Bad OPUS Charger?

AzJames

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Jun 29, 2017
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Hello,

Has anyone had issues with the OPUS BT-C3100 charger not charging to 4.2v? I'm using one I bought from Amazon, I don't think it is charging correctly. The OPUS displays "FULL" after several hours charging, but when I take the battery out and use a volt meter it reads around 4.14. I get the same reading on three volt meters. Then if I put the battery back in the OPUS it will display "4.19" then switch to "FULL".

Maybe I just need a good quality volt meter. :dodgy:
 

Korishan

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Yes, that is a common issue with the opus chargers.

Another thing is it's possible your MM could use a bit of calibration. Depending on the type, there could 1 adjustment, or as many as 4. I just calibrated my 3 cheapo's to read the same based on a known voltage. So everything reads the same.
As long as everything is on par with each other, the readings of the opus isn't quite that big of a deal. You can keep track of the cells performance just the same. If your MM shows .5V drop over X time, it doesn't matter whether it's 4.2V - 3.7V, or 4.15V - 4.0V.
 

daromer

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Yeap normal. They can be all between 4.15 to 4.25.... Yes its not that good but as most of us just use them to do a test it will most likely work. Just make sure you know of the ones going above 4.2
 

hbpowerwall

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I had one that went to 4.34 volts I managed to get in in the bin basketball style on the third attempt
 

Wattsup

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Yep the opus is a good DIScharger.
I mainly use the digital 4s imax with 8 slot tray and nitecore i4 to charge
 

Joost2

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Hello,

I have the same charging result! This morning I got the same problem on all of my 8 opus chargers. Now the cells are 'fully' charge my multimeter measures 4.15v. Normally I pull them out let them rest for a day and put them back and charging at 200Mah. This morning I disconnect all the opus from power and put them back after 10 min.

Fingers crossed;)

What can help it to discharge the cell for a few seconds with a car lightbulb and put it back.
 

daromer

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Note that after charging to 4.2V its normal that they drop to 4.15 or around... Also note that you do not get much more into them so for testing purposes it doesnt give you much in long run.

Note that you charge in A or mA. Not mAh or Ah. And most likely not MAh that is Mega :)
 

Wattsup

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Yeah it's not such a big deal, do wish they would fully charge but overall they seem good. For the price can't really complain
 

owitte

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yep, that's normal for these cells. Keep in mind that nominal voltage is 3.7V, 4.2V is charging cut-off voltage, which means that the charger stops charging as soon as the cell reaches this level. It doesn't mean that cells stay there...
 

Korishan

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Here's an over simplification of the battery voltage charging. It's kinda like an egg. As you approach the tops and bottoms the voltage will move rapidly (fill up or drain)


image_pusbag.jpg


So when you get to 4.2V, it'll drop to 4.15V relatively quickly. However, charging to 4.2V is like going up a steep hill from 4.15V. And when you get to about 3.2V, the voltage will start to rapidly drop as the voltage is drained. that is one of the main reasons why 'not' to drain the voltage to 3.2V; 3.4V is way safer.
 

JVP

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hi all does anyones opus chargers stop discharging at random voltages like 3.6,3.8.3.5 and so on I thought it might be a heat issue but they don't restart and continue the test
 

Korishan

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You might want to check the internals and make sure the lower volt setting isn't set but the 4.2V setting. If you open the Opus up, you'll see a 3 position switch with 4.3V, 4.2V, and 3.8V settings. Worth a shot to see if it's that or not.
 

JVP

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nope switch is set to 4.2 could the charger just sense that the battery has given all its power at 3.6 volts and just stop the discharge cycle very confused at the moment I would think it shoud discharge all the way to 2.8 volts or there abouts with the sag and stop maybe its an internal temp issue some of the cells have gotten warm but not hot maybe 40 degrees which is 20 degrees above ambient
 

Korishan

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Is it's discharging to 3.6, or is it only charging to 3.6? Also, have you check using other known good cells? I'm not sure if the opus does IR checks or not. But if it does, maybe it's detecting too high of a resistance, perhaps?
If it does it to multiple cells, I'd say you have a bad opus, or bad port. If you recently got it, try to get a return/refund/replacement if possible.
 

Robert Baumer

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May 6, 2017
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Yes, I am not getting a warm and fuzzy feeling about these chargers. I have five of them I purchased from different sellers on Amazon, I have given up on eBay for chargers. Anyway, I had one unit that was working fine and then suddenly a slot went bad, oh and it wasn't a magic smoke issue like AvgJoe always talks about. So I contacted the seller and he stated the vendor from China would do 30%. We just all have to remember, this is not rocket science and we are not dealing with expensive equipment and of course the use of USED batteries. I am more worries about the fact that once my batteries come out of the OPUS they are between 4.17 and 4.19, I hope that higher than nominal voltage does not damage the cells.

-Bob
 

JVP

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its only discharging to 3.6 not all the way down to 2.8 as the spec sheet says. even if it went to 3.2 I would be happy otherwise I cant figure out cell capacity
 

daromer

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Sounds bad unit.
I run 10 myself at home without problem. All from Ebay since thats where i buy it all.

I have bought around 15 so far and out of those 15 1 have gone bad and 1 had faulty fan. Both replaced by seller a day after kind of :)
 

Alec_J

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Mar 16, 2017
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The problem I am having is it not displaying the capacity at the end. It shows FULL. It use to show the capacity when it was complete, but decided on its own to change to display FULL. Does anyone have any pointers for that?
 

daromer

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They all display full. Just press the display button once and they tend to change it. Atleast mine does.
 

I'm Batman

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Sep 5, 2017
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If I discharge 4 cells in my opus at 1 amp itwill randomlystop and continue to discharge. I don' know if it's getting hot and stops discharging till it cools down. I can discharge 3 cells at a time with no issues.
 
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