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hello need advice to test my cells 18650
#11
testing on charge test can take a long time. if if the entire test takes 5 hours, it may be that the cells were low voltage when put into the opus first charges to 4.20v discharges to ~2.8v then recharges to 4.0 for a 2000mAh cell 2 hoorrs to charge 2 hours to discharge,2 hours to recharge. if just one section of the test takes 5 hours the cell has a problem.


Later floyd
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#12
Also remember to test IR for each of the cell and rule out > 100ohms

CG
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#13
(07-24-2020, 08:27 PM)stiplanet Wrote: hi everyone, i have started my 18650 cell tests and currently i have cells between 1000mAh to 2000mAh AND 2000mAh to 3000mAh -3000mAh to 3900mAH, i need your advice which cells should i keep?I noticed that the test lasts too 5 hours for some cells, is it normal?  thank you.

Which mode are you using on your Opus? Discharge/Test? Remember that 3900mAh cells will take a lot longer to test than 1000mAh ones obviously. Remember that if you're charging / discharging at 1000mA, in theory, it will take 3.9 hours to fully discharge a fully charged 3900mAh cell and 3.9 hours to then fully charge it again so look for a pattern.  As a matter of caution, if a cell has been in the charger for more than a couple of hours and it hasn't finished, touch it with your hand every now and again to check it isn't too hot. Some faulty cells will dissipate heat above 4 volts instead of fully charging, these are often called "heaters" and the red Sanyo cells are famous for this. Don't use these cell's put them to one side for recycling.

Good luck! ;-)
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#14
I didn't notice the high mAh in post 10, the max for 18650's is around 3500- 3600 mAh, That is for new cells.
Recycle any cell which takes too long in any of the 3 stages, is over 3600mAh.
There are some new cell formats which can have higher mAh 21700 20700 for example.
Later floyd
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#15
thanks everyone for your help, i'm using charge and test mode, tell me what is the correct mode i should use? also how to do IR resistance test also thanks
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#16
Stiplanet English please.
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#17
stiplanet, you can use the discharge test at 1000mAh.
For IR there's a quick test but it's relatively imprecise.
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#18
hi everyone i tried the 1000mA discharge mode after 4 hours it displays the cell capacity the voltage, but at the discharge current level it displays 0, does that mean it has finished the test? because I can't see the IR value of the cells thank you
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#19
yes finished the discharge test, on an opus you should use the charge test, that way the cells are tested all the same.
to get the IR value on an opus use the quick test mode, just beware that theIR tester on most if not all multi bay tester is very in inaccurate.
later floyd
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#20
^^^ It is possible to get usable DC IR results from the Opus BT-C3100, but it requires care to ensure that all terminals are clean and make good contact (contact IR is included in the measurement since it uses a 2-wire, not 4-wire (Kelvin) method).  For example, below are results from HKJ's test which shows the results are consistent within a few percent (ignoring slot 4 - whose internal cabling resistance likely differs from the others). The SkyRC MC3000 is usually reported to be better, but it's still not 4-wire - which would give much better results. (note: the battery+xyz is for testing the linearity of the measurement - for which some chargers fail miserably).

[Image: oL5q8.png]
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