EVE 280Ah Lifepo4

[boboxx]

I just received my 4x Lifepo4 280Ah Batteries for the camper. After looking around I opted to try my luck with Dongguan Billion Electronic Technology. I was dealing with Wilson who was ok do deal with. I was given may excuses after I had placed the order to get an initial tracking number only to realized if was for a different order. Finally after 2 weeks of waiting the correct tracking number was sent. he kept blaming the logistic company. The order took about just under 4 weeks to arrive.

The cost per cell was 72$ (288$ total) and 220$ for shippint to Canada via UPS. Duty and brokerage was 55$ CAN

The cells where packaged poorly, each cell was individually wrapped in cardboard boxed (no padding) in and then placed in a lager box with bubble wrap padding. These where sold as "New EVE Cell A grade" but EV dosen't list a 280Ah cell. Looking at the cell it's hard to believe they are A grade as they have quite a few dents and pucks. Another stage thing is that cell sounds like flooded cells when turning them sideways.

https://www.alibaba.com/product-detail/EVE-LF280-3-2V-Lifepo4-High_62379079690.htm

Cell Voltage / Impedance
Cell A: 3.2879v / 0.19mΩ
Cell B: 3.2925v / 0.19mΩ
Cell C: 3.2927v / 0.19mΩ
Cell D: 3.2921v / 0.18mΩ

I'm still missing my BMS so I can't do much more with the cells as of yet, but I just tought I would share with you. I have no affiliation with Wilson or that company but I would not recommend dealing with that company.

 

[Barb]

I'll be interested to see how this works out. Compared to what I've been seeing on Alibaba and Aliexpress, that's an amazingly low price.

 

[msdmaddog]

thx would like to see more how these cells perform. as we need more reliable information on these alibaba and aliexpress cells

 

[msdmaddog]

haha nearly the same post at the same time, barb

 

[boboxx]

I should add that it did take a few request to get a tracking number from him and the the first one was incorect. The included bussbar are copper and the bolts are brass... interesting selection as the post are aluminium lol

 

[boboxx]

QR Label sample: 02YCB66710000J8CP0002054

 

[April]

Those cells are made by a big player in china and should be OK.

Jiangxi Ganfeng battery technology co., LTD.

Jiangxi Ganfeng battery technology co., LTD. is the first listed company in the lithium industry in China, specializing in the research and development, production and operation of new lithium ion batteries, the main products are lithium iron phosphate battery core, power battery pack, battery...

www.ganfengbattery.com

Make sure they never go under 2.5V though as they fail dramatically if you do let them drop . Notice the terminal you show has aluminium at its bottom . Look at the other terminal which is black is also aluminium but it has copper at its base. The black will test out to be positive and the fawn negative.

Use stainless bolts with a nut and washer . Put nut then washer on bolt screw nut up as far as it will go ,put bolt through the connector and thread into terminal hand tight . Ensure a one or two millimeter gap below the bottom of the bolt. Tighten nut down on washer and connector . A bit elaborate I know but if the bolt is tightened too far down it can pierce the bottom and ruin the cell.

The fluid you hear inside is the electolyte /coolant.If you pierce the cell it can leak or evaporate .
I studied those cells at Uni recently.

 

[Donald Siegel]

Those cells are made by a big player in china and should be OK.

Jiangxi Ganfeng battery technology co., LTD.

Jiangxi Ganfeng battery technology co., LTD. is the first listed company in the lithium industry in China, specializing in the research and development, production and operation of new lithium ion batteries, the main products are lithium iron phosphate battery core, power battery pack, battery...

www.ganfengbattery.com

Make sure they never go under 2.5V though as they fail dramatically if you do let them drop . Notice the terminal you show has aluminium at its bottom . Look at the other terminal which is black is also aluminium but it has copper at its base. The black will test out to be positive and the fawn negative.

Use stainless bolts with a nut and washer . Put nut then washer on bolt screw nut up as far as it will go ,put bolt through the connector and thread into terminal hand tight . Ensure a one or two millimeter gap below the bottom of the bolt. Tighten nut down on washer and connector . A bit elaborate I know but if the bolt is tightened too far down it can pierce the bottom and ruin the cell.

The fluid you hear inside is the electolyte /coolant.If you pierce the cell it can leak or evaporate .
I studied those cells at Uni recently.

I’ll add tighten them very gingery just a tiny bit past hand tight, I have similar cells and striped two. I had to rethread with larger bolts but since I have been very careful with steel bolts on aluminum threads!

 

[April]

I’ll add tighten them very gingery just a tiny bit past hand tight, I have similar cells and striped two. I had to rethread with larger bolts but since I have been very careful with steel bolts on aluminum threads!

No I must not have been quite clear . Ensure the loose bolt hits the bottom then back off one thread or two. Then bring the nut down to tighten. If you stripped the threads and retapped them thats OK but the connections from cell plates to terminal are down the bottom of that threaded hole . Puncture that and electrolyte can evaporate and the aluminium is so thin it turns to powder if exposed to the air. So too the copper foil used .

This was posted for boboxx and relates to the cells he bought

 

[Donald Siegel]

No I must not have been quite clear . Ensure the loose bolt hits the bottom then back off one thread or two. Then bring the nut down to tighten. If you stripped the threads and retapped them thats OK but the connections from cell plates to terminal are down the bottom of that threaded hole . Puncture that and electrolyte can evaporate and the aluminium is so thin it turns to powder if exposed to the air. So too the copper foil used .

This was posted for boboxx and relates to the cells he bought

Your post provided a good tip on how to properly set a bolt into aluminum terminals. It was very clear and a good suggestion. Completely separately from that tip about bolt length and washers needed to get it perfect was the same point Will brought up to be paranoid when tightening that bolt as steel vs aluminum is not a great match.

 

[TJ Tom]

1200.0US $ |4PCS 3.2V280AH LIFEPO4 Battery Cell 2021 Grade A New Rechargeable Lithium Iron For 12V 300AH RV SOLAR EV EU US TAX FREE|Replacement Batteries| - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

4pcs $912 including freight and tax，It looks good. The internal resistance is 0.1~0.3mΩ , which seems more normal.

 

[TJ Tom]

I just received my 4x Lifepo4 280Ah Batteries for the camper. After looking around I opted to try my luck with Dongguan Billion Electronic Technology. I was dealing with Wilson who was great do deal with. The order took about just under 4 weeks to arrive.

The cost per cell was 72$ (288$ total) and 220$ for shippint to Canada via UPS. Duty and brokerage was 55$ CAN

The cells where packaged "ok", each cell was individually boxed (no padding) and then placed in a lager box with bubble wrap padding. These where sold as "New EVE Cell A grade" but by looking at the cell it's hard to believe as they have quite a few dents and pucks. Another stage thing is that cell sounds like flooded cells when turning them sideways.

https://www.alibaba.com/product-detail/EVE-LF280-3-2V-Lifepo4-High_62379079690.htm

Cell Voltage / Internal impedance
Cell A: 3.2879v / 65.1 mΩ
Cell B: 3.2925v /65.7 mΩ
Cell C: 3.2927v / 65.8 mΩ
Cell D: 3.2921v / 65.7 mΩ

I'm still missing my BMS so I can't do much more with the cells as of yet, but I just tought I would share with you. I have no affiliation with Wilson or that company.

The fourth picture looks broken. It's very dangerous.

 

[boboxx]

It has a dent, but it's not leaking.

The fourth picture looks broken. It's very dangerous.

 

[Johan]

@boboxx
The internal resistance, as @TJ Tom said, is a factor (order of magnitude) 100 too high. Plugging the specs of a cell like yours into this thermal model , it is predicted that at 0.5C (140A) (dis)charge rate (a current that this cell should be able to handle without noticeable temperature rise), the temperature would theoretically rise enough to melt it burn it.

I severely doubt if that really would happen because the model assumes a perfectly thermally insulated "normal" battery, i.e. one with a normal internal DC resistance unaffected by parasitic chemical reactions, embedded in a bank. Or...would it get really hot? Now I am getting curious. Could you safely try it at 0.5C out and prove the model wrong (example)? Maybe make a Youtube video of it. Wear some protective glasses .

Or maybe more practical: 25A (0.1C) would result in a 30°C increase to, say, 50°C (120F), enough to feel hot to the touch and deteriorate the cell even further, faster, as Jeff Dahn tought us.

 

[boboxx]

I just edited my post, the measurement I had posted were not correctly calculated! I will re-run the test and report back.

I will use this methode:

@boboxx
The internal resistance, as @TJ Tom said, is a factor (order of magnitude) 100 too high. Plugging the specs of a cell like yours into this thermal model , it is predicted that at 0.5C (140A) (dis)charge rate (a current that this cell should be able to handle without noticeable temperature rise), the temperature would theoretically rise enough to melt it burn it.

I severely doubt if that really would happen because the model assumes a perfectly thermally insulated "normal" battery, i.e. one with a normal internal DC resistance unaffected by parasitic chemical reactions, embedded in a bank. Or...would it get really hot? Now I am getting curious. Could you safely try it at 0.5C out and prove the model wrong (example)? Maybe make a Youtube video of it. Wear some protective glasses .

Or maybe more practical: 25A (0.1C) would result in a 30°C increase to, say, 50°C (120F), enough to feel hot to the touch and deteriorate the cell even further, faster, as Jeff Dahn tought us.

 

[Johan]

Triggered by @April's tip, I felt like making a drawing today just like in kindergarten, probably reinventing the wheel because the cell manufacturers have better drawings..

April suggested case D to avoid case C (if I am correct). However, initially I would prefer case B, provided that I have the right bolt length or an angle grinder or so at hand to cut the bolt to the right length. In case D, the bolt sticks out further, theoretically possibly touching stuff that it should not touch causing a short. Thoughts? Send me a private message if needed to keep this forum-thread clean.

As a generic design rule [1] for the thread engagement e (indicated in case A) in mechanical engineering for "soft metals", e = 2.5 · d with d as the bolt diameter (or, for aluminium, use factor 0.8-2.2 instead of 2.5). In this case, the M6 hole depth is only 7 mm (see other comment below), so only a factor of about 1 is possible.

About the correct torque for minimum electrical contact resistance yet no damage to the thread: Most battery cell-resellers do not provide this info. Starting point: torque table SAE. Problem: The correct torque is highly dependent of the specific aluminium alloy yield strength used as well as the (remnant) lubrication in and around the hole, up to factor 10 difference, rendering calculation models and design tables useless except for an order of magnitude. So someone should experiment on a cell under well-specified conditions after de-greasing as good as possible and report back here for us all to compare against theory. But still this is likely of limited use for other cell makes and models. Or get manufacturer recommendations.

To avoid stripping the cell threads, some cell models include "terminal adapters" (welded? bolted?) - an example is shown behind this link.

20200105 - Torque update:
From [2], a torque of 20Nm (14.75ft-lbs) is recommended for M8 bolts.
From [3]: 20Nm for M8; 9Nm for M6 bolts.
For M4 bolts, assuming similar terminal material properties , by coarse non-linear extrapolation of the above values, 3 Nm.
To be experimentally checked by yourself first, of course.

References
[1] Roloff / Matek, Machine-onderdelen Tabellenboek, 2e geheel herziene druk, Tabel 8-15.
[2] Jaques Rickard, CALB CA180FI
[3] GWL, Starting with LYP/LFP cells from Winston Battery

 

[msdmaddog]

awesome description johan, the good old roloff matek

 

[boboxx]

The bolts are M6 screw, 7mm deep.

 

[April]

The bolts are M6 screw, 7mm deep.

Yes but I suggest using case D in the above because finger tight and back a bit keeps it away from tender tabs connections under the thread and with a nut is fully adjustable for the connections you might want to add or subtract later.

 

[Steve_S]

A slightly different method, better or worse ? At least you can bottom out the "bolt" and back it off 2 turns before hand tightening the nut & final tightening, more tedious & fiddly (gotta be extra tool cautions). I'm surprised this is not the standard method but I'm sure there are varied reasons.