantage / disadvantage to used studs instead of bolts ? Thanks for the help.

Without regard to the case the reason I used studs is because I can take them all the way to the bottom and back them off 1/4 turn. I also use Red Permatex. I still use a hex key when tightening to make sure they don't turn. With bolts I would have to use varying lengths and washers to get maximum thread depth. This way fewer parts, just Nordlock washer and nuts can handle any combination of buss bar and lug thickness.
In your design, are the buss bars above the case?

 

[MatMat]

In your design, are the buss bars above the case?

The busbar is in the case, the case has two "roofs". The holes on the top will be closed with caps, this way I have a clean box.
Once I have this finished I can share the .stl files , if somebody wants to print it...

The use of Nordlock washer is a good idea!

 

[MatMat]

Heap64 said:
I might need to see it with the cells in it? Are you slipping the cell in then adding the buss bars and bolts?

Exactly, you slip each cell in its case module, slide the modules over the 6 studs holding them together and mount the busbars. I will use custom made bus bars from Cu material (4 stripes and 1 "U"), because the pack looks like this:

may be I should move this to another thread not to destroy your flow here, Haugen ?

 

[BiduleOhm]

What would be the main advantage / disadvantage to used studs instead of bolts ? Thanks for the help.

Avoid busbars turning with the bolt when there's only the first one present, torque is more precise, less chances of ripping the terminal threads, more threads engaged in the terminal, can't bottom out in the terminal without clamping the busbar like a bolt who's too long, ...

The use of Nordlock washer is a good idea!

Yea, far better than the split washers (who are almost useless...) but harder to find and more expensive.

Edit: lots of good stuff on this article: https://engineerdog.com/2015/01/11/10-tricks-engineers-need-to-know-about-fasteners/

 

[MatMat]

but harder to find and more expensive

I was brave and just ordered a box of stainless Nordlock washers, matches almost the price of one LF280 cell ?

 

[Luthj]

There are low strength threadlocker options.

Permatex® Low Strength Threadlocker PURPLE

OEM specified. Low strength threadlocker designed for fasteners under 1/4" (6mm) that require occasional adjustment. Removable with hand tools for easy disassembly. Noncorrosive. Conforms to ASTM D 5363 AN0311 (Mil-S-46163A, Type II, Grade M).

www.permatex.com

Amazon.com

• Ideal for fastener diameters of 1/4" and smaller
• Controlled lubricity for accurate clamp loads

 

[Heap64]

Exactly, you slip each cell in its case module, slide the modules over the 6 studs holding them together and mount the busbars. I will use custom made bus bars from Cu material (4 stripes and 1 "U"), because the pack looks like this:

may be I should move this to another thread not to destroy your flow here, Haugen ?

Yes sorry for the detour.

 

[MatMat]

Yes sorry for the detour.

No, no problem , your questions are welcome - I was just unsure myself about the etiquette here...but if nobody is complaining I'll continue to share my LF280 project here too

I was a little uncertain if I would get genuine, new, grade A cells from UNIS. After measuring them everything looks good so far!
A performance and load test is not yet done, as the cells need some more time for loading and balancing....

 

[Haugen]

I would be reluctant to put any version of a thread locker on a bolt that goes into a battery terminal. For starters, it's going to throw off the already miniscule torque setting. Plus, should you need to remove the bolt it may require more torque than the terminal can handle.

Loctite doesn't add a significant amount of adhesion. It fills in the threads after the bolt is torqued. When removing, there should only be a moment where you overcome the grip and the rest is threads chasing down the same path.
Just don't use the red stuff.

 

[HRTKD]

Loctite doesn't add a significant amount of adhesion. It fills in the threads after the bolt is torqued. When removing, there should only be a moment where you overcome the grip and the rest is threads chasing down the same path.
Just don't use the red stuff.

I used Loctite Red on a project a couple weeks ago, thinking the fastener was going to be permanent. Oops. l also used Loctite Blue on the same project. This was on about 150 SAE size 6 bolts/nuts. The red was on there quite tight, but did come off with simply physical persuasion. Oddly enough, the blue was also on tight. Not as tight at red, but tight enough that I needed to secure both ends of the bolt to loosen it. With both red and blue there was an audible breaking of the bond.

 

[MatMat]

I'm looking for 1/0 AWG 54mm2 silicone flexible cables as a connection between the LFP pack and the inverter.

I have such short cables on my DALY 4s 250A BMS, its ultra-flexible (bends at approx. radius = 2* cable diameter), has Sn coated Cu wires and heat resistance up to 200°C.

Do you have any recommendations (brand manufacturer name/ source) ?

Many thanks

 

[HRTKD]

I'll be using TEMCo wiring. It's welding wire in 2/0 gauge. Go to this page to see what they have: https://temcoindustrial.com/shop/wire-cable-accessories/welding-cable

 

[Ampster]

Just don't use the red stuff.

Of course the red stuff is precisely what I used to lock my studs in my cells. After 24 hours they are in and don't seem to want to move. I still use a hex key when I tighten the nuts but they haven't moved.

 

[Pi3.14]

Liquid electrical tape, or hot glue gun will seal from oxidation.

 

[Haugen]

Liquid electrical tape, or hot glue gun will seal from oxidation.

In the very short term, sure.
More than a couple months, there will not be a seal.
Even military grade "sealed" connectors allow moisture and oxygen in. Changes in barometric pressure or temperature will force moisture and air past any seal. I have seen it when testing to MIL-STD-810.
Unless the device is going to be in a climate controlled area with minimal humidity, you have to design it to resist corrosion.

 

[Haugen]

I'm looking for 1/0 AWG 54mm2 silicone flexible cables as a connection between the LFP pack and the inverter.

I have such short cables on my DALY 4s 250A BMS, its ultra-flexible (bends at approx. radius = 2* cable diameter), has Sn coated Cu wires and heat resistance up to 200°C.

Do you have any recommendations (brand manufacturer name/ source) ?

Many thanks

I have some Arctic Superflex Blue that might be just what you are looking for.

Arctic Ultraflex Blue Wire - Bulk - 8 AWG to 500 MCM - Polar Wire

store.polarwire.com

 

[AussieSim]

I ordered the cells from Shenzen UNIS. The pandemic made the delivery time 52 days.
They arrived in good condition. The only physical damage was one label on top of a cell was peeled up on one end. It might have happened when sliding the cell into the box and the edge caught the foam.
They want me to test first before sending a replacement label.
Cell voltages as received:
1 - 3.2970
2 - 3.2992
3 - 3.2997
4 - 3.2995
View attachment 15398View attachment 15399

I made my first order from Xuba (still shipping) at about $82 but see there are other Alibaba vendors selling from :
$70-73 with zero sales/reputation
$74-78 like Basen, UNIS, Billion

What worries me in this $74-78 range is that I see multiple Alibaba feedback posts saying one cell had a low voltage, and several posts like yours showing a damaged label



Having seen Will's video on an Aliexpress vendor sending him a used rewrapped unmatched battery, seeing multiple reports of low cell voltage and damaged labels worries me.

In the same vein, Will posts about buying used reduced capacity batteries on Aliexpress and see BLS are selling "Grade A ? 240Ah" CATL cells.

1150.0US $ |4pcs 3.2v 240ah Ess Lfp Cell Lifepo4 Aluminum Shell Battery Catl Lithium Iron Phosphate Solar Not 200ah 280ah Eu Us Tax Free - Rechargeable Batteries - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

a.aliexpress.com

New BLS Battery Cells - Small amount of liquid leaking from the vent cap - normal?

I've had these cells for about 2 days and I've noticed on 2 of the cells there's a tiny amount of liquid bubbling out of the vent as they're being charged. I've been very careful not to overcharge them. Is this something to be concerned about? The voltage of the cells are all in the normal...

diysolarforum.com

I have no idea whether the EVE 280Ah cells Xuba / Luyuan are selling are of better grade or warranty support than those of Billion/UNIS/Basen, etc but for my needs (8 cells + shipping by sea) I am happy to pay a few dollars more. Perhaps if I were ordering several dozen cells, I might have to haggle over the price.

I've just seen this post in my new feed

Amy of Xuba confirmed to me that the 280Ah LFB Xuba sells are from EVE and stated that they are Grade-A as well as in continuous supply under a long-term supply agreement with EVE...

 

[Haugen]

I made my first order from Xuba (still shipping) at about $82 but see there are other vendors selling from :
$70-73 with zero sales/reputation
$74-78 like Basen, UNIS, Billion

What worries me is that in this $74-78 range I see multiple Alibaba feedback posts saying one cell had a low voltage, and several posts like yours showing a damaged label

Having seen Will's video on a used repackaged battery he was sold, seeing multiple reports of low cell voltage and damaged labels worries me.

I have no idea whether the 280Ah Xuba / Luyuan are selling are of better grade or warranty support than those of Billion/UNIS/Basen, etc but for my needs (8 cells + shipping by sea) I am happy pack a few dollars more. Perhaps if I were ordering several dozen cells, I might have to haggle over the price.

My cells definitely were not used when I received them. As I mentioned in posts above, there were a couple of light marks on the terminals which probably came from when they tested them. The internal resistance, voltages, and capacity all check out to the specification.
The label had an edge catch the packing foam either when packed, or from shipping.
I guess what I'm trying to say is that I've heard horror stories about Xuba as well. UNIS is no better or worse. I suspect that they all get the cells from the same source.
Pick the vendor you are comfortable with. You'll get the same stuff either way.

 

[Michael B Caro]

I made my first order from Xuba (still shipping) at about $82 but see there are other Alibaba vendors selling from :
$70-73 with zero sales/reputation
$74-78 like Basen, UNIS, Billion

What worries me in this $74-78 range is that I see multiple Alibaba feedback posts saying one cell had a low voltage, and several posts like yours showing a damaged label

View attachment 19940View attachment 19941

Having seen Will's video on an Aliexpress vendor sending him a used rewrapped unmatched battery, seeing multiple reports of low cell voltage and damaged labels worries me.

I have no idea whether the EVE 280Ah cells Xuba / Luyuan are selling are of better grade or warranty support than those of Billion/UNIS/Basen, etc but for my needs (8 cells + shipping by sea) I am happy to pay a few dollars more. Perhaps if I were ordering several dozen cells, I might have to haggle over the price.

I've just seen this post in my new feed

The companies that have been used by guys on here like Xuba, Billion, Basen, Unis, and Lightening are all selling basically the same cells, I believe.
They all say they are A cells, but I did have one vendor that said that there is no way to get true A cells for these prices. He sells them at the prices that the others do but says they are A- cells. He says that A- cells are the same good quality in every way, but they tested at 279ah instead of the full 280ah.
Now guys on here have tested these cells (Craig has tested a lot of them) and I am only aware of 1 cell being found that was not 280ah or more according to their tests, and that one was 279ah I believe.
So.....who knows for sure. I tend to believe the story about them being A-, but wouldn't bet the farm on them NOT being A cells either. In any case, they seem to be just fine for what we do with them.