Lithium Battery Cells

Randy Anderson National Technical Sales & Training Manager

Our topic today is lithium batteries and battery packs and what is in those battery packs.

The lithium cells in the battery packs that we provide are Discover Advanced Energy 32700 lithium iron phosphate cells.

So, what does a 32700 mean? Well, that represents the diameter of the cell, so 32 millimeters representing the diameter, 70 millimeters long. So, it would be like an oversized alkaline D-cell, essentially, in size. Lithium ion phosphate being the chemistry. Now, we know there's a lot of negative stories out there today on lithium and 'thermal events'. Well, the good news is, lithium ion phosphate is one of the most stable lithium technologies out there, so not a lot of concerns there in the thermal department.

What size are the cells? Typically, we use a 5-amp hour cell in the lithium packs. Many people believe that, like lead acid, we'll have larger capacity cells in there, but that's not the case. We simply have more cells in parallel. Voltage on the lithium ion phosphate cell is 3.2 volts nominal. This means that in order to get higher voltage, we need to connect a bunch of cells in series.

How do we achieve higher voltages in capacities? Well, to achieve higher voltage, we simply connect more cells in series. This will increase the voltage up to, you know, almost whatever you want. Typically, in electric vehicles, floor scrubbers, those type of things, we're using low voltage packs. We see electric cars using a higher voltage pack, up to the 300 and 400 volt range, but most of the products that we're dealing in is low voltage, so a few cells connected in series.

How do we increase the capacity? We connect those series strings into parallel. So, if we've got a string of 5-amp power cells and we connect 10 of those strings in parallel, we're going to end up with a 50-amp power pack. So, it's fairly simple. We have a bunch of cells in series, parallel, in that pack.

If you have any questions or comments on the lithium battery technology, please contact us!

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