Recharging our batteries

The local bicycle shop was an important part of my life as I became interested in all things electronic and electrical and especially radio. In common with many other young lads, I would join a procession of other young lads as we all swung our accumulators about like so many handbags as we descended on the bike shop to get the wet batteries recharged.

For these batteries, a modern version of the original Leyden Jar, were vital not only to us dabblers but to the huge number of battery-powered family radios that were far more common than those that worked off the mains. These accumulators, although expensive initially, were far cheaper to run to power the valve filaments. Dry batteries did not have the current capacity to power the valves long term. On the other hand, the accumulators were capable of providing  2 V at up to 2 A continuously and ensured that the rather inefficient valves of the day had enough emission to provide a reasonable volume of sound for the listener.

The accumulators were about 23 cm tall by 5 cm square and made of thick, acid-resisting glass. Sometimes a hydrometer was fitted so that the owner could see the state of charge. On the top were two heavy-duty terminals, red and black with a bleeder valve in the middle. For its size it was quite heavy, so to make it portable a strong wire handle that could be laid flat against the glass was let into the neck. In fact, it was a miniature car battery.

Because these wet cells usually had to visit a bicycle shop weekly, most households had at least two of them as the charging took several hours and was seldom completed the same day of delivery.

Meanwhile, by comparison, the high-tension battery made up of 1.5 V dry cells wired together in a slab, whose output was 120 V, lasted many weeks or months, which was just as well because they were not cheap to replace.

But then there was a third power source needed. Simply called a grid bias battery, it was much smaller than the HT one and again it was a composite of small 1.5 V cells to make up a nominal 9 V.  However, it was tapped at 4.5 and 7.5 V to suit the grid requirements of different valves that in those days were almost all directly heated.

The accumulators would not, of course, be sealed, otherwise there would be no escape route for the hydrogen gas generated. And the sulfuric acid, although diluted, was still corrosive - enough to play havoc with the French polished surface on which most of the radios sat. Usually there was no room inside the cabinet for any of the batteries so they had to sit outside, usually behind and out of sight.

At the time it seemed quite normal to take a discharged accumulator to a bicycle shop for treatment. But on reflection, why a bike shop and not an electrical or radio shop? In those days the only batteries sold by bicycle shops were the dry batteries for the front and rear lights of the heavy iron steeds. Maybe it was just free enterprise at its best, but even that came to an end with the advent of cheaper mains-powered radios and their widespread adoption - free of the tedious batteries.

For those who persisted with battery-operated equipment, there came the ‘battery eliminator’ but that is another story.