Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Opus charging
#1
Given the Opus charging features which setting would be the most effective in sorting through cells.

1. Current settings have me using charge test @500mA

I have 4 chargers roughly getting through 16 cells every 10hrs at most.

Any other strategies/tactics I can use?
Reply
#2
Charge and discharge at 1A
mike likes this post
Reply
#3
The higher you set the current, the shorter are the testing times.
On the other hand, you testing should reflect the (Max) loading the cell may get in your application. If this is small, like 0,5 Amps or 0.2C, then a testing at 0.5 Amp would be accetable. But it takes longer to test them.
So you have to make your compromise on what your expectations are.
1 kWp in Test
4 kWh battery target - plus Mobile Home battery
Ultra low cost
Electronics ? No clue. Am machinery engineer.
Reply
#4
Thanks. On what basis would you reject the cells?
At 1amp all cells should heat up?

Ie. How would you reject these without a thermal imaging system. 1 off the 4 cells are hotter than the other?
Without a FLIR type system this would be hard to asses.

Or am I on the wrong path and rather look at capacity and holding voltage ONLY.

I have been checking voltage after 1 to 2 weeks in storage and keeping capacities over 2000mah after charging.

Step 1: keep capacities over 2000mah
Step 2: after 1 week remeasure voltage reading
Reply
#5
(04-26-2019, 09:42 AM)Milanbeh Wrote: Thanks. On what basis would you reject the cells?
At 1amp all cells should heat up?

Ie. How would you reject these without a thermal imaging system. 1 off the 4 cells are hotter than the other?
Without a FLIR type system this would be hard to asses.

Or am I on the wrong path and rather look at capacity and holding voltage ONLY.

I have been checking voltage after 1 to 2 weeks in storage and keeping capacities over 2000mah after charging.

Step 1: keep capacities over 2000mah
Step 2: after 1 week remeasure voltage reading

Milan, with respect, on most of your questions are many different threads just here in you sub-folder.  You will have to take a little time to read into some of them.

But, sure i can give you some outlines.
- make separate dealing with cells which have less than 2.5 Volt.
- at 1 Amp no cell should heat up. (but distinguish heat coming from the cell and heat coming from the opus. There is a fan issue with the opus as well). Heating is bin-ware.
- sorting into 100 mAh ranges. What groups you will use is your choice depending from your usage and your resources of cells. lower cells are usable for other projects.
- SD check may be after a little more than a week, but basically its right. how sensible you are on this again depends on your choice.  "To much" SD is bin-ware.
- Additionally you may introduce or leave out an IR check, there are as well many threads here. majorly used cells tend to have increased IR, but its not possible to summarize all in one sentence.
- additionally you should look for leaking cells, removing the nickel strip on the negative pole might open tiny holes all through the casing. That is bin-ware.

I hope that gives you ideas for what to look for.
1 kWp in Test
4 kWh battery target - plus Mobile Home battery
Ultra low cost
Electronics ? No clue. Am machinery engineer.
Reply
#6
(04-26-2019, 09:42 AM)Milanbeh Wrote: Thanks. On what basis would you reject the cells?
If you are referring to what cells you should reject on other than obvious reasons (physical damage, rust, etc) than my first criteria would be IR.
These are the criteria I use. Others may have different opinions.
Any cell with more than 100mΩ IR is cause for total rejection.( Always use a proper 4 wire kelvin 1kHz Ac mΩ meter)
Any cell with less than 80% of its rated capacity is cause for rejection in a power wall build.  (they may be used in other applications)

Quote:At 1 amp all cells should heat up?

Absolutely most cells will heat up a little at that charging rate. How much should it, that is the question. Any decent low drain cell will have a "Standard" charge rate" and for most of them its around 0.5C. Example ICR18650-26D Standard Charge rate is 1300mA and standard discharge rate is 520mA


Maximum Charging is 1C 2600mA and Maximum Discharge is 2C 5200mA (all this info can be found in the cell database).
I agree with Sean to a certain point Charge at 1A and Discharge at 1A is a quick way to weed out certain cells.
I do look at the powerwall cell build just a little differently. I believe the standard discharge rate should be your criteria in the cell selection and in sizing your powerwall. Does that mean you will never go above the standard discharge rating of the cell? Of course not the cells maximum discharge rate is that buffer for that induction motor startup current (as long as your inverter is up to the task).

Quote:Ie. How would you reject these without a thermal imaging system. 1 off the 4 cells are hotter than the other?
Without a FLIR type system this would be hard to asses. 
That is a problem but you can get a simple point and shoot laser temp gun. They are pretty cheap i've seen them on Amazon for ~$15.00
The hand method works pretty good at least in determining a really hot cell Big Grin

Chart which shows the temp of an average cell going through the charge and discharge cycle. Notice the charge temp doesn't rise much above ~30°C except at the end. These where LGDBB11865 cells. Standard charge rate of 1275mA and Standard Discharge of 510mA.
During discharge the max temp was ~37°C. During charging the temp was lower than during discharging even at a lower discharge amperage.
That is the typical cycle of a reasonably healthy cell.

Quote:Or am I on the wrong path and rather look at capacity and holding voltage ONLY. 
Looking at capacity is a good indicator of a good cell when comparing it to rated capacity.
Don't make your 2000mAh capacity your final criteria. Take into account what the initial capacity of the battery was. As in a LGABD11865 which is a 3000mAh cell if your cut off is 2000mAh that basically means you have 66% of the cells capacity left. That particular cell would need to have at least 2250mAh to make it in my world. If you have a LGDS318650 which is a 2200mAh cell with 2000mAh you still have 90% of the cells capacity. So my Criteria is at least 80% of rated capacity. In my personal instance my cell mAh rating criteria is 2200mAh. So if a 2200mAh cell tests out at 100% its a bonus.

Quote:I have been checking voltage after 1 to 2 weeks in storage and keeping capacities over 2000mah after charging.

I am checking cells at a minimum of 30 days after initial test. It took 30 days to build a backlog of tested cells so now I try to do 100 voltage and IR rechecks every day. (Doesn't happen all the time)  Dodgy

Wolf
If 18 X 650 = 2200+mAh then we have power! 
May all your Cells have an IR of 75mΩ or less Smile
Last count as of 5/23/2019
Total Number of Cells                          5354
Cells  >80% of Capacity                      3801
Cells <80% of Capacity                       1553
Cells ≥2200mAh & ≥ 80% & ≤75mΩ    2645 (155) to go
For Info Google Drive
Not your average Wolf       
            Cool



Reply
#7
Another suggestion is charging with a cheaper charger, and only using the Opus for the test itself. TP4056 can be had fairly cheaply.

Others have already covered checking for self discharge, and heating before testing.
Reply
#8
(04-26-2019, 08:25 AM)Sean Wrote: Charge and discharge at 1A

Agreed.

I also added fans over them to prevent the charger from pausing half the time it should C/D.


@Geek that's how I filter cells that may overheat. The ones arriving alive and well at full charge I send the Opus way.
Reply
#9
Do not put fans on top of the opus and cool the cells. That will give you unwanted results! The fan can ONLY cool the opus PCB and therefore should be from underneath.
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcoming: 14S 18650~30kWh | Automatic trip breakers, and alot more
Reply
#10
As I said, I pre-test the cells for overheating. What else can occur ?
Reply


Who read this thread?
44 User(s) read this thread:
daromer, Sean, mike, Korishan, jdeadman, The-J-Man, watts-on, Stefaan De Ridder, Mazlem, Geek, Oz18650, bogptrsn, Solexx X, djuro, gpn, Chablis_m, jonyjoe505, Oliman, SilverNodashi, Cherry67, Riplash, 100fuegos, michaell, chuckp, emuland-metroman, jaeger-audiodesign, Shawndoe, Wolf, ibikunle, Solardad, stevelectric, LEDSchlucker, Overmind, ma3006he, beserker786, 100kwh-hunter, Irah, juanjo57, ben teker, Milanbeh, BitcoinBandit, Zonax, pacmix, jacen17

Forum Jump:


Users browsing this thread: 1 Guest(s)