"Service Engineering" Cell Voltmeter?

[Vintage Veloce]

Found this thing at a vintage meet Saturday:
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I'me guessing it is a tester for individual battery cells? Seems to indicate "good" at around 1.5V.
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But the brass bezel ring has "1", "2" and "3" Volt markings?

Cool logo on the back:
View media item 76576Probably from the late 1930s or 1940s? I'm guessing from the car in the logo.

I also note the wire had been replaced, and should be black or green as it is the negative terminal.

 

[Vintage Veloce]

I guess my question... is what is this "apparently 3V" battery tester for?

 

[humber2]

I'm thinking it had a cadmium electrode to do acid to terminal post checking on lead acid batteries. The high readings were for a battery on charge measuring post to post.

A better test than just using a hydrometer but rendered all but impossible to do with the way automobile batteries are built nowadays.

 

[Roberts210]

In the old days you could check each cell of a car battery.

 

[theoldwizard1]

I'm thinking it had a cadmium electrode to do acid to terminal post checking on lead acid batteries. The high readings were for a battery on charge measuring post to post.

"Back in the day" (almost 50 years ago) I worked in the Sears garage. One of my jobs was testing/installing batteries. (First really cold snap we would have 30-40 cars line up to buy a DieHard !) If requested, we would do a free in vehicle charging system test using a Sun VAT 26 or 33 (sure wish I could find a working one for a reasonable price today !)

We also had a LARGE bench top charger/tester that had a voltmeter attached to cadmium probes. You would give that battery a 5 minute high current charge (after making sure it was full of water) and then test cell-to-cell. Much faster than a hydrometer which had a life span of less than one shift before they got broken.

I sure wish I could find cadmium probes !

 

[theoldwizard1]

In the old days you could check each cell of a car battery.

You still can ! Most (all?) "maintenance free" batteries actually have caps that can be removed with a screwdriver. Snap off, snap back on.