Today I tested the KeepPower 3400mah cells I’ve been using on the bike. Very well used and likely well over 500 top-off charges and at least 100 near-full charges. one read 3105mah and the other 3171mah. This actually makes me happy, except the fact that I don’t know what the test state was for sure. But I did notice this. I always fully charge on the XTAR charger. I know it terminated perfectly every time at 4.20V. When the test was started on the Opus V2.1, it started its charge routing as normal and then showed 4.25V just before it went into the discharge for the test. Again, I left the J1 jumper in place.
Tomorrow I will test my brand new 3400mah evva-tech cells from Mtn Electronics. This should be interesting. I’ll do the same, top them off on the XTAR WP2 and see if they come close to the expected capacity according to Opus.
However, I am skeptical about all the readings. I know the meter is not reading the terminals. It is doing some level of interpolation. That J1 jumper could be affecting a lot more than termination voltage including internal calculations. I know the same thing happens when it reads voltage on the discharge and doesn’t come close to the terminal voltage (in this case always reads high). The display is simply =some= internal reference, but who knows exactly what.
Also, per the review on the charger, this is =not= a true CV/CC charger and this does cause some really wild readings during the charging phase at the terminals. Yes, this unit is feature packed in firmware, but the deviation in the CC portion really is what makes this thing suspect for a reliable charger. It could well be that the J1 jumper is all about how it manipulates the pulse current for emulate the CC cycle.
Reference: see conclusion here - Test/Review of Charger Opus BT-C3100 V2.1