Servicing a Maintenance Free Battery. Start Up Project 29

6BI found that my UPS is not giving sufficient back up as expected for 20 minutes. I thought that I have to spend Rs. 800 to replace the battery. But I was not in a hurry. Want to find out the reason. After 5 minutes, the PC shutdowns. Why so? The UPS battery is not giving sufficient power (Ampere Hour) to run the load. The UPS battery is a 12 volt 7 Ah (Ampere hour) Maintenance free Sealed LeadAcid battery (SLA). That means, it is “Maintenance free” and can be used for long time without any attention. But what happens is, the cells dry out due to heat generation. This happens after 6 months to 1 year of use . It is a Lead Acid battery that requires Electrolyte in the cells. So water is necessary inside. It has 6 individual cells giving 2V each. After removing the battery from the UPS, I found that it is very easy to rejuvenate the battery through “Hydration”. The battery will become top, if the dry cells are filled with battery water. Hydrated the battery and charged. Well, now it is giving more than 15 minutes back up. Saved Rs. 800 and reduced an e-waste. You can also rejuvenate the 6V Emergency lamp battery like this. So do it yourself. It is only a 10 minutes job.

The Method is explained in the images. Do like that

1On the top of the battery , you can see either circular cap for individual cells or a complete cap over the all the cells. Carefully remove that. Take utmost care while removing the cap.

Caution : There is chance for spilling the electrolyte, if there is gas inside. So protect the eyes to avoid spilling on the eyes. Wearing a Spectacle is a good precaution. While removing the cap, face should be away from the battery. Do these precautions throughout the process. Use a small screw driver to remove the caps.The metal screwdriver  should not short the battery terminals. It may cause  spark and injury.

While filling the water in the cells using a dropper we face a problem. Bubble appears and we feel that, the cell is full. puncture the bubble using a pin. Again fill.


Provide 14-15 V , 1-2 Amps current for external charging


It takes more than 200 mA current initially for charging. Keep in it the charger for 6-10 hours.Battery  terminal voltage rises to 12.8V. Then fix it in the UPS.

After 6 hours of charging, the Terminal voltage of the Battery raised to 13.2V. Kept the battery for few hours without connecting in the UPS. The Terminal voltage is steady . It is not going down.