Electric Cars are Easy - Batteries are NOT

In an article on his personal blog (Defending the Upgrade of Highway 1 - Gateway Project) Richard Pitt talks about the critical role batteries and the electric vehicles of the future will play in our North American transportation infrastructure.

The march of time is showing just how true this is.

The practical electric car actually predates the major use of internal combustion engine powered ones. Then, as now, the biggest problem was the maintenance of the batteries. Then they were lead-acid, and things like keeping them filled with water and not sloshing it (and its acid content) around, corroding the chassis and eating clothing and upholstry was the biggest problem. The actual batteries themselves were and remain relatively inexpensive compared to the long-term cost of the gasoline they help replace.

The biggest problem with batteries has been that their lifetime has been so variable. It depends on external (and internal) temperatures, load, charge current, discharge rate and a whole host of other variables that mean you might get 6-7 years out of your car battery and I might get 3 out of exactly the same one. One person we know got 12 years out of the original battery in her old Datsun for example. The guy who finally replaced it was amazed.

The big car manufacturers simply can't deal with such variability in a key component of their product. This is one of the reasons they have not yet done a big push with electric vehicles.

Now comes some technology that promises to even out the variability and do some protecting against the potential for catastrophic release of energy (explosion, fire, etc.) in batteries like the Lithium Ion (Li Ion) ones that have at times been blamed in laptop fires and such. Li Ion batteries have the advantage over traditional lead-acid ones that they store a lot more electricity for a given volume and weight - the so-called "charge density". The problem with them is that they are much more sensitive to heat and variable charge rates than are other battery types, either failiing early or failing hard, with explosive results.

The new technologies are battery monitoring chips - embedded into the batteries at manufacture, and monitored in real-time by the vehicle's comuter systems. The chips ensure that individual cells in the batteries all match each other at all times so no one cell causes failure in the others. The chip monitors cell temperature, charge rates and discharge rates, and evens out the current flows so no damage can be caused. It will even take the cell offline if a major failure is predicted.

 If you're interested in the chip itself, take a look at the news release about it. A major user of this technology has just announced a facility to produce 15,000 units/year, some of which will be put into a Mercedes S400 BlueHYBRID vehicle in mid 2009.