Hi Roy
On (27 Oct 96) Roy J. Tellason wrote to Alec Cameron...
 AC> Maybe you remember the old Tungar chargers- these were a 1/2 
 AC> wave setup, a glass tube mercury diode the size of a 150 watt 
 AC> lamp having a plate lead at top and a GES base 
 RJ> What's a "GES base"?  (I probably know these,  but not by that name.)
Giant Edison Screw. Like your regular 110v lamp bases but larger, about 1 1/4
ins dia, due to the very heavy current for the filament- about 25 amps.
 AC> Discharge/ recharge is a works remedy for increasing the stored 
 AC> energy. It works. When we used to factory-test a new battery 
 AC> for customer Inspector approval, a poor result [eg 3000 amp 
 AC> hours guaranteed but only 2600 achieved] then one or two cycles 
 AC> of recharge discharge would bring the battery up to spec. But 
 AC> at some cost-
 RJ> Ok,  makes some sense to me,  though in one way of looking at it that's
 RJ> adding wear and tear to the battery...
It certainly does *BUT* the alternative is rejection of the finished battery.
Manufacturer was obliged to meet a guaranteed performance!
 RJ> I think that if I ever do rig some of these up I'll add some of those
 RJ> variable duty cycle astable circuits (what Don Lancaster showed as being
 RJ> for a "caver's lamp" in his CMOS Cookbook) to give me control over
 RJ> brightness.  They sure do come on bright when I hit that test button!
For that reason, some large batteries are provided with "end cells". The
charger floats across [say] 55 cells but the load is connected across only 50
of these. When an emergency arises and the battery volts fall after [say] 15
minutes loading, a contactor would automatically switch in the rested 5 end
cells. Presto! 110 volts at the loads isntead of maybe 125 immediately at the
start of the emergency.
                       
 RJ> Even looking in the Sylvania book at the auto parts store I can't find a
 RJ> reference to the bulbs in this thing,  H126 is the number.  I'd be 
curious
 RJ> to know what kind of power they're drawing at full briliance.  Probably 

 RJ> bunch.
Sylvania has no trade here, in auto lamps. Tungsten filaments have higher
reistance when the volts hike. So for 10% excess voltage, you maybe get only 

3% increase in amps. And for say 10% loss of voltage, the current drops by
less than 10%. A tungsten filament, behaves like a constant current load.
               
 RJ> Anyone know how long emergency lights are supposed to stay lit?
How long is a piece of string!  For cinemas and large stores, this is 
robably
legislated by State or City laws. For submarines, I guess one week. For 
odern
generating stations, just an hour or two- long enough to start up and switch
in, the emergency diesel or gas turbine generator. For railroad cars, maybe 4
to 6 hours.   Cheers....ALEC
... ....Horsepower was a wonderful thing when only horses had it
--- PPoint 1.92
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