That is interesting, but gosh, so much hard work and a posh battery charger that is great but........ Again I ask how old is the 12 volt battery? For £50-52 all you problems go away for 4 years. My Bosch sliver battery is still great after 9 monthsish. Every time I lock it it is a strong chunk chunk, and ...... so far it 'feels' so strong and reliable. Just buy one.......really.