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Senberry EVE LF280 transactions

The New JC777

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Sep 17, 2020
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1st order 07-12-2020 4 cells EVE LF280. Total price to my door with shipping and all taxes and fees $376.00 USD
2nd order 07-13-2020 12 cells EVE LF280. Total price to my door with shipping and all taxes and fees $1128.00 USD
3rd order 09-12-2020 32 cells EVE LF280. Total price to my door with shipping and all taxes and fees $3012.00 USD (Shipping delayed)

The first 2 orders were shipped together. From date of order to tracking number was 10 days. They arrived 09-02-2020.
3 of the boxes were in good condition with (all things considered) and well packed. One box had a torn corner.

Visual inspection of the cells found 1 cell with a dent in the corner and in the middle of the cell. After a few posts on the Alibaba messaging system, Mr Dao, the owner of Senberry sent a new cell. it is in transit. He gave me the wrong tracking number. I was frustrated to say the least, but he apologized over and over. He was always checking with me to see if they had arrived.Open Circuit Voltage of the cells were all reasonable when compared to each other with only a few mv spread. The measuerments of the cells match EVEs specs. I did notice that on a few of cells that one of the wide sides is very slightly concave and the other was slightly bowed out.

Included in the purchase were stainless steel studs, nuts and nickel plated copper cell interconnects. The studs and nuts are of good quality. The cell interconnects suck, they are very thin, narrow. I will not use them.
The US dime is there for a reference and is appx. 1mm larger that the cell terminal and about 1mm thinner than the cell interconnect. Notice all of the un-used contact patch.

20200917_111440.jpg


Top Balance charge was done with a 1s 3.65VDC CC/CV 10 amp charger. The OCV of the chrarger is 3.656 vdc. The current was measured with a clamp meter at 9.77 amps all the way through the charge. Each cell was charged independently. Some went to 3.656 in as little as 10 minuets while others took up to 76 minuets. I also noticed that once the cells reached 3.4 vdc the mv rose at about 1mv every every 15 seconds and at about 3.55vdc the mv rose at 1mv per second. It is my belief that this method of top balancing is the most accurate, but you can not leave the charger connected for long periods of time at 3.656 because LFP cells will overcharge.

Internal resistance readings are consistent @ 0.16m/ohms to 0.17m/ohms in all 16 cells after top balance charge.

About Mr. Dao. I am not affiliated with him except as a customer, however, w have conversed many many times at all hours of his night and my day. We are 12 hours apart. some of our chats got personal which I initiated so I could get to know the man I was sending thousands of dollars to half way around the world. He is full of piss and vinegar like I was at his age. He is 27 years old, his Grandmother is 75 years old,he failed English at university. When I told him my age he started calling me Sir. He is very aggressive in his business and has sold 2000 cells since August. I told him about his cell interconnects and he is looking for better ones, I am looking for him as well. I have plenty of 1" x 1/8" copper bars.

Yesterday I was shopping Alibaba to purchase other components but the shipping was ridiculous. I asked Mr Dao if he would ship them for me with the current shipment of my batteries. He said Yes so I made my purchase with the other vendor. They charged me $11.00 USD to ship the components across town to Mr. Daos facality saving me about $150.00 USD. This is what caused the delayed shipment.

Please forgive my punctuation and spelling as I failed English too!
 
:) Thanks to Rob for his support. I really appreciate his help
 
Was wondering what happened to you. Thanks for sharing your experience. (y)

I did notice that on a few of cells that one of the wide sides is very slightly concave and the other was slightly bowed out.

So what do you think about compressing the cells? Do you think they will flatten out without problems?

Top Balance charge was done with a 1s 3.65VDC CC/CV 10 amp charger. The OCV of the chrarger is 3.656 vdc. The current was measured with a clamp meter at 9.77 amps all the way through the charge. Each cell was charged independently. Some went to 3.656 in as little as 10 minuets while others took up to 76 minuets. I also noticed that once the cells reached 3.4 vdc the mv rose at about 1mv every every 15 seconds and at about 3.55vdc the mv rose at 1mv per second. It is my belief that this method of top balancing is the most accurate, but you can not leave the charger connected for long periods of time at 3.656 because LFP cells will overcharge.

As far as the top balancing goes I also am beginning to think topping off each cell individually might be the best approach before connecting in series. I am wondering what charger you used? 3.656 would be a bit of an overcharge but I don't think it would damage the cells as long as the charger cut off.

Internal resistance readings are consistent @ 0.16m/ohms to 0.17m/ohms in all 16 cells after top balance charge.

What did you use to measure the IR? The readings look good. I am wondering if you would mind measuring at a lower state of charge when it's convenient for you. I am curious about the difference. Also of course capacity tests.

Good to know you have had a good experience so far with SBR. Please keep us updated as you have a chance to do further testing on the cells.. :)
 
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I asked to be deleted. I was making too many mistakes on posts. The New JC777 will be asking alot more questions?

So what do you think about compressing the cells? Do you think they will flatten out without problems?
[/QUOTE]
It is very slight. Only time will tell though.

As far as the top balancing goes I also am beginning to think topping off each cell individually might be the best approach before connecting in series. I am wondering what charger you used? 3.656 would be a bit of an overcharge but I don't think it would damage the cells as long as the charger cut off.
If 6mv for a minuet is going to hurt the cell I could be in trouble. The cells are in my office and I watch them like a hawk. When the green light comes on I manually disconnect. I would apricate any input on this. BTW reverse polarity releases the magic smoke!!!!! Here is a link to the charger https://www.amazon.com/gp/product/B07P66KB5L/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

What did you use to measure the IR? The readings look good. I am wondering if you would mind measuring at a lower state of charge when it's convenient for you. I am curious about the difference. Also of course capacity tests.

Vapecell YR1030 https://lygte-info.dk/review/InternalResistanceMeterYR1030 UK.html
I'm now second guessing the the readings. I just rechecked and meter shows 1.2mR up to 1.4mR R=Ohms I could really use some input on this. The EVE manual states .25 mRo_O
 
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I asked to be deleted. I was making too many mistakes on posts. The New JC777 will be asking alot more questions?

Please do ask questions. We all learn something when questions are asked. I am going through a learning curve too.

If 6mv for a minuet is going to hurt the cell I could be in trouble. The cells are in my office and I watch them like a hawk. When the green light comes on I manually disconnect. I would apricate any input on this. BTW reverse polarity releases the magic smoke!!!!! Here is a link to the charger https://www.amazon.com/gp/product/B07P66KB5L/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

I will be watching mine like a hawk too, at least initially as they will be in my apartment...but only 8 of them. You will have a bunch. I really don't think the .6mv is going to hurt anything. The 10 amp charger you used is fine for top balancing. I have a 12 volt LifePo4 charger I use to charge my Valence batteries. It always charges to 14.62 volts before cutting off. The Valence uses cylindrical cells but there has been no damage. Thanks for the link.

Vapecell YR1030 https://lygte-info.dk/review/InternalResistanceMeterYR1030 UK.html
I'm now second guessing the the readings. I just rechecked and meter shows 1.2mR up to 1.4mR R=Ohms I could really use some input on this. The EVE manual states .25 mRo_O

Are you zeroing the ohm reading before taking the measurements? That's the only thing I can think of. @snoobler posted about it in this thread:

 
IR can vary with SoC. It's common to see higher IR when the SoC/voltage is in the "legs" of the voltage curve (less so at the lower leg). This is related to the reduced Coulombic efficiency at higher SoC.
 
Thank you both. I read that thread. I read this forum almost all day every day. I reached out the the seller too. I did zero it.
 
I'm in the process of building a simple charge/discharge jig for a single cell. My intent is to charge/discharge according to section 5 of the LF280 spec sheet which is .5c. I will monitor and document Voltage, current and IR over several cycles. My goal is to get relatively matched cells and build batteries into 16S packs using the Chargery 16T. I may go to 8S since my 2 favorite BMSs are the Electrodacus SBMS120 with DMS modules for control and the Overkill since he is close by and gets good reviews.

1. Is there any reason I can't parallel multiple chargers to increase current? The chargers are 20 amp 3.65 volt CC/CV. The sales people from the vendor say NO, but I've done this in the past with various chargers and Pb batteries. Has something changed?

I realize that this time and labor intensive, but hands on is the way I learn best.

This is the online calculator I used. https://www.rapidtables.com/calc/electric/watt-volt-amp-calculator.html

This drawing is for 1 charger and resister per on off on switch. The resister is .18 ohms (not .18 mOhms per the drawing) 50 watts which comes out to about 15 +/- amps (depending on voltage) @3 volts. I used 3 volts as the average. I will have additional resistors that I can add or subtract to keep the current close to specs of 140 amps. over a 2 hr period. Wire is 12awg. A blower will cool the resistors, the chargers have their own fan.

I appreciate your input...be gentle please.



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I bought the Juntek VAT4300 but it hasn't arrived yet.

How do you find the 1300 ?
 
Haven't pushed any current through it yet. It does read the cell voltage of 3.42v which is within a couple of mv of my Kline mm600. The instruction are vague, but lots of features that I do not need. I just need it to count A/H accurately and display accurate voltage. This is not a lab quality device, but for $35.00 it will do what I need.
 
1. Is there any reason I can't parallel multiple chargers to increase current? The chargers are 20 amp 3.65 volt CC/CV. The sales people from the vendor say NO, but I've done this in the past with various chargers and Pb batteries. Has something changed?

No, it's perfectly fine ;)

This drawing is for 1 charger and resister per on off on switch. The resister is .18 ohms (not .18 mOhms per the drawing) 50 watts which comes out to about 15 +/- amps (depending on voltage) @3 volts. I used 3 volts as the average. I will have additional resistors that I can add or subtract to keep the current close to specs of 140 amps. over a 2 hr period. Wire is 12awg. A blower will cool the resistors, the chargers have their own fan.

What resistors do you plan to use?
 
Thank you for your re-affirming my thoughts on the charger.

The resistors are the problem. I intend to use 12 awg wire which means 20 amp max so I'm wanting appx 15 amps per switch.
I'm looking for wire wound, insulated, fined aluminum encapsulated resistors. I do not know the proper name for them. I found 1.8 Ohms resisters as I just described 20 miles from me on Ebay so I bought a open bag of 66 resistors for $50.00 USD I got all excited about my great find and went to the online calculator I entered .18 Ohms and 3 volts. Later that night went to check the order and realized my mistake but didn't want to cancel the order, Now I'm thinking I can put them in series to get some of the load that I need. I can also use switched, single resistors to fine tune the load. Does this make sense?

Years ago I build a 12 volt load bank from a 120 vac 1200 watt space heater by cutting the element into 10 equal links to make 12 volt heat elements. I may have to find a cheap used heater and do the same but cut them into 40 equal lengths for 3 volt elements. As I remember, it is was a pain to make a good connection to ring terminals.

Here is the link to the resistors I bought. Might have to scroll down a bit. https://www.ebay.com/itm/66-Sei-Sta...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

Thank you for your help.
 
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