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Valve-regulated battery with improved separators avoiding electrolyte stratification and charge controller for low-cost photovoltaic and wind installations

Objective



PROJECT OBJECTIVES

The objective of this project is the development of improved and low cost PV/wind systems, to be used mainly in special locations like isolated areas, farmhouses, etc, in which it is more advantageous to install such systems than to be connected to the main network what would be too costly in most cases.
These systems are composed of three main subsystems : Solar or wind turbine generators, batteries for storing generated energy, and charge controller/conditioner. Among these systems, the most important for determing the performance and life are the batteries and the charge regulator. The specific objective of the project is to improve the performance of both components, with special incidence in the battery.

TECHNICAL APPROACH

The specific problem, that at the battery level limits the performance and especially the system life, is the progressive development of acid stratification (different acid densities from the bottom to the top) in the battery. This is mainly due to the fact that in solar/wind applications, due to their random nature, a complete recharge of the batteries cannot be always assured. The development of electrolyte stratification will lead to the following problems : Lower energy available from the battery, high sulphation of the plates, and, especially, high corrosion. The result is a severe limitation of the attainable life.

In this project, the intention is to overcome this problem developing a new separator material, that will decrease, or even eliminate, the acid stratification in the battery. To achieve this, the structure of the glass mat separator will be modified by the inclusion of especial filling materials. Concerning charge regulator the main feature will be the degree of overcharge, depth of discharge) along the previous two weeks, for optmizing the using conditions and life.

EXPECTED ACHIEVEMENTS AND EXPLOITATION

After completion of the project, the life of these systems is expected to be improved from the actual value (around 400 cycles), to more than 800 deep discharge cycles. This marked increase will lead to a significant decrease of the cost of these systems, on a life basis, making them more competitive and attractive to the user. If successful, the new battery with the new separator could be also applied to other uses that imply heavy and repetitive cycling, like light motive power applications. The financial involvement of several industrial partners a big company like TUDOR and small and specialized ones like BERNARD DUMAS and ATERSA, is an indication of their interest in the exploitation of the results.

Coordinator

SEA TUDOR - SOCIEDAD ESPANOLA DEL ACUMULADOR S.A.
Address
2,Carretera Nacional Ii, Km 42
19200 Azuqueca De Henares
Spain

Participants (3)

APLICACIONES TECNICAS DE LA ENERGIA SA
Spain
Address
6,Fernando Poò 6
28045 Madrid
BERNARD DUMAS SA
France
Address
Rue De La Papeterie
24100 Creysse
COUNCIL FOR THE CENTRAL LABORATORY OF THE RESEARCH COUNCILS
United Kingdom
Address
Chilton
OX11 0QX Didcot,harwell,chilton