Remaining Battery Capacity

jon_slider · 2018-06-11T17:41:43.000Z

I dont know what doc you have, I googled your text and found this
http://journals.sagepub.com/doi/abs/10.1155/2013/154831

I dont understand it

it seems there are chargers that do all the estimating…

imho 3.6v is half empty, and it is good for LiIon not to be deep cycled

I hope you find the info you seek

mattheww1950 · 2018-06-11T17:45:35.000Z

I suspect the reason you may not find much on Samsung is that Samsung has produced a very wide variety of Li-ion cells with widely varying capacity and current supply capabilities. Each of those variation is the result of variations in the construction and/or chemistry of the battery, and latter largely determines the actual behavior of the cell. Consequently any relationship between voltage and remaining capacity is going to be specific to whatever specific Samsung cell is involved. Given the vast number of different cells the Samsung has made, I doubt anyone is willing to even make the effort to try to categorize each and every one of them.

jerm03 · 2018-06-11T17:49:12.000Z

Thanks. The article I have is just a chart.
Here are the values for remaining capacity for three batteries at 3.6 V.

AW 2600 mAh 0%
Sanyo 2600 m/ah 2%
Panasonic 1860B 3400mAh 37%.

Seems a wide range of values.
Jerry

flydiver · 2018-06-11T18:05:47.000Z

Pretty useless chart if it has that kind of discrepancy for brand name batteries.

Charts like that are estimates. As such they are possibly better than nothing.

WalkIntoTheLight · 2018-06-11T18:45:52.000Z

You really have to do run-time tests on your battery to be sure.

But, as a general rule, here is what I find I my 18650 batteries (various Samsung, Sanyo, and Sony):

4.20v 100%
4.10v 90%
4.00v 80%
3.90v 65%
3.75v 50%
3.60v 30%
3.30v 10%
2.90v 0%

That’s a rough rule for remaining energy (in watt-hours, not amp-hours, since I use a regulated light with a boost driver to do comparisons). It seems pretty consistent for the popular 18650 cells (30Q’s, VTC6, GA), as well as some older cells.

Protected cells and 14500 cells seem to have way higher voltages when they’re just about empty. I have no idea why.

Usually I top up anything under 3.9v, so I’m never really worried about cells getting low.

jerm03 · 2018-06-11T20:30:53.000Z

Thanks, WalkIntoTheLight, I sometimes try to do run-time tests,but I always fail to keep watching and do not do a good job.
Jerry

jon_slider · 2018-06-11T22:22:13.000Z

I do runtime tests using 15 or 30 minute alarms on my phone. At each alarm i take lumen teadings plus voltmeter readings

jerm03 · 2018-06-11T22:07:35.000Z

Thanks, Jon, I might try that.
Jerry

jon_slider · 2018-06-11T22:36:31.000Z

I like lights that have battery level indicators, which i crosscheck w a voltmeter.

Zebra does it, my Utorch S1 mini does it, although its not well calibrated, it helps. At one flash i know its at 3.7v. Without having to open the light.

my 0light S1 Mini has a low battery indicator light that turns on Red. That’s really idiot proof for me. It does that at 3.4v. I carry a spare battery, in a spare light lol

I hope you find stategies that fit your needs

Pete7874 · 2018-06-11T22:43:00.000Z

Jerry, is this what you were talking about?

https://tinyurl.com/y9d5c6y5

klrman · 2018-06-11T23:00:16.000Z

WalkIntoTheLight:

You really have to do run-time tests on your battery to be sure. But, as a general rule, here is what I find I my 18650 batteries (various Samsung, Sanyo, and Sony): 4.20v 100% 4.10v 90% 4.00v 80% 3.90v 65% 3.75v 50% 3.60v 30% 3.30v 10% 2.90v 0% That’s a rough rule for remaining energy (in watt-hours, not amp-hours, since I use a regulated light with a boost driver to do comparisons). It seems pretty consistent for the popular 18650 cells (30Q’s, VTC6, GA), as well as some older cells. Protected cells and 14500 cells seem to have way higher voltages when they’re just about empty. I have no idea why. Usually I top up anything under 3.9v, so I’m never really worried about cells getting low.

Do you think your 18650 figures would be similar to 26650 batteries?

jon_slider · 2018-06-11T23:22:54.000Z

klrman:

WalkIntoTheLight:

You really have to do run-time tests on your battery to be sure. But, as a general rule, here is what I find I my 18650 batteries (various Samsung, Sanyo, and Sony): 4.20v 100% 4.10v 90% 4.00v 80% 3.90v 65% 3.75v 50% 3.60v 30% 3.30v 10% 2.90v 0% That’s a rough rule for remaining energy (in watt-hours, not amp-hours, since I use a regulated light with a boost driver to do comparisons). It seems pretty consistent for the popular 18650 cells (30Q’s, VTC6, GA), as well as some older cells. Protected cells and 14500 cells seem to have way higher voltages when they’re just about empty. I have no idea why. Usually I top up anything under 3.9v, so I’m never really worried about cells getting low.

Do you think your 18650 figures would be similar to 26650 batteries?

Imo yes, those are reasonable numbers for any 3.7v liion

I also find that my utorch drops out of medium @3.5v, so if that happens, i swap in fresh.

Speed4goal · 2018-06-11T23:20:22.000Z

WalkIntoTheLight:

You really have to do run-time tests on your battery to be sure.

But, as a general rule, here is what I find I my 18650 batteries (various Samsung, Sanyo, and Sony):

That’s a pretty good rule of thumb chart there. Protected batteries

4.20v 100%
4.10v 90%
4.00v 80%
3.90v 65%
3.75v 50%
3.60v 30%
3.30v 10%
2.90v 0%

That’s a rough rule for remaining energy (in watt-hours, not amp-hours, since I use a regulated light with a boost driver to do comparisons). It seems pretty consistent for the popular 18650 cells (30Q’s, VTC6, GA), as well as some older cells.

Protected cells and 14500 cells seem to have way higher voltages when they’re just about empty. I have no idea why.

Usually I top up anything under 3.9v, so I’m never really worried about cells getting low.

I’ve noticed with protected cells when they are empty show higher voltages then the same unprotected cell. I always chalked it up to the higher resistance from the protection circuit. Like a normal cell drained to 3 volts under load shows about 3.2 to 3.3 when placed on the charger. And some protected cells and worn out cells with higher internal resistance will go up to 3.5+ once the load is removed.

Barkuti · 2018-06-11T23:21:31.000Z

jon_slider:

…

imho 3.6v is half empty, and it is good for LiIon not to be deep cycled

…

For a cell like the PLB 26650 5000mAh (LiitoKala INR26650-50A), at 3.6V no-load less than 2Ah of capacity are left (to infer this just look at the 0.2A discharge curve and maybe add 25 - 30mV because of the very small additional (besides I × R) loaded cell voltage drop. Other cells (different chemistries and etc) may vary.

With regards to deep cycling being detrimental for li-ion… I've heard it many times, but found absolutely no proof of it, whereas high voltage (high state of charge) is known to be detrimental and there's plenty of experiential and experimental proof. Thus, as far as I am concerned I'm gonna give that a Big Bullsh1t Award.

Cheers ^:)

Enderman · 2018-06-11T23:24:43.000Z

Remaining battery capacity depends on the voltage, the discharge curve of the cell voltage, the current draw at the moment of reading the voltage, and the average discharge rate.
Without these things all you will have is a rough guess.

jon_slider · 2018-06-11T23:38:44.000Z

Barkuti:

jon_slider:

… it is good for LiIon not to be deep cycled

…

I’m gonna give that a Big Bullsh1t Award

Lol
You misunderstand, my point. I will try to clarify:

It is not bad to recharge liion at 50%.

It is not necessay to drain completely before recharging

Liion does not build recharge level memory

I agree liion can be stored half empty

If you want to disagree with something I said you should criticize the 3.6 V comment which is not accurate.
Or better yet just post your own opinion instead of taking the time to criticize mine

moderator007 · 2018-06-12T00:11:17.000Z

These voltage to remaining capacity charts you see floating around, were mostly published and used when there were very few 18650 battery types and makes around. They were always considered a close estimate even then. Now you have several different types of 18650’s coming from each manufacture of the many, including a lot of china cells. The discharge curves vary a lot, so there measured resting voltage after partial use vary’s also, making the old voltage remaining capacity chart even further off. The chart is just a estimate and isn’t as reliable as it use to be because of so many differences in cells now a days. To make a somewhat accurate chart, you would need to discharge each type of cell and make a chart for that cell. Even then there could be slight differences. HKJ’s graphs would get you a close estimate under load, but you would have to use the same load as he tested with to get a close estimate. That reminds me, HKJ always tries to test two battery’s in his test because of the differences that sometimes causes different results when testing. These voltage to remaining capacity charts are just a estimate.

klrman · 2018-06-12T00:40:03.000Z

jon_slider:

klrman:

WalkIntoTheLight:

You really have to do run-time tests on your battery to be sure. But, as a general rule, here is what I find I my 18650 batteries (various Samsung, Sanyo, and Sony): 4.20v 100% 4.10v 90% 4.00v 80% 3.90v 65% 3.75v 50% 3.60v 30% 3.30v 10% 2.90v 0% That’s a rough rule for remaining energy (in watt-hours, not amp-hours, since I use a regulated light with a boost driver to do comparisons). It seems pretty consistent for the popular 18650 cells (30Q’s, VTC6, GA), as well as some older cells. Protected cells and 14500 cells seem to have way higher voltages when they’re just about empty. I have no idea why. Usually I top up anything under 3.9v, so I’m never really worried about cells getting low.

Do you think your 18650 figures would be similar to 26650 batteries?

Imo yes, those are reasonable numbers for any 3.7v liion I also find that my utorch drops out of medium @3.5v, so if that happens, i swap in fresh.

So far, I've recharged the batteries when they reach around 3.6v to 3.7v but always wondered what would happen if I just let them regularly go down to 3.0V. Never did that yet except when doing a capacity test on the charger.

CRX · 2018-06-12T00:42:02.000Z

Some members did a voltage reading after letting cells sit for two months.
I did a voltage measurement with a small selection of cells at 50% capacity.

jerm03 · 2018-06-12T01:00:58.000Z

Yes, that’s it. Thanks.
Jerry