>Boilers??????
The point i was making was about the fierce charging 
regimes inflicted by cheap car chargers.I believe the 
main reason for the long life of UPS batteries is not strictly
because of their quality;but due to the fact they are a
'float' type cell not a 'cyclic' one; which become 'washed-out'
far quicker,and tend to deliver much higher short-term 
currents;meaning internal resistance changes render them
no longer fit for service as starter batteries.If the original
post was as i thought about producing a inexpensive
(not 'cheap'!) but reliable charger,then as you quite rightly say
well designed SCR chargers still take a lot of beating.
The main reason for the rise of charge control I.C.'s
is the sometimes impossibly fast charge times demanded by 
consumers;which make designing a 'traditional' charger
very difficult..%<(
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