A Faulty "B" Battery

Radio Record, Volume VI, Issue 37, 24 March 1933, Unnumbered Page

A Faulty "B" Battery

Useful Test Method CORRESPONDENT, "Sparks," writes: "One of my ‘RB’ batteries gave trouble recently, and while testing it I struck a method which actuaily enubles one to see when a battery is noisy. Here is what oceurred. I used three super batteries in series, with tappings for various yolltages. Quite suddenly the set became extraordinarily noisy, and I naturally suspected the ‘RB’ batteries. The units were tested out separately with a good volimeter, and ali were found well up. It seemed that therefore there was a loose or dirty. connection somewhere, but investigation proved there wasn’t. "hhe grid battery and accumulator wey: next suspected,’ but substitution «f both still left the noises just as bad ss ever, "YT resolved therefore to make another examintion of the ‘B’ battery. Taking the units one by one I rigged up a suitable resistance in series with a milliameter and connected them across the extreme terminals, The current passing was 10 mils, which is what, the set-an ‘Outspan Four’ -- normally consumes, At this load the milliameter gave no indication of any currelt fluctuation. It then oceurred to me to increase the load a little by reducing the resistance, and by using a potentiometer as a rheostat I was able to-do this gradually. Two out of the three units showed no fluctuation when the current was increased to 2U mils, and one part of the third unit was also, blameless. "When, however, I came to another portion of it, I found the needle remained motionless as long as the current did not exceed 10 mils, but when the resistance was reduced a little, it began to vibrate rapidly, and the trouble was at last tracked down. The fluctuations were evidently there when the battery was on 10 mils drain, but they were so small or so rapid that they did not cause a visible moyemeut of-the needle,"