This is the battery my Ford Fiesta. It's developed a white powdery substance on the top. Can anyone explain what it is and is it a problem? Thankyou.

Found on http://www.2carpros.com:

Question: 1995 Nissan Micra 1000 mileage: 36000. I have two questions: 1) For the last two years I have found increasing deposits of white powder around my battery terminal. What could be causing this? 2) Twice in the last two months when I have gone to start my car for the first time it has crunched and not started as if the starter motor is not engaged properly. How can this problem be solved? Could this problem be related to the battery problem? Thank you

Answer: Remove the battery cables and clean the battery. Get yourself a carbonated soft drink, no do not drink it, and pour it on the battery to neutralize the white powdery substance. Rinse the battery with water, clean the battery terminals, and reconnect. This may help your "crunching" starter motor problems. If it does not, you will probably have to replace the starter. In addition, load test the battery.

From those pics i would say that your battery is shagged out, you can see the stains around the filler plugs were the battery acid is seeping out, its then making contact with the clamp bar and reacting causing the white powder.Its not loose terminals otherwise the white powder would be around the terminals too.

Give it a very good clean, check and top up the cells and see if it returns.

Looking at the date stamp its a 1997 ,ten years old the ST wasnt out in 97

don't think its an ST but rather an old fiesta! as for the battery think its dead and need to be changes!

Batteries create electromagnetic fields and the battery you have is one that requires maintenance by filling with distilled water what happens is air gets in to the battery and starts a reaction like electrolyses and makes the water evaporate the vapour rises and will escape from the battery and react with any full it can in your case the battery clamp. You could clean the batt and replace the distilled water and recharge, all will be good but it wont work as well as it use to. Suggest buying a new non maintenance one it’s the future and will probably provide your engine with a better current load.