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The application of Appropriate Technology

Part 5: Maintenance And Safty

Care and Maintenance

Some Lead-acid batteries are designed to be maintenance free, such batteries are sealed and the electrolyte can not be topped up. Batteries that are sealed and not vented should not receive equalisation charges.

  1. Batteries should not be left standing for any length of time, either charged or uncharged.
  2. Batteries supplied dry have a shelf life of about 2 to 3 years.
  3. Batteries should neither be over charged or discharged by more 60% of their capacity.
  4. Batteries in a bank should all be the same make and the same model.
  5. Once a battery bank has been operating for more than a few weeks, new batteries should not be added.
  6. The electrolyte should be topped up regularly with distilled water. Refer to the manufactures literature to find the recommended specific gravity.
  7. Equalisation charges should be used about once a month for batteries that are regularly cycled.


Lead-acid batteries can be dangerous because they vent hydrogen and oxygen gas during operation. The following points should be remembered:

  1. Keep the electrolyte in flooded cells at the correct level with distilled water, to make good losses due to evaporation and gassing.
  2. Use no materials or finishes which will be attacked by acid in the battery room. Spilled acid, and acid vapour given off during gassing, will quickly corrode most exposed metals other than lead. Use an asphalt floor where possible and coat wooden surfaces with anti-acid paint.
  3. Ventilate the battery room well, if necessary using corrosion-proofed fans.
  4. Do not allow a naked flame in the room; and prevent sparking by switching off a circuit before connecting and disconnecting. The gases present are explosive when in the correct proportions.
  5. Mop up spilt acid immediately and wash with soda solution. Acid on clothing will quickly cause holes to appear.
  6. Do not allow acid to enter the eyes. If it does so, immediately lie down and run clean water over the eyes for as long as possible. Consult a doctor. Acid on the hands is not itself dangerous, but can easily be transferred to more vulnerable parts of the body.
  7. When mixing acid for the initial charge of new cells, always add acid to water, and not the reverse.
  8. Watch cell temperature, as excessive heat will damage lead-acid cells. Acid temperature should not exceed 36°C.
  9. Keep battery terminals clean and coated with petroleum jelly.
  10. Remember that a short-circuit across the battery or cell terminals can result in very high currents which may result in fire or burns. Use only insulated tools and take great care not to allow terminals to connect together inadvertently.