[VAC] Re: Batteries and Converters

[Dr. Gerald N. Johnson, electrical engineer]

Univolt and automotive regulators of the 50s and 60s were abusive to
batteries. They were allowed to hold the charging voltage between 12 and
16 volts. If one was lucky to have on that was 13.5 to 14.2 volts,
battery life was good, of not battery life was bad. Today with solid
state regulators, battery life can be drastically increased. There have
also been improvements in battery design replacing antimony in the lead
alloy with calcium for much lower local self discharging action. At the
same time this monumental change in battery construction has made
batteries structurally weaker and far less tolerant of overcharging that
was typical with the voltage regulators of the old era and with Univolt.

Back about 1969, I changed an engine in my VW beetle, installing a 12
volt engine (generator NOT interchangeable with the 6 volt engine I took
out). So I built a transistorized voltage regulator of my own design
that even was slightly temperature compensated. The next battery lasted
3 times its two year guarantee because it was fully charged but not over
charged. I already had both voltmeter and ammeter in the bug and found
that the factory regulator tried to charge that 6 volt battery to 7.5
volts at high engine speeds which required far more than regular
additions of water. And the fumes tended to eat the seat and floor under
the battery.

What was satisfactory in 1958 is not satisfactory now when far better
battery charging apparatus such as that made by Statpower is available.

If one insists on using the Univolt, one should use the cheapest
batteries off the Walmart rack and expect only a year or two life,
planning to replace them regularly and accept occasional failures in the
field.

Gerald



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