I had not been in the company of Mr. Webb for long before I discovered two facts. The first that he is an enthusiastic member of the Camping Club, and the second that he is an electronics wizard. Finding that I knew just a little about this, out poured a stream of technical information and I soon had to cry "Halt" for I was Out of my depth. So he showed me his little black box of magic. Small as a match box. Yet inside is almost a brain.

Almost all our members use a motorcar to take them camping and will know of the importance of the battery. Also how much it costs to replace! So it is well worth looking after. Obviously one keeps the electrolyte topped up but it is most important to maintain the battery fully charged. Even half charge is not so good for a modern battery and discharges spells disaster.

Driving at a reasonable speed keeps the battery charged, though not so well at night. But crawling along as town dwellers so often do, is not so good. You must be going at a reason­able speed before the dynamo starts to charge at all, though an alternator starts earlier. So the prudent motorist has a battery charger in his garage. But this raises another problem. How long to charge? If you are about all the time you can test the battery electrolyte. It's specific gravity will tell you the state of charge. A convenient time is at night. But over charging is almost as bad as under charging.

Mr. Webb has solved this problem for us. With his black box in the circuit all the thinking is done for you. For test purposes I took into the workshop a well charged battery from my caravan and one that had been lying, uncared for, for several years, in a corner of my garage. First we put the good battery on charge and watched on oscillograph and ammeter the operation of the unit. For a few moments the maximum output of the battery charger passed, but the internal battery losses were soon made good, the current began to fall and eventually practically ceased. The battery could stay connected thus indefinitely and no harm done.

It was a different matter when we connected the old battery. Full amperage straight away and a couple of hours later it was still flowing. I took it out to my garage and left it on charge. The next day it was still going full tilt and the black box was quite warm. This is quite in order; the internal design conducts the heat away from sensitive transistors. A day later the box was cold and my meter said that only a trickle of current was passing. Even this old battery was nearly fully charged. This warming up of the box is of no consequence and it will give you an indication as to how the charge is going, if you have no meter. For anyone with a battery charger and particularly if you are one of the growing number of caravanners with a second battery, I can recommend this unit. I have fitted one permanently into my charger.