Question Problem Li-Po battery

cloudff7ps1

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I have a handheld handheld console but something strange happened to me twice, I kept the device turned off with the xiaomi BM20 battery inserted and both times after a period of non-use (maximum 2 months) when I went to use the device the battery was swollen swollen, what could be happening? if I store the BM20 outside the device it does not swell in the stove but it is very annoying to keep putting and removing the battery from the device
 

lvt

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It mean that there was a leak inside the battery producing a high pressure gas.

The battery is simply faulty, you might have bought a fake or low quality battery.
 

cloudff7ps1

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I bought several BM20 batteries on Aliexpress the same from the same seller but they only swell if they are inserted in the device for a long time without use he said they are original and their value is high, they had a voltage of 4.1v
 

lvt

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I bought several BM20 batteries on Aliexpress the same from the same seller but they only swell if they are inserted in the device for a long time without use he said they are original and their value is high, they had a voltage of 4.1v
A faulty battery starts leaking as soon as there is enough of electricity stored in it, the process could be much faster while charging or being heavily used. That's why you can't transport Lithium batteries (LiPo included) in the cargo bay nowadays.
 
I have 2 possible ideas. Li-Po batteries are more susceptible to damage compared to Li-ion. If not being used they should not be left in a high charge state, it is best to store them at 50-60% charge. Being fully charged is a high stress state for a Li-Po. Were the batteries fully charged when you stopped using?

The other idea is the device is still taking a minimal current when switched off. In this scenario if the battery is draining close to zero % it will suffer damage.

A swollen Li-Po is damaged and far more susceptible to catching fire. You should dispose of the battery and not try to use it.
 

OrlyP

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Can't have it both ways. More often than not, cheap batteries will have lousy shelf life.

You can help prevent that from happening if you only keep the batteries charged at no more than 60% before you store it. These battery chemistries are susceptible to accelerated internal corrosion when kept fully-charged or fully-discharged for a length of time. 50% state-of-charge (SoC) is the sweet spot that slows down this ageing process.

Just fully-charge it on the day you plan to use it.
 

cloudff7ps1

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the batteries were at 75% in the Chinese universal charger but the voltage with multimeter they were on was 4.1v

I don't know if the device even off draws battery charge I just pressed poweroff in its firmware and turned it off and stored the device with the battery inserted

can you tell me a good universal charger for BM20 and BP-5L batteries?
 
I thought I would find something to reference rather than just memory, this was one of the first that came up. This is in line with my understanding and you see they say Li-Po should be stored at 3.6-3.8v https://www.large.net/news/8du43ps.html

I don’t know about a good charger for those. The Li-Po’s I use are much bigger and the chargers I use are way over the top for your needs. This is my main charger, you don’t need this but FYI https://hobbyking.com/en_us/turnigy-reaktor-d6-pro-duo-ac-dc-6s-balance-charger-discharger-w-smartphone-wireless-charging-dc325w-x-2-uk-plug.html?queryID=7a3ac30d8ee9bc5a3898b0d3b482243c&objectID=80914&indexName=hbk_live_products_analytics
 

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