ITTSB.EU Blog Forum
AC or DC Electrical Energy related topics => Battery Internal resistance meter | Li-ion cells theory => Topic started by: Kiriakos GR on March 21, 2026, 07:50:34 AM
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Polymer Li-ion battery this is specific class of batteries, as their body / packaging this is made due soft materials.
Instead a 16850, this is enclosed within metal.
Polymer Li-ion battery soft pack, this made due reliable factories in China, by gaining UN 38.3 certification, they are aloud for by Air shipping.
According to IATA requirements, such cargo it can be shipped by Air, only with cargo plains.
Second and significant detail, the batteries must be at SOC (State of charge of 30%).
When consumers buying small quantity of cells, from China.
They usually all shipped by SLOW Shipping (45 days).
And this is because the sellers, do not have much education, when selling branded goods, them to also deliver the necessary UN 38.3 certification (copy of document), at the shipping company.
From electrical point of view, about branded and full of certifications Polymer Li-ion battery, these even be shipped by Air or other option.
The factory will deliver all of them in the market with 30% state of charge.
Due all the above conditions, all branded batteries they need to be fully charged before use.
How to tell of which Brand / factory, this is classified as Branded , reliable source, full of international specifications?
This task includes manual labor, the willing buyer he should perform his own research, he should find traces of certifications, about products of a specific brand.
What about unbranded Polymer Li-ion battery?
If you are after a replacement battery for a cheap mobile phone power bank ? They are about twenty small factory available for you.
If you are after a replacement battery for a critical application, power source for an expensive T&M equipment?
They are approximately no more than four large factory, and only two visible over the web.
Back to the important note of this article. :)
Always charge before use, any new Polymer Li-ion battery.
At the occasion of random buy, of a new Polymer Li-ion battery, if this found with low state of SOC? This might be very good news.
Within piles of unbranded goods, you were lucky getting a branded one.
If the new Polymer Li-ion battery, this gets fully charged and still does not deliver named capacity? This could translate to several meanings.
Polymer Li-ion battery:
Might be very old?
Might be of high internal resistance? Poor quality of active components
Might be light weight ? Factory cheating
Long story in sort, with out a copy of original data sheet, an accurate battery evaluation this is not possible.
According to official Polymer Li-ion battery, general specifications, life cycle performance.
An new Polymer Li-ion battery, this has full named capacity, and when this is cycled 80 times, then this fall to 85% for the rest of it life, while this further decreases when the battery complete 500 cycles or more.
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Aha, this is not a simple article.
There is a Wiki message inside ;)