Beginners Guide to Processing 18650 Cells | Cell Database


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Opus BT-C3100 v2.2 Review and Discussion
#1
I've seen a lot of questions regarding this charger, and I thought I'd make a thread that might answer them all in one place, and also offer my experience using it. Hopefully you all will offer your experiences and questions too.

So I've tested around 300 cells so far with the Opus, and I thought I'd offer some observations about it. I use it primarily to discharge cells for testing capacity.
Charge Mode: It doesn't seem to have the pre-charge mode where the cell is started charging at .1A until it reaches 2.9V or so. It jumps right into the constant current mode. Otherwise, it seems to charge fine.
Discharge Mode: I really like that it discharges cells to 2.8V. Other dischargers I've used won't do that. So I think this device is more accurate as far as capacity testing.
Discharge Refresh Mode: I haven't used this one. It would tie up the device for too long in my opinion. Also, I'm not sure if it works for lithium based cells. I think its more for nickle based cells.
Charge Test Mode: I'm not sure what this one is for. I read the manual, but it seems it does the same thing as the discharge mode? Maybe it recharges after?
Quick Test Mode: Measures internal resistance. Basically, a load tester with a bit of math involved. The general consensus is that internal resistance is not a particularly useful number since it doesn't really predict whether the cell is good or bad. Generally, low milliohms is good; like 100mOhm or so. Higher resistance like 500mOhms is less good. I've found that values over 800mOhms indicates a cell that is not in very good condition. This test also tends to give different numbers each time one cell is tested, so its hard to know the exact internal resistance anyway.

Some quirks and details about this charger:
- You can open the back cover and there's a little selector switch inside. It allows you to choose more varieties of battery chemistry for charging. Options are 4.2V (default), 4.35V (for high voltage cells), and 3.7V (for LiFePO4 cells).
- Although the charger has 6 temperature sensors and a fan, it still seems to get hot while discharging. I've found that just having a desk fan blow across it make a huge difference.
- It has a standard 5.5mm x 2.1mm barrel connector, so you can plug it into any 12V DC power supply that can feed it enough amps.
- Make sure the power supply your using to feed the charger can give enough Amps to cover what you're using. Example, if you're charging all four cells at the default 500mA, you're 3A supply should be fine. But if you want to charge each cell at 1A, you may need to upgrade the power supply.
- When the charger gets hot enough, it will pause its function until the temperature goes down. I think it resumes automatically, but I'm not sure. The current display will read 000mA rather than 0mA, indicating a temperature interruption.

My own opinion is that this is a great little machine, and it has a very important place in my overall cell testing routine. Here's some quick pros and cons:
Pros:
- Best discharge/capacity tester I've used so far.
- Processes 4 cells individually, with independent settings.
- Can be used for a wide variety of cell chemistries and sizes.
- This single unit can run several different functions, and each slot can do those functions independently.
- Seems very reliable and is popular among us 18650 people.

Cons:
- No pre-charge mode. Overly discharged cells could be damaged by trying to charge them in this device.
- No way to calibrate voltage.
- No way to upgrade firmware.
- No storage charge function.
- Runs hot despite the internal fan. I've also heard the internal fan is prone to failure.
- No memory. Losing power means starting the discharge test over.

Finally, here's a few pictures I took the other day while messing around with it:
[Image: a5a4fc0f15930dbc832264f5f6e11378.jpg]
[Image: 8755b2ef4ee7d60dd1ade7a3139c9982.jpg]
[Image: cd7328f62957007537169c0ca7e9a53c.jpg]

That's all I can think of for now. What's been your experience with this device? Also, post questions, and someone around here should be able to answer! Smile
hbpowerwall, BlueSwordM, Robert Baumer like this post
-Mike G
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#2
Charge Test Mode I think does the capacity test in charging, rather than discharging.
Fan to help keep it cool during charging is recommended. However, during capacity testing, only a fan blowing through the unit, not across the cells, is recommended, as this would alter the capacity of the cells. Plus, you want to catch a leaker in the act of testing, not when it's in the build later.
I think there's a wire upgrade, but I dont remember where that was done at.

Good write up, btw.
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Dollar Shave Club. Best Razor I've ever used
Certified 18650 Cell Reclamation Technician
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#3
Charge Test Mode is the one I use at night, you insert the cell and start to charge it, when it's full start to discharge but don't show mAh as in Discharge mode, when the cell reaches 2.8V shows discharged capacity and charges the cell again.

Confirmed that when the charged stops by temperature it starts again when cools down, in the summer of south Spain that can be 2 or 3 minutes.
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#4
some odd behaviour I noticed: When using the Quick Test for IR test right after powering it up, it gives very strange results from 0 up to 9000:

 

Same cells, second test after taking them out and putting them back in again:


Cells tested: 4238 (overall: 8077 Ah, average: 1906 mAh)
Cells in production: 2240 (overall: 4704 Ah, average: 2100 mAh)
Powerwall config: 7s320p, 672 Ah, 16 kWh
What's left: my current grid consumption

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#5
I just notice that one of my OPUs have a faulty port, one cell leaked and damaged something.



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#6
(08-15-2017, 03:04 PM)jesusangel Wrote: I just notice that one of my OPUs have a faulty port, one cell leaked and damaged something.

I've had the same problem. Leaky cell damaged one slot. This is a weakness of having the open slider slots under the cell. Maybe this wouldn't happen if the unit was wall mounted?

Cheers, Paul
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#7
(08-15-2017, 11:02 PM)PaulKennett Wrote:
(08-15-2017, 03:04 PM)jesusangel Wrote: I just notice that one of my OPUs have a faulty port, one cell leaked and damaged something.

I've had the same problem. Leaky cell damaged one slot. This is a weakness of having the open slider slots under the cell. Maybe this wouldn't happen if the unit was wall mounted?

Cheers, Paul

Wall mounting would help. What happens is electrolyte droozles down onto the terminals for the cell temperature sensor, essentially shorting them out. Then Opus thinks it has an overheating cell and shuts down (in my case) current to all the cells. And the fan won't quit. Bottome line: if a cell has ANY crud on its (+) terminal, toss it!

You have to take it apart and clean off the electrolyte, rinse it, dry it and you are good to go again. Tips: not all screws need removing (2 are for the display) and the metal spring rods lift out (no need to remove the white gunkus holding the springs to the rods).
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#8
Yesterday, my Opus's screen started going wonky. Randomly dimming or some of the little pixel things would disappear, or they'd all light up. Turns out if I tap on the screen, It suddenly works again. I think I may have a loose connection somewhere. Before I tear into it, has anyone else solved this issue before?

Here's an example. Should say Discharge, h, 2:56
[Image: b876f0d0a2619b5f8ea4cd6ab071e4e0.jpg]
-Mike G
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#9
Yeah. the lcd screen has come slightly out of alignment with the contactor strip. I think someone in another video mentioned about that if you take it apart, you need to make sure it stays in place when your moving the unit around.
You're gonna hafta take it apart and make sure it's lined up with it's contactors.
If you dont see any and it's just solder joints, then you may need to just reheat the solder to make it get contact again.
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Dollar Shave Club. Best Razor I've ever used
Certified 18650 Cell Reclamation Technician
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#10
I have had a different problem, one of my slots just keeps reading random information even when there is no battery in the slow. I contacted the seller which stated they needed a video of the issue to send to the vendor in China. They offered me 30% refund, initially I was pissed, but I eventually took it as it was getting to be too much of a hassle. So I lost one slot, the other 3 seem to be working good. I wish there was a charger which could tell you the health of the battery. 

Ok, guys, I think I damaged the slot with heat. I noticed yesterday when I was charging Duracell 2650  AA that it was a burner, I mean a extreme burner. It did not leak, but I had to pull the plug on the charger and let the battery cool down, now I am witnessing the same results. When I plug the charger in without a battery it says FULL, when I put a battery in, it keeps giving me random readings. Looks like I need to stick with 18650's in these chargers only.
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