by Collyn Rivers
How Long Can Lead Acid Batteries last
How long can lead-acid batteries last affects millions of users. Most written and believed, however, has little factual basis. What people really buy are amp-hours
The best text written about how long can lead-acid batteries last is Life Time Modelling of Lead Acid Batteries. It is readable, hugely informative and tightly written. It deserves to be better known. It is truly worth reading. Some parts are very technical but much is easy to follow and understand. It is rare to find such a readable yet rigorous approach. The multiple authors are: Henrik Bindner, Tom Cronin, Per Lundsager, James F. Manwell, Utama Abdulwahid, and Ian Baring-Gould. All are from Denmark’s Risu National Laboratory. They and Risu generously enabled RV Books to publish the preface here.
They have also allowed the paper (in its entirety) to be down-loaded free of charge. It is at: http://orbit.dtu.dk/en/publications/lifetime-modelling-of-lead-acid-batteries(6f8d323d-dbbb-40d0-91b7-fbf74af5e017).html
‘Power system implementers commonly agree that one of the key weak links in the long-term operation of renewable-based rural energy systems is the system batteries. Batteries not only impact on the system operation and performance but also can greatly affect the life cycle cost of a specific power system. Numerous hybrid power system performance and economic models that are currently in use provide an estimate of battery life. It is based on a number of different mathematical calculations and assumptions. These life calculations are then used to develop the cost of energy estimates for the power systems.
‘Unfortunately, the varying methods currently used are quite diverse with many different assumptions, and very little effort has gone into the validation of these methods. Additionally, most of the methods use calculation techniques based on information provided by manufacturers, usually under conditions that are not at all similar to the ones experienced by batteries in remote power systems.
‘Under the Benchmarking project work, two different battery life calculation methodologies have been investigated and further developed. The aim is of improving the prediction of the life of batteries in hybrid power systems. One is based on a cycle counting approach similar to that used in structural fatigue analysis. The other is based on the application of a cross matrix, developed by the project for linking a number of stress factors with the recognised lead-acid battery damage mechanisms.
‘Both methodologies are combined with their own battery performance model in order to link the predicted battery life-time with the actual use of the battery in terms of simulated or measured charge/discharge patterns.
Preface – summary
‘The project combines the model development with experimental verification, using both specific lab tests of selected batteries as well as field test results collected in the project’s systems test database. Reliable prediction of battery life in a given system is a precondition for providing a proper decision basis for system costs & performance. The validation procedure established by the project is an essential part of this. This paper describes the first results of the battery model development effort as well as results from the initial model validation using standard battery performance testing for operating profiles considered representative of wind and PV powered remote power systems.’
Care is essential
As the full paper shows, it’s vital that your solar and battery system is competently designed and installed. Essential also is to choose carefully when you buy electrical equipment. If you choose the wrong products you waste money. Furthermore, they may only partially work. Or worse, leave you stranded.
Solar Success cover homes and properties. All explain in plain English everything you need to know about batteries and related electrics. My other books are the Caravan & Motorhome Book, and the Camper Trailer Book.
These books have helped tens of thousands worldwide to make the right decisions. All will save you many times their cost. For information about Collyn Rivers please Click on Bio.