Author Topic: Questions batterys lithium  (Read 2721 times)

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Offline tiago1986

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Re: Questions batterys lithium
« Reply #25 on: June 07, 2021, 03:34:49 pm »
For both batteries it is best for long term storage to charge to 3.6V???

why the batteries have different voltages 3.7 or 4.2v and you say they all have a single voltage of 100%?

store in voltage of 3.6v (50%) the self-discharge is slower and after how many months do I need to recharge so that it doesn't go below 3.0v?
 

Offline tunk

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Re: Questions batterys lithium
« Reply #26 on: June 07, 2021, 03:43:20 pm »
It's marketing, 4.2 sounds better than 3.7.
There is a large variation in self discharge, nobody here can say
how your cells behave. You have to test them periodically.
 

Offline Siwastaja

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Re: Questions batterys lithium
« Reply #27 on: June 07, 2021, 04:38:27 pm »
You have just received wrong information; it's definitely not 100% at 3.7V. Neither is one of the cells 4.2V nominal.

100% state-of-charge is at 4.2V, very likely for both of your cells.

Nominal "nameplate" voltage is roughly as measured at 50% state-of-charge. This is 3.6V or 3.7V for both of your cells.

There is no li-ion cell in existence with 4.2V nominal.

50% is approximately at 3.65V but exact value depends on the exact chemistry used. Being close to 3.65V, you can see how other manufacturers round it to 3.6V nominal, others 3.7V nominal. There is no big difference.

Empty sits usually at around 3.4V, but when near empty, voltage drops under load more so cutoff limits are significantly lower than that, like 2.8V.

There are higher-voltage cells that may be labeled 3.8V nominal and they can be charged to 4.30V or 4.35V but these are special cases and not that common anymore. Your cells likely aren't such.
 

Offline tiago1986

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Re: Questions batterys lithium
« Reply #28 on: June 07, 2021, 07:32:04 pm »
For both batteries it is best for long term storage to charge to 3.6V???

store in voltage of 3.6v (50%) the self-discharge is slower and after how many months do I need to recharge so that it doesn't go below 3.0v?
Modify message

how many months under these charging conditions can the battery maintain its useful life?
 

Offline tunk

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Re: Questions batterys lithium
« Reply #29 on: June 07, 2021, 09:18:24 pm »
We know nothing about your cells: They could be new high quality cells
which could be stored for years with minimal self-discharge, or they could
be repurposed used cells which could fully self-discharge in days or weeks.
 

Offline tiago1986

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Re: Questions batterys lithium
« Reply #30 on: June 07, 2021, 09:30:28 pm »
between 3.5v and 3.8v is the best for long term storage for these two mentioned batteries?

Please guide me the scale to test with multimeter if it is among these good loads for storage

is it possible to test if the batteries have any defect due to improper charging or storage?


Does any test reveal if the battery has already dropped the voltage to a voltage that harms its useful life?
« Last Edit: June 08, 2021, 12:20:24 am by tiago1986 »
 

Offline Siwastaja

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Re: Questions batterys lithium
« Reply #31 on: June 08, 2021, 09:14:27 am »
Let the cell sit for a day or two without being in charger.

Measure voltage. Write the measured voltage down on a piece of paper and don't lose it.

If between about 3.5V to 3.6V, this is the optimal storage voltage, but even up to 3.8V is a fairly good storage voltage. Put it on the shelf, forget about it and go enjoy life.

Measure again after a year, maybe two. If it has significantly dropped from what you wrote down on paper, for example from 3.65V to 3.50V, the cell wasn't in very good condition to begin with, but it may be still usable.

If it has dropped below about 3.0V, the cell is dead, forget about it and dispose of it properly. Storage revealed this, but it was not the storage which "harmed" it, it was originally bad because it won't hold the charge properly. Proper cells survive storage at any state-of-charge without dying.

Actually storing for a long time is a surprisingly good "defect test" for mere mortals without expensive analyzer tools. A proper cell doesn't significantly lose voltage when kept below about 3.7V. To your question, after how many months you need to recharge - you don't! Well maybe you can check the situation after two years, but if the cells are any good, you likely won't need to recharge at all even after 5-10 years!

Finally, we know nothing about the quality of your cells. They might be bad counterfeits.
 


Offline Siwastaja

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Re: Questions batterys lithium
« Reply #33 on: June 08, 2021, 05:18:39 pm »
Nobody knows about that charger, it's a cheap toy and it can be anything. I wouldn't trust it at all. Maybe it works. Having a mains 100-240VAC input, it may be lethally dangerous.

Verify with a digital multimeter but make sure you can correctly use a multimeter to measure voltage first.
 

Offline tiago1986

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Re: Questions batterys lithium
« Reply #34 on: June 08, 2021, 05:39:55 pm »
I'm going to charge the battery using this charger and I'm going to measure the voltages with the digital multimeter

is the battery medication correct at 20 DCV and the cables at COM and VOMEGAmA?

on the 4 gold contacts of the batteries where to play with the multimeter?
 

Offline Siwastaja

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Re: Questions batterys lithium
« Reply #35 on: June 09, 2021, 01:31:41 pm »
Yes, 20 DCV range and probes connected to COM (-) and V omega mA (+) is correct. Measure a 9V battery first like this, if it shows something like 8 to 10 V you are doing it right.

If you probe carefully (i.e., not accidentally shorting the multimeter probe tips together!!), there is no risk of measuring the wrong contacts, so you can try different combinations until you find which two contacts carry the cell voltage.

You do this at your own risk, of course.
 

Offline tunk

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Re: Questions batterys lithium
« Reply #36 on: June 09, 2021, 01:54:37 pm »
For measuring the voltage, use the same contacts as you use for charging.
 

Offline tiago1986

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Re: Questions batterys lithium
« Reply #37 on: June 09, 2021, 02:02:27 pm »
i not have 9v battery

golden contacts battery:
« Last Edit: June 09, 2021, 02:18:47 pm by tiago1986 »
 

Offline tiago1986

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Re: Questions batterys lithium
« Reply #38 on: June 10, 2021, 10:20:39 am »
with the digital multimeter scale 20 DCV I tested the batteries BM20 4.2v 2000mah and BP-5L 3.7v 1800mah and the result was BM20 4.14v and battery BP-5L the result was 4.09v but I didn't understand the BP-5L because it is 3.7 v, are these results good for long-term storage or not? What should I do? it's been 2 or 3 months since the last recharge and the universal charger LCD showed 75%
 

Offline Siwastaja

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Re: Questions batterys lithium
« Reply #39 on: June 10, 2021, 10:27:18 am »
Great to hear you were able to measure the voltage.

BM20 is at maybe 97% and BP-5L at maybe 90%. I would trust this multimeter-measured value more than the "universal charger LCD".

They are both too full if you consider long-term storage.

You can just discharge them until around 3.6V.

The simplest way of discharging them is to just use them in your phone.
 

Offline tiago1986

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Re: Questions batterys lithium
« Reply #40 on: June 10, 2021, 12:39:26 pm »
is it possible to discharge them keeping the batteries inserted in the universal charger? the charger has LCD and the LCD will be battery powered

Did this time the batteries were stored at 97-90% permanently damage them?

is it possible to discharge the battery through the digital multimeter?

3.6v or 3.8v is better?
« Last Edit: June 10, 2021, 12:44:47 pm by tiago1986 »
 

Offline tiago1986

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Re: Questions batterys lithium
« Reply #41 on: June 10, 2021, 04:38:39 pm »
I don't have the smartphone compatible with the BM20 battery so I'm discharging it through the universal charger but on the universal charger it shows 50% charge but when I go to measure the voltage with the multimeter it remains at 4.1v and I didn't understand it would be correct 50% shown on the display of the universal charger and on the digital multimeter will be shown something close to 3.8v and this does not occur

Is 3.8v voltage best for long term storage?
 

Offline tunk

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Re: Questions batterys lithium
« Reply #42 on: June 10, 2021, 05:31:49 pm »
Your multimeter cannot discharge the cells.
Try to connect the battery to the charger without plugging it to mains.
If there's a LED backlight then it will discharge the battery very slowly (with a few mA).
 

Offline tiago1986

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Re: Questions batterys lithium
« Reply #43 on: June 10, 2021, 05:45:26 pm »
I connected the battery to the universal charger but I didn't plug the charger into the electric network and the charger lights the screen with LED but the discharging is slow, does slow discharging affect the useful life of these batteries?

is normal so I'm discharging it through the universal charger but on the universal charger it shows 50% charge but when I go to measure the voltage with the multimeter it remains at 4.1v and I didn't understand it would be correct 50% shown on the display of the universal charger and on the digital multimeter will be shown something close to 3.8v and this does not occur
 

Offline tunk

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Re: Questions batterys lithium
« Reply #44 on: June 10, 2021, 06:19:08 pm »
That's a low quality charger, and the display just gives a very rough estimate.
 

Offline tiago1986

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Re: Questions batterys lithium
« Reply #45 on: June 10, 2021, 08:33:16 pm »
what good charger for two batteries?
 

Offline Siwastaja

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Re: Questions batterys lithium
« Reply #46 on: June 11, 2021, 10:51:22 am »
Really, the most suitable charger would be the phone itself.

These phone batteries are custom manufactured for the phones, and phone manufacturers have not manufactured stand-alone chargers.

Everything else is unofficial crap.
 

Offline tiago1986

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Re: Questions batterys lithium
« Reply #47 on: June 12, 2021, 10:23:13 am »
i not have smartphone
 

Offline Siwastaja

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Re: Questions batterys lithium
« Reply #48 on: June 12, 2021, 12:04:16 pm »
May I ask you, why are you buying these batteries in order not to use them but store them long term? Really the only reason coming into my mind is you have the phone itself and fear the batteries dying and want to store replacements to be self-sustained, but if you don't even have the phone, what's the point of storing the batteries for years for something you don't have?
 

Offline tiago1986

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Re: Questions batterys lithium
« Reply #49 on: June 13, 2021, 12:10:59 am »
these batteries are used in a Powkiddy Q80 and RS-97 Plus handheld consoles but it's tiring for me to take and place the battery several times so I want to charge or discharge externally and store the spare batteries

i thought of the imax b6 but this charger was only made for model airplane batteries and the smartphone batteries have built-in IC and this charger doesn't have IC so if I charge these batteries with the imax b6 will it reduce their useful life? imax b6 is an RC charger and these batteries is not RC?
 


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