new hamfest finds

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Sun Jun 6 12:26:39 2004

>
> I just looked at my battery aggain and sure enough it has the three
> columns in the back of it with the balls inside. I didn't notice that
> before. I don't think I've ever seen a battery with them built in. Usually
> we used a Hydrometer to suck out part of the electrolyte and test it. It's

This is, of course, a built-in hydrometer.

> a large syringe with a clear plastic or glass tube in it and has 3, 5 or 7
> balls inside the tube. The ratio of sulphuric acid to water in the

The battery-testing hydrometers we use in the UK have a special float
with a calibrated stem. The height it floats at depends on the density of
the electrolyte. It's normally housed in a glass tube with a rubber bulb
on the end to suck up some of the elctrolyte...

> electrolyte changes depending on the state of charge of the battery. As the
> acid/water ratio changes the specific gravilty of the solution also
> changes. The different balls in the hydrometer have different specific
> gravities so more of them will float when the charge is higher and there is
> more acid in the solution. Most LA batteries sold in this country in the
> past 25 years are now sealed and are SUPPOSED to be maintenance free so

And if you believe that you believe anything :-). Car batteries still
seem to benefit from being topped up with distilled water from time to
time...

> very few people know how to check one any more.

-tony
Received on Sun Jun 06 2004 - 12:26:39 BST