Alec Cameron wrote in a message to Roy J. Tellason:
 AC> On (20 Oct 96) Roy J. Tellason wrote to Alec Cameron...
 AC> I found it helpful to use an extremely high source voltage of 
 AC> [memory] maybe 20 volts/ cell BUT with a lot of series 
 AC> resistance, to protect the cells [and charger] if and when the 
 AC> cell v locked in to the normal range 2.0> 2.6 volts. 
 RJ> When I ran that battery store,  there were times when I'd get a unit
 RJ> which wasn't responding and I'd stick it on a series charger 
 RJ> and crank it *way* up there,  usually with my DVM in series to 
 RJ> see when current started to flow,  then I'd back it off 
 RJ> significantly.
 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 
What's a "GES base"?  (I probably know these,  but not by that name.)
 AC> to supply the heater at about 2v 25amps. These were the common 
 AC> service station charger, and a variable number of batteries 
 AC> would be series connected with the cell caps removed. No 
 AC> adjustments as the tranny had enough reactance that a constant 
 AC> 6 amps would flow for the range 2volts up to about 80 volts.
Sounds like an old charger my grandfather had...
 AC> So at the beginning of the "charge" the cell terminals were 
 AC> reading very high [over 5v/cell]. As the hours/ days passed,
 AC> with an input current of about C/30 the cell v dropped back to 
 AC> about 2.2, slowly increasing to a conventional value of about 
 AC> 2.4. When the volts stabilised, I discharged the cells and then 
 AC> gave a normal recharge and got OK service thereafter. Probably 
 AC> for a couple of years, in float service, burglar alarm system.
 RJ> Why discharge them and re-do it?  I've had to push some to "wake 'em 
p",
 RJ> but never did that with them...
 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-
 AC> * Delivery delay of a couple of days, costly in big business. 
 AC> * Cost of kwH charging energy, and test bay labour required. 
 AC> * Corrosion of the plates and immersed connections, ie a 
 AC> marginal loss of battery durability.
 AC> Why does it work? I think that the first charge cycle is 
 AC> incomplete because the active material hasn't "bedded" neatly 
 AC> into the plate pockets, and maybe there are some harmless but 
 AC> inhibiting substances [impurities] that need to be persuaded to 
 AC> move along and the cycles of charge help. BUT some [not much] 
 AC> of the stored energy is provided by surface conversion of the 
 AC> lead/ lead alloy structures of the plates framework and 
 AC> submerged bus connectors. These surfaces probably become deeper 
 AC> and more porous with cycles
Ok,  makes some sense to me,  though in one way of looking at it that's 
adding wear and tear to the battery...
 AC>  [re flush and refill.......
 RJ> I've heard of people trying this,  but would tend to think that the
 RJ> separators between the plates would tend to trap any of that material
 RJ> that was stuck under the plates,  so I don't know how 
 RJ> successful it'd be. I've never felt ambitious enough to want to 
 RJ> try it myself.
 AC> I have only had one really good success, that was a 12v acid 
 AC> battery. I have had failures too ie the duds stayed dud. 
The articles recently posted to here were somewhat interesting in their talk 
about that.  It made sense when they spoke about some sort of a rig to make 
doing that easier...
I'm still charging those gels,  been stuck on the "low" one for some days 
now. It's still taking up over 400 mA,  but down a bit from where it was this 
morning.  I figure that a long slow charge is best anyhow...
I've also been fiddling a bit with an old (couple of decades) Exide emergency 
lighting box model ESS.  This is one of a bunch of these that I was given a 
while back,  and I finally got around to taking it apart enough to do at 
least a partial trace of the board that's in there.  Four transistors and an 
SCR,  not that much to it once I get past the interconnections...
This thing was originally designed to hold a "wet" 6v/30AH battery and at 
least one of the units that came out of there had been cooked dry and warped 
plates,  etc. as you'd expect.  Right now I've got a 6v/33AH gel in there and 
it's on "high" rate charge,  we'll see what happens after a bit.  Since 
they're only using 1A and 3A rectifiers in there,  it can't be pushing it 
_that_ hard.    Maybe one of these days I'll have a go at seeing if Exide 
will part with a schematic diagram of one of these beasties.
I think that if I ever do rig some of these up I'll add some of those 
variable duty cycle astable circuits (what Don Lancaster showed as being for 
a "caver's lamp" in his CMOS Cookbook) to give me control over brightness.  
They sure do come on bright when I hit that test button!
Even looking in the Sylvania book at the auto parts store I can't find a 
reference to the bulbs in this thing,  H126 is the number.  I'd be curious to 
know what kind of power they're drawing at full briliance.  Probably a bunch.
Anyone know how long emergency lights are supposed to stay lit?
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