As I understand it, the only time that any sealed lead acid battery will
vent is in the case of gross overcharging. The battery is designed so
that normal charge rates and correct float voltage will result in
recombination of any hydrogen and oxygen produced. Was there a fault in
the charging circuit or perhaps, the charging circuit didn't have proper
temperature compensation of the charge voltage?
Ed
On 7/28/2014 10:56 AM, Brooke Clarke wrote:
Hi:
Using lead acid batteries and a precision frequency standard is not a
good thing if they are too close together.
A number of decades ago (before the Time Nuts or the internet) I was
able to purchase a rack mount Gibbs 5 MHz double oven frequency
standard that used a very nice Bliley glass tube crystal because it
was not as precise as is was supposed to be. It used GelCell backup
batteries that were physically in the same rack chassis as the oven.
The fumes from the batteries when charging etched some traces off the
PCB inside the oven defeating the temperature control but leaving the
oscillator. It took a long time to reverse engineer and repair it.
I've added a photo of the cord wood construction of the cylindrical
oscillator. The core of the cylinder holds the glass bottle crystal
and the glass piston coarse tuning capacitor, surrounded by the first
heater, circuitry for the oscillator and dual temperature control
circuits on ring shaped boards. These fit inside a cylindrical cavity
which is the outer oven. I've added a photo of the inner assembly at:
http://prc68.com/I/office_equip.html
Have Fun,
Brooke Clarke
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