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Batteries and Battery Management

This bank of batteries is used to store power at Cap Hatien in Haiti. (Photo: Walt Ratterman)

Batteries are a critical component of almost all energy systems which involve an intermittent power generation source – including a diesel generator, solar PV system, wind, or intermittent grid. Batteries provide a means to store energy which can be used to power the health facility when the intermittent power supply source is not operational (e.g. when the sun is not shining, the wind is not blowing, or the grid power is off). Batteries have proven to be one of the most challenging components of an energy system to keep operational.

Why do Batteries Fail?

Several factors can lead to battery failure including lack of routine maintenance, insufficient charging, and excessive depth of discharge. It should be noted that even under ideal conditions batteries can be expected to last between 3-7 years – which is significantly shorter than the expected lifetime of other system components (e.g. the solar panel). Batteries which are not used properly often fail in less than a year. Thus, if there is insufficient focus on proper battery use and maintenance, and if funds are not available to replace batteries when they fail, the sustainability of off-grid energy systems will be severely compromised.

What can be done to maximize their performance?

An NGO provided this battery bank to a hospital in Haiti to provide back-up power to the maternity ward. The battery bank was drastically undersized for the connected loads, quickly resulting in battery failure. (Photo: Jeff Haeni)

Several steps can be taken to maximize the lifetime of batteries.

Proper System Design

Proper system design and sizing are a critical pre-requisite to optimal battery operation. If a battery bank is sized too large for the charging capacity of the system, it may slowly descend into a persistent discharged state which greatly shortens battery life. A battery bank which is too small will not provide sufficient energy to power a facility and can results in users bypassing recommended low-voltage cutoffs in order to get more power out of the system. Proper system design is a complex process involving the input of many stakeholders. Additional design features which can help ensure proper battery use include the use of diesel/PV hybrid systems (rather than pure PV systems), the installation of an alarm system to alert users when battery voltage levels are low, and use of remote monitoring of critical system data.

Energy Management

Ultimately, all battery based energy systems will be designed using an estimated load and care must be taken to operate the system in a manner which does not deviate from these initial use assumptions. Additional loads should not be added to the system and loads should not be left on when not in use. Achieving this objective requires training of staff, and designating a person with the authority to disconnect loads which are not approved. (More on Energy Management...)

Battery Maintenance and Replacement

At the time of system installation a local user should be trained, and made responsible for routine battery maintenance. This includes checking the water level of wet cell batteries, cleaning terminals, and checking voltage levels. If wet cell batteries are used access to distilled water is required. Periodic equalization of batteries should be performed according to the recommendations of the battery manufacturer. (See for instance: Trojan Battery Equalizing.) At the time of installation a plan must be implemented which will allow the health facility to purchase replacement batteries. Experience has proven that most public health facilities do not have sufficient funds within their normal operating budget to replace battery banks.

Battery Recycling

The high cost of lead and acid within a battery makes recycling both a cost effective and environmentally responsible endeavor. Health facility electrification programs should ensure that provisions are in place for battery recycling.

Additional Resources

These are links to external publications and Web sites that have information on issues related to providing reliable electricity and energy services at health facilities. USAID and Powering Health make no warrantee or guarantee regarding these external resources, and the organizations hosting these resources are solely responsible for their content.