Opus behaviour: Normal?


Aug 9, 2019
Hello folks,

I just got a new OPUS BT-3100 charger.

Before I had a «Liito Kala li500» but it startet behaving strange on me (didn't measure voltages correctly and repeatedly accurate (at least not lately); not all slots had the same end-voltages and thus tested cells with different results) and lately I had cells that were overcharged to over 4.30V which is completely inacceptable if not to say very dangerous too. So this one will be disposed.

Now I just started a first «TEST» with the new OPUS charger. I have four 18650 cells in it (they were tested before and charged; the former test showed >2800mAh per cell and they are rated for 10A continuous discharge, cell type is LGDBMH11865).
Now during the discharge (I do it with 1000mA) it shows ~1000mA as the discharge current ±5mA or so. But from time to time it goes to 0mA (Thermal shutdown). Is this normal/usual at the 1000mA setup? I read it happens due to overheating (>60°C) but for my feeling the batteries get only warm - I can easily touch them - I think at 60°C they would be burning hot and not touchable...?!

What is your expirience with 1A discharge? Should all stay cool, do I have some heater cells there or is it the charger that misinterprets the temperature?
Looking forward to your replies.



Staff member
Oct 8, 2016
Its normal. You have it warm in the room and the device itself gets warm. its not the cell that is arm. If you have it warm where they sit you can always print a new bottom case and add a bigger fan there to cool the device. its due to you try to dissipate alot of energy at same time.


Well-known member
Dec 15, 2018
This happened to me from day 1 on all my OPUSs - e.g. room temp and trying to do 1000ma discharge. So I started doing 500ma discharges - which is OK in my situation since my powerwall is designed for <500ma per cell - but lengthens the time. Since I started this way, I continue it so that all my cells are tested the same on day 1 as on day 800 - but the extra time is really starting to add up after 10,000 cells. So I would figure things out now and not wait :)


Active member
May 25, 2017
If you're worried about a large fan masking actual "heaters", what I do is an initial charge with tp4056 boards. The heaters will show themselves during the initial charging on the tp4056, and if they leak, it won't get on the Opus. Plus you can charge one set while the Opus runs the discharge on a second set. Faster processing that way.


Well-known member
Sep 25, 2018
If you're worried about a large fan masking actual "heaters", what I do is an initial charge with tp4056 boards
I still don't quite get this 'heater" thing why are people still getting heaters?
This can be totally avoided by checking the IR of the cells first.
Heater problem solved.
I haven't had a heater in 2 years and yes I do process all kinds of Sanyos.