Accumulator battery

Characteristics of the various types of accumulators

Evolution of the batteries

The batteries necessary for the electric cars but also to the cars Hybrides followed a continuous technological change and progress is important, unfortunately currently, no solution is not entirely satisfactory. Some of these batteries are of a common use with other sectors as the wind one or the solar one.

Research and discoveries in progress are very promising, so much so that certain manufacturers of batteries promise an autonomy of the electric cars of 800 km for very soon. Whereas the lead-acid batteries have a capacity of 30 Wh per kg, other types developed:

Nickel - cadnium (Ni-Cd) 50 Wh per kg
Lead 2nd generation (2006) 75 Wh per kg
Die lithium - ion of 1992 (Li - Ion) 90 Wh per polymeric kg
Lithium (Li - Po) 120 Wh per kg
Lithium - ion 2nd generation (2000) 150 Wh per kg
Zinc - money (2007) 200 Wh per kg
manganese - lithium - ion (2007) 250 Wh per kg

And for soon:

Powder of ceramics - aluminum (EEStor in the United States) (and): They should be used initially for the electric cars , then later for the storage of energy applied to wind and the solar one.
Condensing - lithium - ion (FHI): in test in Japan.

Use

the Accessoire S of the Véhicule S truck drivers are fed in electricity by accumulator batteries, in general with the lead.

the tension of this battery is usually of 12 Volts on the cars, 6 Volts on certain old models still in circulation;
Of 24 Volts for the Heavy truck S.

For the traction of the electric vehicles, of the batteries often of Technologie S other than lead and of a higher tension is used, in order to limit the running S in plays.

Charge with the batteries

Loadmeters

Loading of the batteries is a paramount operation so that the batteries preserve their initial characteristics.

One can evaluate the level of load of a battery by measuring his no-load voltage (without load). For example for a Lead-acid battery:

a battery quite charged with a tension higher than 12,6V .
a battery under 12,4V can be put in load.
a battery with 11,7V is completely discharged or in bad condition.

In the case of technologies more recent, like the NiMh or the Lithium, of the more elaborate methods are necessary to check the level of load. For these technologies the chargers evaluate the load factor by monitoring the evolution of the charging voltage and by taking of account the charging current and time, ( $\ frac {d_v} {d_t}$ or $\ frac {d_v^2} {d_t^2}$ ).

Precautions of loading

the load of batteries in parallel is disadvised, because each battery is specific and will evolve/move differently according to its initial state of load, its age, its intrinsic characteristics. It is thus important that a battery in load is connected only to a Power source.
the load in series must be only carried out on batteries of same characteristics and in an identical state of load.
In a general way, the load of the batteries in a unit way must be privileged.
the duration of load can be roughly calculated according to and the capacity charging current of the battery: Capacity (in A.H) = Charging current (in A) X Time of load (out of H). This is rigorously exact in the case of a discharged new battery completion.

Possible evolutions

an American innovation of MIT (2007), the Witricity , if it were applied to the electric car , makes it possible to reload the batteries without wire and thus to remotely reload them without having to establish a physical connection to an electrical outlet. This automatic refill without having to think of it would free the owners from electric cars of the concern of the refill.
the lifespan and the wear of the batteries must be increased, just as their recycling, and the cleanliness of their manufacture.

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