Monday, March 26, 2018
Plus ça charge.....
A few rechargeable batteries now have a BRAND NEW feature: a built-in charge indicator.
Brand-new? Nope.
From a 1935 radio journal:
NEAT GADGET!
The picture is clear but the description isn't. The crescent thing is pivoted at left, and it has a glass-enclosed air bubble at the lower end. When the specific gravity of the electrolyte is higher, the air bubble is more buoyant, so the crescent thing pivots upward and the air bubble covers HALF, then FULL. Similar to the syringe-like tester used with car batteries.
Later: I wasn't convinced that the device actually went into production, because I couldn't find it in later advertisements for Oldham batteries. But Exide had a more stylish variant which was definitely advertised and sold:
¶ 2:49 PM 
NEAT GADGET!
The picture is clear but the description isn't. The crescent thing is pivoted at left, and it has a glass-enclosed air bubble at the lower end. When the specific gravity of the electrolyte is higher, the air bubble is more buoyant, so the crescent thing pivots upward and the air bubble covers HALF, then FULL. Similar to the syringe-like tester used with car batteries.
Later: I wasn't convinced that the device actually went into production, because I couldn't find it in later advertisements for Oldham batteries. But Exide had a more stylish variant which was definitely advertised and sold:
¶ 2:49 PM
