Pack Mass from Cell Density

It is possible to use the battery pack database to estimate the pack mass from cell density. The key relationship we have is between cell and pack gravimetric energy density. This graph has been pulled together by scouring the internet for cell and battery data. The ratio of cell density to pack density is 0.6235 … Read more

Cold Climate EV Range

Summer vs Winter Electric Vehicle range

Cold climate EV range is determined by a number of factors. First of all though, let’s look at the range results as conducted by Motor.no in their winter range tests. An impressive test with 29 different electric vehicles. Read the full description of the tests on the Motor page and there you can see some … Read more

Cell Capacity and Pack Size

Size of battery packs vs cell capacity

Obviously Cell Capacity and Pack Size are linked. The total energy content in a battery pack in it’s simplest terms is: Energy (Wh) = S x P x Ah x Vnom  Hence the simple diagram showing cells connected together in series and parallel. What about flexibility in pack size? There are very good reasons for … Read more

Pack Size versus Application

Battery pack size versus application is an interesting comparison. The plot is based on real data from real products in the market and shows total battery pack size. The Y-axis is a logarithmic scale and hence the eLorry battery is nearly 6 orders of magnitude, or 1 million times, bigger than the smart watch battery.

Usable Energy

In the simplest terms the usable energy of a battery is the Total Energy multiplied by the Usable SoC Window. The total energy is the nominal voltage multiplied by the nominal rated capacity. However, if you have been through the Battery Basics you will have realised that the battery cell and pack do not have … Read more

Electrified Aircraft Propulsion Targets

NASA electrified aircraft

A look at the electrified aircraft propulsion targets. NASA state in their November 2021 presentation that they have the following requirements for the battery pack: The targets at pack level are rather tough: The gravimetric energy density plotted versus total pack energy shows that the automotive packs are currently plateauing around 180Wh/kg. The roadmap to … Read more

Inputs to Pack Sizing

cyantron modules, bms and packs

Lets look at the inputs to pack sizing, what do we need to know in order to size a pack? At the early stage you don’t need to think about total energy, concentrate on the usable requirement and conditions at which that needs to be achieved. The minimum and maximum voltage is likely to be … Read more

Cell to Pack

Cell to Pack is all about reducing cost and increasing the volumetric density of battery packs. This is primarily aimed at road vehicle battery design. Conventional battery pack design has taken the form: Cell -> Module -> Pack This means we add material to make the module strong enough to be handled, it needs fixings … Read more