EEVblog Electronics Community Forum
Electronics => Power/Renewable Energy/EV's => Topic started by: tiago1986 on June 01, 2021, 01:37:00 pm
-
I am in doubt if these two BM20 and BP-5L batteries are lithium or lithium polymer batteries or lithium ions
the BP-5L batteries are 1800mah and the BM20 battery is 2000 I charged them using this photo charger for 75% after how many days do I need to recharge them again so they have long storage and durability?
https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTXi58e_qNfzMCh8Kjr8ghv_fioU1COM08HvA&usqp=CAU (https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTXi58e_qNfzMCh8Kjr8ghv_fioU1COM08HvA&usqp=CAU)
https://cf.shopee.com.br/file/247c2106d63885dc17be99b61824b8f1 (https://cf.shopee.com.br/file/247c2106d63885dc17be99b61824b8f1)
https://www.dhresource.com/0x0/f2/albu/g8/M00/89/F0/rBVaVFzuMVGACHY8AAHs3FpwpDE386.jpg/universal-cellphone-battery-lcd-charger-single.jpg (https://www.dhresource.com/0x0/f2/albu/g8/M00/89/F0/rBVaVFzuMVGACHY8AAHs3FpwpDE386.jpg/universal-cellphone-battery-lcd-charger-single.jpg)
https://www.dhresource.com/0x0/f2/albu/g4/M01/99/29/rBVaEFdqVmqAN_XSAAIMWAUWzYk355.jpg/mobile-universal-battery-charger-usb-port.jpg (https://www.dhresource.com/0x0/f2/albu/g4/M01/99/29/rBVaEFdqVmqAN_XSAAIMWAUWzYk355.jpg/mobile-universal-battery-charger-usb-port.jpg)
-
Please help
-
Those are lithium polymer cells. The chemistry is basically the same but standard lithium ion are usually metal cylindrical cells while flat/rectangular cells are almost always lithium polymer. Technically it doesn't have to be, you can make a polymer electrolyte cell rolled in a cylinder or a liquid electrolyte in a prismatic cell but it is very uncommon.
Regardless, self discharge depends on temperature, battery condition, and age, but takes about a year. Topping them up every few months should be enough to keep them healthy.
-
I have xiaomi BM20 2000mah 4.2v and Chinese BP-5L 1800mah 3.7v batteries and I recharged it to 75% and stored it using this photo charger and I need to know how much I will recharge again to preserve battery life
temperature my home varies 31-34ºC
https://pt.aliexpress.com/item/32581647988.html
-
It's not super sensitive, probably storing anywhere from 40-85% will avoid unnecessary damage. Really if you that concerned about battery longevity you probably shouldn't be buying the cheapest batteries and chargers from aliexpress.
-
the BM20 battery is original xiaomi the seller said and it is more expensive, the Chinese BP-5L is a Nokia copy, the universal charger is the only one I know and it has a charge display
-
For long term storage, charge them to about 3.85V/cell and pack them with some desiccant in a ziploc type bag in the refrigerator. Allow them to warm up to room temperature before removing from bag for use.
-
"Lithium polymer" is a marketing term. It doesn't have any technical meaning. It is sometimes, but not always, used to describe pouch cells. Pouch cells designated as either "li-ion" or "li-poly" have no difference.
There are other chemistry differences, though. Always refer to the correct datasheet of the exact product - if available, of course.
You do not need to maintenance charge li-ion cells. For best lifetime, keep at between 30-50%. Ignoring LiFePO4, in voltage, that would be roughly around 3.50 to 3.70V, depending on chemistry. 3.6V never goes wrong. At that state-of-charge, they won't practically self-discharge unless they are faulty. Maybe you can check the voltage every 2-3 years.
NiHaoMike's 3.85V is on the high side but really it doesn't matter that much, especially if he stores the cells in a refrigerator. Avoiding >3.9V and avoiding hot places is usually enough.
On the other hand, if they have a poorly designed permanently connected protection circuit pulling significant current, you may need to check the voltage periodically (like twice a year) and recharge if necessary.
-
is it true or myth that these BM20 2000mah 4.2v and BP-5L 3.7v 1800 batteries discharge slower with 30-50%??? i recharged them to 75% with this chinese charger
link charger
https://www.aliexpress.com/item/32880328764.html?spm=a2g0o.productlist.0.0.34b34c3aVrthkh&algo_pvid=8e6f96f2-6824-422e-8bc5-1c3aec313360&algo_expid=8e6f96f2-6824-422e-8bc5-1c3aec313360-21&btsid=0b0a556b16228892246966149e38c4&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_ (https://www.aliexpress.com/item/32880328764.html?spm=a2g0o.productlist.0.0.34b34c3aVrthkh&algo_pvid=8e6f96f2-6824-422e-8bc5-1c3aec313360&algo_expid=8e6f96f2-6824-422e-8bc5-1c3aec313360-21&btsid=0b0a556b16228892246966149e38c4&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_)
-
It is true that self-discharge rate is higher at higher state-of-charge. Conversely, at lower state-of-charge there is less self-discharge. Temperature has similar effect: hotter = more self-discharge. I know this because I have measured this myself with various cells of LCO and NCA chemistries. Typical quality cells self-discharge approx. 1-6% of their capacity per year near full SoC at room temperature (+23 degC). At 50% SoC, the self-discharge is practically zero unless stored really hot.
At 75%, who knows? It's likely better than 100% but not necessarily nearly as good as 50%.
Self-discharge usually isn't of any concern at any SoC, any temperature. Irreversible damage, i.e., permanent loss of capacity or permanent loss of current handling capability, is. And this aging is similarly related to the state-of-charge and temperature as described above.
Nobody knows about your cells, though. They might be some random counterfeit crap which may or may not be of acceptable quality. It they self-discharge into oblivion, that doesn't matter; good cells do not self-discharge significantly. If they self-destruct, they were total crap to begin with.
Just use the cells for the intended purpose and replace with better ones if they die.
-
the temperature in my house varies between 31-34ºC what would be the best percentage of charge for self-discharge not to reduce the useful life of these batteries? BM20 and BP-5L batteries
Today I charge to 75% but I have to analyze my ambient temperature, percentage of charge and interval to perform a recharge before it goes down to %
-
As many have pointed out, there's a large variation on how cells behave.
The only way find out how your cells behave, is to check them periodically,
e.g. once a month. If you want to reduce self discharge, put them in a
sealed bag and then put them in the fridge.
-
the temperature in my house varies between 31-34ºC what would be the best percentage of charge for self-discharge not to reduce the useful life of these batteries? BM20 and BP-5L batteries
Between 30% and 50% is best to reduce aging in such warm environment.
-
this temperature is the temperature of my region i can't change it and i don't have air conditioning so what's the best for my situation?
-
Keeping between 30% and 50% is best in all situations for long-term storage. In yours, it's even more important. The answer is still the same: between approx. 30% and 50%. This isn't rocket science, 51% isn't magically bad. Even the 75% you are talking about is likely just fine.
-
I'm in doubt if I continue charging to 75% or 50% is better, my temperature is 31-34C high so 50% will drop faster for a dangerous charge its useful life? if I remember before I charge it to 50% but after 1 or 3 months I plugged the battery into the charger and it had dropped to 25%
-
No, li-ion cells do not self-discharge into dangerously too low region by themselves. The self-discharge basically stops well before they are too empty. If a cell self-destructs in storage due to self-discharge, it was a bad cell to begin with.
You can safely charge or discharge a good cell to as low as 30% and put it on a shelf for 5 years if you want to.
Protection circuit may play games with you, though, and some broken-by-design protection circuits have caused destruction of cells. If a protection circuit is so badly broken it overdischarges a 30% cell into oblivion, using 50% storage instead doesn't give you much more margin, it will die anyway.
If unsure, measure voltage twice a year for example. It shouldn't go below about 3.45V.
If your cell has dropped from 50% to 25% during 1 to 3 months either your measurement shows wrong or the cell is faulty. Instead of the charger showing some percentage, I would trust a simple voltage measurement using a multimeter.
Faulty cells can behave any funny way and it isn't worth anyone's time to guess how they behave, just get some good cells.
-
I have the digital multimeter but I don't know how to test and which scale to use without damaging the battery? would you recommend recharging both to 50% and measuring with a multimeter? what is the best long-term storage voltage for these two batteries? BM20 4.2v 2000mah and BP-5L 3.7v 1800mah
-
Let the cell rest for a few hours or a day before measuring. Be sure to measure using DC VOLTS mode in your multimeter, and make sure the test leads are plugged in the voltage measurement connectors. You can first measure a normal 1.5V or 9V alkaline battery to see you can do it right.
Be very careful not to accidentally short-circuit the pins while measuring.
Between 3.5V to 3.6V is the optimum long-term storage voltage for your cells, but up to 3.7V is still just fine.
-
does the test consist of DC volts on 200 scale? red and black tips connected to COM and 10A?
i want to test if the batteries have any damage caused by charging or storage and the other test is to find out if it is at the correct voltage for long term storage
for storage you said that up to 3.7v is enough but 3.7 is 100% battery and charge and not 50%
-
NO, this will short the cell.
Connect it to COM and V/ohm, and set it to the 20V DC range.
-
NO, this will short the cell.
Connect it to COM and V/ohm, and set it to the 20V DC range.
my multimeter
(https://http2.mlstatic.com/D_NQ_NP_829240-MLB31075161295_062019-O.webp)
-
Try to find a tutorial on how to measure a voltage with a multimeter. Definitely do NOT plug anything into the "10A" socket.
Try with a 9V battery first. It should read something between 8V and 10V if you do it correctly.
20V scale is more accurate than 200V scale when you want to measure a small voltage.
-
the correct is 20v scale and COM/VmA??
BM20 battery is 4.2v 100% and BP-5L is 3.7v 100%, for long term storage the V has to be half being 50%
-
They're both li-po cells with a fully charged voltage at 4.2-4.3V
and fully discharged at 3.0V. At half charge they're around 3.6V.
And do as Siwastaja suggests, find a tutorial.
-
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?
-
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.
-
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.
-
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?
-
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.
-
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?
-
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.
-
the batteries I don't use in smartphones they are separate and I charge it through this charger and it shows on the LCD 25%, 50%, 75%, 100% so it is correct for me to recharge them in this charger and measure the voltages with a digital multimeter?
https://www.aliexpress.com/item/4000332104474.html?spm=a2g0o.detail.1000014.1.4cf916264QAtS1&gps-id=pcDetailBottomMoreOtherSeller&scm=1007.13338.183347.0&scm_id=1007.13338.183347.0&scm-url=1007.13338.183347.0&pvid=b3f880c6-8746-4818-b85f-48d2eb7a2243&_t=gps-id:pcDetailBottomMoreOtherSeller,scm-url:1007.13338.183347.0,pvid:b3f880c6-8746-4818-b85f-48d2eb7a2243,tpp_buckets:668%230%23131923%230_668%23888%233325%236_3338%230%23183347%230_3338%233142%239890%235_668%232846%238113%231998_668%235811%2327188%2383_668%232717%237564%23669_668%231000022185%231000066058%230_668%233422%2315392%23679 (https://www.aliexpress.com/item/4000332104474.html?spm=a2g0o.detail.1000014.1.4cf916264QAtS1&gps-id=pcDetailBottomMoreOtherSeller&scm=1007.13338.183347.0&scm_id=1007.13338.183347.0&scm-url=1007.13338.183347.0&pvid=b3f880c6-8746-4818-b85f-48d2eb7a2243&_t=gps-id:pcDetailBottomMoreOtherSeller,scm-url:1007.13338.183347.0,pvid:b3f880c6-8746-4818-b85f-48d2eb7a2243,tpp_buckets:668%230%23131923%230_668%23888%233325%236_3338%230%23183347%230_3338%233142%239890%235_668%232846%238113%231998_668%235811%2327188%2383_668%232717%237564%23669_668%231000022185%231000066058%230_668%233422%2315392%23679)
-
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.
-
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?
-
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.
-
For measuring the voltage, use the same contacts as you use for charging.
-
i not have 9v battery
golden contacts battery:
-
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%
-
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.
-
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?
-
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?
-
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).
-
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
-
That's a low quality charger, and the display just gives a very rough estimate.
-
what good charger for two batteries?
-
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.
-
i not have smartphone
-
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?
-
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?
-
IMAX B6 is a fairly big charger capable of large currents. I don't know if it can reliably be configured for small currents, if it can and you are careful on getting the max current setting right, it will be suitable.
It's also capable of balance charging multiple cells in series which is a feature you don't need so end up paying premium for a more capable unit than your needs are.
Specs says it can deliver minimum 0.1A charge current, so it should work assuming you get a working non-counterfeit unit.
0.5A would be a good charging current for your cells, maybe occasionally 1.0A if you are in hurry but no more than that.
The problem is engineering reliable and easy-to-use contact pins for those cells.
-
IMAX B6 is a fairly big charger capable of large currents. I don't know if it can reliably be configured for small currents, if it can and you are careful on getting the max current setting right, it will be suitable.
It's also capable of balance charging multiple cells in series which is a feature you don't need so end up paying premium for a more capable unit than your needs are.
Specs says it can deliver minimum 0.1A charge current, so it should work assuming you get a working non-counterfeit unit.
0.5A would be a good charging current for your cells, maybe occasionally 1.0A if you are in hurry but no more than that.
The problem is engineering reliable and easy-to-use contact pins for those cells.
would you recommend or not the Imax B6 for BM20 and BP5L batteries is it safe for these batteries? I would need an adapter to charge these batteries but I don't know where to buy
or would you recommend a cheaper, reliable charger to charge and discharge these smartphone batteries?
-
It's likely safe if not counterfeit and if you read the manuals, understand how to use it, and configure the charge current correctly.
I personally have a small XTAR brand charger which can charge a single cell, with a switch to choose between 0.5A and 1A charging. I pretty much trust it to be safe and would recommend. But this is for 18650 form factor so you need to design some connecting pins to your cellphone cells. I have used a few pogo pins soldered in parallel in the past for this purpose.
-
It's likely safe if not counterfeit and if you read the manuals, understand how to use it, and configure the charge current correctly.
I personally have a small XTAR brand charger which can charge a single cell, with a switch to choose between 0.5A and 1A charging. I pretty much trust it to be safe and would recommend. But this is for 18650 form factor so you need to design some connecting pins to your cellphone cells. I have used a few pogo pins soldered in parallel in the past for this purpose.
i need to buy a good charger and a good adapter for my removable lipo BM20 and BP-L5 batteries i have no experience in creating adapter, ineed help for choose
-
Please help me find a good universal charger/discharger for my BM20 and BP-5L batteries