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If you’ve ever wondered what’s inside a lithium battery, this video is for you!  When you see them on a web site, they’re all just boxes with terminals, but they’re NOT all the same inside.  When we visited Lithionics Battery recently, they showed us inside their batteries, and also inside a competitor’s battery that they had taken apart as a research exercise.  The result is this video:

 

So, I’m not a battery scientist, but I learned a few important things here.

The number of cells matters

There are a lot of ways to get to 100 amp hours at 12.8 volts.  But there’s a big difference between doing it with a couple hundred tiny cells, or doing it with 12 large ones.  Every cell represents a number of things that can go wrong.  The connections on it may come loose; or the internal resistance of the cell can be different from its neighbors.  So the fewer cells you have, the less opportunity there is for things to go wrong.

Cylindrical vs. Prismatic cells and battery heating

Any time you pack a square box with round objects, there’s going to be some wasted space.  Inside a battery, that space is filled with air.  That’s not bad in itself… until you want to install a heater kit on the battery.  Heat traveling through air by convection is a lot less efficient than traveling directly through the battery via conduction, so the cylindrical cells are at a distinct disadvantage when it comes to heater kits.

Waste heat management

When lithium batteries are working near their limits, they generate waste heat.  The best thing you can do to manage this is avoid generating heat in the first place.  Since their construction has half (or less) the internal resistance of Brand B, the Lithionics batteries are only going to generate half as much (or less) heat to begin with.  And once they’ve generated that heat, some batteries are designed to dissipate it faster.

 

There’s more in the video, but you’ll just need to watch it to get the rest.  I’d actually really like to see this kind of tear-down done with more brands of batteries, but it seems like that could be an expensive video series!  Sound off in the comments below and let me know what you think!