Opus BT-C3100 discharge and test modes

Hank33 · 2019-12-29T01:16:16.000Z

For Discharge mode, does one need to have the battery fully charged before doing the test? For Test mode, manual says “…maximum capacity is determined by discharging battery after it was fully charged”. Does that mean after the Test mode is done I still need to fully charge the battery?

Petr_J · 2019-12-29T01:31:34.000Z

Discharge mode:
Discharges a fully charged battery. It should be recharged after the test.

Charging test mode:
It charges the battery to its full capacity, discharges it, and recharges it to its full capacity.

Hank33 · 2019-12-29T01:43:27.000Z

Ok got it! and that’s why my last couple of Test modes took so long!

chops728 · 2019-12-29T03:12:51.000Z

I usually have my cells close to full charge before I do a capacity test —just my preference I guess—I just feel if you fully charge a cell then right after it goes into discharge,then it recharges again can’t be good for a cell—~~maybe even affecting capacity—~~ some one correct me if I’m wrong

Hank33 · 2019-12-29T03:39:57.000Z

Yeah I’m gonna keep the cells topped up.

CNCman · 2019-12-29T04:11:18.000Z

That cycle can take all night long.

Barkuti · 2019-12-29T04:51:03.000Z

There's soo much @#$% going on with li-ion care it is just amazing. Lots of disinformation, of course.

Keeping standard li-ion cells fully charged at all times is detrimental. This is a known fact. You can find related information in BU-808: How to Prolong Lithium-based Batteries.

chops728:

I usually have my cells close to full charge before I do a capacity test --just my preference I guess–I just feel if you fully charge a cell then right after it goes into discharge,then it recharges again can’t be good for a cell—maybe even affecting capacity— some one correct me if I’m wrong

Well, that's incorrect. In order to feel something correctly, correct believing is required. If a cell is discharged right after being fully charged the time it dwells at high voltage is minimum. Hence, minimum damage. Concerning the “full recharge right after discharging” I nearly always prevent it, this is because I usually keep my ready to use cells at ≈3.95 V and at least slightly below if they're to be stored.

And now, concerning the “recharge after discharge” thing, it is not really required. A cell discharged within specs will very quickly raise its voltage above 3 V again. Check this article by Henrik: How far can LiIon be discharged? @ lygte-info.dk

For reference, I once salvaged some old laptop cells which were slightly above or below 2 V out of a pack, and after testing and self discharge test analysis I discarded 2 out of 6 units (the ones with perceptible self discharge over a few weeks). The rest did and are doing good, on average delivering ≈85.43% of their specified capacity.

Take care. :-)

tatasal · 2019-12-29T23:37:54.000Z

In response to the OP:

In the Opus BT-C3100, the ‘Discharge’ mode will simply discharge any capacity left in the cell down to IIRC, 2.9v, then the process ends, displaying whatever mAh the cell had as the process is terminated automatically. If you need to know the Full capacity, then it’s better to fully-charge the cell first.

In Capacity test, the process is Charge-Discharge-Charge, but it depends on the State-of-charge of the cell to be tested. If the cell to be tested is already fully-charged and the charger detects it, ( However, if the charger detects there is still some “space” in the cell, it will Charge it first to full) it will dispense with the initial Charge and go to Discharge mode, down to 2.9 I believe, then fully-charge the cell (again), then the process ends. The charger will then display the Capacity of the tested cell after the C-D-C process terminates automatically.

Rayoui · 2019-12-29T05:12:12.000Z

I always keep my cells topped up. Having a drawer full of half-dead batteries doesn’t do me any good. If the capacities are diminished after a couple of years, I’ll just replace them. When the power goes out, I want my batteries to be ready to go.

Barkuti · 2019-12-29T07:07:09.000Z

I often find amusing the way some of you believe (it could also be said from me, of course, I also laugh at me sometimes).

Rayoui:

… Having a drawer full of half-dead batteries doesn’t do me any good. … When the power goes out, I want my batteries to be ready to go.

Half-dead? Funny. Even at 3.92 V modern li-ion batteries aren't half-dead, but more like ≈70% capacity full. Also, newer chemistries are more resilient. In a Samsung 35E datasheet I read the OEM recommends 4 V charge voltage for ESS/UPS (Energy Storage System / Uninterrupted Power Supply) use. So you can give longer life to your cells while still keeping them “more ready to use”.

Concerning “when the power goes out” sounds dramatic too. Blackouts are extremely rare where I live, and usually very short lived (also, a bunch of candles is cheap and never :-D expires).

The main problem I see with the maximum charge voltage thing, though, is that most chargers only allow the usual 4.2 / 4.35 V standards. On top of this some overcharge or even apply :facepalm: trickle charge to li-ion cells (whoever does this needs his arse be beaten; are you listening, LiitoKala?).

My advice is to get advanced chargers, of course. Hope the BLF UC4 gets well done, by the way.

Rayoui · 2019-12-29T08:58:57.000Z

Barkuti:

I often find amusing the way some of you believe (it could also be said from me, of course, I also laugh at me sometimes).

Rayoui:

… Having a drawer full of half-dead batteries doesn’t do me any good. … When the power goes out, I want my batteries to be ready to go.

Half-dead? Funny. Even at 3.92 V modern li-ion batteries aren’t half-dead, but more like ≈70% capacity full. Also, newer chemistries are more resilient. In a Samsung 35E datasheet I read the OEM recommends 4 V charge voltage for ESS/UPS (Energy Storage System / Uninterrupted Power Supply) use. So you can give longer life to your cells while still keeping them “more ready to use”.

Concerning “when the power goes out” sounds dramatic too. Blackouts are extremely rare where I live, and usually very short lived (also, a bunch of candles is cheap and never expires).

The main problem I see with the maximum charge voltage thing, though, is that most chargers only allow the usual 4.2 / 4.35 V standards. On top of this some overcharge or even apply :person_facepalming: trickle charge to li-ion cells (whoever does this needs his arse be beaten; are you listening, LiitoKala?).

My advice is to get advanced chargers, of course. Hope the BLF UC4 gets well done, by the way.

I wasn’t trying to imply that your way of doing things is wrong. It just depends on whether you want to prioritize maximum capacity or maximum longevity. With the chargers I use, the cell voltage usually settles around 4.15v. I’ve never had any issues with any of my cells seemingly wearing out too quickly from being stored fully charged. It’s no big deal to just replace them when they do eventually wear out anyways.

I don’t get many blackouts in my area either but I still like to be prepared. I still put on my seatbelt when I get in my car despite the fact that I don’t expect to crash it every day.

I had a LiitoKala charger that was consistently overcharging my cells. I tossed it in the trash.

I am on the list for the BLF UC4 but I’ve also been looking at the SkyRC MC3000 as well. It seems to be a feature rich charger with lots of analyzing functionality and support for lots of different chemistries. Just wish I could find one on sale…