A battery is a device for storing chemical energy and converting that chemical energy into electricity. A battery is made up of one or more electrochemical cells, each of which consists of two half-cells or electrodes. One half-cell, called the negative electrode, has an overabundance of the tiny, negatively charged subatomic particles called electrons. The other, called the positive electrode, has a deficit of electrons. When the two halves are connected by a wire or an electrical cable, electrons will flow from the negative electrode to the positive electrode. We call this flow of electrons electricity. The energy of these moving electrons can be harnessed to do work -- running a motor, for instance. As electrons pass to the positive side, the flow gradually slows down and the voltage of the electricity produced by the battery drops. Eventually, when there are as many electrons on the positive side as on the negative side, the battery is considered 'dead' and is no longer capable of producing an electric flow.
The electrons are generated by chemical reactions, and there are many different chemical reactions that are used in commercially available batteries. For example, the familiar alkaline batteries commonly used in flashlights and television remote controls generate electricity through a chemical reaction involving zinc and manganese oxide. Most alkaline batteries are considered to be a disposable battery. Once they go dead, they're useless and should be recycled. Automobile batteries, on the other hand, need to be rechargeable, so they don't require constant replacement. In a rechargeable battery, electrical energy is used to reverse the negative and positive halves of the electrochemical cells, restarting the electron flow.
Automobile manufacturers have identified three types of rechargeable battery as suitable for electric car use. Those types are lead-acid batteries, nickel metal hydride (NiMH) batteries, and lithium-ion (Li-ion) batteries.
Lead-acid batteries were invented in 1859 and are the oldest form of rechargeable battery still in use. They've been used in all types of cars -- including electric cars -- since the 19th century. Lead-acid batteries are a kind of wet cell battery and usually contain a mild solution of sulfuric acid in an open container. The name comes from the combination of lead electrodes and acid used to generate electricity in these batteries. The major advantage of lead-acid batteries is that, after having been used for so many years, they are well understood and cheap to produce. However, they do produce dangerous gases while being used and if the battery is overcharged there's a risk of explosion.
Nickel metal hydride batteries came into commercial use in the late 1980s. They have a high energy density -- that is, a great deal of energy can be packed into a relatively small battery -- and don't contain any toxic metals, so they're easy to recycle.
Lithium-ion batteries, which came into commercial use in the early 1990s, have a very high energy density and are less likely than most batteries to lose their charge when not being used -- a property called self discharge. Because of their light weight and low maintenance requirements, lithium-ion batteries are widely used in electronic devices such as laptop computers. Some experts believe that lithium-ion batteries are about as close as science has yet come to developing a perfect rechargeable battery, and this type of battery is the best candidate for powering the electric cars of the near future. A variation on lithium-ion batteries, called lithium-ion polymer batteries, may also prove valuable to the future of EVs. These batteries may eventually cost less to build than lithium-ion batteries; however, at the present time, lithium-ion polymer batteries are prohibitively expensive.
Perhaps the greatest problem associated with electric car batteries is recharging them. How do you charge an electric car battery? More importantly, where do you charge an electric car battery? Can you do it yourself? Can you do it at home?
You’ve ordered your electric car and like many, you’ve been put off by the seemingly extortionate quote given to install a level 2 electric charging station at your home.
As we’ve discussed before, sourcing your own Electric Vehicle Supply Equipment (EVSE) can save you hundreds of dollars on the cost of preparing your home for your electric car, but an increasingly large number of budget-priced, so-called EVSE charge stations which are not what they appear to be.
As regular visitors to the MyNissanLeaf discussion forum may have noticed, some owners have purchased equipment priced well below the competition which cannot even charge their electric cars.
After ordering a $649 EV-ChargeAmerica Charge@Home Level 2 EVSE, one member claims that he was sent a unit which EV-Charge America reportedly referred to as a prototype.
After looking inside, he discovered that the unit did not contain the necessary components to enable it to communicate with an attached electric car. Moreover, two of the required wires from the charging gun were disconnected
Don’t be confused: an EVSE is not just a cable inside a fancy box.
All EVSE charging stations on the market today should comply to the outlined in the J1772 (2010) specification devised by the Society of Automotive Engineers (SAE). As part of this standard, a two-way signalling process is used by the charge station and car to ensure that various safety requirements are met before the 230V supply is switched on to the car’s charger.
Without the correct data interchange between the vehicle and EVSE, charging is not allowed. This prevents charging from taking place when there is a fault with either vehicle or supply and prevents electrocution.
However, you may have seen examples of J1772 conversion boxes. These are designed to allow owners of older electric vehicles to make use of the more modern J1772 charging stations. These work by electrically mimicking a connected car at the end of the J1772 charging cable, convincing the EVSE to commence power delivery to the charger.
This ‘hack’ is achieved by using a few resistors of the correct value across the two wires used to communicate between EVSE and car. But to hack the EVSE side of the charging process, much more complex circuitry is required.
So is it safe to buy your own EVSE from a third-party supplier?
Yes, provided you follow a few simple steps:
Firstly, make sure you check to see if the equipment is certified by the Underwriters Laboratories (UL). UL certified EVSE is safe to buy and install, as it complies with all the current safety laws.
What’s more, you may find that neither the automaker or your insurance company will honor a claim if you have charged your car with non UL-certified equipment.
Secondly, check the company out. Your automaker should know of them and they should be listed on reputable owners’ forums.
Olivier Chalouhi, the first customer in the U.S. to take delivery of the 2011 Nissan LEAF back in December, knows only too well that it is possible to save money on the installation of his home EVSE.
Instead of paying for an official nissan-sanctioned installation of his level 2 domestic EVSE, Chalouhi purchased the unit at trade price from Nissan-recommended EVSE supplier Areovironment and found a local electrician to install it for him. He saved a massive $900 in the process.
If you want to follow in his footsteps, make sure you don’t buy from un-known EVSE suppliers and always check for UL certification.
If in doubt, buy with a credit card. That way if you have any disputes your card issuer should offer some form of dispute resolution for goods which do not perform as described.
