16S, 272Ah Lishen + TinyBMS - Build Thread

schroederjd

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Hi Everyone,

Starting a build thread now that my cells are officially on US soil. The pack will ultimately be configured in as 16s1P feeding two 48V 3000W Growatt inverters (set up as an off-grid, split-phase 120/240 system).

First off, here’s a summary of my Alibaba purchasing experience to date:
  • Vendor: Shenzhen Basen Technology Co., Ltd (contact: Sheila Chou)
  • Cells: Lishen 272 Ah (sold as Grade A), 16ea
  • Price paid: $75.20/cell + $394.00 shipping/tax/fees, Total cost: $1597
  • Order date: Nov 16, 2020
  • Shipment date: Nov 19, 2020 (to Wisconsin, USA)
  • Date of US arrival (port of LA): Dec 21st, 2020
  • Date transferred to FedEx: Jan 10, 2020
  • Date of receipt (expected): Jan 15, 2020 (total transit time: 57 days)
Note: I originally purchased EVE 280Ah cells, but was informed the day after I placed the order that those were out of stock and they would be shipping Lishen cells. I gave the go-ahead based on the generally positive feedback about Lishen cells on this forum.

Here’s my plan to get them up and running:
Step 1 – Top Balance: Parallel top balance using a Mean Well HRG-300-3.3 with Arduino control/monitoring. To minimize the risk of damaging all of my cells, I’m planning to start the process by taking groups of 4 cells to 3.55v. I’ll then parallel the entire group and top them off to 3.65v.​
Step 2 – Series Connect: Compress cells in groups of four using ¼” aluminum plates and ½” stainless steel cable ties. Series connect using bus bars made from 3/4” x 1/8” copper flat stock. I’m planning to try my hand at nickel plating the bars myself, but I may end up sending them out if that doesn’t go well.​
Step 3 – BMS Connection/Setup: Connect/configure TinyBMS s516 for battery management. I’m planning to use a separate port configuration with 5A SSRs switching the inverters off for LVD/HVD/LTD protection. Very excited to get the BMS up and running so I can start tinkering to determine functionality. Lots of analog and digital pins to play with, assuming I can figure out the programming.​
Step 4 – Capacity Testing: Use one of my Growatt inverters and a ~2600w load (~0.2C) to capacity test the bank.​
Step 5 – Battery Case: I’m planning to use a insulated/heated steel box for cell storage. A 16”x12”x30” ‘welders box’ with 1” of XPS insulation all around seems to be a very good fit for the cell configuration I’m using. Heat will come from four 12v silicone heating pads run in series off the 48v supply. Not settled on control system for that yet (Arduino vs. off-the-shelf PID vs. BMS control).​
Step 6 – Install & Test

Much more detail on each of these steps to follow, but please feel free to comment on anything listed above that doesn’t make sense.
 

markver

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Hi Everyone,

Starting a build thread now that my cells are officially on US soil. The pack will ultimately be configured in as 16s1P feeding two 48V 3000W Growatt inverters (set up as an off-grid, split-phase 120/240 system).

First off, here’s a summary of my Alibaba purchasing experience to date:
  • Vendor: Shenzhen Basen Technology Co., Ltd (contact: Sheila Chou)
  • Cells: Lishen 272 Ah (sold as Grade A), 16ea
  • Price paid: $75.20/cell + $394.00 shipping/tax/fees, Total cost: $1597
  • Order date: Nov 16, 2020
  • Shipment date: Nov 19, 2020 (to Wisconsin, USA)
  • Date of US arrival (port of LA): Dec 21st, 2020
  • Date transferred to FedEx: Jan 10, 2020
  • Date of receipt (expected): Jan 15, 2020 (total transit time: 57 days)
Note: I originally purchased EVE 280Ah cells, but was informed the day after I placed the order that those were out of stock and they would be shipping Lishen cells. I gave the go-ahead based on the generally positive feedback about Lishen cells on this forum.

Here’s my plan to get them up and running:
Step 1 – Top Balance: Parallel top balance using a Mean Well HRG-300-3.3 with Arduino control/monitoring. To minimize the risk of damaging all of my cells, I’m planning to start the process by taking groups of 4 cells to 3.55v. I’ll then parallel the entire group and top them off to 3.65v.​
Step 2 – Series Connect: Compress cells in groups of four using ¼” aluminum plates and ½” stainless steel cable ties. Series connect using bus bars made from 3/4” x 1/8” copper flat stock. I’m planning to try my hand at nickel plating the bars myself, but I may end up sending them out if that doesn’t go well.​
Step 3 – BMS Connection/Setup: Connect/configure TinyBMS s516 for battery management. I’m planning to use a separate port configuration with 5A SSRs switching the inverters off for LVD/HVD/LTD protection. Very excited to get the BMS up and running so I can start tinkering to determine functionality. Lots of analog and digital pins to play with, assuming I can figure out the programming.​
Step 4 – Capacity Testing: Use one of my Growatt inverters and a ~2600w load (~0.2C) to capacity test the bank.​
Step 5 – Battery Case: I’m planning to use a insulated/heated steel box for cell storage. A 16”x12”x30” ‘welders box’ with 1” of XPS insulation all around seems to be a very good fit for the cell configuration I’m using. Heat will come from four 12v silicone heating pads run in series off the 48v supply. Not settled on control system for that yet (Arduino vs. off-the-shelf PID vs. BMS control).​
Step 6 – Install & Test

Much more detail on each of these steps to follow, but please feel free to comment on anything listed above that doesn’t make sense.
Sounds like a solid system, I would like to do something similar with Growatt inverters. Keep us updated with your progress and photos!
 

schroederjd

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Well, the first of four boxes of Lishen cells showed up today. At first glance, things are not looking great. If these are "Grade A, Brand New" cells (as indicated in the listing), I'd hate to see what "Grade B" must look like... Threads on all four cells are a mess. QR code is scratched off on one of the cells. Most concerning is that the Aluminum foil under the plastic vent cap is heavily corroded and caved in on two of the cells (anyone know what would cause this?). On the slightly brigher side, cases are all quite clean, and no sign of any 'bloating'.

Voltages came in at 3.272, 3.268, 3.273, and 3.267, which I believe is in the neighborhood of 30 - 40% SoC (do I have that right?).

I've sent some photos to Sheila at Basen. We'll see how they respond.

Anyone on this forum want to talk me off the ledge???

IMG_7472.jpgIMG_7467.jpg
 

Dzl

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Well, the first of four boxes of Lishen cells showed up today. At first glance, things are not looking great. If these are "Grade A, Brand New" cells (as indicated in the listing), I'd hate to see what "Grade B" must look like... Threads on all four cells are a mess. QR code is scratched off on one of the cells. Most concerning is that the Aluminum foil under the plastic vent cap is heavily corroded and caved in on two of the cells (anyone know what would cause this?). On the slightly brigher side, cases are all quite clean, and no sign of any 'bloating'.

Voltages came in at 3.272, 3.268, 3.273, and 3.267, which I believe is in the neighborhood of 30 - 40% SoC (do I have that right?).

I've sent some photos to Sheila at Basen. We'll see how they respond.

Anyone on this forum want to talk me off the ledge???

View attachment 33155View attachment 33154

I never put much faith in a reseller's (even the more "trusted" ones) claims about cell grade. But even with the low bar assumption that reseller Grade A probably = Grade B what the pictures show is unacceptable in my eyes. I would be upset as well. Are the pictures representative of the whole group or is this the bad apple of the bunch?

I have not seen QR codes removed on Lishen cells before. Has anyone else?

Edit: it really frustrates me that resellers feel okay misrepresenting their products so freely, and feel comfortable shipping cells with zero QA. Hopefully Basen will do the right thing and work with you to make things right.
 

schmism

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Edit: it really frustrates me that resellers feel okay misrepresenting their products so freely, and feel comfortable shipping cells with zero QA. Hopefully Basen will do the right thing and work with you to make things right.
Have you seen the markets in Shenzhen? You think someone is crammed into a tinny cube boxing up hundreds of aluminum case cells? I find that to be unlikely. I think "resellers" that we talk to... are people who process orders and send a wechat to some warehouse worker that pulls them off pallets and stuffs them in boxes. I find it hard to believe that the person you would talk to in email, is the same one that is putting cells in boxes and foam. Therefore I do not believe for a sec that the "reseller" knows at all what goes in the boxes that gets sent to us.
 

Dzl

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I think you may have misunderstood. When I say reseller I mean the entity/business, not the individual on the other side of the computer screen. The fact that the salesperson may or may not have a role in the sourcing, QA, cell selection, or packing, in no way justifies the widespread misrepresentation in this market (or even just plain ignorance with no intent to mislead). From the customers point of view the business is an entity, "but maybe the salesperson didn't know" is not a satisfying or acceptable excuse.
 
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schroederjd

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I heard back from Sheila at Basen last night. One thing I can say is that she has been extremely responsive throughout the entire ordering process. I won't paste the full response. She confirmed that I did purchase Grade A Cells, brand new cells, and indicated that the 'defects' that I showed her were not acceptable. She asked me to inspect the full order once i've received the remaining boxes and provide her with a full summary of the condition of all cells (with photos).

More to follow...
 

schroederjd

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Step 1 - Top Balancing.

I decided to test my setup on the worst two cells I've received, just in case something goes wrong. Here's a summary of my charging setup:
  • Power Supply: Mean Well HRPG-300-3.3 with voltage sensing leads running to the + and - bus bars.
  • Wiring: 2 x 10 awg stranded wire to and from the supply. Positive side includes a set of four 30A Schottky diodes to prevent backfeed upon power supply shutdown.
  • Control/Monitoring: Node32s (ESP-32 microcontroller) programed through Arduino IDE to monitor Voltage, Current, and Temperature (refer to Top Balancing Setup for more details).
  • Setup: I'm starting by taking two cells in parallel to 3.55v. I've set the mean well to it's max voltage, so it should stay in CC mode until it hits 3.55V, at which point the Node32s will shut the charger down using the remote on/off lines of the HRPG (yes, I've tested this MANY times to make sure it's working...).
So far, everything seems to be working as expected. The HRPG-300-3.3 is charging at a constant 50 - 55 amps and seems to be staying pretty cool. I do have a fan blowing on it for some added assurance. The diode 'array' is also staying relatively cool. I'm running them at just under 1/2 the rated capacity, and I've included small heat sinks under each diode. Without a cooling fan, the diode cases get up to about 95C (they're rated to 175C), and with the fan they're running at about 45 - 50C. Seems very reasonable.

I'm estimating that it will take somewhere in the neighborhood of 6 hrs to get the first two cells from the current SoC (maybe 35%) to 90%.

IMG_7484.JPGIMG_7485.JPGIMG_7486.JPGIMG_7487.PNG
 

schroederjd

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Update on Condition of Cells: The remaining 3 boxes arrived today. Of those twelve cells, four more have the corrosion under the vent cap and QR codes partially or fully scratched off. The threading on all of the cells is terrible. Here's a few more pics:
IMG_7529.JPG IMG_7530.JPG IMG_7492 copy 2.jpg
 

Steve_S

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Those cells are certainly unacceptable, at 'best' they are grade B. Whoever tapped the cells must have been drunk.
A word of caution, verify the depth of each hole before doing stuff, do not be surprised if they are not the same. It's also worth reporting that in your defect list. Look at the bottom of each hole, is it clean, any 'dark' material or corrosion. If not clean a Q-Tip with 90%+ alcohol works and is safe.

From the pictures, I couldn't tell, is the plastic "bubble" over the vent there or not ? does not appear to be but it could just be the photo.
If not, that would explain the corrosion and these may have 'popped' because the closer I look at the vents, the rough edges and marks around them just isn't right. I have some used cells that I got a while back, and even with their quirks, the vents are pristine with the bubble intact.

Make note of all such things, take photos with closeups of the vents. do crop the pictures down though... lol

If you are going to charge & test them, I suggest you make a log and also test the cells once you stop charging, take a voltage reading every hour to watch the settling & behaviour. They should settle hopefully to 3.450-3.500 within 4 hours, maybe 6. To verify each cell, separate them once you stop charging. Once they're all settled and your done logging that, you can put them back in parallel and top them off again if you want to.

From your excellent details above, you're likely doing it anyway and even more in-depth, but I figured I'd mention it anyway, might be good for future readers though, just in case.
 

Maast

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Kudos on your diode array. Well done. Sorry to hear about your cells. Maybe you'll get lucky and they'll pan out.

FWIW when I'm evaluating cells I:
1. charge to 3.65v and let them sit for a week, new should not self discharge below 3.5 in a week, higher is better.
2. charge again to 3.65 and then discharge at .5C all the way down to 2.5v through a shunt or hall effect capacity meter. Make a note of the initial drop when the load is applied - you can use that to calculate the internal resistance. lower is better. It doent have to be .5C, .2 or .1 is okay - but makes for a longer test.
3. Feel the cells during the discharge, they should be ambient temperature.
4. Charge and discharge the cell again, capacity should be identical, if its not then there is something wrong.
 

schroederjd

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Maast / Steve S - Thanks a lot for the feedback and constructive suggestions. Maast, I should have given you a shout-out for helping me with that Diode setup. Honestly, without guys like you posting helpful content on this forum, guys like me would be lost...

The plastic over the vent is intact and seems to be in good shape on all cells. One observation I made is that all of the cells were packaged 'upside down' with regard to all the text on boxes. There was a small 'fragile' label on each box with the correct orientation noted, but it was pretty easy to miss. Is it possible that if these saw a wide range of temperatures during shipment that this could have caused some level of leakage through the vent?

I'll keep a detailed log of voltages by time after charging. I was originally intending to test capacity as a 16s pack, using the TinyBMS for monitoring. Now I'm wishing I had some method of testing individual cell capacity (without buying a capacity tester...). Ideas?

With regard to the threading issues, I think I'm going to use a plug tap to chase the threads and make sure they're all threaded to the same depth. Will perform a deep cleaning with a Q-tip after that.

Thanks again,
Jon
 

Steve_S

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IF you are retapping the holes, which is I think a really good idea, to make sure you have good clean solid thread, Set the depth to no more than 6mm. I believe at 8mm your going through the bottom, at which point the cell becomes recycling stock. Be sure to get the oil out if you are using it when retapping, it's PITA but it's important, luckily the aluminum is so soft, you likely won't need oil as it is just a re-tap. The cells being upside down during shipping would not make a difference in transit, only when in use.
 

schroederjd

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Top Balancing Update: I'm in the middle of charging my cells individually up to 3.55v. I'm on my 4th cell, and my power supply has started shutting down about every 15 - 30 min. I had been running with the short-circuit voltage set to 3.65, which kept the power supply in CC mode pushing about 56 amps. It ran that way fine for the first three cells, now it seems to be cutting out. Only thing I can think of is that the over-temp protection is being tripped, but I don't know why. Power supply is up on stand-offs with a fan blowing on it, and its in a 50F basement.

Any idea why the over temp protection would start tripping? Are these supplies designed to be run at peak current for extended periods, or should I be dialing back the voltage to keep current below some percentage of peak (I'm currently running it at 40 - 50A and seems to be ok)?

Is there another fault that could be tripping the power supply off?

Edit: One other clue...the power supply does not seem to 'recover' from these faults. Both the over temp and overload protection functions have an auto-recovery feature. The one fault type that does not auto-recover is overvoltage, but I can't figure out why that would be tripping. Maybe something to do with the voltage drop across my diode array, and the fact that I'm using voltage sensing leads?

Thanks again.
 
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Steve_S

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Can't speak to that PowerSupply specifically.
The TekPower unit I use very clearly states NOT to run it at 100% Capacity, to keep it below max by 2 amps or so.
Meanwell types (the kind I have anyways) also will not tolerate that for long.
Impatience can be costly.
 

schroederjd

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Ok, back to the subject at hand...I think I figured out why the power supply was faulting out. I was able to recreate the fault under several different conditions, and it seems that in all cases, if the supply voltage hits ~4.20 volts, it cuts out. At 50 amps, I'm seeing about a 0.5v drop across my diode array. That, plus the 0.1v drop i'm seeing over all my wiring/connections, means that to achieve the voltage set point (3.65v), it's putting out over 4.2 volts, which triggers the over voltage protection fault.

So, I'm not sure if any of that makes sense, but it does seem to explain what I'm seeing. I probably need to add a couple more diodes to reduce the voltage drop further. I'm also finding that everything runs great with voltage dialed in to keep the current under 50A. So, for now, we'll keep chugging along. At this pace, I can charge up 4 cells at a time and they'll take about 20 hrs to get to 3.55v. Once I've got them all there, I'll parallel all 16 and take them up to 3.65v.
 

Maast

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If you're using schottkkey diodes thats a very large forward drop, even at fairly high amperages you shouldnt be seeing more than .3 If they're silicon diodes than thats normal. Or the diodes are getting extremely hot, did you put any heat transfer compound between the diodes and the copper bar you used?

BTW, when setting your charging voltage do it without a load on it, as the amperage tapers down near the top you'll see that the resistance in your wiring won't matter because at that point you'll be moving not much current and resistance in a wire is proportional to the current it's carrying.

If you set it with a load you'll actually overvolt your batteries because the voltage will continue to raise as the current goes down and you'll have set your PS voltage too high.

The short of it is that you adjust your voltage you maybe won't have to add diodes and your PS stays on.
 

schroederjd

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If you're using schottkkey diodes thats a very large forward drop, even at fairly high amperages you shouldnt be seeing more than .3 If they're silicon diodes than thats normal. Or the diodes are getting extremely hot, did you put any heat transfer compound between the diodes and the copper bar you used?

BTW, when setting your charging voltage do it without a load on it, as the amperage tapers down near the top you'll see that the resistance in your wiring won't matter because at that point you'll be moving not much current and resistance in a wire is proportional to the current it's carrying.

If you set it with a load you'll actually overvolt your batteries because the voltage will continue to raise as the current goes down and you'll have set your PS voltage too high.

The short of it is that you adjust your voltage you maybe won't have to add diodes and your PS stays on.
I'm using four of these diodes: LINK. According to the spec sheet, 'typical' forward voltage drop at 1/2 rated current is 0.5, so I think my numbers aren't too far off. I may have selected the wrong diode... I do have heat sinks with thermal paste under each diode, along with a fan blowing on them. I also have a NTC thermistor directly on top of one of the diodes (with thermal paste between the two), and i'm not seeing temps much above 50C (they're rated to 175C).

I've been setting the charge voltage before I connect the cells, so I think i'm setting things up correctly. Like you said, as I get closer to target voltage, the issue goes away, so it's really not that big of an issue. Just forces me to slow things down a bit, which is probably a good thing anyway...

Thanks!
 

Maast

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Just looked at the specs and .5v drop is normal for this one. Huh, big drop for a shotty. My bad. Man I bet they generate a ton of heat. If they're the ones I linked to a few weeks ago I profoundly apologize as I made a recommendation but didnt read the specs on it - I just saw 'shotty' and linked it to the post.

Well, as long as you NEVER discharge the cell with the power supply attached to it you can forgo the diode bank, I do that a lot too if all I'm doing is pushing charge into a cell that'll be subsequently attached to something else for discharge.
 
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