Lithium Ion Batteries

Started by VK5MCH, Nov 28, 2024, 11:38 AM

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VK5MCH

Did you see the 40K repair bill on one of his other videos?

What happened to the simplicity of the original flat 4 air cooled VW?



Mick VK5MCH

VK5TOM

21700 5000mah ordered from tinkertechau.com.au

68g
British Amateur Television Club
ACRMGB
WICEN SA

VK5TM

I want to know what packet of fairy dust they are extracting their mythical mAh ratings from - 5 Amp from 1 AA battery for 1hour?

VK5MCH

Quote from: VK5TOM on Dec 29, 2024, 06:17 PM21700 5000mah ordered from tinkertechau.com.au

68g

That's a decent weight. My new battery supplier.
Mick VK5MCH

VK5TM

All the above got me interested in what the correlation was between weight and battery capacity so I went of and did some digging - came across this page https://www.ufinebattery.com/blog/how-does-lithium-battery-capacity-affect-weight/.

I extracted the most important bit, would be interesting to see how all the weighed batteries compare to their marked capacities according to the formula below.

"While not exact, it is possible to estimate battery capacity based on weight using the concept of specific energy. Specific energy, measured in watt-hours per kilogram (Wh/kg), indicates how much energy a battery can store relative to its weight.

The basic formula for this calculation is:
Capacity (Wh) = Specific Energy (Wh/kg) × Weight (kg)

However, it's crucial to note that specific energy varies depending on battery chemistry and design. For lithium-ion batteries, it typically ranges from 100 to 265 Wh/kg. This calculation provides a theoretical capacity, and real-world factors such as depth of discharge and battery age must be considered for practical applications."


There's plenty of other pages on the topic (some quite obviously dubious), most of which say much the same as the above link.

VK5MCH

This is why I want to load test them Tim. I want to see if there is any correlation.

I am making the assumption that there is because of the weight of lithium. Lead also weighs a lot and some of these batteries may have some sinkers inside instead of said lithium.

And there is only one way to find out. Load em up baby. See if they go bang.
Mick VK5MCH

VK5TOM

Liitokala 21700 Aliexpress
British Amateur Television Club
ACRMGB
WICEN SA

VK5TM

I came across a book about batteries today - Linden's Handbook Of Batteries - that although dating to 2011, has quite a bit about various battery chemistries including Lithium types.

Lot of interesting info if you really want to dig in to the subject - this is not an historical look at batteries, but an in depth scientific look at the various chemistry and uses of batteries as it stood in the first decade of the 21st century.

It's on the 'net if you know where to look ;)