In message <356948F4.65C1@midcoast.com.au>, Paul B. Webster writes >Alex Holden wrote: > >> I do know that the only reason they are not more popular than they >> are is that the electrolyte is extremely nasty stuff (considerably >> more dangerous than sulphuric acid). > > Mmmm, I don4t know about that! It is certainly quite dangerous to >splash strong alkalis in your eyes, but sulphuric acid is pretty nasty >too. Both corrode metals, acids usually faster. Much of a muchness as >to skin damage, you wouldn4t want to drink either... As an ex-caver I always used lead acid cells (they were FAR! cheaper), but a small number of people used the alkali ones. I was always told that the alkali ones were far more dangerous than the lead acid ones, in particular that the alkali produced very little sensation whilst it was 'dissolving' your flesh!. At least with lead acid you could feel it burning :-). Bear in mind, these cells are strapped on your bum! :-). > I think the main limitation is that they are *wet* - they haven4t a >particularly good gel version. Nor an overcharge limiting technology, >i.e., you have to top them up with water. All the lead acid cells used for caving were 'wet' as well, I never saw any which used gel versions. Basically the caving lights were the same as those used in mining, and although all the mines around here have now closed, many of my friends used to work down the pit - they only ever used wet lead acid equipment. Obviously times move on, perhaps gel cells are used now, but I imagine wet cells are still cheaper - there may also be safety reasons for using wet cells, the UK mining industry has ridiculous safety regulations (if something's not broke, why try and fix it?). -- Nigel. /--------------------------------------------------------------\ | Nigel Goodwin | Internet : nigelg@lpilsley.demon.co.uk | | Lower Pilsley | Web Page : http://www.lpilsley.demon.co.uk | | Chesterfield | | | England | | \--------------------------------------------------------------/