Questions conserve battery polymer lithium and lithium

[John rodrigues]

1) is charging up to 50% using these chargers a good indication that the voltage is 3.7 or 3.8V?

2) does the battery stored at 50% charge have an automatic discharge rate lower than a battery stored at 80, 90-100%?

3) I am afraid to store the batteries at 50% and after 1 year they will be charged 0%

 

[c_mitra]

is charging up to 50% using these chargers a good indication that the voltage is 3.7 or 3.8V?

Right; the battery voltage should be around 3.65-3.75V. Basically it depends on the chemistry. There will be variations due to manufacturing process, intra batch and inter batch variations. I shall be more generous and say that the battery voltage should be around 3.6 to 3.8V.

does the battery stored at 50% charge have an automatic discharge rate lower than a battery stored at 80, 90-100%?

Yes. The higher the voltage the greater is the self discharge current. But that does not mean that you can store fully discharged cells. When the cell is fully discharged, the chemicals are not in balanced condition.

I am afraid to store the batteries at 50% and after 1 year they will be charged 0%

Even if it appears discharged after 1 year, you can charge it before use. There may be some loss of capacity, usually 10-20%

Even if you are using the battery regularly for one year (using recommended cycles), after one year there will be 20% loss of capacity (a 1000mAH cell will be effectively 800mAH).

These are general guidelines. There may be small variations in details.

 

[Audioguru]

I have purchased many Li-PO batteries over 11 years and they are always sold at 3.7V to 3.8V, so that they are in good condition after being stored in a store maybe for years before being sold.

I always buy good quality Name Brand batteries because the cheap ones are garbage. Most of my batteries have been charged and discharged to 3.2V per cell hundreds of times and have been stored for many winters at 3.7V and each summer I charge them and use them many more hundreds of times.
Maybe you are worried about cheap batteries not surviving being stored at 50% charge for one year? Then don't buy cheap garbage batteries, they are probably fakes.

 

[John rodrigues]

my batteries are chinese or pirated but i intend to conserve the maximum they then charge up to 100% and store or charge up to 50% and store? I can't let them get 0% after a year

 

[Audioguru]

Buying a cheap battery is like playing a game. Sometimes you win but usually you lose and the fake battery seller laughs at you.
A good battery stored at 100% is stressed and fails in weeks or months. A battery that has discharged below 3.2V per cell is damaged and if discharged below 2.5V is destroyed and might catch on fire of you try charging it.

 

[John rodrigues]

For my case, what is the recommendation? i can't change the batteries but i keep them stored

 

[Audioguru]

Lithium-cobalt batteries are stored at 3.7V to 3.8V per cell.

 

[c_mitra]

my batteries are chinese or pirated but i intend to conserve the maximum they then charge up to 100% and store or charge up to 50% and store? I can't let them get 0% after a year

Most of the batteries are made in China these days. Have you heard any modern batteries made in the US today? Even the iPhones are made in China.

You need to understand two key concepts: state of charge (SoC) and the state of health (SoH) of a given battery.

I strongly suggest that you read the page https://www.mpoweruk.com/soc.htm and also, just to get some basic idea: https://www.mpoweruk.com/battery_manufacturing.htm.

The basic principles are old and well known but the problems are always in the details.

The problem is that the Li cells are high voltage and they cannot use water based electrolyte. But organic solvents are prone to gas formation.

Best luck!

 

[John rodrigues]

My BP-5L and BM20 batteries are Chinese and I use these two chargers from the photo I showed before, if I charge at 50% it will be 3.7 and 3.8V and will not reset the charge after 1 year stored?

 

[Audioguru]

My BP-5L and BM20 batteries are Chinese and I use these two chargers from the photo I showed before, if I charge at 50% it will be 3.7 and 3.8V and will not reset the charge after 1 year stored?

We do not know if your batteries are good or are garbage that was picked up by an ebay seller.
What does a Chinese battery manufacturer do with the batteries that fail their tests? Do they put them in the garbage or do they sell these bad batteries cheaply to an ebay seller?
Companies over there make fake batteries with flour inside for the proper weight. There are lots of videos showing the garbage:

 

[ads-ee]

This thread has now been locked as the storage voltage question has been answer multiple times and further questions posted are repeating the questions from previous posts.

Previous posts have already stated that the optimal storage voltage of Li batteries is 50% charge (i.e. 3.6V-3.7V)

• The self discharge is greater when at 100% charge.
• The self discharge at 50% will perhaps result in 10-20% self discharge (see post 17) after 1 year.
• For storage charge up to 50% or discharge from full to 50% (ads-ee: if you can't measure guess, you'll be better off is you store closer to 50% than not)
• Storing at anything other than 50% will reduce the capacity and life expectancy of the battery at a higher than normal rate.
• Don't buy cheap Chinese knock-off batteries and chargers, lack of QC or even honesty about the product will result disappointment and likely early failures.

This list isn't all inclusive of previously posted useful information.