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Question removable battery lithium

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://cf.shopee.com.br/file/247c2106d63885dc17be99b61824b8f1
https://www.dhresource.com/0x0/f2/a...rsal-cellphone-battery-lcd-charger-single.jpg
https://www.dhresource.com/0x0/f2/a...mobile-universal-battery-charger-usb-port.jpg
 

audioguru

Well-Known Member
Most Helpful Member
A Li-PO battery is a Lithium-Ion battery in a polymer case. Storing them fully charged at 4.2V per cell reduces their lifetime and capacity. Store them at 3.7V to 3.8V per cell. I have some Name-Brand Lithium-Ion batteries stored at 3.75V per cell for 20 years and they still hold the 3.75V today.
Your batteries are no-name-brand so they might not hold a charge for long.

You charged the battery at 75% of what?? 75% of 4.2V is only 3.15V which is too low.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
after how many days do I need to recharge them again so they have long storage and durability?
If you are going to store them for a long period, they should be charged to around 50% capacity.

Then put them in an airtight "zip" bag and store them in the refrigerator (not freezer).
That is the general advice from the battery pack makers, for such as camera/video batteries etc. that are unused for long periods.
It equally applies to any general rechargeable lithium cells, laptop batteries etc.

The cell capacity loss should be no more than around 1% per year at 4'C

They do not need any attention until you are ready to use them.

(Let them reach room temperature before unsealing the bag when you plan to use them, to avoid condensation).
 

audioguru

Well-Known Member
Most Helpful Member
Since the capacity of a battery is difficult to measure, most people store them at 3.7V to 3.8V per cell.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Seeing as I'm in the process of assembling four 4S battery packs, using new Samsung batteries - I thought I'd take the opportunity to measure them. All 12 read 3.59V, they were all out of the same new box of 100.
 
I charged the battery at 75% using the charger in the image I posted at the beginning topic of the third link

How much time after this charge do I need to charge again in order not to decrease battery life? BM20 2000mah and BP-5L 1800mah batteries
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Li-Ion are very good as regards charging, as long as it's done properly there shouldn't be any issues - don't over charge them (a proper charger shouldn't let you), and don't discharge them too far, as this damages them.
 
you not respond my questions

I charged the battery at 75% using the charger in the image I posted at the beginning topic of the third link

How much time after this charge do I need to charge again in order not to decrease battery life? BM20 2000mah and BP-5L 1800mah batteries
 

Nigel Goodwin

Super Moderator
Most Helpful Member
you not respond my questions

I charged the battery at 75% using the charger in the image I posted at the beginning topic of the third link

How much time after this charge do I need to charge again in order not to decrease battery life? BM20 2000mah and BP-5L 1800mah batteries
75% is meaningless, as it's purely dependent on that specific charger - not the state of the batteries. As I've already said, there shouldn't be any issues if they are charged properly.
 

audioguru

Well-Known Member
Most Helpful Member
In post #2 I said, "You charged the battery at 75% of what?? 75% of 4.2V is only 3.15V which is too low."
A lithium battery fails soon if it is stored at a full charge. Also, it should have a circuit to disconnect its load when the load discharges the battery cell to below 3.0V.
A good Lithium battery cell holds a charge for many years, a cheap one maybe a few months.
 
do you recommend charging the BM20 and BP-5L batteries to 90%? You said 75% of 4.2V is only 3.15V, which is too low??

the charger has charged the battery to 75% but the battery has an automatic discharge rate are the batteries stored and will they discharge to 0% or to a bad % for them? my aim is to charge when it's low and not harm the batteries but i can't check every day

charger dc 4.2v dc 400 ma max

 
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audioguru

Well-Known Member
Most Helpful Member
You cannot say 90% unless you say what it is measuring. Voltage? Current? Is it mAh?
If a Lithium-Ion battery cell is discharged below about 3.0V then its power and capacity are damaged. If it is discharged below about 2.8V then it is a hazard to charge because it might explode and/or catch on fire.

The 7 years old ebay charger you show was very cheap and its ad had no technical details.
EDIT: AliExpress sells the same charger today for only $2.44US. Their ad also has no technical details.
 
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I only have this charger what is your opinion for what percentage to charge and what is the time interval for a new recharge? I currently carry at 75 percent and store
 
these batteries at 75% charge need to be recharged after how many months?

do you have batteries Lipo stored for 20 years without constant charging? it is possible? they all have an automatic discharge rate
 
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audioguru

Well-Known Member
Most Helpful Member
Name-brand batteries have very low leakage current and hold a charge for 20 years.
Cheap ebay batteries are no-name-brand garbage and must be charged often.
You showed photos of no name-brand batteries.
 
The BM20 I believe is Original by Xiaomi because I bought it on Aliexpress and the seller said it was original

The BP-5L is Chinese and has 1800mah

Can they hold a charge for 20 years or charge often?

20 years is something very interesting but I don't know how to do it.
 

audioguru

Well-Known Member
Most Helpful Member
AliExpress sell clothes, shoes and any cheap stuff from China. A seller on AliExpress can say anything about the junk he sells. Some of the stuff is fake or defective.
Sanyo, Panasonic and Samsung batteries are high quality name brands and i do not think are sold by AliExpress. Xiaomi is not a name-brand.
 

augustinetez

Active Member
I just received some rechargeable Lithium AAA batteries and the manual that came with them said to recharge fully every three months, so I would do the same with yours.

20 year charge holding, don't think so, accepted wisdom is that Lithium batteries lose approx 5% charge per month, so in 20 months, they are flat.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
you not respond my questions

I charged the battery at 75% using the charger in the image I posted at the beginning topic of the third link

How much time after this charge do I need to charge again in order not to decrease battery life? BM20 2000mah and BP-5L 1800mah batteries
Fully answered - read the answers!

If you are going to store them for a long period, they should be charged to around 50% capacity.

Then put them in an airtight "zip" bag and store them in the refrigerator (not freezer).
That is the general advice from the battery pack makers, for such as camera/video batteries etc. that are unused for long periods.
It equally applies to any general rechargeable lithium cells, laptop batteries etc.

The cell capacity loss should be no more than around 1% per year at 4'C

They do not need any attention until you are ready to use them.
 

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